Idle is fine on start up but then!!!

**joelee669** · 02-24-2013

2000 gtp 126k pretty stockish
but been having the same problem for a couple weeks

cold start and it idles fine, but if i hit the gas too hard it bogs down, until it warms up.. but then whenever i let off the gas the rpms dip down sometimes down to 500 and jump up to as high as 1500 while in gear or in park.. ses light on don't know the code yet and the whole time it is doing this the lights dim and fan slows like it may just be an electrical problem but i wanna know what u think...

just cleaned my air filter
installed a zzp downpipe and walker(stock replacement) resonator
high flow fuel filter
and new radiator
problem still persist
even a little worse now because it will still now and it never did the before, it just seemed like it was going to..

any info u need just ask

**Fivefingerdeathpunch** · 02-24-2013

Get the code (s) read and see what they are.

Might be a sensor on the throttle body tossing a code.

**joelee669** · 02-25-2013

Will do

**joelee669** · 02-26-2013

P0 102
p0 135

**Scottydoggs** · 02-26-2013

OBD-II Trouble Code: P0102 Mass Air Flow (MAF) Circuit Low Input

OBD-II Trouble Code: P0135 Oxygen O2 Sensor Heater Circuit Malfunction (Bank1, Sensor1)

**joelee669** · 02-26-2013

What should I do replace the sensor or check the voltage at the sensor?

**Scottydoggs** · 02-26-2013

check the wires to the maf first, if they are still good id just get a used maf from a junk yard, they run about 40.

and it looks like you need a o2 sensor as well. or the wires are messed up.

check your wires for cracks or missing insulation. flip the plug over and bend it back to see if they cracked. if you see bare wire showing at all you need a new pig tail. it could be the cause of the code.

**joelee669** · 02-26-2013

the whole wire harness for my car is as hard as a rock!!! no heat shield on it and i do electrical for a living and these wires scare me because the all change color every 2 inches.. and i don't want a 100 splices under my hood!!! what do harnesses cost?

and thank you everyone you were great help hope it works it is a dd so gotta get it back out there even if it is only 12 miles a day 5 days a week..

**Scottydoggs** · 02-26-2013

dont know what a whole harness would run you but new pig tails are in the 10 to 12 dollar range, new.

problem is they just bake in the heat from the cross over for years and become brittle.

i had the same code, changed the pig tail all was good. i did have to keep cutting back the old wires to get to good wires again, i was a bout 2 or 3 inches from the main harness, and i got clean shinny copper wire finally. soldered the new pig tail on.

how to i did for pig tails. the link in there is the e bay seller i used. they can and will make you any GM pig tail under the sun. http://www.grandprixforums.net/how-p...ent-73671.html

**joelee669** · 02-26-2013

Thank again

**joelee669** · 02-27-2013

Bought a used maf from zzp and a new o2 sensor.. I will check the wires and connectors when i install them.. I hope this fixes this.. cuz I hate driving the car like this..

**mskram1** · 03-01-2013

moradpartscompany.com

ur new best friend

**joelee669** · 03-01-2013

ok so installed the used maf and o2 sensor and reset the codes and start it up and running alot better but still not perfect... rpms are jumping alot less... but it will go down a lil too far like 600rpm and the lights dim a little and then it is fine for a min then it studders for a min and so on..
when im at 1500rpms it feels like a missfire but there are no codes... going to drive it around for a while tomorrow and see how it runs on a cold start..... question( i changed the radiator and installed a new one then refilled it with dex cool. is it possible for the dex cool to get into my transmission fluid through the oil cooler line when i was putting in the dex cool?) i was checking the level of fluid because i lost some when i disconnected the lines.. the fluid looks likes the same color as the dex cool and doesn't smell like trans fluid but also doesn't smell like dex cool.. ANY INPUT WOULD HELP THANKS EVERYONE

**Scottydoggs** · 03-01-2013

your trans would be over full or under filled if the trans cooler cracked, chances are your ok.

dex is a nasty looking dark color, with little brown buggers everywhere.

**joelee669** · 03-01-2013

ok good to hear.. my old radiator was leaking so i put in new dex cool ALL the time so it is like new, does it push trans fluid through the side of the radiator or does the coolant go through the trans i was pretty sure red trans fluid was coming out of the line

**Scottydoggs** · 03-01-2013

it was lol

inside the rad is a trans cooler, so you took the lines off, ( from the cooler really) and what leaked out was trans fluid in the cooler still. and the lines to the trans.

you maybe a bit low on tranny fluid now, its worth a check when its all warmed up.

**joelee669** · 03-01-2013

Yes thats why I was asking because I checked and the color was a little lighter than I've ever seen it.. usually it gets darker and more brownish not orange..I will check it again tomorrow maybe it was the color of the light I was using Idk..

**joelee669** · 03-02-2013

drove it today and codes are back and the car idles like crap and stalls.. when the car is cold if i hit the gas the slightest bit the car bogs and goes to shut off so i let off and it goes back to idling at 1200rpms while cold then warms up and is all over the place.. time to pull the harness apart and get the resistance out of those wires and that will be it.. yea ok im not that lucky!!!!

**Scottydoggs** · 03-02-2013

you try un plugging the maf, then starting it? that should put it in closed loop, like when its cold, if it runs better unhooked it usually mean the maf or wires are bad.

you also checked all the fuses, under hood and in car, there is a maf fuse in GP's.

**dieyanks13** · 03-02-2013

Did you check your intake house for cracks? Especially around the throttle body?

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