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The story begins with a 1986 S4 N/A of the following:

Sitting for 3 years due to lack of funds. . . .She has a bad idle. .. .. .But she lives in CA where she must run good to pass smog. .. . .And she wants one last breath before she dies.
Not leaking water, pushing water or sucking water.
302k miles
Engine core and select parts rebuilt at 263k about 12 years ago. (who says they don't last)
Borla exhaust
Bonez single cat mid pipe
Tranny rebuilt once at 163k
Rear end original ......only oil changes.
5 speed .. .3rd clutch
Suspension Techniques springs bought from JC Whitney in 1995
CA raised outside her whole life.
Salvage title because she is a theft recovery. . . .. . .Whole story behind that.
Serviced by Ricks Rotary in Pleasanton CA since she become mine.
. . . . .. . . ... . .. . .Until one day. . . .Rick no longer works on Rotarys. . . And then you find out, nobody you trust will work on it.. . . In fact, nobody you don't trust will work on it either.

If you want it, you must work for it now.. . .. And therefore, redemption must occur.











Thankfully I am pretty good with hand tools and have 30 years experience with this car.. . . If I can get her to smog, I will fix her up. . . ..This may be an exercise in futility, but here goes.

This service will cover what it takes to get this particular car back on the road, in CA, after 3 years of sitting outside. . . . . For those that are not aware, California requires a Smog test once every 2 years and registration for this car runs about $160 bucks per year.

Off goes the intake. . . . .I would go through that but I followed: https://www.rx7club.com/2nd-generati...te-up-1139279/

From WonderousBread .. .Thank you by the way.

This thread may jump around a bit. . . Prior to the intake removal, I used a hand vacuum pump and checked what I could to the FSM. I also used the starting fluid trick and sprayed around the engine bay, (trying not to set things on fire). . . .Using starting fluid I only got a rise in RPM's when I sprayed under the Upper Intake. . . .This of course indicates an air leak and the most likely culprit in my search for the cause of the bad idle.



Anything I could ohm out easily, I did. . . ..Air temp intake, radiator switch, BACV, ACV. . .All this can be found in the Field Service Manual that is easily downloadable.

The most helpful thing I found was the $20 hand vacuum pump kit. .. . .I bought the $50 dollar fuel pressure kit. . . .The $20 dollar vacuum gauge. . . I just started checking everything that was easy assuming it would eventually lead me to the answer.

The 20 dollar vacuum pump discovered that the brake booster and the EGR valve leaked. I broke 1 vacuum line that was hard as a rock during the intake removal.. . .. I will most likely replace everything I can with silicon tubing. . . .Thankfully, during the engine rebuild, Rick at Rotary Performance replaced a lot of the hoses with silicon at 263K

After struggling with the air leak, I decided to attack the exhaust because I knew it was going to be an issue when smogging. The Bonez pipe I had a muffler pipe add a EGT type K probe and an extra O2 sensor port.
. . When I first installed the single cat system, it would pass smog.. . . . But that was 15+ years ago now.

The 3 cat system went back on the car.. . .Thankfully the 3 aftermarket cats were still unbroken. . . .. The jury is out on whether they are still good enough for this smog monster. . . .All three OEM cats broke over the course of her life.





Time to tackle the double throttle valve broken diaphragm problem I have been putting off for 30 years. Nobody makes this part anymore. . .. I had to come up with my own solution. The broken diaphragm acted like an air leak on the vacuum system during warm up.






Next up was dealing with the Brake Booster. . . ..Vacuum leak. . . . .. .The only company I found who will deal with it is Rock Auto. . . .. If you take yours off and send it to them they will have somebody rebuild it.. . . .. . Wish me luck. . Getting one of those is hard.

Next up was the intake removal. . .

The first thing that stood out after the intake removal was the stain. . . . .That kind of stain indicates a leak in the trailing injector port. .. . .Air leak?

More to inspect.



Time to inspect the plastic spider.

After all these years any plastic part gives me concern. . .. . .Atkins Rotary still sells the large vacuum hose so I bought it. . . Awaiting delivery.

I discovered any new OEM part under 50 bucks I should buy.. . . The scarcity.

I vacuum tested the spider and it came up OK amazingly.. . . .Rick changed the oil metering vacuum lines to silicon thankfully, but the larger diameter main line from the intake was ROCK HARD due to it's age. I noticed that larger line had a white dot on it. Does that mean anything?



Getting late. . . .will update later .. . . .. Much to do there is.

 

Here are the trailing injectors.


Pulled out of the suspect leaking trailing 1/2 side.



Something is going on. . . . .

I will ultrasonic bath clean them and then put new pintles and seals on them.. . .I make this choice because five-0 motor sent me injectors that did not match their advertisement. The expectation being I wanted new Denso 460cc's red tops as advertised and got some green top rebuilds. . . .NO reply from them yet.

Looking at the leading injectors they don't seem so bad on the outside. . .. .No real signs of leakage.. . . . . Dirty yes. . .Greasy Grimey I'd say not.

Disconnecting the injector electrical connectors is problematic for older vehicles. . .. .They break easily now and you might have to cut open the harness for some length to get a good splice joint.. . . . .A harness next to leaky injectors can take their toll on the harness and connector.

I want to leave these alone right now. ... . . .But the cracked pulsation damper might force my hand.



Let's look at the injector diffusers on the trailing side. ..




Pretty crappy.

 

Fuel Pulsation Damper. . . . .Best to change it now.

 

MazdaTrix still sells this. . .Might as well change it now. .. . . .Hope the hose barb is not rusted to much on the engine core side. . .. Always hard to get a hose to seal on a rusted hose barb.

 

 

 

Amazing work this far!! I'm impressed with how determined you are to make this car right. You're not cobbling it together and misdiagnosis things. You are spot on and it makes me happy to see how much you love the car! Did you buy the car new?

 

Hello Mazdaverx,

I got the car used at 58k miles or something like that in 1990. . .. It was a salvage title from theft recovery that had the rear quarter panel damaged at 3 years old.. .It was repainted/rebuilt and the frame was straight so I bought it.. . .My first loan. . .It was $5300 bucks.

I'm posting some more progress now. !!!!

Thanks for asking !!

RL

 

After I bought the fuel damper I realized Standard Motor Products sells one that is all metal.. . . . .And 80 bucks cheaper.. . .If I had to do this again I would get all metal.

Standard Motor Products FPD13 - Standard Motor Fuel Injection Pressure Dampers

 

 

After calling Five O , I got ahold of a guy who owns the place. . .. He told me that he special makes this 460cc injector for the rx7, and that in fact, what was advertised as a brand new Denso 460cc low impendence injector, is really a rebuilt unit by him. The injector does come matched with a spec sheet showing the flow of both injectors I purchased.. . . 1 injector came in right at 2.5 ohms and the other at 2.3 ish ohms. . . Both are low impedance and with the right connector and seals.

I will go with the five o injectors simply because they do not have the mileage my old ones had. . .. . They are the right height, and seals, and connector. . . .. They are the trailing side so as long as they don't leak, they won't work against me in finding a good idle because they don't turn on till over 3,500 rpm. .. But the new seals they have will solve the leaky stain issue and potential air leak.

If they work well when all this is done, I will buy two more for the leading.. . . ..Let's see. . . .I hate spending money not knowing if it will help, but this thing needs to run right.

 

Following is from November work.

Oil injectors
trailing fuel injectors
Re-assembly
Startup

Old oil injectors would not hold vacuum. . .Replaced .. new injectors working like they should.. . .checking all 4 injectors at once. . ..


Don't forge the copper gaskets.



Oil injectors act as a check valve. . . .When the pressure delta allows air to flow from upper intake through oil injector, it acts like a venturi to move oil into the engine. 2 injectors are located on the lower intake and two go right in the rotor housing. If the oil injector is compromised, it allows air to flow back into the upper intake. It is an air leak you won't find with the starting fluid trick.




Getting the fuel rail back together.. .

 

OK .. . .The car idles well once warmed up. It is very hard to start when cold but will always easily start when warm. I think the fuel check valve is bad. Once the engine is shut off for 12 hours or longer, I think the fuel will slowly flow back to the tank and it takes a little bit before the injectors see gas. . .. .It will usually take about 15 revolutions to start cold. . . Usually around 3 to 5 revolutions when warm. .. . Repeatable. Sometimes it will go to 3k rpms and warm up, but last time it went to 1,500 rpms and was stable till it fell to 850 where I set it.

I think the bad idle was cause by multiple factors.

• Leaky brake booster. . brake booster is the leaker not the line.
• Leaky EGR valve. . I know the diaphragm is leaking and suspect it leaks through on the plunger sealing side..
• Leaky seal around trailing injector. .
• Leaky oil injectors, check valve not working inside each injector.

I cannot understate the importance of the hand held vacuum pump. The hand held vacuum pump allowed me to verify the issue on 3 out of the 4 problems and it allowed me to leak check all the vacuum lines.

It's very important for all the vacuum lines to be converted to silicon. After all these years, those lines are suspect just by virtue of their age

The field service manual FSM is the best resource. It would not have been possible for me to verify all the things I needed without it.

Next up is the suspension and interior. . . .. But first let's get this thing to smog.

 

I'm going to have to check that myself. Unfortunately it means the intake needs to come off again...

Excellent work, your attention to detail is impeccable.

 

Well, this weekend is the smog.

I received my new air pump. Which feels good by the way.

It is replacing a unit I recently bought that just doesn't sound right.. . . .Buying a cheap unit on Ebay doesn't always work out right.

I also need to change the oil. . .Gas in the oil will work against you during smog.

Here's a couple more pics.



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Will absolutely do nothing to help me smog, but I still like it.

 

Amazing work thus far!!! I never considered that the oil injectors would fail, causing excessive vacuum to enter the intake manifold and the idle is then increased as if there were an external vacuum leak. It does make sense as they are indeed much like a check valve. I also love that you're back probing connectors. Too many people mess up the female pins by front probing and then they create more problems because of pin fit issues and are chasing their tail. Well done! Excellent write up to date. Will be continuing to follow your thread!

 

Well,

No smog today. I plugged the old brake booster in, and the idle went to ****.

Previously, I had just turned the vacuum line with integral check valve backwards and plugged it back on the metal pipe side while I debugged the engine. This allowed me to isolate the brake booster system while I set the TPS, idle screw, and adjustable resistor.

But went I connected brake booster hose correctly to get the brakes working in order to drive it down to the smog shop, apparently the leak in the brake booster is large enough to wreck the idle and cause hesitation in the low rpm range.

The vacuum gauge I installed in the engine bay also dropped 2" Hg. It shows it doesn't take much vacuum loss to effect performance.

The good news is the new Secondary Air Pump I bought and installed doesn't sound like a silver dollar in a blender.. . .This one looks good and sounds good.

I checked Rock Auto today and magically they got a shipment of CarDone 53-2120 brake booster units. $165 shipped with tax. .. .I had to get that while I can.

Hopefully this will be the last thing to do pre-smog.. . . So far I am in it for around $1,800. . And I still need tires that aren't 10 years old.

Here's a list of parts currently.

Spark plugs
Oil filter
Double throttle valve setup
Mass Air Meter
Air Pump
water hoses, vacuum hoses
Water temp switches, sensor. . Not installed yet
Re-mfg BAC valve from china/ebay .. .Not here yet
PCV valve
2 fuel injectors - Re-mfg
4 oil injectors - new OEM
Gaskets, seals
TPS sensor. . new oem
Fuel pres damper . . new oem
Fuel regulator. . .new oem
Fuel Filter
Brake Booster . . Re-Mfg

This project is going to have to wait longer.

 

Is it a vacuum leak? . . .. You know I'm not really sure. .. Kinds depends on how we define a vacuum leak.

I think with a failure of an oil injector, air has the ability to get pushed back and forth between oil injector and upper intake as pressures go from high to low. (delta P between intake and oil injector between acceleration and deceleration cycles.)

This pulsation from positive to negative pressure probably causes the oil in the effected oil metering line to break up and form inclusions, or what looks like bubbles in the line. . . . .I would think if the oil metering line has what looks like bubbles in it after a long run, the oil injector is suspect. (of course using a hand vacuum pump has proved effective in testing to see)

The oil injectors in the rotor housing probably effect performance more than the ones in the intake manifold when they fail. I'd imagine it effects compression to some degree when the oil injectors fail on the rotor housing, and air can escape and get pushed back to the intake though that small diameter line.

Either way, having air move back and forth uncontrollably between where the injector resides, and where the tube connects at the upper intake, is not a good thing.

 

It would be a metered air leak, I suppose. The air is still going through the AFM, so it's not a vacuum leak per se. It would cause more or less air to pass through to the engine under certain conditions, but not affect mixture as far as I can tell.

I've been going down the rabbit hole of reading how the oil injectors work now. I'd never really thought about it until you brought it up. Mine hold about 5" hg of vacuum, so I'll probably replace them next time I'm in there.

Anecdotally, my idle drops when I put a set of visegrips on that vacuum line. Which makes sense now that I know how they work.

 

So I went ahead and changed the water temp sensor. I had to remove the alternator but that wasn't too hard. The tricky part is getting the connector off without breaking it.

The temp sensor change-out did make a very noticeable change in the cars ability to start up cold. But the idle is now really low once warm and the idle adjustment screw is all the way down.

It's still drivable, but I feel as if I need to do the initial set couple again. I set up the car previously with what looks like an out of spec water temp sensor.

The water temp sensor is a thermistor.

I'll change out the BACV with the re-mfg unit and see what happens next. Most likely I will do the initial set coupler again.

 

Good progress. One thing, not sure if it was a typo or not, but the idle screw bypasses more air when it's turned out (or up). If yours is screwed all the way down and you have a low idle, you can just turn it back outward to pass more air in.

Doing the process with the initial set coupler is a good idea though. Takes the BAC out of the equation.

 

AH HA !!!! . .. .

I just came here to make an update on that topic and you are right to question the idle intake screw.

What I noticed is that when I removed the cork sport intake and put the OEM snorkel back on it because I have to smog it, I managed to get the O-ring to slip out of groove between the plastic snorkel and the aluminum intake. . . I noticed a large gap where the snorkel bolts up to the intake and thought, man, that don't look right.

SO I reseat the o ring in that triangle groove and whammo !!!. .. . Now the Idle Adjustment screw actually works like it should !!!! .. Before, I had to screw the idle adjustment screw all the way in to idle right, and when I unscrewed it out, it would only screw out about 3/4 turn before the engine wanted to stutter and then ultimately die. .. I had no range on adjustment but I was still able to tune it to run "better".

Apparently, I had to completely close the idle adjustment screw to make up for the fact that I had a large unmetered air leak into the intake. That $10 o-ring from Ebay is small and takes some stretching. It's a pain in the *** to install and that was my leak after I swapped back to the OEM snorkle. . . .

The real test is when I start it up tomorrow morning. How does she handle cold start now?. .. Does the 3,000 rpm work?. . . .Because she runs fine with the exception of that. .. . At this point, I am highly confident she will pass smog once warmed up. . She even smells cleaner out the pipe.

The AWS system and switching solenoid related stuff are the last things I really haven't touched. .. . There's a lot of testing procedures regarding measuring times and vacuum levels that I haven't done.

. .. .. .Good day today ....

 

Well today was the day.

AWS still does not work like it should during warm up.

The gas gauge does not work but the gas warning light comes on when you look at the warning light cluster. (means dash gauge is bad and not the level sender?) The gas warning lamp was on, so I put 5 gallons of new gas in it. I did not do anything to the gasoline.

I had Oil Changers do an oil change prior to the smog. Any gas in the oil will work against me. I was surprised Oil Changers still had an oil filter on site, but I guess the oil filter is probably used on multiple models.. . . They only had 10/30. My preference is 20/50 or 10/40 but they no longer carry those viscosities.

I ran it down some long streets in 3rd gear at high RPM to get the cats hot. Then I took it to the smog shop.. . . .Long story short, it passed.

It's always funny watching techs try to smog it. They always struggle with the details.





During this recommissioning process I discovered that the brake booster was not bad after all. . .. .It was the way I was using the hand pump. . . Which is fine to me, getting one of those proved to be problematic.

The car needs a lot of work still. . . .. Interior is falling apart. . .There are bondo cracks on drivers rear quarter panel. There are weather seals that are bad. . . Still much to do. But now the car is street legal.

What I found interesting is that the car was registered Non-OP, but the smog shop could issue the sticker and register it. That was excellent cause it meant I did not have to go to the DMV and I drove away with the sticker.

 

Congratulations! Man, the e-tests you have down there are strict.

It is fun watching them try to figure out where everything is on an Rx7 though. I have an old e-test slip where the number of cylinders is listed as "17".

 

Awesome. Its coming together.