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im stumped please help

S

sic40th

New member
okay I have a 2000 gtp that I use as a dd it has 138000 on the clock. anyways I just got done doing a bunch of stuff to it. oil change, dropped the trans pan and did the filter, fuel filter, plugs, right side axle and hub, new belts, front struts, cai, thermostat and I put a new cat back on. so when I started it up for the first time after I did all of this it ran horrible. I thought it was from just sitting for a couple of weeks.the next day I drove it and it ran awesome great power and no problems but the temp light would come on but the gauge read just like before. so today drove it to put gas in and just like the day before it ran awesome but the temp light came on again, but when I got almost home it started running horrible again just like it did when I first started it up. it had no power like it was on 2 cylinders. when I got home I plugged it in and it showed no codes so I don't know where to start. I have a newer zzp down pipe on it so I guess i can rule out a clogged cat. forgot to say i changed out the plugs after it started running bad. im sure if i let it sit for a few hours it will run great again. also i checked the wires and they are fine. any help here would be awesome.
 


Make sure you bled the cooling system correctly, also double check plug wires and change them if you haven't could have a faulty one. Also look for shorts going to the ICM on the harness.

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could be a bad icm, the part under the coils. seen posts where once warmed up the coil heats up and fails.

and bleed the air out if that has not been done.

and change the plug wires if those have not been changed. and what plugs did you use?
 
Edit: Reread post. Im guessing your maf could be going out. Try unplugging it and see if it runs correctly. Also sounds like you did not bleed your coolant properly. Take off your rad cap while the car is cold. start up the car and put the heat on high. wait untill the car gets up to operating temp then top off the rad and then pop the bleeder screw slowly untill it starts pissing out in a stream. Put soem extra coolant in the overflow tank about 1/4 the way up and call it a day. Any excess air will bleed out by itself over the next few days, just keep an eye on the coolant.
 
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Scottydoggs said:
could be a bad icm, the part under the coils. seen posts where once warmed up the coil heats up and fails.

and bleed the air out if that has not been done.

and change the plug wires if those have not been changed. and what plugs did you use?
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okay i just went out and bought new wires and installed them no change. used autolite 104s and gapped to .050. mods on this car are plog downpipe and cai. it also ran like this before i changed out the plugs.
 


Try to get another ICM but before you do that, check the wires leading to the ICM make sure non are broke or cracked.

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Scottydoggs said:
if you got a junk yard near by pick up a used icm and try that.
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I tried a icm off my other grand prix and I also swapped out all 3 coils and no change. car has no power at start up now. starts fine on first crank, checked all wiring and all looks good also unplugged maf sensor no change. could I have a problem with my zzp down pipe? could it be plugged? it has around 50k on it.
 


the check engine light on?

the downpipe have a cat? even still id think a zzp catted dp would be high flow and would never clog up.
 
Sounds to me like the intake air temp sensor is continuing to tell the computer temps are low after warmup, so she keeps throwing a rich mix. Like a stuck choke on a carb. Thats the thing stuck in the rubber hose going to the air cleaner box. Wiring for it could be damaged or it could be bad. Would be easy to check what it is "saying" with a scan tool. If its staying in closed loop, there ya go. Might run like crazy but its hell on cylinder bores and cat converters.
 
idrivejunk said:
Sounds to me like the intake air temp sensor is continuing to tell the computer temps are low after warmup, so she keeps throwing a rich mix. Like a stuck choke on a carb. Thats the thing stuck in the rubber hose going to the air cleaner box. Wiring for it could be damaged or it could be bad. Would be easy to check what it is "saying" with a scan tool. If its staying in closed loop, there ya go. Might run like crazy but its hell on cylinder bores and cat converters.
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would that throw a code? I have not thrown any codes yet.
 


the temp sensor is under the t stat in the lim. its plug is a short harness that can bake on the cross over pipe. so those wires could be bad, or the temp sensor could be bad.

the fans work? and the temp gauge needle seem to work ok when its all warmed up and running?
 
Scottydoggs said:
the temp sensor is under the t stat in the lim. its plug is a short harness that can bake on the cross over pipe. so those wires could be bad, or the temp sensor could be bad.

the fans work? and the temp gauge needle seem to work ok when its all warmed up and running?
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yes fans work gauge works like it should I will check the wires you are probably right. what is the best way to check for a vacuum leak and also could this be fuel related.?
 
for vac leaks idle the engine and spray carb cleaner at the vac lines, if the idle jumps up you found a leak.

the temp sensor could be covered in dex sludge messing up its readings or its on its last legs so to say.

coolant is full and air is bleed out right?

it could be fuel, check the line pressure at the rail. you can get a free rental at the local parts stores. you leave a deposit on the tool, they refund you in full when you return the tool.
 
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