RoninRX7

Now that i have my 10th AE on the road, ive noticed it has a problem idling after warm up. Durring warm up, the tach is right about 1300 rpms, and it will run just fine. Once it heats up though the idle will drop so low it shuts off. I have searched, and came across different articles for adjusting the TPS, and it is now in spec with 1.004K Ohms at idle, and 4.293K Ohms at WOT. The car has all the emissions removed, except for the thermowax and ASV near the firewall on the rear of the UIM. So that means no BAC valve to adjust. How can i go about fixing this?


On a related note, the car will occasionally drop a rotor and run with little power when under light/no throttle until i go over 3k. As soon as i push it down just a little further it picks up again. What do i need to do to fix this?

Thanks guys

RoninRX7

I found the idle set screw, and turned it up. when i found it, the screw wasnt even touching the throttle stop at all!!! Now its set, and i readjusted the TPS. It still has problems idling though. Now it seems to bounce between 1600rpms and 1200rpms. The bounce is caused by one rotor seeming to turn off, then once it hits 1200rpms, the rotor turns back on and it climbs again. Im pretty sure there are no vaccum leaks, as i fixed them already. What could cause this? Anyone? Could a faulty CPS cause my car to want to turn off one rotor below 3000rpms?

RoninRX7

do you guys know if the S4 Turbo had a different CAS then the NA? Would an S5 NA cas work in my 88 10th AE?......

Hellkat

once you touch the idle screw, the tps will need to be readjusted.

RoninRX7

yep, i adjusted the idle screw, and then reset the TPS so that it was back in spec. However, the idle is still all screwy, and the car likes to turn one rotor off under partial throttle below 3k rpms. Could it be something wrong with the ECU or what? Im out of ideas on what sensor to look at next. I also checked the CAS last night, and between the Ne leads i got 187.6 OHMS, and between the G leads i got 192.9. According to the S4 fsm it says they should be between 110-220 ohms, so it appears to be in spec. What should i check next? Thanks

RoninRX7

how much vacuum should the engine pull at idle?

BoostedRotors

It is sounding a bit like some vacuum problems. Have you run the car without emissions before all this happened? Just wondering if everything is capped and block off properly.

Mankdrake 2661

iTrader: (8)

I second the vacuum leak.....
Get out a can of carb cleaner and start checking.

HAILERS

Your right. Your tps is cutting the fuel much like on a NORMAL car, where you are driving along and let off the throttle. Let off and the TPS signal tells the ECU to cut fuel til the rpms drop down to the low 1000-1100 range whereupon the ECU turns the injectors back on.

What you have is HIGH RPMS combined with a TPS set at those HIGH RPMS INSTEAD OF TPS set at approx 750 rpms. And in addition you have the ECU seeing a figure over 1100 rpms so it's advancing the timing at the same time. All screwed up and somehow you need to get to square one again...i.e. at 750 rpms at idle.

RoninRX7

i dont think there are any vaccuum leaks because it pulls about 16psi of vac at idle. the reason i turned the throttle speed back up is because since its shutting off the rotor it wont idle that low. 1200 is the lowest it can go and still keep running.

HAILERS

Square one could be hard to get to.

Initial set coupler jumpered to set the duty cycle of the BAC at....a set duty cycle. This step won't do squat because the *idle* is waaay highj.

Set the TPS. This won't do you any good because the throttle linkage is NOT where it's supposed to be with the idle at 750-800.

Set the timing.......This won't do you any good because it can't be done with a idle over 1100 rpm (ECU automatically advances the timing at that speed).

I'd spend as little time as possible even remotely thinking about the tps until the idle is set to approx 750-800 rpms. Very little time thinking about it.

The water thermowax can hold the throttle open if there is no water flowing thru it from the rear rotor housing. IF it does not extend the throttle plates will always be open more than they should be. See the FSM, Fuel section and the part about setting the water thermowax/fast idle cam etc.

Since you turned a screw to hold the throttle shaft open, that needs to be undone first. Then tackle the water thermowax then once the idle is down to around 800 or less, set the timing and install the initial set coupler and turn the BACs air bleed screw til the idle is where it should be.

Setting the idle can't be done or explained very well online.

RoninRX7

I actually no longer have the BAC. All of the emissions and stuff are removed and blocked off. I have the timing set, and i did have the idle set at 800 rpms, with the tps adjusted correctly, and it wouldnt stay running once it started to spudder on one rotor. I had to turn the idle up, because when it was at the regular spot, it shut off. i couldnt even leave the car because as soon as the throttle was lifted off it died. The thermowax is still intact, but the TB is modded and the secondary throttle cam and butterflys have been removed as well.

Another thing i forgot to mention is that there is a large exhaust leak at the exhaust manifold. It is somewhere between the turbo and manifold, so its one of those flanges. Could a large exhaust leak cause the extreme hesitation that sounds like a rotor is shutting down and a massive loss of power?