96 GA 3.1L irratic idle

[meow700]

-The vacuum modulator seems fine, all vacuum lines going to it seem -fine....engine light bulb is blown(ironic isnt it) so i don't know if check engine light is on
-trans fluid level is good


What would cause the rpm gauge to go berserk??? it definitely has never acted like this before and is not showing what the true engine rpm's are

[3100]

rpm is icm/pcm controlled, what exactly is rpm gauge showing at what speed?
do you feel up shifts or not? You need to scan it for codes - go to autozone write your codes and we will see what we can do.

what happens when you remove that vacuum line form the top of the fuel pressure regulator? Do you have vacuum pump? if you do connect it to vacuum modulator and apply 15 inHG of vacuum it should hold vacuum.

also test your TPS sensor, when sensor is connected engine runing, you have to probe at the back of the signal wire, it should read about .59 V DC at idle and should smoothly increase as you increase throttle if you see any gaps in voltage replace tps.
wait 5 min I will tell you what color is your tps signal wire.

[meow700]

I dont have a vacuum pump.....

The gauge is accurate when im at idle but if i accelerate it will jump lets say if i have it floor the car only revs to maybe at the most 4k and pops and bogs, and cant get over that point but the rpm gauge will be sweeping from 2-6k or steady out at some random rpm.....but the engine remains generally in the same place

it has a new TPS sensor in it.....maybe at the most 30k on the new one....I also can no longer wrench and clunk around outside as im worried about making to much noise at 2 in the morning......gotta love living in town

[3100]

ok it is pin "C" DK Blue wire, don't have diagram for 96 but 98 should be the same.. Get some sleep now and in the morning go to autozone ask them to scan your pcm

in PARK you cant rev it more than 4000 rpm it is engine protection feature.

we will see tomorrow maybe ICM?

[meow700]

switched ICM today. still no difference...I want to take it over to autozone and get the codes read but I don't want to drive it clear across town to get to it...I don't know if it would make it...it still does the same thing Rpm gauge bounces all over(not the engine rpm just gauge)...and it still pops through intake, and has no power, also whatever is affecting the engine and rpm gauge is also making the car shift funny.

[xeroinfinity]

If its backfiring in the intake, the timing is off.

did it run better before the crank sensor was replaced ?
Might have to do a CKP relearn...

[meow700]

how do i do a CKP sensor relearn??

[3100]

you need a good scan tool for that,

- you must not have any codes
-engine temp. must be at the normal engine operating temp.
-go to ckp relearn procedure
-scan tool will tell you what to do
(most likely it will tell you this) - start engine, in Park press brake pedal with left foot, press gas pedal up to 4000 rpm (fast at once) if everything was done correctly it would show you that the relearn procedure was successful

[xeroinfinity]

Well you need to know if its throwing a DTC for the CKP.
And you need a good scan tool that can performe the CKP relearn, if it even does need done. Doesnt always happen to throw the trouble code or cause problems.

But your popping in the intake sure sounds like its outta timing.

[meow700]

So here is something interesting i switched the ICM back to the one I had on it before because oviously there was nothing wrong with and now the car won't start...so i think i might have a bad wire in one of the connections to the ICM...I wiggled wires and tightened the prongs up within the plugs but so far it still won't start.... I have to go to work now so i guess this weekend i will be diggin out the volt meter and check wiring

[3100]

When you engine is warm and you turn off the engine and key is out, does the coolant temp gauge go down to cold?

[meow700]

I have tonight off from work...I am going to try to get it running again and i will see what the temp gauge does...

[3100]

to help you start it ICM has 3 connectors. 2 on the drivers side of the ICM and one on the passenger side of ICM. The one on the passenger side of the ICM I almost all of the time forget to plug in since it is hidden by all kinds of hoses and wires. So check if all 3 connectors at the ICM are connected.

[xeroinfinity]

when you switch the ICP back and forth its not going to start with out doing a relearn for the ICP.
Same as the others, key "ON" for 11mins (or more)
Off for at least 30secs, then repeat. The security light should come on and flash off after the 2-3 time.

This thread is gotten out of hand for just a simple irratic idle problem.

If you seen my previous post, #7 you'd have this narrowed down.