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LQ1: Puzzling Code 24 problem


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Posted

Well, the Cutlass began acting incredibly strange and revving for no apparent reason earlier today. It would rev at idle, in neutral, whenever. It would hover between 1000 and 2500 RPM. I originally thought it could be an IAC problem, so I removed it and cleaned it, and made sure the TPS was properly attached. I took it for another drive to see if it made any difference. None at all. I pulled the battery and let the ECM reset. Idled for 10 minutes. Idled fine. No revving, no strange behavior. Put the car in first and began to slowly drive off. Revving started again. A code was thrown at this time. Code 24, which is a VSS problem. Okay? Strange. Reset the ECM again. The SECOND the car was turned back on, it started revving again and threw the code once more. This makes the problem very puzzling. Why?

 

Test Description:

 

1. Code 24 will set if vehicle speed equals 0 MPH when:

    VSS indicates less than 2 MPH.
    MAP is less than 30 kPa.
    Engine speed is between 2200 and 4400 RPM.
    TPS is less than 2%.
    Not in park or neutral.
    No Code 21, 22, 33, or 34.
    All conditions met for 3 seconds.

These conditions are met during a road load deceleration. Disregard Code 24 that sets when drive wheels are not turning.

 

    The PM generator only produces a signal if drive wheels are turning greater than 3 MPH.

2. If CKT's 400, 401 and 389 are OK, and if the speedometer works properly, Code 24 is being caused by a faulty ECM, faulty MEM-CAL, or incorrect MEM-CAL.

So.. I threw the code under both circumstances.. WTF?! Not only that, where the fuck does this whole revving issue come into the picture?!

Posted

VSS less than 2 mph-- the transmission speed is not causing a high idle

MAP is less than 30kPA-- there is not a vacuum leak

Engine speed is between 2200 and 4400 RPMs-- Car is idling high

TPS is less than 2%-- you are not pressing the gas

Not in park or neutral-- I would guess does not pertain to you

 

That is what the computer is acknowledging and it doesn't know why.

 

Basically the car is idling high, while there is not vacuum leak, you are not pressing the gas, and the transmission rotation is not causing it. I would check for a vacuum leak.

Posted

i had the weird reving problem when i first got the car..I mean, it was all over the place. when i'd let off the gas and take it out of gear, it would rev to 3500 and hang there for like 5 seconds and then drop back donw. At idle, it was between 1k and 2500.....and 1 month later, the ICM went out....

 

 

I pulled the code 24 also when I had the car because the SES light was always flashing and the shift light was always off and on, but when sean had the car, he found out it had an auto Chip in it when the car is a 5-speed. He put ben's chip in and i think it fixed it....i dunno what ur problem is now....

 

if the ICM does go, I gave sean the reciept from oreillys where i got the ICM. It has a lifetime warranty and I told him if it goes out, to sent the ICM and reciept to me and i'll get a new one, and send it back. I'll do the same if he gave the reciept to you also.....

 

Good luck with what you find out.

Posted

Thanks, Adam. I'll go through my folder and see if I can find the reciept for the ICM. But yeah, that's pretty much what it's doing. I left the battery unplugged all night to see if that makes any difference. I have to go to the post office right now, so I'll post my findings when I return.

Posted

UGH. Absolutely nothing has changed. To make matters worse, my license is getting suspended AGAIN because of a FUCKING ERROR THE STATE MADE. I don't have time to be fucking with this car, and I'm going to need some more reliable than something that's 15-years-old. It may be up for sale again once more..

Posted

Upper Intake manifold gaskets are somtimes a problem on the 3.4 DOHCs arnt they?

Posted

You can hear the IAC being open, and you can feel the air being sucked in through it's port in the TB. Something is telling it to open and close randomly.

Posted
You can hear the IAC being open, and you can feel the air being sucked in through it's port in the TB. Something is telling it to open and close randomly.

 

Mabye find a known good one and swap it in and see if it solves it?

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