hot mess

[pontiac3100]

well i replaced the pcm with the right pcm.
and it runs good.

till recently it starts....bogging at high rpms.
till is warm up under the hood.

i checked two of the plugs and they have some crap on the tips and they look worn....and i replaced them not to long ago.
and they're rapid fire....someone said i was supposed to used the platium

also she seems to misfire....but it seems the pcm does'nt see the misfire.
why not?
and is it possible the coils crap out till they're hot

[pontiac3100]

anyone...please

[MATT2007]

if you are sure it is misfiring try swiching the coils around and see if the miss fire falowes the coil

[pontiac3100]

okay i replaced 2 coils (one was already replaced) replaced 3 wires(engine too hot to replace the rear 3)
and her idle was smooth.

drover her and the high rpm stumble was somewhat there.....she only did it eh 2 times within the 3 hour drive.

the second time was on the highway:

i kept passing and the 5th time i passed.
the tranny tc locked then she bogged.
while not feeling it i seen it on the tach and smelled it in the exhaust.

[geoffinbc]

Well try the back wires. Did you check the back plugs too?

Also the modules are known for failing when they get about 100,000 miles or so on them

[pontiac3100]

damn!
wait the pcm or icm?
that would make since though(on the icm).....once it's hot under the hood she performs so damn good.

i did'nt check the back plugs....seeing that the two front were screwed.

i'm still wondering how come the pcm does'nt know the misfire?

[pontiac3100]

i replaced the back wires.....now this is gonna seem weird to you.
it seemed fine when i replaced them.

then when i used bp mid grade the problem seem to come back till she warmed up a bit more....

i'll try the icm this week...again
what else could it be?

[torq455]

if it's not the ICM maybe cause BP isn't a top tier gas company. maybe using a low grade fuel is leaving deposits on things. get some good fuel injector cleaner and start using top tier gas. for dealers go to topteirgas.com

it may not be reading a misfire code since it's obdI.

[pontiac3100]

but even obd1 has mifire codes...
hmm the last time i used fuel injection cleaner...chevron techtron(some people recondmend it since some gm cars/trucks fuel sender gets crud on it.

i've used shell before but she seem to drink it like water.
bp and shell seems like to be the top tier gas.

something under the hood is not relaying the right message to the icm/pcm till it gots hot under the hood.

i went onto the site...whoa, bp's not on there.

[torq455]

yeah!!

[pontiac3100]

ya wanna know something funny...i just reread what you wrote...lol.
okay well lets see....i can use my a/c the rest of the week and driver her hard...that sould got trough the tank.

today i got another pcm from a grand am gt.
i matched the numbers and they matched.
the only thing different is the speed rating the original one was u rating(top speed 124mph)
while the "new" one is h rating (130mph)....
and she runs good.

but i should be able to refill by sunday...i got alot of places to go.

and i'll come back wth an update

[pontiac3100]

okay (sighs) here's the update.

replaced icm, coils,wires.

i removed the cam sensor harness whil ethe car was running...no ses light.
figured eh she's still in open loop mode.

i read in the chiltons manual that when the cam sensor is bad the pcm will shift to a calculated program but when you shut off the car and try to restart it...you won't be able to.

okay i drove her for about a good hour...no ses light.
i stopped at my first stop shut her off and started her up....and she started?

i left it out for a while.

each and evrytime she started...only differences is theres a slight hesitation between 600-1000 rpms on take off.

flooring it it did'nt do the bogging, or stumble.

hooked up my scanner came up with two codes cam sensor circuit.

no egr code.

connected the cam sensr and egr harness back.

drove started to floor her and she acted up.
i thought damn so it is the cam sensor.

so to be sure i removed the harness again.
and she still did it.

but after the icm replacement here's the thing she only does it around 5,000-5500rpms.

so i hooked the scanner up.
the coolant sensor is fine.

what i find suspicious(msp?) right now is the tps or o2 sensor.

when the engine is cold the volts flunctuate between .40v-.50v quickly.

when warmed the volts read out .51v at idle.
at wot the volts read 4.34v

the o2 sensor readings changes quickly but where the readings are makes you wonder.

on the highway the readings are above 500mV.
but when you let the gas go or when you sometimes floor it the readings are under 500mV.

oh yea also when the bogging happens i smell the richness.
other than that...nothing.

[pontiac3100]

^^^^^please?

it's back to the same thing.

[Steevo]

I don't believe it would be your O2 sensor as it should be a narrow band sensor just for tuning the car at steady load.



Sounds more like a MAF or MAP problem to me. Then again, I do not work on these every day, or very much to be honest. I usually am working on my Celi these days.

[pontiac3100]

this morning in drive the rpms sometimes get low (500rpms)and it bouces up and down a little.