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'03 GTP. Driving me crazy.



So it did act up today for me finally. A quick check of the battery was something like 14.3v. I had battery voltage at the ecm fuse (hadn't checked at the ecm yet. I got a good 5v reference at the maf, tps, iat, upstream o2, and the coolant temp semsor. ( ran out of time was on my lunch break). On the drive home from work it continued to act up. Usually after sitting for a few minutes it is fine. On the drive home 18-20 miles highway it burned thru 1/8 tank of fuel. I tested the battery and altenator today at work and they tested fine. The wife is making me drive her monte for now so hopefully I can tear into it a bit and get voltage readings at the ecm. Also tried running with the gas cap loose and no changes there.
 
I can't believe you're not getting a P0300 random misfire. Hmm.

The only things I can think of:
Check injector duty cycle when it acts up.
If duty cycle is normal then it may be a dead injector - have any laying around? (should get P030X though)
Bad temperature sensor (you already replaced?)
Is there a gasoline smell coming from your oil?
Is there any coolant in the oil? (TB coolant o-rings)
Are you sure the SC BBV is in working order?

It looks like you've thrown everything but the kitchen sink at this thing. If it were mine I'd pull the supercharger and LIM and check everything.
 
Once again thank you. I will try the coolant sensor again and check all those things. I think for now it is going to sit for a few days and maybe I can regain some sanity there and besides I need to clean out the garage and make room for it anyways.
 
rcktmn455 said:
Once again thank you. I will try the coolant sensor again and check all those things. I think for now it is going to sit for a few days and maybe I can regain some sanity there and besides I need to clean out the garage and make room for it anyways.
Click to expand...

If you do all this and it still acts up then it might be time for a re-flash or a new PCM.

Maybe someone here will chime in with an easy way to check for a faulty PCM?

Good luck
 


PCm is usually the kind of thing that you do after you've lost all your hair.

Chuck.. hows the TB o-rings allow coolant in the oil?
 
BillBoost37 said:
PCm is usually the kind of thing that you do after you've lost all your hair.

Chuck.. hows the TB o-rings allow coolant in the oil?
Click to expand...

I'm thinking coolant getting into the cyclinders and seeping by the pistons. I guess LIM gaskets would be a better culprit.

Could the BBV cause any of these symptoms Bill?

I think this guy has lost almost all of his hair at this point.
 
He doesn't have a BBV, he's got a BCS. But no.. I doubt it.

Lim's not often leak enough to put oil in the cylinders and usually not enough for misfires. The TB o-rings would allow coolant to be burned, very little would get past the rings though.
 
The coolant level doesn't seem to change and at the last oil change it didn't smell of gas or anything like that. When I changed the plugs they just looked worn. None of them appeared steam cleaned. I forgot to mention yesterday that when it was being a pita it didn't want to shift. Nothing like screaming down the highway in second gear. As far as the hair goes well yeah..... lol.
 
Which is understandable with some of the codes that you are getting for the various sensors.

I'm wondering...maybe a break in a wire where it's getting contact some of the time. Have you tried wiggling the engine harness with the engine running?
 


Let's review.

Symptoms:
After engine is hot, starts running rich and sometimes won't shift
O2 sensor signal high (rich)

Codes:
P0101 MAF circuit range performance
P0102 MAF circuit low input
P0121 TPS intermittent signal
P0502 VSS circuit low input
P0446 EVAP incorrect purge flow

Things you've thrown at it:
MAF
MAP
TPS
Plugs/Wires
Fuel filter
FP regulator
Coils
Downstream O2
Catalytic converter
Temp sensor
Checked grounds
Cleaned TB
 
My attention is toward P0121. If you replaced the TPS and you're still getting P0121 then there may be a problem with the wiring. Have you checked the TPS for a smooth signal from idle to WOT? Should be 0.5 volts to 4.1 volts without dead spots.
 
Ehhhh start car.. fiddle with wiring.. you'll hear it get goofy if wigglin does the trick. Then the issue is....finding it. Seems like ti's power or ground related. Unless the circuitry in the pcm went south.

If this were a 95 H body car...I'd have suggested a pcm long ago.
 
I have tried wiggling the wiring when it was acting up no changes there, hell I even smacked the air box a couple times no luck there either. I just checked the tps. It is nice and smooth from .433v to 4.07v.

So tomorrow I am going to bite the bullet. swallow my pride. admit defeat and take it into the dealer. ughh.... I will let you all know what they find out.
 
So I realized that I have been slacking on an update here. So here goes the long and amusing story.

The car went to the dealer on Thursday morning. On the way in it acted up for like 4 blocks and came right out of it. (Go figure). The tech drove it around for about an hour with no luck getting it to reproduce the problem. After a bit he deicded to replace the ecm. The car drove better afterwards and we were both happy with the results. So at the end of the day I go to pick up the car and it wont start now. The tech did some checking and found the crank sensor went out. On Friday the crank sensor was replaced and the car wouldn't start. The tech ended up putting the old ecm back in and the car started and ran fine with the old ecm. So now I go pick it up again and it starts and runs fine. I get about 4 blocks away and it acts up again. I turn around and head back and of course the car goes out of it before I get back. (grrrrr). He pulls the pending code real quick and comes up with the maf code again. Beings they didn't have a genuine gm one in stock we didn't replace it at that time. But he did end up tighting the pins in the connector and one my way I went.
So now I am back to new crank sensor old ecm. I get to thinking and checking and realize that all the maf sensors I have put in have been reman and not new. So I ordered up a new unit and kept it in the car. Now Tuesday it acts up at lunch, Sweet! I pull the code, maf again. The scan tool also shows a 14% load on the engine at idle, strange. So I replace the maf, clear the code and it has run fine since.
I hope this takes care of the problem because it is driving people crazy.
 


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