Back in the rotary game! Time to make this S5 battle ready and rock solid
 

I've been quiet for a while. Probably a little over a year ago I sold my "S3" project car (a beat to hell GSL-SE) to a friend who is a little bit more talented than me. This past July, I wrecked my 1987 Porsche 944S, and left for school a couple months later. I still have half the 944 back home (in Portland, OR), but school is in Lima, OH, which left me without a project.

A couple months ago I decided I wanted pick up a project car. I was initially looking at 944s, but I didn't really want to deal with all the BS that comes with owning one. Don't get me wrong, I'll own many more of them, but for right now, given my budget and amount of space, I needed something a little bit more modular and easy to deal with.

On a whim, I decided to scour Craigslist for RX-7s. My friend (the same one who I sold the S3 to) had owned a couple FCs over the years, and I'd grown to like them. Especially the S5 cars.

Sure enough, a black S5 popped up south of Cleveland that caught my eye.

It was advertised as having "coil overs", "a 6 speed transmission" and "a new clutch" which I thought seemed kind of cool. Even without those things it seemed worth the price.

...Which is a good thing.

I sort of saw it coming, since this appeared to be a seller younger than myself, who's dad desperately wanted for him to get rid of this basket case.

Heres what I ended up with:

1989 S5 RX7 "GXL" - Brilliant Black

I soon found the proverbial "coil overs" and "6 speed transmission" were nothing more than wasted Koni Yellows, cut rear springs, front lowering springs and a good condition, but misleading 6-speed shift knob from an RX-8. As for the clutch, I'll have to pull it apart one of these days and have a look. It doesn't feel stock, but it also feels like the flywheel is badly warped. Updates to come on that.

What I did get, however is some GXL goodies: Big brakes up front, potentially upgraded differential and the 3 port 15:1 steering rack. The exterior is largely clean. Some dents here and there, but nothing major. The underbody is largely rust free. The electrical features all seem to work (which is awesome) and the chassis has relatively low miles on it at 119,000.

The PO said something about the engine having been gone through at some point. At this point I'm not sure I believe him, but things under the hood (minus wiring, which I'll speak more on later) look decent. Theres also no evidence (yet) of engine internals going bad or seal failure. The engine also has a racing beat streetable header on it, which makes me happy.

One interesting fact is that the car had the OMP deleted at some point in favor of running a premix. It seems to me that someone wanted to make this a fun car at some point but chose to neglect a lot of little (and some big) things.

What I found is that the under hood of this thing is a wiring nightmare. Lots of oily electrical tape, way too many wire nuts and a lot of general loose ends to be tied.

I also have been having a hard time getting this thing to run right, which I believe to be a combination of electrical and fuel system problems. I may make a separate post on that all together.

Heres some pics of the car:

https://cimg3.ibsrv.net/gimg/www.rx7...eeb2499cf7.jpg

https://cimg3.ibsrv.net/gimg/www.rx7...610806300d.jpg

If any of you Ohio guys know anything about the car, definitely post up here or shoot me a PM. The more I know, the better.

On to the fun stuff. The tentative upgrade/improvement list includes, but is not limited to:
-More comfortable race buckets that accommodate my 6'3" (skinny) build
-Crank windows
-Racing beat universal pre silencer and muffler to replace the obnoxious glass pack and generic fart can combo. I'll be opting for a larger diameter single exhaust to save weight
-Bilstien B6 HD strut inserts up front with matching rear shocks
-Ground Control coil over sleeves with Eibach springs, rates TBD
-Ground Control camber/caster plates
-Ground Control rear camber adjusters
-Bushing overhaul (unsure what I want to do with the passive rear steer)
-Possible steering rack de-power, not sure if I want to use the 15:1 rack or not
-16x8 summer wheels and tires. Most likely 225/50 up front and 245/45 in the rear. I'll run 245s at all 4 corners if they'll fit with the coil overs
-Possible fuel system overhaul with aftermarket rails in order to run remote after market pressure regulator and gauge
-Build some better oil cooler lines
-Quick release hub for my Momo Mod 7 wheel (especially depending on what seat I end up with)
-Rotary shack short shifter w/delrin knob
-Rear wiper delete
-Possible different clutch depending on what I find in there now
-Possible underhood wiring harness pull and repair operation depending on how OCD I get
-Fix all the shift boots
-Possible battery relocation to the rear of the car

The engine I plan to leave largely untouched for now, provided I can get it to run right. May opt for an RTEK-7 chip so the OMP isn't dangling in the engine bay anymore.

That list isn't in any type of order, but most of it I'd like to get done around the time the snow starts to melt after this winter.

My overall goal is to build this car to be basically as good as my 944 was. It just so happens that the 944 had a very similar suspension recipe, but utilized Koni Sport shocks instead. I plan to have quite a bit of fun setting up a grippy and sporty suspension in this car. Its probably my favorite thing to mess with. I'll also have this thing on a strict diet. I'm hoping to make it pretty light weight in lieu of upped power.

Hopefully this won't be too crazy of a journey. I'm attending a technical school at the moment, so lift, welding, alignment, and other tech access is all provided for me. Just a matter of staying organized and getting it all done right the first time.

Stay tuned for a detailed post on the car's current running issues. In short it has a nasty misfire under throttle and runs so rich that I have to induce a vacuum leak just to get it to idle, but there are lots of other ins and outs. More to come. Currently targeting a bad fuel pressure regulator or a stuck injector. We shall see.

Thats all I've got for now. Peace.

Alright, its time to dive into whatever is making this thing run like crap. I think what I'll do is write up a series of events for my own reconciliation, and if any of y'all have some helpful hints and/or ideas for me, feel free to voice them.

*wall of text below*

Couple months ago I went to pick up the car. It started and ran just as expected, but with a slightly high idle.

I drove the car home (roughly 2.5 hours) with no drama whatsoever. No check engine lights, no misfiring, nothing.

Once it was home, I'd occasionally take it for a spin around campus. I noticed that when I'd blip the throttle not under load, sometimes the check engine light would flash on with said throttle input, but go away as soon as my foot was off the throttle.

I noticed that I had lots of vacuum leaks. A PO had done an air pump delete, and subsequently there were a lot of vacuum nipples that were to be plugged, but most of the rubber caps had disintegrated. Half of them just had electrical tape wrapped around them (wtf?).

I got all new vacuum nipples and stopped all the leaks, but then, once the car starts reaching operating temperatures, it doesn't want to idle. It'll try and stay at ~750 RPMs, but the idle would hunt and bog. Normally if I let it sit for long enough doing this, the car would just die after the cycle had repeated several times. Otherwise, startup, high idle, mid idle and coming down to regular idle seemed to work fine.

This tells me that the motor is running pig rich, and the computer is unable to dial back the fuel to its "warmed up" map. So I start looking for causes.

Noticed that the O2 sensor wire had been resting on the header for some period of time. sure enough it had melted through the sheathing and worn down the wire a little bit. I replaced the wire to see if it made a difference. None.

Heres where things got interesting (and probably where I screwed it up): I noticed some kind of actuator resting in-between the passenger front brake line and the frame rail. Unplugged it to pull it and see what it was. Determined it was the OMP, but over looked the fact that when you unplug them the car goes into limp mode. The three wire connector that is secured by two philips head screws is slightly cracked & the screws are stripped, so I cut the wires to remove it (because I'm dumb and didn't notice there was a connector near the alternator for it).

Tried starting the car, unknowing that it would go into limp mode. Car ran like absolute sh*t & check engine light went on, did some googling and found out about the electric OMPs.

Decided to pull the ECU to see if it had any weird stuff going on with board connections. Found that a resistor (unknown value) had gotten quite hot, but the solders looked in tact. Also found that the base of a transistor had also gotten hot but the connection remained there. As to whether the circuit is still functional...no clue. A later resort will be sending out the ECU for testing if the car still isn't behaving. Heres a picture of the back of the board showing the burnt contacts:

https://cimg7.ibsrv.net/gimg/www.rx7...57138c3fd6.jpg

Re-connected OMP and wires, fired car up. Still ran rough on start up, but a couple revs after it warmed up and it started to smooth out. A quick drive and the check engine light went off. Rough start and smoothing out happened consistently.

I opened up a vacuum leak just so it would actually idle and not die. Not sure if this is contributing to check engine light.

At idle during warm up, the check engine light was doing weird stuff. It would flash both quickly and slowly. I tried to get a pattern out of it, but it seemed to be pretty random. Sometimes it would just stay on. I took a video of what it was doing in conjunction with a sort of whacky idle:

https://youtu.be/f61QxCA8sQM

The car ran consistently like this. I drove it to class a couple times with no issues, but sometimes on cold start up, you could tell it wanted high idle, but would end up with a really nasty idle lope right around 1500 RPMs. Once the high idle cycle finished, it would smooth out at 1500, then eventually drop down to its "normal" high idle with a vacuum leak.

Went out last weekend to fire it up. Struggled to high idle, but got there. Smoothed out and came down to "normal" high idle, only now, when I gave it any type of throttle input it would develop a nasty misfire. Under load the car will just buck and pop/backfire. Not under load, it will pop/backfire, and also cannot be held at any steady RPM.

I haven't touched the car since the weekend. The symptoms it most recently exhibited are very similar to those it exhibited when it went into limp mode earlier with the OMP debacle. I'm suspect of a butt connector having come loose on one of those three wires I cut since I'm an idiot...:icon_no2:

The car is obviously running VERY rich. At this point I'm unsure of wither its an electrical issue, or a mechanical fuel system issue.

Im suspecting perhaps a bad FPR, a stuck open injector, OR those burnt up spots in the ECU aren't from me, and are causing fueling issue.

I'm fairly sure the sporadic running condition has something to do with my disconnecting & re-connecting of the OMP.

Despite seeming to run so rich, I've yet to have a flooding issue with the car, which seems weird, so it may be wise to dig further into anything that helps regulate idle. The BAC and all associated vacuum hardware seem to be intact. I think my first steps will be to pull the plugs and closely inspect them (and likely replace them), then pull the injectors and have them tested/cleaned.

I may also take a video of the the misfire under throttle if shoddy wiring isn't the cause. I'll edit this post and bump the thread if thats the case.

s5's are not really my bag, but I know that if the OMP malfunctions, chances are high the it also fries the ECU and makes the car do some WEIRD things

see if you can pull any codes and see what they tell you, also, another thing that makes them run crappy at warm idle is the thermo sensor behind the waterpump, its good you fixed the o2 sensor, but the o2 sensor does MINIMAL on how our engines run

also, TRIPLE check that you have no vacuum leaks, vacuum leaks can be a pain to find

another thing, since you recently bought the car, compression check it, that will at least give you an idea on engine health.

and give it a FULL tune-up, nitpick it, all new fluids, maybe even replace all the vacuum lines and intake gaskets to be on the safe side

Forgot to mention that i did indeed change the thermoswitch in the back of the water pump housing. I did think at first that perhaps there was a dead spot in the thermistor and it wasn't telling the ecu to give the motor the "warmed up" map. Of course to no avail...

I'll do a full tune up soon and see if that will yield results. My fear at the moment is that I did indeed fry the ECU. Given the symptoms, that seems most likely. Updates to come!

I had been watching this car good to see that some one picked it up!

Yep, unfortunately it is more a basket case than I expected, but honestly it's no worse than some of the times I had with the 944. Getting it running and operating correctly is shaping up to be a bit of a chore but I know it'll pay off. Once it's looking solid I'll start getting to re build the suspension which I'm REALLY excited about.

So, quick update as of today:

I have not gotten out to pull the plugs and see how things are looking (I'll replace them soon but I'm hoping they have some information hidden behind them). What I did do however is go blast over to Columbus to snag some wheels I stumbled upon last night.

They're some 16x7 Ford/Lincoln/Mercury speed line 390s. These ones are the single lip (et25?) ones. From what I've heard, these ones are only found on Lincoln MKVIIs, which makes them a little more tricky to get a hold of.

I wanted the single lips for up front just to avoid fitment issues with bigger tires. I plan to find a pair of the double lips (et6 or et0?) for the rear since there will be no issues back there. Unfortunately this means things will end up a little different from the original plan to try and fit 245 rubber, but with how good tire technology has gotten, the light weight of these cars and inherently less spun weight with this combo, a good 225/50 tire will be more than enough for my purpose.

Originally I wanted to hunt down some early 90's Pontiac GTP wheels since they're 16x8s but they're so low volume that they're just too damn hard to find. You take what you can get. Any cool mesh wheel is a win in my book.

Anyway, here they are:

Attachment 569010

I'll clean them up at some point. Planning to do polished lips with gold painted centers and likewise for the rears whenever I get a hold of some. Fun stuff!

I'll go mess around with some wiring and the spark plugs tomorrow. Peace.

Update as of today:

As I expected, my shoddy wiring (butt connectors) were the cause of my car not wanting to rev at all. The visual inspection checked out, but as soon I started pulling on stuff a wire popped out of its butt connector. I re-crimped everything, fired her up and voila!!!

As an experiment, I drove over to school to meet up with some people. It ran great on the way over. I turned it off, hung out for a bit, went to fire it back up and the check engine light came on. Once again it didn't want to rev, but it ended up all the sudden smoothing out and idling at 1500 RPMs after a couple blips on the throttle. Fortunately I was lucky enough to catch it on video! Check it out:



I also completely forgot to pull plugs and have a look, but it is back to running well (not perfect) with one vacuum leak to ensure the car won't just die while idling. Power band seems relatively smooth. I'm happy.

It definitely is running rich. I know rotaries smell (especially catless) but it is BAD! So, sooner or later I'm going to at least get a stethoscope and listen to make sure all the injectors are clicking. If that doesn't work I'll pull them and see if they click with voltage. If they check out, I'll probably send them out to be cleaned and flow tested. Next after that is the FPR...which I don't really want to deal with.

Full tune up supplies will be the next thing bought. That needs to be gotten out of the way for sure.

Updates to come!!!

Alright, quick update as of today:

The car has been running good! I've been driving it around town just for fun and to try and get a better idea of whats been going on.

One thing that has become consistent, though, is an odd "high idle". It does this every time the cars been started after its sat for a while. The colder the ambient temp, the longer it sits there and lopes before things smooth out. Made a video so ya'll could check it out:



Plugs might come out later today if I have time. If not, it'll happen tomorrow.

Another not so notable update:

FINALLY, after much holiday and school craziness, I started messing with things under the hood of the 7 again.

First order of business: Pulled the plugs to have a look.

Upon disassembly it appeared that everything was installed correctly. The plugs themselves didn't look out of the ordinary. Some definite carbon build up, but none of them were soaked with fuel, and all of them were pretty uniform in appearance. Check it out:

R1, T, L

https://cimg9.ibsrv.net/gimg/www.rx7...1b4bc19004.jpg

R2, T, L

https://cimg5.ibsrv.net/gimg/www.rx7...1e3776e752.jpg

I'll be ordering some new ones as well as some new NGK wires soon. Doubt they'll make any difference, but its always good to rule these things out.


Second order of business: What the MOTHER-LOVING F*** is going on with this idle problem!?!

So...I got curious and started messing with stuff.

See, heres the thing with problems like this...I'm am not skilled enough, nor armed with all the resources to efficiently spend an afternoon figuring out whats going on. I also don't have enough money to start throwing parts at this type of thing hoping something will eventually work. Add to that all the discrepancies between the S4 and S5 cars, which makes the googling/forum searching even more challenging.

Ok, ok...enough with the excuses. I'm doing what the son of a data-scientist should do - collect some data!

Using this information, feel free to point me in a direction. Otherwise this will be for my own personal reconciliation purposes:

-From the jump, I've had ZERO issues with flooding. NONE. This makes me re-think my rich running/stuck injector assumptions.
-In the beginning, the 3k RPM high idle was functional
-Calibrated the TPS, but did so off of Ohm readings, which of course, are without power to the system. The ECU actually gets a voltage reading, so I've heard the connectors should really be back probed and calibrated that way.
-Seems after I started messing with the TPS the high idle stopped being functional.
-From the jump, the car WOULD NOT idle WITHOUT vacuum leaks induced.
-Car smells like its running rich, BUT it is a rotary, and is currently without a cat.
-Temp sensor replaced in water pump housing.
-After OMP disconnection episode, things are back to normal (or at least how they were when I bought the car), minus the high idle, which was already an issue before the OMP.
-All evidence says either the burnt spot on the ECU either wasn't from me, or has no real effect on the car, so thats on the back burner for now.
-There hasn't been any check engine light action at idle for quite a while now.
-Check engine light seems to be correlated to certain types of throttle input, usually rapid, and isn't always consistent. Sometimes I see it, sometimes I don't.
-Idle adjustment screw atop the intake manifold is all the way counter-clockwise, which makes it idle the highest.

With all this data collected, I had my eye on a couple things under the engine bay.

I decided to crank the idle screw a ways clockwise while there was a vacuum leak to see if it would come down from ~1400RPM, to a normal RPM. It did. Then I noticed another adjustment that I'd previously overlooked...

Theres a small flathead screw with an 8mm lock nut on it, which when turned, effectively changes the position of the entire throttle blade. I noticed that mine was extended down almost all the way clockwise, which I'm assuming actually is causing the throttle body to be slightly cracked "open". This assumption was somewhat validated by playing around with it. I could plug all my vacuum leaks and actually get it to idle, mimicking very slight throttle input. Whats important is that it also changed where the TPS positions were.

So riddle me this; why on earth would you want your entire throttle body ever so slightly cracked? In all my car experience, I've always assumed you'd just let your idle control system do what tis supposed to do, which is bypass the closed throttle body. Of course in this case, there is also the idle screw up top, which from my understanding, only effects one part of the throttle blade assembly...and is purely for speed purposes, not idle quality.

This kind of leads me to another conclusion and presumable plan of action:

I don't think that TPS is correctly adjusted. The throttle body has been cracked open this whole time, which makes me think back to when I was messing with the Ohm reading...I believe one end of the interval for wide range was hard to reach. I can't help but wonder if the fuel ratio/delivery is FUBAR'd, but not to the point where its causing flooding issues.

Whats more weird is that you'd think the TPS being roughly calibrated for idle, but the mechanical pieces being set in a 1500RPM idle position, it'd have a lean condition...which doesn't explain why opening up a vacuum leak makes it actually idle where it should. Could be I'm not thinking deep enough into this, OR the voltage specs that the computer wants are somehow getting distorted somewhere due to excess or not enough resistance on the way back to the computer.

Now that I've stewed on this for a while, I'm planning to go out tomorrow and do an actual voltage test on the TPS ranges with the throttle body in full CLOSED position. I see no reason for it to be open like it is.

I came across specs for the voltage test a while back, so I'll try and dig those up. I'm assuming the ECU runs a 5V system, so it shouldn't be anything too complicated. It could very well be that if one end of either the narrow or wide range sensor is slightly out of resistance spec, the ECU might be getting a wonky voltage reading and fueling it rich. We shall see.

Updates to come.

Quick add on to original update:

Found the FSM TPS adjustment info I was looking for. Check it out:

So check this out, resistance goes from low to high as the throttle goes from closed to open. It seems entirely probable that for whatever reason the ECU is getting too little voltage at idle due to either excess resistance somewhere else, OR just straight up maladjustment of the TPS in relation to where the TB is actually supposed to be. This is getting interesting.

OK! Went out today and did some testing.

First things first, not entirely related, but does it look like I'm missing something here?

https://cimg9.ibsrv.net/gimg/www.rx7...150a6ca738.jpg

I'm all for deletes and making things simple, but holy hell! This car doesn't have much left under this hood! Making it pretty hard to piece things back together.

Anyway... I did about 3 hours of testing, adjusting, testing, adjusting and more testing.

Heres what I've concluded: On the calibration of the TPS, it is necessary for both full and narrow range to be within spec. On my car, it seemed that only one could be calibrated at spec, but the other would not. HOWEVER, this was determined to be the case based on voltage taken from pins 2G and 2F back probed at the ECU harness. It just so happens though, that the resistances at the sensors can both be calibrated within spec. This seemed odd to me. In the end, with the full an narrow range sensors both at a point where they were in spec, it appeared that the voltage for the full range was coming up about .3 volts short at idle/closed throttle, which I think is my problem. I tested the resistance of the wire that goes from the connector to the pin in the ECU (black with green stripe) and found a whole 1 Ohm or resistance. I doubt that length of wire is much more than 4ft. I happened to have a 5ft long length of 18gauge wire laying around, so I took the resistance of that for comparison, and found .5 Ohms.

Looks to me like I have a voltage drop somewhere along the line...likely in the neighborhood of .3V. What I'm going to do is get out my ECU pinout for this car and make sure that wire doesn't have any splices on its way down to the ECU. If not, I'll probably put a jumper in there and see if I get results.

Whats also interesting is that the Voltage spec for wide range at WOT is 4.3V and I'm getting about 4.1V. Not a huge difference, but I'd bet its due to the same thing.

I realize I left out some other testing points I probably should have covered, but it was getting cold and I'd found basically everything I was looking for in terms of electrical discrepancies. When I have time, I'll go back out try a couple more things and hopefully have this thing running worth a crap. Then its time for a new clutch!!!

You are indeed missing stuff on your throttle body. Somewhere along the line, a previous owner must have done the infamous throttle body mod.

Figured...Ugh...

Well, an update as of tonight:

Thanks to my bud Casey, I got cleared up on exactly how to pull diagnostic codes off this OBD1 system. Cool stuff for sure! Not a luxury I've had on any previous cars. Anyway, this is codes cleared, TPS narrow voltage set in spec, both narrow and full sensor resistance in spec, but full range voltage falling short at ~.5V.

Right before I made this video I cleared all codes by disconnecting the battery for half a minute, then reconnected everything, fired it up and let things warm up a bit. Gave it a rev or two and shut her down.

Car sort of ran a warm up idle, came down and then idled at about 200-400 RPMs. Didn't sound or feel smooth. A couple brief revs were also not the smoothest but largely fluid. As usual the check engine light flashed briefly when the car was revved rapidly.

After I shut it down, this is a video of the codes it displayed. I let it cycle twice just to be sure I got everything:



From the looks of it, the computer is throwing the following codes:

13 - Pressure Sensor (intake manifold pressure) - Fixed at 29.9 inHg
20 - Metering Oil Pump (MOP) position sensor - Basic Fuel Inj and fixed timing
25 - Solenoid, Pressure Regulator Control
30 - Solenoid, Split Air Valve
31 - Solenoid, Relief Valve
32 - Solenoid, Switch Valve
33 - Solenoid, Port Air Valve
38 - Solenoid, Accelerated Warm-up System (AWS)
40 - Solenoid, Auxiliary Port (6PI) Valve
41 - Solenoid, Variable Dynamic Effect Intake (VDI)

Looks to me like the the PO pulling all the emissions AND auxiliary port stuff is causing the car to throw all kinds of codes, but whats interesting to me is the fact that MOP stuff is still causing issues. Looks like its still in a partial limp mode or some sort.

So looks like I have a vacuum leak, the shoddy MOP delete is still causing problems, and the port actuation deletes aren't making the computer happy.

I'm curious about 25, the pressure regulator control. I'm assuming its part of the air pressure kit for the auxiliary ports, but I'm wondering if theres an off chance it has something to do with the fuel pressure regulator. I don't think the vacuum line coming off it goes anywhere special, but I'll have to check.

Looks like it might be time to shell out for an RTEK7 chip so I can get rid of all the MOP bullshit for good. Yikes.

DAMN YOU POs! I tell ya, the way some people choose to go about "modifying" their cars astounds me.

Updates to come.

Sub'd. Got your hands full on this one. Shell looks pretty clean though.

Yep, it's reasonably clean. Everything is actually pretty clean, but naturally with some projects you have to clean up a lot of mistakes, which is the case here.

Small update:

ECU sent to get the RTEK7 chip put in. Not the best use of $140+shipping, but ya gotta do what ya gotta do. A consistent mostly stock running motor is what's I'm after so I can move on more exciting stuff.

Which brings me to my second part of the update...

Found the other two crown Vic wheels I need and ordered them for cheap off eBay. Those should roll in early next week. Pretty stoked on that find.

Hopefully my ECU tests out good and makes its way back to me before the weekend. Id like to get this thing running the way it should be.

A couple small observations...

I've been running an "infamously" modded throttle body on my daily driver for a few years now and while I noticed no performance improvement, I noticed no degradation either. Sometimes on snap decel she emits a little ladylike fart- not a real backfire- but that's about it. Not really sure what the purpose of the secondary throttles is supposed to be but deleting them didn't make any diff that I could feel.
I dislike being "that guy" but man, that is one nasty ass throttle body. All that corrosion...yuk. I'd strip it down and at least make sure the adjustment screws aren't frozen and the linkage is free and smooth.



If you all-weather drive your car, I'd seriously consider keeping the rear wiper and making it functional. The big, relatively flat rear glass is a snow magnet and without the wiper, rear visibility is awful.

A couple years ago I gleefully swapped the drivetrain from my GXL into a much nicer GTU chassis, losing the sunroof (which I never used) and all the power stuff in the process.
I miss the power windows/locks...didn't think I would, but there you have it. My Z interior is so narrow that reaching across to wind down the passenger window is no big deal but the FC ain't so easy. I had grown weary of fixing the window switches and thought the manual window reliability would be a fair trade off but now I'd just keep the power and relay the system...if I had the option.

I didn't necessarily want to pass judgement on the TB mod, but I guess I did purely with my word choice. I wouldn't argue for or against it either way.

If thats the case I probably won't go through the trouble of re-creating what once was.

It looks far worse than it is. All the adjustment screws are buttery smooth and there doesn't seem to be any corrosion inhibiting any of the movements or linkages. I agree, it looks awful, but unfortunately its looking like I have bigger fish to fry.



I was just thinking about this! I almost want to keep it simply because the motor and controls work. The downside is that some idiot took the physical wiper arm off, so I'd have to hunt one of those down.

My other thought is that this thing probably won't see snow...or at least won't get driven around in it regularly. As far as rain...my 944 had an even more flat hatch and never had a wiper. Never had a problem with it. Rained 8-9 months out of the year in Portland too. I'll put some thought into this one...you bring up some good points.

I'll have to do a reach test and see if my long ass arms could handle crank windows. Power locks I'll probably keep, its a nice feature to have.

Heres my vice with the windows: You know how you pull up on the switches too hard and they break off? Both the driver side switches are gone (were that way when I bought it). So I either have to go through the hassle of finding a good switch panel from a parts car, find an MPV and jury-rig those switches into my door PLUS do relays either way. OR I could find some manual units and swap em on in. You do have a good point though, and I DO like my power windows.

One of the goals of this build is to make the car light weight. I know I won't have the means to make power out of this thing for quite a while, so the sure fire fix for that is to take weight away. Already I've ditched the AC setup and entire stereo system. I'll have to drive it some more, but I'm actually leaning towards keeping the power steering. I'm SO impressed with how the 15:1 rack feels. Doesn't seem like a numb 80's/90's system at all. Once the car can handle half decent I'll take it out on some back roads and see what its really all about.

I'll have to get this thing on some scales soon and see where its at. My 944 weighed in at 2910 with no spare and a quarter tank. This thing already feels faster with at least 30 less HP so I'm guessing it started its life much lighter than the 944 did. Very exciting :ylsuper:

My friend who knows way too much about cars told me that, although the 944 and RX7 are similar cars, the RX7 is a much better value because it will probably have less mechanical/electrical problems and therefore cost less. You might have said something about your experience with that but I trust that that's true.

Anyways, welcome to the FC game! Have fun with your build and keep on updating!

I would disagree.
FC's have numerous well documented electrical flaws (looking at you, switchgear) and engine issues can be much worse with rotaries since you can't really refurb them...if a housing is scored, you can't bore it out, you need a new one.

I haven't a lot of experience with German cars but I've heard that parts can be rather spendy, which might tip the scales a bit in the FC's favor but I can't really say.

I think many people (and I'm not necessarily referring to the OP) half ass their "new" cars from the beginning and then spend years chasing faults down the line.
Brakes for instance...one of the first things I do with a car is redo the entire system.
Rebuild calipers, new pads, skim/replace rotors, new hoses and new MC.
All new and as long as the car is regularly driven, the system should be trouble free for years with normal maintenance.
Same with the cooling...new thermostat and rad cap, new hoses, new waterpump, new belt(s), remove rad and at least clean, maybe replace and evaluate the fan system (like, is the thermoclutch even working?).

Not only does this scorched earth approach set you up for a more trouble free future, it also gets you up close and personal with all four corners of the chassis and into the engine bay (without a major commitment). You get a much more thorough idea of the condition of the car, like is the hardware all frozen/corroded, what does the suspension look like, etc.

Depending on one's experience and tooling (none of the above requires anything exotic), this is a one or two weekend job and not very expensive (at least for the FC, a Porsche could be more...) and will save countless headaches down the road.

Well having been in both, I can't say definitively which is better. What I've decided, though, is that what I didn't really like about the 944 is vastly improved with the RX-7. For instance, the 7 seems to have a pretty reliable power steering system, which is something thats always given 944 owners a headache since the dawn of time. Another thing is how all the weatherstripping/doors & hatch are designed. The 944 is just designed shitty in those aspects...once things start leaking its really hard and expensive to fix.

What I've said to a lot of people that ask for a comparison, is that the 944 is a brilliant car, but is kinda stuck in the 80's. The RX-7 on the other hand has some definite 90's colors showing, and because of it is much more pleasant to work with.

The thing that I'm not sure I'll get with the 7 is chassis rigidity and strength. The 944 was built STRONG. and since the trans is in the back, and theres a big ass torque tube that connects the engine and trans (which is why a clutch replacement is an 8 hour job) the tunnel is super tall. Probably around a foot or so. Everything is pretty beefy. Seems to me that the 7's chassis is not quite as rigid. No idea about strength.

God forbid it happens again, but my 944 ended up on its roof with me still in it. Nothing buckled or collapsed and I was able to get out with just a couple scratches. If the same can be said about the integrity of the FC I'll be pretty happy!

Indeed. And its all on the list I'll have you know.

I assure you there will be no half-assery here. Things will get done slow, and possibly in a weird order but it will all be thorough, no doubt. Doing major overhauls is also not as intimidating because, yes, it is WAY cheaper to do all this stuff.


Well, tomorrow my wheels and freshened up ECU come in, so I should have another actual update in a day or two. Yippie!

Ok! Update as of tonight:

Wheels came in! I now have a full set of Ford/Mercury/Lincoln mesh wheels! As promised, the fronts are the ET25 version and the rears are the ET6 version. Now I can run bigger tires (225/50) without having to worry too much about having to run excessive camber and/or extensive body modification. Will probably roll the fenders, but that should do it.

Check em out!

https://cimg0.ibsrv.net/gimg/www.rx7...18c8244801.jpg

Next order of business, the ECU! It also came in today! Chip installed by DTI, whatever testing they do checked out.

https://cimg1.ibsrv.net/gimg/www.rx7...66e55ffab1.jpg


So, popped it in and heres where we're at:

Car is quite smooth, under power seems good, no weird "2-step" revs. The only problem seems to be that the car still isn't happy at idle. I have to set the screw I mentioned earlier open so that the revs are around 1200-1400. Anything below that and the idle starts doing this:



I think at this point something is just screwed up with the BAC. I've heard rumor that that American spec BACs have an adjustment screw of some sort that allows some sort of fine tuning abilities. My FSM says nothing about that, but I'll go out and have a look tomorrow. I'll test the resistances and probably make sure it clicks with 12V too. I may just take it off and clean it or something. Seems to me thats whats causing the last of my issues.

Also, remember the scorched resistor and transistor I mentioned a ways back? Had another look really quick when I opened up the ECU and its on the path for pin 2N, which is something having to do with the auxiliary port up in the intake manifold. No idea if that would be related to anything with the BAC, but some of you veterans would know better than me.

The clutch is getting BAD. I'll probably buy all the parts for that overhaul a little after christmas. Until then the thread should be pretty quiet.

Make sure you're looking at the NA FSM where applicable. The TPS adjustment page you posted is for the turbo. Although similar, can lead to confusion.

Your idle speed is too low, it won't idle well below 750. FYI, it's idling between 500 and 800 in your video. And the Only S4 turbo BAC's have the idle speed adjustment on the BAC. Others are on the top of the throttle body.

Pin 2N is for the port air solenoid on the ACV. It's an emissions component that doesn't affect how the car runs.

I'm aware. I've been calibrating off my S5 NA FSM. That picture was just convenient to post. Specs are all the same there.

I'm aware that it is low. My question is why. That video was taken with the idle screw atop the manifold maxed out open. The small screw with the 8mm lock nut on it was backed out such that the throttle blades were all closed completely (I'm unsure how that one should be oriented, but I'd assume they should be closed).

However, I believe I found the answer to my question this afternoon. Two more data points:

-I don't believe the BAC was making its 120htz duty cycle sound. Its been said that you should here some sort of audible buzz coming the valve, correct?
-I unplugged it, and absolutely nothing changed. Which I'm hearing isn't a good sign.

Once it warms up a bit outside, probably Sunday, I'll go out and take it off to inspect. I'll give it 12V and ground and see what happens. I'm wondering if it is stuck closed, and if not, is running it unplugged the same as running a block off plate?

Good, won't worry about it then.

I'm pretty sure the throttle plates are NOT supposed to be fully closed and that's why your idle is so low.
The screw on top of the body (which you call the "idle screw") is an air bypass and it's simply not big enough to compensate for the flow you should have but don't.
See page F1-35 of the FSM.