I have had this issue for about two weeks now and i cannot figure it out. Car sat for a year and half. Towed it around and got it running. Car ran great until a few weeks ago. When the engine is cold and partial temp it runs great. Once it's to full operarting temp i can give it anymore than about 15% throttle or it cuts out and feels like fuel has been shut off. It doesn't matter how fast i put the throttle down or what rpm i do it at. I have checked, TPS, BAC, Air bypass, AFM, Pressure sensor, EGR, all the engine grounds and ECU ground under intake plenum and everything is i checked is in great shape. EGR diaphram seems to be ripped because when i vacuumed tested it with a vacumm gun it doesn't hold vacuum but i put my finger on the back of the diaphram and it moves but closes right away, so it isn't stuck open which is fine. ALSO WHEN I REV THE ENGINE AND HOLD THE THROTTLE WOT, IT WILL REV TO ABOUT 3-5K AND THEN DIE TO 1K LIKE I LET OFF THE THROTTLE AND THEN REV BACK TO 3-5K ALL WITHOUT RELEASING THE THROTTLE... I can not figure this problem out and i have posted about it a few times and so far haven't gotten any leads on the problem. I know about the 5th and 6th ports power loss on higher end which i also think are giving me a problem but that isn't my main problem at state right now. PLEASE HELP! I think this might be a new problem, i haven't found anything like it.

 

What is your fuel pressure and volume looking like. Sounds like its not getting enough fuel or barely enough for the occasional high revs.

Check fuel filter.

When it had been sitting for that time was there gas in the tank and did you bother draining it and putting fresh gas in?

 

Oh and also the pump may be going bad or pump sock is clogged.

 

Sorry forgot to mention, Pump was replaced shortly after i got the car because the stock one was fried. Replaced with Walbro 255 and fuel filter was replaced last week after problem started. Filter didn't help but was much needed due to the nasty grabage gas that came out when i blew through it...

Also when the car sat there was gas in the tank but it was all ran out and i filled the tank about 6 or 7 time until this problem started. I put almost 2000 miles on the car since i got it running and it is just now giving me problems

 

You still need to check the fuel pressure.

 

How about a clogged cat?

 

I still don't understand how fuel pressure would change after the car was warm because if the gas was getting warm from circulating through the engine and back to the tank then the problem wouldnt be present after filling up the tank on a warm engine because the gas in the ground would be cold but the car still does it when filled up on a warm engine. I can still check pressure but last time i check pressure it was within spec on the new pump...

 

How about your fuel injectors?

 

I'd check your compression.
I'd say you'd know if the compression was that low, but on both my fc's when the compression was getting really low it didn't want to burn the fuel.
It would act like it wasn't getting fuel at all and would have the symptoms of the engine being starved of fuel.
Even though it had a fuel tank.
You might want to check your compression just to rule out that it is compression related.

 

Check it when the car has fully warmed up when you know that it is more likely the engine is going to give you problems as opposed to when the engine is cold and doesn't show the problematic symptoms. So place the gauge in the proper place when cold and observe for any differences as it warms up. This will at least rule out certain aspects rather than hope it's not the pressure.

 

What year is this car? I'm thinking limp mode.

Are you getting any check engine lights?

 

It's an 88. No check engine lights when it happens.

Checked compression and it's mid 70's both rotors on all rotor faces. If i let the compression build on the gauge without holding the air release it gets to 125psi both rotors. I will check fuel pressure when engine is cold and when engine is warm. Does anyone know what pressure should be? And i place the gauge at the hard line right after the filter right?

 

Limp mode on other cars (not wankels) doesn't necessarily mean engine light. My Passat went in limp mode similar to what happens to yours.

Loads of fuel going through, but wouldn't rev past 3k. Suddenly it just shot up to 7.5k.

 

S4's do not have limp mode. They also do not have check engine lights. You need to manually pull the codes from the ECU. http://www.banzai-racing.com/series_4_error_codes.htm

If I had the car in the shop, after ruling out the TPS, I would suspect the water thermosensor. If that checks out then look at the double throttle system, sounds like it is operating in reverse, allowing air in during warm up , then closing at operating temp.

 

How do you check the double throttle system and the water thermosensor??

 

Also, how do i check ecu codes on the RX7? Never done it before on a rotary. I kow there are many different ways to do it with all makes and models. Done it on BMW, MErcedes, Porsche, Toyota, Lexus, Volkswagen and Nissan, but never Mazda and especially this old haha

 

you have build a diagnostic checker. here is pretty much everything you need to know about building, and using the diagnostics checker.
http://www.teamfc3s.org/info/article...odes/main.html

 

Factory Service Manual

Follow the link I gave you. Then click on the link on that page http://2ndgenrx7.freeservers.com/error%20codes.html

 

Fuel pressure test results: Jumper jumped and key ON (engine not running) Fuel Pressure is 49psi. This is with a Walbro 255. I don't think they run any higher fuel pressure than factory, only more fuel flow... If these results are correct it shows the regulator is bad. But i would think if the regulator is bad it would run like garbage at all times. Still scratching my head on what is bugging my car and bugging me in return. Car ran great for two months (roughly 1,600 miles) and out of no where it started slowly acting up the warmer the car gets. Also when i drove the car yesterday in warmer weather than it has been in lately, the problem poccured sooner. Which almsot makes me think a temp sensor somewhere is freakling out. Air temp sensor? If so, where is it located and what resistence should spec be?

 

The factory psi would be close to 30 when the gauge is teed but that would be with the engine running or engine turning over I believe. The factory pressure would be close to 80 if measuring just the pump.

When a car is cold and it's started there is more fuel injected than a warm car upon start up as dictated by the start up fuel map in the ECU. Makes one think after the car is started that more fuel is used when the engine is still cold and less when it is fully warmed up but I may be wrong about this.

If you want to check the Water Thermosensor you would take the reading at the ECU ( pin 2I Green/White wire) and it would show 2 to 3 volts if cold and about .5 volts when the engine is fully warmed up. Also, the FPR has a vacuum hose connected to it and w/o vacuum, vacuum hose disconnected, the fuel pressure increases by about 10 psi.

 

Then your compression is low then right?
Might want to try and crank it with the radiator cap off and see if you get bubbles or explosions of antifreeze/water.
When you said that it runs worse when it is warmer were you talking about warmer outside or when the car is warmed up?

 

Replaced the Water Temp Sensor, still no change. BlackRotary23 sent me an email saying his car did the same as mine and the temp sesnor tells the ecu if engine is cold, warm or hot (obviously) and if this is bad air/fuel will be off and car will bog/cut out. Well i replaced the sensor and still no change. If this is the problem, it might not have made a difference due to me changing the sensor while the engine was still hot and with the new sensor in, the computer still might just be in "cold" mode. So i am going to try to let the engine get back to full cold and restart with new sensor in and see if this annoying issue is finally gone. If this doesn't help, then i have no idea where to turn next, unless the air temp sensor is bad, which i tested. Air temp senor located in intake manifold under BACV, correct? Well resistance on this sensor was high, and i thought i read somwhere about the specs being kind of low, but can't find specs on it. If anyone has specs for the air temp sensor, please post..

 

When the car is warmed up. Although when i drove it yesterday when the outside ait temp was roughly 20* higher than what it has been lately, the car acted up sooner, befoer it got to full engine temp, which made me think it was possible intake air temp sensor...

 

If the ECU doesn't see the proper signal then changing the Thermosensor won't help. You need to check pin 2I. Also, check fuel pressure while the engine is idling. Close to 50 is a bit off the chart.

 

Where is the ecu located? I looked in kick panels, under passenger dash and glove box. Either i missed it or i'm not even close. I will check fuel pressure tomorrow again, i am exhausted from all day tampering, and fed up with the issue.