1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

studder under accelaration. (ive searched)

Old Mar 30, 2011 | 08:03 AM
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studder under accelaration. (ive searched)

I have a 85 se. i have recently put 2gen manifolds and tb on this car. it was doing this before i did the swap. i thought it might have been my air flow meter. cause when i would play with it or turn it sideways it wouldnt hesitate as bad. the tps was dialed in at that point. since i have swapped the tb and manifolds for the 2gen upgrade. the 1st gen tps would not bolt up. i thought i saw some where that says the 2gen tps will not work. is this true? if so then thats my issue. i need to try and take the old bracket off of the se tps and transfer it. when i accelerate and push it to the floor it kind of studders and then goes, and through out the whole power band it feels like it is fighting with itself. Just wanted to know the difference between a bad air flow meter vs tps. everything else on the car has been replaced. so these are the only 2 left and i cannot get a good reading for the tps with my ohmeter.

thanks
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Old Mar 30, 2011 | 02:59 PM
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Doesn't sound like TPS to me, it sounds like maybe airflow and/or fuel flow.

A bad TPS will have the symptoms of 'juddering' when under steady-state driving. Once you go WOT, the TPS doesn't matter, and the far end of the spectrum is sent to the ECU saying "He wants to go fast - pour it on!".

When you described it as seeming to fight itself throughout the powerband, that almost sounds like a fuel flow issue, and since you mentioned you put a FC manifold and TB on it, it's very likely that unless you also installed the larger 4-injector setup, the harness and ECU to support it, and basically recreated the running setup of an FC, then you've got more air than fuel coming in, and it's running lean.

As you likely know, running lean is bad for rotaries. A quick check would be to get in engine bay after running it hard and looking for glowing exhaust manifolds or cats (if installed).

When you increase airflow to the engine, if you've just blocked off the other 2 injector ports on the intake manifold, then you're only taking advantage of part of the benefits of going with a better FC manifold and TB setup; and you have to adjust fuel flow accordingly. You probably already know this, but the SE's only have 2 fuel injectors of 680cc nominal flow, and the FC's had 4 injectors of 540cc nominal flow (IIRC) - but there were 4 of them running to keep up with fuel demand.
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Old Mar 31, 2011 | 08:02 AM
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yep im aware. i was having this issue even with the se manifolds. so i thought it may be the tps. but like u said at wot if its still fighting then its something else.. im thinking air flow meter so im off to buy that. i thought about trying to buy some 850cc injectors if they would plug and play. i thought the s4na's where like 440 or 450s. i think t2s are 550s
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Old Apr 1, 2011 | 04:45 PM
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When was the last time you changed your fuel filter? This is the EFI fuel filter made out of steel that I'm talking about, of course.

Possibly, you've gotten some crap in the filter which is restricting flow - or possibly build-up in the feed or return line which is affecting volume.

Good luck,
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Old Apr 3, 2011 | 09:03 PM
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if by stutter you mean sounds resemblant to a semi truck down shifting than its fuel delivery.
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Old Apr 3, 2011 | 10:30 PM
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can someone post a pic of their gsl-se air flow meter. i have a hole drilled in min where the top rear circle spot is. and i have a sensor that can unscrew and it looks like that actually limits my gate from opening up all the way when is wot
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