2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Uneven idle, RPMs jumping, car stalls.

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Old Nov 26, 2004 | 02:36 PM
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Thumbs down Uneven idle, RPMs jumping, car stalls.

I had a thread earlier and i was explaining what was wrong with my car... i got the 5000rpm to stop.... now the car starts jumps to 1500 and then dies... i tried to start it with the throttle cable as tight as it can go.. and the engine revs up to 7000rpm+.. i shut off the car.. now i tested it with the throttle cable off and all the vacuum plugs are intact... and the engine starts up to 1500rpm and then just dies... i doesn't stay on for a couple seconds it just starts and dies... i jumped the yellow connector and it does the same thing... i tried the atf trick and it does the same thing it revs up to 1500rpm and dies... it does smoke alot tho for that whole second it starts up... i tried to reverse the fuel lines and it doesn't start at all... i cleaned out my intake and throttlebody with carb cleaner and tried to start it up again and nothing... well im just explaining what ive done so far... this is the best i can explain my problem...
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Old Nov 26, 2004 | 03:28 PM
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You have a huge vacuum leak somewhere. Did you check the brake booster line that goes back side of the UIM? Re-check what you took off.
AFM ?
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Old Nov 26, 2004 | 04:09 PM
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Check you're water thermo sensor. It's below the front of the alternator on the back of the water pump housing. It's a green connector with a wire clip holding it in place. If it's disconnected or not working the car will start then die after a few seconds. I had the same problem last week. I forgot to reconnect it after i ran my new fuel lines.
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Old Nov 26, 2004 | 06:59 PM
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fuel pump, take it out and see if the in tank filter is clogged or you might just need to get a new pump.
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Old Nov 26, 2004 | 07:29 PM
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From: Lindenhurst
im going to check everything tomorrow.. its 8:28 in new york right now and its cold and dark... and i dont have a garage yet...
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Old Nov 26, 2004 | 07:43 PM
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about the water temp my gauge does work i have an extra clip back there tho that could hook up to the water temp sensor clip but i haven't tested the other one... could this be what your talking about ???
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Old Nov 26, 2004 | 07:51 PM
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why would i needa new fuel pump if when i press the gas the engine does rev up it just doesn't stay on by itself or idle.. and lets say i press the gas when trying to start it... it will turn on one in a while but not every time... oh and i didn't mention the fuel filter is new but the fuel pump has 72,000 miles thats who much the car itself has
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Old Nov 26, 2004 | 08:49 PM
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Vaccum leak or bad TPS. Thats my guess.
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Old Nov 26, 2004 | 09:25 PM
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From: Zeeland/Holland ,Michigan
TPS or Vac leak or leak intake after air flow sensor, guaranteed..

Also what year car is this? I know the S5's can have the vaccum line pinched and controls the scondary throttles(if they are still there) and this can cause a similiar problem
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Old Nov 26, 2004 | 09:39 PM
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Other then whats satated I would like to greet to the Official Elite club here, the "Whats an Idle......Your car turns on in 3 seconds?.....It moves foward? club"
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Old Nov 26, 2004 | 10:03 PM
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From: Lindenhurst
mines a s4 .. its a 87... and i dont know what the hell Aesop Rock is talkin about ... but i am really thinkin about getting a new throttle body and new tps... i just took of the throttle body because im bored out of my mind and it looks like somebody took out the screws on the butterfly flaps... maybe there was play and messed the whole tb up... could this cause my problem?
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Old Nov 27, 2004 | 12:13 AM
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Before you replace the TPS, test it with a DMM and see if you are getting the correct resistance readings, as per FSM.
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Old Nov 27, 2004 | 08:22 AM
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Originally Posted by rx7reality
about the water temp my gauge does work i have an extra clip back there tho that could hook up to the water temp sensor clip but i haven't tested the other one... could this be what your talking about ???

No, it isn't.

On the backside of the water pump, right under the alternator, is where a coolant temperature sensor plugs in. It's a green plug, and it sends information only to the ECU. The temp gauge in your dash gets its info from another sensor elsewhere on the block (one that's down below the oil filter.)

If this sensor stops sending a signal to the ECU, for whatever reason, the ECU assumes that the car is up to operating temperature (b/c it can't 'see' the actual coolant temp anymore) and sets the air/fuel mixture accordingly. And unless it's a warm, summer day where you are the car will be a bitch to start.

But once she catches she will start and run. You just have to babysit the throttle until she warms up. I went through this two winters ago.

Anyway, this isn't your problem.



The most common reply to 'my engine starts then dies instantly' is 'check your AFM.' Have you checked yours?
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Old Nov 27, 2004 | 10:01 AM
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From: Lindenhurst
ok i will test that today
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Old Nov 27, 2004 | 10:02 AM
  #15  
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From: Lindenhurst
i can't find the specs for the tps in the FSM
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Old Nov 27, 2004 | 11:29 AM
  #16  
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Oh its in there.....I did this about 2 months back.
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Old Nov 27, 2004 | 09:24 PM
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For TPS:

Idle position: 1k ohms
Full open: 5k ohms +/- 1k ohms
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Old Nov 27, 2004 | 10:47 PM
  #18  
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From: Lindenhurst
i put my multimeter on voltage drop?? or ohms or what ...
another not to smart question because it does say ohms on there but just making sure
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Old Nov 28, 2004 | 11:14 AM
  #19  
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From: Lindenhurst
i can't do nothing today... its raining over here... so im gonna wait till monday
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Old Nov 29, 2004 | 02:13 PM
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got your PM. I'll go through the FSM for all you need. Also I have a spare TPS, if you need it.
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Old Nov 29, 2004 | 02:14 PM
  #21  
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Out of curiousity, is your dash pot installed still?
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Old Nov 29, 2004 | 04:21 PM
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Originally Posted by rx7reality
i put my multimeter on voltage drop?? or ohms or what ...
another not to smart question because it does say ohms on there but just making sure
Yep. Ohms, preferably on K Ohms. Again, with the throttle closed, you should be getting 1K Ohms (1000 Ohms) and at Wide Open Throttle (WOT) 5K Ohms +/- 1K Ohms.

Warm up your engine first and shut it off. Disconnect the TPS and connect the DMM.
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Old Dec 1, 2004 | 07:54 PM
  #23  
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Bump, whats the progress?
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