need help

[87boostedbuick]

hey so i have a problum and this time its not with my gn lol its my 96 buick park ave i was driving the outher day and it started running rilly rough missfireing sputtering barly i would have to have it allmost to the floor to do 50 kph so i got it home and hooked it up to my scanner and i got to codes a random missfire code and a map sencor code map sencor is pluged in no vacume leaks car has new plugs wires injectors are good im not rilly shure where elce to look it seems to be getting good spark from the coils any help with this would be great i have no idea where to look next oh and also after this happend i also noticed that a cupple time i went to go stop and the brake peddal was as hard as a rock i had to use 2 feet and it still barly stoped i dont see anything unhooked from the brakes it has lots of fluid and there not leaking

 

[Brad Zeidler]

Is this a regular 3800, then I would say the upper intake crapped out and started pushing coolant into the plenum. This happens because it cracks between the EGR port and coolant passage. This is the only bad thing about the 3800. I always wonder what some of these engineers are thinking when they design stuff. Who in their right mind would run exhaust gas through a plastic intake? This is a very common problem and the dealer sells alot of upper manifolds because of it. You can even get new upper intakes from a company called Dorman which also makes oil cooler lines for popular GM vehicles

 

[steveX]

Is this a regular 3800, then I would say the upper intake crapped out and started pushing coolant into the plenum. This happens because it cracks between the EGR port and coolant passage. This is the only bad thing about the 3800. I always wonder what some of these engineers are thinking when they design stuff. Who in their right mind would run exhaust gas through a plastic intake? This is a very common problem and the dealer sells alot of upper manifolds because of it. You can even get new upper intakes from a company called Dorman which also makes oil cooler lines for popular GM vehicles

Don`t you know most car are made of plastic (bags)..lol

Yes, the plastic intake is a to me. i will never buy a car with plastic engine parts (I see BMW using it on the 08 M3 and M5), i don`t see these engine lasting long. I believe the reason the automaker when with a plastic intake. maybe weight reduction..lol. I know for a fact when the anti-freez does not get service, it will become corrosive, and will eat the aluminum parts. Plastic do rot, or does it. plastic is just not a good item in hi-temp areas. I have see this 3800 intake manifold look like a bomb hit it, if a back-fire should happen in the engine. I see the northstar engine has the same intake (what a trouble motor ,do like nstar). The automakers are producting car like cell phone. cheap and lots of un-nessary bells and wisle.

 

[Boostin TA]

if your brake pedal was rock hard sounds like you have a major vac leak somewhere. It may even be internal in the brake booster if the diaphram has ruptured (also the reason for a map code) id check eng vac with a gauge if you have one or check all vac sources for a crack or break.

 

[87boostedbuick]

ok thanks for your help guys i will check the vacume and the booster and i was gonna pull the intake off and have a look tomorow

 

[95scpa]

Checking spark at the plug is useless on our cars.
If it only misses under a load, acceleration, it's the coils or module.
To check; pull off a plug wire @ the coil and move it out of the way.
Start the motor and if the coil does NOT spark to the nearest bolt, that coil is bad or module.
To eliminate the module; swap that coil, with one of the others.
Pull the plug wire on the new coil you put in the place of the one that didn't spark to a bolt.
Start the motor; if that coil does NOT fire to the nearest bolt, the module IS bad.
If it DOES fire, the coil was bad.
Clean the coil bolt hole that has metal on it to improve grounding.
And if replacing the module, use ONLY the white paste "heat-sink" grease under it, NOT dielectric. Napa and Radioshack carries it here, sometimes Autozone, but it's behind the counter in "stock", not out on the floor..