'03 GTP. Driving me crazy.

**rcktmn455** · 04-26-2012

Hey all.

Sorry this may get a bit lengthy.

I have been having a random issue with the car. A little back ground on the car. It is a 2003 gtp with 145k miles. It will whenever it feels like it, it will start to run rough and rich. The idle will fluctuate. Sometimes it will drop and sputter. Then sometimes it will climb up to 3000rpm. It will smell like it is running rich and the o2 sensors will both have a high voltage reading according to the scan tool. At times it wont want to shift unless I ease up on the throttle. There have been times it would act up and I could put my foot to the floor and it will do nothing then all of a sudden it will take off.

The codes that it will give me when it will give me any. It doesn't always have a code. The codes will be po101, po102, po121, po502, and sometimes p0446? I think.

Things I have tried. Replaced the Maf, Map, Tps, Plugs, Wires, Air filter, Fuel Filter, Fuel Pressure regulator, Ignition Coils, Vacuum lines, Downstream o2 and cat, Temp sensor. I cleaned out the throttle body. Cleaned the ground at the transmission. I have sprayed it down repeatedly with carb cleaner and no luck finding any kind of vacuum leak.

The damn thing is driving me crazy. If anybody has any good ideas I would love to hear them.

Thanks.

**FordMan77** · 04-26-2012

Maybe you have a flaky ECU?

**rcktmn455** · 04-27-2012

That is kind of what I have wondered from the beginning. I forgot to mention when it does all this it also retards the timing and the boost bar graph on the dash goes crazy too. I am thinking maybe it is time to order a new ecm and have them dealer flash it for me.

**BillBoost37** · 04-27-2012

Guessing after a night of drinking...so keep that in mind.

Looks like you have a pile of sensor codes there (I'd know more if you named them, but hey.. I'll guess just the same) If I saw a tps, maf and blah something or other, my first thoughts would be grounds and or power related. It's unlikely that 3-1,000,000 of your sensors all eff up at the same time.

Someone gimme another beer, I hear it helps.

**rcktmn455** · 04-27-2012

Originally Posted by BillBoost37

Guessing after a night of drinking...so keep that in mind.

Looks like you have a pile of sensor codes there (I'd know more if you named them, but hey.. I'll guess just the same) If I saw a tps, maf and blah something or other, my first thoughts would be grounds and or power related. It's unlikely that 3-1,000,000 of your sensors all eff up at the same time.

Someone gimme another beer, I hear it helps.

I guess code definitions would help lol.
po101 Mass or Volume Air flow circuit range /performance problem
p0102 Mass or Volume Air flow circuit low input
p0121 Throttle Position Sensor/Switch A Circuit range/performance problem.
P0502 Vehicle Speed Sensor Low Input
p0446 Evaporative Emission Control System vent control circuit malfunction.

I tried passing you another beer thru the computer but... yeah.

**BillBoost37** · 04-27-2012

That explains the splashed beer on your keyboard. lol

All those circuit malfunctions have me wondering. Where's Chuck with the power schematics for the sensors. There's commonalities for power and ground in some of the sensors. i'm thinking along those lines at the moment.

hey Chuck... got a schematic laying around?

**Rico** · 04-27-2012

No, but I can tell you that all 5 volt references are bundled in the PCM. Once one is bad they're all bad. This doesn't look good. Make sure his battery isn't on the fritz.

**BillBoost37** · 04-27-2012

Originally Posted by Rico

No, but I can tell you that all 5 volt references are bundled in the PCM. Once one is bad they're all bad. This doesn't look good. Make sure his battery isn't on the fritz.

What the heck is that, that's not a schematic...lol

**Rico** · 04-27-2012

**Rico** · 04-27-2012

All 5 volt references are from the same place (top of schematic) and the return signals are all separate, of course, on (bottom of schematic).

**BillBoost37** · 04-27-2012

Knew ya had it in ya.

**rcktmn455** · 04-27-2012

Awesome. Thank you guys. It looks like I have some wiring to check this weekend. Thank you all very much.

**Rico** · 04-27-2012

After looking at the schematic I noticed that the MAF is not part of the 5 volt bundle. This would force me to check the system voltage at the PCM. With the key in the "on" postion it should havea about 12.5 volts. Also check the ground distribution for the PCM.

Power distribution schematic (early 2003):

**Rico** · 04-27-2012

2003 fuse block diagram:

**rcktmn455** · 04-29-2012

Something I was wondering here. As I was thinking about when it does actually act up. It seems to act up more often when the car has ran for a bit. I was thinking that maybe it could be a cracked pcb in the ecm. As it warmed up the board would expand and cause a crack in the board and make it run like this. Any thoughts oh great ones?

**Rico** · 04-29-2012

Possible but highly unlikely. The sub component structure or PCB is very hardened. They were designed for abuse; cold, hot, vibration etc.

Start out with the easy stuff like:
System voltage
Supply voltage at the sensors
vacuum leaks
Evap system
etc.

Unless you have a PCM laying around, check for other problems. If all else fails get a new PCM or have yours tuned.

BTW Why would you change the downstream O2 sensor? What about the upstream O2 sensor? You say you replaced the catalytic converter?

**Speedy1973** · 04-29-2012

by the way you descrobed it in your 1st post, i had the same kind of problem with my dads old jeep (its a 89)
On my way to school with it one morning i stoped and got gas at a Woods Station (cheap sh*t) i filled the jeep, and on my way into towm it was doing exactally what you described, when i got to the school, i skipped 1st period took it to the autoshop, where me and my tech teacher came to the conclusion that there was insane amount of water in the gas.

sorry but thats my 2 cents*

**rcktmn455** · 04-29-2012

Rico- I changed to downstream o2 when I changed to cat ( it was glowing red one night on the way home form work). The upstream I didn't change because I had snapped my swivel socket when I was trying to get it loose.

Speedy1973- I have used different gas stations and still the same luck, but thanks for the input.

**Rico** · 04-29-2012

What is the supply voltage at the PCM?..Should be at least 12.5 volts.

Have you tried unplugging the MAF sensor when it starts to act up? This will force the engine to run from the tables without sensor input (speed density mode).

Where did you get the MAF from? The MAF's sold at local auto part stores have been known to caused many people a lot of grief.

**rcktmn455** · 04-29-2012

I haven't checked the supply voltage at the ecm yet (been a rainy crappy day today).

I tried unplugging the maf and map with no change to it acting up when I can get it to act up it is very temperamental. I have even plugged in different ones when it is acting up and no change.

I have used new and reman pieces with the same results. Used multiplies of each. (advantages of working in auto parts.)

It has been a battle for months now. I do appreciate every bodys help here and hopefully with your guys help I can kick this ### in the A33.