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Revving issues on FC

Old 11-14-17, 05:16 PM
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Revving issues on FC

Hi guys,

I have a 85 turbo s4 rx7 that has been sitting in storage for quite a while (it's seen better days unfortunately). A mate and I decided recently that we should pull it out of storage and start to get her back up to the glory days but we have struck an issue that we can't diagnose.

Long story short we have got it running again but it won't rev properly - when it's cold it revs up OK but once it gets up to full temp it won't rev at all, it just stalls.

So far we have had the injectors reconditioned, replaced the CAS and replaced the O2 sensor. And a full oil change of course.

It's running a microtech lt8 so airflow meter etc are removed.

Any ideas would be great.

Thanks for the help! Apologies if this is the wrong place to post.

Last edited by aobrnz; 11-14-17 at 05:19 PM.
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Old 11-14-17, 06:44 PM
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Can you connect to the ecu and log it? Is it going rich or lean of where it should be when you try to rev it?

If it revs out cold but not hot I would suspect a manifold leak opening up with temp or a faulty coolant or air temp sensor. Even if you just have a hand controller you should be ablt to check the sensor inputs including throttle to make dure they are reading as expected to narrow it down.

Last edited by Slides; 11-14-17 at 06:57 PM.
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Old 11-15-17, 01:55 PM
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Awesome thanks, I do have the hand controller so will check this weekend!
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Old 11-20-17, 05:47 PM
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We gave this a try on the weekend and might be getting somewhere! Long story short there don't seem to be any errors showing on the controller (except for the missing airflow meter).

The A/F mix sat around 14.7 - 15 on idle which if I remember correctly is within range?

What we did notice though was that the TPS position basically jumped straight to 99% open with just about any movement on the throttle. In other words if we pushed the throttle up to about 10% open you would get the TPS sensor slowly increasing but anything over 10% open it was reading 99%. This definitely doesn't seem right to me, and it looks like something is missing from the assembly that holds the TPS sensor for longer (after that 10% throttle there isn't anything pushing against the TPS anymore), but I can't see why this would be different from when the car was running fine as that hasn't been played with. I also can't find an example online as to what might be missing.
Would that TPS position cause the engine to lean out?
Some pics attached for reference
Attached Thumbnails Revving issues on FC-img-4620.jpg   Revving issues on FC-img-4622.jpg   Revving issues on FC-img-4621.jpg   Revving issues on FC-img-4618.jpg  

Last edited by aobrnz; 11-20-17 at 05:49 PM.
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Old 11-20-17, 11:20 PM
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The s4 Tps is an odd bird and is either Pushed in or all the way out..They don't give an accurate's like ON or OFF!
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Old 11-23-17, 11:28 PM
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Still didnít answer what the coolant temps were showing. Iím suspect of a faulty coolant temp sensor as well. Fuel trims are dependent upon coolant temp readings. Just saying itís worth checking. Check when cold to see if it makes sense and make sure the temps show rising until full warm condition and see what full warm is.

S4 tps only shows 0-30% throttle range compared to s5 which has 0-100%

never touched that ecu before, but are you running a map sensor? Is it calibrated in your software?

Last edited by DR_Knight; 11-23-17 at 11:30 PM. Reason: Adding stuff
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