2001 VW Jetta VR6 with the 2.8 misfire code and over heating
Asked by tgcheermom Aug 29, 2022 at 10:27 PM about the 2001 Volkswagen Jetta GLS VR6
Question type: Maintenance & Repair
I recently bought a 2001 Jetta VR6 with the 2.8 DOHC. We knew when we
bought it that it needed a water pump. We replaced it but found even more
problems. The car constantly overheats and it runs really rough (sounds like
a diesel). The code comes up as P0304 number 4 misfire. We have replaced
the radiator, coil packs, injectors, freeze plug, plugs and wires. When we pull
spark plug 4 the car almost dies out, when we pull spark plug 3 nothing
changes. I am not sure what to try next. Can anyone help give me an idea
what to do next?
11 Answers
Run a compression test. I fear you have some engine problems.
beatupchevy answered 2 years ago
They sold you a car with a blown head gasket and told you it only needed a water pump , then instead of some simple diagnosis you go and buy a bunch of parts you didn't need .
tgcheermom answered 2 years ago
We ran a compression test it and everything checks out fine. We did notice that the guy before had by passed the heater core. I don't know if that could be why it runs hot.
tgcheermom answered 2 years ago
How can it be a head gasket if I don't have coolant in my oil or in the plugs. It shows no signs of head gasket being bad.
There must be a reason for you to have a dead cylinder. Have you done a head check or cylinder leak down test. The head gasket maybe blown between cylinders and not into a coolant passage.
Hopefully, you did not install the water pump impeller in the wrong direction.
tgcheermom answered 2 years ago
We've double checked everything we did. While we were doing this the cam sensor was unplugged and the car never change the way it ran. It stayed running with a miss it's always had. Shouldn't it have killed the car? Could that be the problem?
No, a lot of systems will look at a sensor reading and if it is out of specs they will apply a preset parameter for that sensor and turn on the check engine light but keep the engine running if it’s not detrimental for the engine.
tgcheermom answered 2 years ago
I'm so lost with this car. We know GMs like the back of our hand but this one is my dream car and it won't run right. Could it be a bad catalytic converter?
Only if it was totally melted down so no exhaust could escape. you could disconnect just to find out but I don't think that your trouble. I still think you have a head or head gasket problem, you should not have a dead #3 cylinder.
tgcheermom answered 2 years ago
My husband try something today since it was something. He moved spark three to spot four and four to three and it runs better. I don't know why that would help but it's still over heating. The kid we bought it from bypassed the heater core so maybe a hose isn't hooked up right. Does anyone have a heater hose diagram for this motor?
