shiznizzletech

I have owned a 1988 RX-7 convertible for a day...and it is great, when it starts. I am looking for any advice on these issues. Any comments or suggestions are welcome. If you have had and fixed any of these then please post away!!
I have had the following issues so far:

1. It just sits and cranks, sometimes, the engine can be cold or hot. I do get a heavy odor of gasoline when it does not start. I am guessing I may have leaky or internally worn fuel injectors??

2. It hesitates at normal throttle pressure, kind of surges ( the car, not RPM's). When you are at normal throttle pressure and remove your foot from the gas it sounds "off", maybe like it is not getting any gas. I had an issue with an old ford probe, some house paint accidentally found its way into the gas tank and when I would be driving at any random point it would surge because no fuel was making it to the engine. Again, could this be the injectors?? Or is this more of timing issue??

3. I took the car all the way to about 7,000 RPM's and shifted to 2nd with a bit of speed and well, rough shifting. There was a very loud clunk from underneath as I shifted and the clutch stayed on the floor. it came back up after I shut it off and played with the pedal for a minute. I checked the trans mount and it seems ok. Could this be the clutch or its components simply getting worn out?? Does it need a new transmission?? Any ideas will be great on this. under normal driving it shifts great and feels great.

4. When I initially start the car after it has been parked overnight or allowed to cool completely, the RPM's surge up and down (about from 1,000 to 2,000 back and forth), this goes away after the engine heats up for about 5 minutes of idling. I was told by the previous owner that it was something to do with the A/C??? Again, any ideas would be greatly appreciated.

What I have done thus far is order a new Throttle Position Sensor and a new fuel filter. I want to wait to get the new fuel injectors until I receive some feedback. Any and all comments are welcome. If you have had any of these problems and know how to correct them, PLEASE write me.

Again, this is a 1988 Mazda RX-7 13B S4, non-turbo.

MrGoodnight

iTrader: (1)

Ill try to help with what I know,

1. Sounds like your flooding, there is a fuse box under the hood of the car, with the key off you pull that fuse out and crank the engine a few cycles to remove excess gasoline from the engine then replace the fuse and hopefully it will start.

Also you may want to check your spark plugs and replace them if there are really worn or carboned up.


Hope this helps!!

nicdchris

iTrader: (1)

1. Mine does that too. Flooding so badly it won't fire. Simply pull the EGI fuse under the hood, crank till it fires, then turn it off and re-insert the fuse.

I just disconnect the fuel pump connector in the trunk as I am missing most of the interior.

Both have the same effect: turn the fuel off to get the excess fuel out of the combustion chambers.

2. New throttle position sensor, maybe... but did you properly adjust it? The two biggest problems with these cars are flooding and a mis-adjusted TPS.

3. Transmission worn, driveline worn, differential worn/diff mount broken, axles worn or have damaged boots.

Don't shift like an idiot and you'll save yourself the headache of having to drop the entire rear end...

As for the clutch sticking down, that sounds like an issue with the throwout bearing arm or the bearing itself. The pressure plate SHOULD have enough pressure to push the pedal back up... Best case: add fluid and bleed the clutch line, worst case: have to pull the transmission and lube/change the throwout bearing.

4. The cars were designed to surge to 3k rpm, then slowly drop back down in the 1500-2000 range, eventually settling on the 750 mark for idle when warm. If your car is having problems it's probably your TPS.


If you haven't changed the fuel filter at the fire wall and checked the pre-filter in the tank, you should probably do that too. A lean engine is a blown engine.

Good luck, and may the fourth be with you.

Aaron Cake

iTrader: (1)

Flooding problems are very common and have a number of causes. The two primary causes are leaking/worn injectors and low compression.

The injectors need to be serviced by an injection shop.

Could be related to #1. However start by testing and adjusting the TPS as per the FSM specs. TPS issues are very common.

If the clutch stayed on the floor, something is up with the clutch fork or the hydraulics. Old clutch hydraulics should be replaced just on age, so replace the master, slave and flex hose. Also check the release fork. Very occasionally, they will pop off the ball (if improperly installed in the past) or bend.

The clunk is likely either related to what happened to the clutch, or the front diff mount is broken.

Fix all the vacuum leaks, adjust the TPS.

A new TPS? The last time I checked they were near $400! There may be nothing wrong with yours, it just might be out of adjustment. No point getting new injectors when they can likely be returned to almost new condition at an injection shop.

The Factory Service Manuals for all years of RX-7 (and many other rotary cars) can be downloaded for free here: http://foxed.ca/foxed/index.php?page=rx7manual . They contain all common service information information and more, and are an essential tool for any sort of service work that needs to be performed on these cars.

Additionally, the Haynes service manual for the 1986 thru 1991 RX-7 (both turbo and NA) can be found at most local auto parts stores or purchased from any good bookstore (ISBN number 1 56392 007 7). It is only about $25 and is a great quick reference for things like this. Not only does it contain most of the information in the FSM condensed into an easy to read format, but it includes full wiring diagrams as well.

These manuals will answer 99% of service related questions for the car and if you intend to do your own repair work, you will need at least one of them. Preferably both, since the FSM is a free download. The Haynes is a good quick reference covering 99% of questions, while the FSMs show complete and detailed procedures.

shiznizzletech

I've found several ways to adjust this TPS. I check voltage on the green three female prong connector right behind the air filter correct?? And I am looking for voltage in only one of the ground prongs??
If I could get some help on how to adjust this and maybe a picture if I am not asking too much. Thanks for the help guys!!

BTW, I did get a haynes manual. It is helpful. Some thing need more detail but t did help already!

shiznizzletech

Also, spark plugs look new. Wires look ancient. Should I change even though they are not arching??

SAT_Leo814

Hey , what fuse should i take out? im having the same problem my car braps , 1000-2000rpms back and forth , but today i started it , it went well, but it doesnt idle correctly , when i crank the car it revs all the way to 3000rpms and then drops to 750-1000rpms , but when i go ahead and rev the car myself to 3000rpms and let go of the throttle , my RPMs just drop to 0 and shuts my car off , and ideas?? this is my first car/rotary xD , thnx for the info bruh!

SAT_Leo814

Hey , what fuse should i take out? im having the same problem my car braps , 1000-2000rpms back and forth , but today i started it , it went well, but it doesnt idle correctly , when i crank the car it revs all the way to 3000rpms and then drops to 750-1000rpms , but when i go ahead and rev the car myself to 3000rpms and let go of the throttle , my RPMs just drop to 0 and shuts my car off , and ideas?? this is my first car/rotary xD , thnx for the info bruh!

Aaron Cake

iTrader: (1)

Pulling the EGI fuse under the hood will disable the fuel injection and allow you to unflood the car. Disconnecting the fuel pump relay under the dash (drivers side knee) will accomplish the same thing.

But the underlying cause should be fixed.

shiznizzletech

OK, I did this the other night to start me car. It was late, I was at a friends house and my top was down so everything got a little damp from the dew and condensation. I did the EGI fuse pull to un-flood my car and get it started. My questions is, what can you break or short out from doing this.

I pulled the fuse, cranked for 10 to 12 secs, removed my key (always do), put the fuse back and the car started. It ran for about 10 secs and sounded like it was misfiring on "all the cylinders". Throttle response was near dead and the car sounded like a constant whoopie cushion. It dies after those ten seconds and would not restart.

Also, when I cranked the engine, it sounded slower and off pace, almost like a dead battery, which I charged to be sure it wasnt.
The slow crank was there the next day and it never started, we eventually push started it so i could at least get it to my house. It made the misfire/whoopie cushion noise the whole way, died out twice in less than a mile and had very little power.

There are some other things I noticed also that were strange. Until the point of it acting like this, the door and brake lights were the only lights that appeared on my little warning system. After this crap started, all the lights appeared on the system, and the door light failed to go out even when they were closed. No lights were on the dash system when the car actually ran for that mile or so.

Last thing, when I do crank the car, there is a very small amount of white vapor, not smoke, that comes out of the exhaust that smells like pure gasoline. just a very small amount that is hard to even notice as it does not rush out like exhaust.

After you have read my essay above let me know if you think this may be an electrical problem as I hate them and will probably end up selling the car because of it.

Thanks guys, going to keep tinkering here. Be well and drive safe!!

RobbyWally

iTrader: (2)

When badly flooded, the excess fuel rinses the oil from the seals resulting in very low compression. Sounds like that might be your starting situation. There are several detailed write ups and even some YouTube videos. Search for rotary engine unflooding. I wrote up the procedure that worked for me & can send a pdf if you want it.

The key point is to remove all four plugs and the EGI fuse. Add some motor oil to both rotors through the leading plug hole. Crank the engine to blow out excess fuel & distribute the oil. Then replace the plugs and fuse.

After you get it running, then you can begin to diagnose the root cause(s).

Aaron Cake

iTrader: (1)

Pulling the EGI fuse and cranking won't damage anything. Removing that fuse just cuts power to the fuel injection system, nothing more.

It sounds like you may have some underlying problem such as a failing injector.

Also, major flooding will foul out a set of spark plugs so they will never fire properly again.

shiznizzletech

I have begun to take apart the intake and dynamic chamber on the engine as I have ordered all new injectors, a new FPR, fuel filter and a new fuel pump. Are there any other parts of the fuel system I should replace??

Again, my main concern is the sound difference the motor makes when it is rotating. It has definitely changed. i spoke with a person who "claims" to be an expert on these and he said that you can "chip" the edge of a rotor (or something of that nature). there is also gasoline in the oil, when you remove the dipstick the odor is quite powerful.

The engine does not consume a lot of oil, nor did it make knocks or funny sounds prior to this issue. Does anyone think I should just go ahead and rebuild the motor?? It has 168,000 on it and I know it has never been rebuilt.

Do these rotary motors make the same kind of noise as piston motors when they are failing?? The usual knocks and metal to metal noise?? If not, what should I listen for??

Even though this car has issues and hasnt ran correctly since I owned it I still love it!! If I do decide to rebuild are there any internal parts that can deliver more power?? Since I am taking almost everything apart in the first place please give some information on what I can buy to boost the BHP. I am not looking to spend $10,000, yet, but if I can do smaller, simpler things i would love to do it.
Please do not scald me for asking this. I have read almost all of the FAQ, I do like the direct approach of threads much better.

Can anyone go into a little more detail about bridgeporting?? If so, what is it exacly, where can I get it done reliably and about how much will it cost?? Will I have to buy new rotors or seals or bearings?? I read your build thread (Aaron's) last night where someone did a half-assed job of it. Got me curious.

Thanks guys, drift with care!!

RobbyWally

iTrader: (2)

The strong fuel odor in the oil means the engine was badly flooded. When this happens, the excess fuel washes all of the oil from the various rotor seals. Among other things, this increases friction & changes the sound (and speed) of the engine when it is cranking. Removing the plugs and injecting some oil into each rotor housing through the bottom plug holes should fix this.

Before you jump to conclusions about needing a rebuild or doing major work, i strongly advise several 'post-flood' remediations: oil change, new plugs (existing may permanently fouled) and service the injectors (you probably [U]don't[U] need new injectors.

I will add details later today.

shiznizzletech

It has been a long and expensive couple weeks of trying to once and for all correct my flooding/fuel problems. I have bought all new injectors, factory Mazda 460cc, a Walbro 255 fuel pump, a new adjustable fuel pressure regulator, new iridium spark plugs, I have installed an Air/fuel gauge and attached a dual pillar pod ( I think I did a great job, post photos later), all new fuel hoses and screw tight clamps and I also got a deal on a HKS F-CON which I have yet to install. The last thing I must do is get the fuel/oil mix out of the oil pan. The bolt is on so tight I am fearful of stripping it and I do not have the strength to get it off. I am determined to control the flooding issues and if it will not start after all of this there will be car for sale soon!

Thank you all for the help or advice. You lads have been the greatest even though I am new and have not been able to help anyone else yet. I appreciate everything and will keep you updated on how things turn out. I hope they fix this flooding situation, not just for my own want but so I may help people who have the same problems. Thanks, one again.

Knowledge is Power!!!

Aaron Cake

iTrader: (1)

I think that's about the most expensive way you could go about this.

You likely don't need a new FPR. A stock replacement fuel pump is all that is required, and the injectors can be serviced by a local injection shop for about $30 each. You may end up having to replace one or more, but it would be cheaper than just buying new injectors.

While you are in there, replace all the vacuum hoses.

Massively flooding the engine will without question change the sound while it cranks. Compression will be very low and uneven. This is why about an ounce of oil needs to be put into each leading plug hole to build compression back up. The flooding also pollutes the engine oil with fuel.

That's not to say an apex corner has not been chipped, but I'd assume the much more obvious answer before jumping to engine damage. That said, a chipped apex seal corner could cause the symptoms you are fighting as it will result in low compression on two faces of a rotor...and then at high RPM will be far less noticable.

Nope. Smoke is a sign of worn oil seals. When a rotary typically fails, compression just disappears in half the engine. This is due to apex seal failure. Unfortunately the 3 piece seals that Mazda used in the FC have much less wear room than the older 2 piece, and tend to "roll" out of the rotor once worn.

A street port is about all you can do the NA engine to increase power a little and not begin to destroy drivability.

Trust me, you don't want a bridgeport. A bridgeport is the equivelant of installing a race cam on a piston engine. On the rotary, this means massive port overlap (the intake and exhaust ports are almost always open to one another) which results in poor fuel economy, weak low end, poor vacuum, high loping idle, but a huge jump in top end power. To support that top end power means ditching the stock intake, installing a very open (LOUD!) exhaust, and moving to a standalone EMS system so that the engine can be tuned.

shiznizzletech

Quick question...if I take the plugs out and crank the engine and get large "pow" type noises from where the spark plugs should be then my compression is most likely okay?? Should there also be a "fuel fog" when I do this?? Thanks.

Aaron Cake

iTrader: (1)

You should get a good "pew" everytime a rotor face passes a spark plug hole. If you have both leading plugs out, that should be once every half rotation of the eccentric shaft.

A blown engine will sound like this: http://www.aaroncake.net/rx-7/blown.htm

If the engine is flooded, you will indeed get a massive fuel fog out of the spark plug holes.

shiznizzletech

I got the engine to run for about 3 minutes yesterday. There was smoke absolutely everywhere and the throttle did almost nothing. It died and would not restart. I did get a compression tester and the back rotor read 80 psi and the front did not even move.

shiznizzletech

I have been taking everything apart again, I have noticed that my EGR was totally clogged, not even close to being able to breathe.
Also, to Aaron, i have been watching your YouTube videos and they are the best!! Would you recommend any particular place to buy new seals?? Also, as newcomer to the rotary world, what special tools should I have around, besides good vasoline?? Are there any other thing I should know before pulling my block out and taking it apart?? thanks

shiznizzletech

Forgot to ask last time, my oil i just changed out that was mixed with fuel is now fixed with fuel again. After that and the failed compression test is why I decided to pull the engine. What seal or part should I replace if my oil keeps getting contaminated with gasoline?? Should I just go ahead and replace all the seals?? You guys have been great all throughout this. thanks again!!!

sick_dippin

sounds like someone might need a rebuild soon.

Aaron Cake

iTrader: (1)

That's not a good sign. However just to be sure, put a little oil into each leading plug hole and repeat the test to see if the compression comes up. If it comes up to almost normal, then you may just be looking at a stuck front injector, massively flooding the front with fuel and lowering compression. Long shot, but it's worth checking.

EGR has no consequence as far as how the engine runs. Mazda seemed to eliminate and add EGR based on the year anyway, or the position of the moon, or random chance. S4NA and TII are the only 2nd gens that had it.

You can buy a complete rebuild kit from Atkins which contains everything you will need. Pull the engine apart first and inspect the bearings so that you can order the kit with bearings if you need to.

You really don't need any special tools past the 54MM / 2 1/8" flywheel socket. You'll need a grinder to clearance the side seals, and a dial indicator to set front endplay.

A rotor making no compression will absolutely pollute the oil with fuel.

Yes, all seals should be replaced if the engine is apart.