Random Stalling Out
 

I just got my 93' back about a week ago from having the engine rebuilt and even though I'm still breaking in the engine; it tends to randomly idle down to nothing and cut off. :confused: Some days it runs perfectly and other days it will just idle off as many as 5 times in 20 stops or so. When it does happen, it always does it when there is no load on the engine. ie. - nuetral or the clutch disengaged. Any suggestions on where to try to troubleshoot would be great. Below is a list of my pertinent mods/parts. Thanks in advance...

Streetport
Stock Twins
Aluminum AST tank
GReddy Alt/water pump pulleys
Air Pump removed
AWS removed
GReddy 2 Row FMIC
Efini Y-pipe
3" SS downpipe
3" Gotham Racing High Flow Cat
3" GReddy SP2 Cat-back
APEX'I PowerFC w/Commander
GReddy Profec B 2
Nology Spark Plug Wires
Silicone Hose Kit
GReddy AIRINX intake
GReddy Type S BOV
Koyo Radiator

If EVERTHING is hooked up properly, most likely your idle parameters are not set up properly in the PFC, or you need to manually adjust the throttle for more air using either of the two mechanical idle adjustments.

That, and the TPS could be slightly off (voltage-wise). It controls your idle as well. But when your TPS is off, the problem is consistant, not intermittent. Just wanted to throw it out there as a *possible* but unlikely option.

Use your commander to check the clutch switch too. You should see a on/off or solid/hollow dot for the clutch switch sensor. On your good days, what is the stable idle speed? You may also consider the dashpot and, as suggested, look at the idle/decel idle screen for various electrical loads. Sometimes setting a higher decel idle can help prevent stalling out. When checking the TPS, warm the car up first, then shut off engine with electrical still on and press the gas a few times, you'll see the full range. There is a recommended process for manually adjusting idle though so reference the shop manual (www.iluvmyrx7.com ?) online if you don't have a hard/digital copy. (If you know all this already sorry to speak as if you don't, no insult intended.)

Thanks for the suggestions guys...I will take note of the TPS electrical load and post the readings in a day or 2. I took my car back up to the shop and had the owner of the shop completely retune my PFC. He adjusted the TPS as well as 2 of the mechanical idle adjustment screws. It drives smoother than ever with the adjustments he made, but as soon as there is an electrical load. ie - lights, AC... it will bump up the RPMs like it should, but once it does that; the car can't maintain a solid Idle. The RPMs bounce from 1200 or so to as low as 562... which makes the car sputter, but it sometimes catches itself and revs back up to the 1200s before repeating the cycle. The owner of the shop said in the 20+ years hes been doing this, he has never had a car do this on him. Just my luck... One of his theories has something to do with my electrical system... great start there... The other theory has something to do with my idle control unit. I apologize if I bastardized the proper term for that part. Hope some of this new information helps to narrow down the search for a solution since my initial post..

So hold up...the idle is bouncing between 600 and 1200 or so, and continues to cycle as such? Sounds to me like the famous PFC idle bounce/search, which I have on and off, too. It can be caused by not allowing the PFC to learn your idle when you first map it (or any time you erase the maps and retune). The PFC requires that you run the car for x minutes, then turn on the A/C and lights and run it for x minutes etc etc so it can learn the idle. Something to think about.

Do share what you find is the problem. Mine does the exact same thing, but I'm on a stock ECU. Let me add that on start-up, when I blip the gas to bring it out of the 3,000 rpm jump...the tach. drops like a rock and it dies. My mechanic thinks it may be a vacuum issue. Everything's a guessing game with this car! Maybe between your mechanic and my mechanic, someone will figure it out.

It sounds like you just have your idle set too low. When you blip the throttle, it jumps outta the AWS, and the revs drop. They drop too low, and the engine stalls.

Next time she's warm, find where she's idling at. She's prob at around 600rpms or so. Normal's 750 - 800 rpm IIRC (haven't had a normal idle in YEARS lol). Mess w/ the idle set screw to bring it up to the proper idle level, and your problem *should* disappear.

FD... would you suggest just letting the car warm up at idle and once fully warmed up, turn on the A/C... and let it cycle the RPMs until it has that smoothed out before turning on the lights? It is almost guaranteed to stall out after I turn on the lights however. I do recall the original fuel map being wiped and having a revised map being uploaded into my system. He might not have allowed it enough time to learn the proper RPM settings for the AC & the Lights though. Were you able to fix your issues with your PFC?

Not unless you have the map saved and can load it again (need a dataloggit, right?). Cuz to relearn your idle, you have to erase the existing maps/settings on the PFC. Gotta start from scratch. It can't relearn it mid-way. Of course, you could also prob have a senior tuner smooth out the idle.

Ray @ PFS tried fixing mine, but I have a figity TPS and I don't have the FIC on my TB. I'd have to address those issues first. So in short, nope, I still have the bounce. I like it tho...it's grown on me :D

Thanks! I'll give it a shot. It does seem to idle where it should, but then again...my tach. has been acting funny...might need to get a new one.

I'm about to lose it. Today, for the first time... the car cut out on me 3 times in less than half a mile. Each time it happened when I had the clutch pushed in. I had nothing else running... no AC, lights, or even my radio. This is driving me crazy. As soon as I get another day off, I'm taking it straight back to the shop.