3800 series 2

I have a 98 GP GT, runs rough, no power until the engine gets hot. I've replace the eng temp sensor, the MAP to clear a code and plugs. It runs great once it gets hot, but like crap until then. Step on the gas cold and it just sits or bogs down. I've cleared all the codes since the sensor's were replaced and nothing esle has shown up. any thoughs.


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im guessing it would be the thermostat stuck open.

Tried that aslo didn't help. only does it when cold or raining.

Wow. Where do you possibly conclude the thermostat might be stuck open?
I don't get THAT logic at all!

try this place http://www.grandprixforums.net/ they might help you.

I'm no EFI expert but I would look at the car and see if it has an open loop or closed loop EFI system, maybe there is no signal being sent, the O2 sensor, or?

do you know what the codes were?

have you ever changed the plug wires on it?
the plug wires breaking down is pretty common and can cause a number of run problems.
the reason im thinking plug wires is the "or raining" part.

if you do change the wires, i recommend using a set of A/C Delcos, the aftermarket wires just don't last like the OEM wires will.

Yeah, it was P0103 for the MAP sensor high input (I replaced it yesterday). I did not change the wires, i did inspect them very well there not soft, oil soaked, or cracked at all and the boots have a heat shield on then. I was thinking it might be an O2 sensor but there aren't any codes for it.

You'd be amazed at how so many seemingly non related parts can influence how one of the newer computer controlled cars runs...Once you know about what's telling the computer what to do , it becomes perfectly logical.

That's why I don't even attempt to answer these types of threads....( where's my matchbook so I can set my points )

Later, mikey

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BE different....ACT normal.

No one is completely useless..They can always be used as a bad example

P0108 is for a high MAP sensor circut voltage.

P0103 shows to be for the Mass Air Flow sensor.

without looking at the data stream from a scan tool, you can only guess why its setting the code.
the harness at the connector for the MAF sensor could be bad, its a fairly common problem.
but with your car running ok after it warms up, i would suspect the MAF is going out.
when i have car that intermittently sets a MAF code, i always replace the pigtail before replacing the MAF sensor.
if i know the MAF is bad, i still pretty much always replace the pigtail to prevent a future problem caused by the harness.


Mike, you chicken, LOL

MAF setting codes huh?

Any chance you're running a K&N (or similar) air filter?

The oil that is used to treat that style of filter invariably ends up gumming up the carona wire in the MAF.

Air flowing across this wire cools it, which has an effect on the voltage resistance. It's this voltage fluctuation that tell the computer how much air is flowing. Gumming up the wire insulates it, fooling the computer into thinking that it should supply fuel for a lower RPM ... leaning out the mixture.

If this is the case, you can usually use an air intake cleaner to clean that carona wire up.