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vwnewton
vwnewton, VW Owner,ASE Master and L1 Advanced
Category: VW
Satisfied Customers: 307
Experience:  25 years of VW obsession turned into a job, last 15 years as a VW Tech.
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I've gotta 2003 jetta gli vr6. It's getting multiple random

Customer Question

Hey, I've gotta 2003 jetta gli vr6. It's getting multiple random misfires so it idles really rough, and the brake pedal is really stiff. The engine light is on and so is the EPC light. We tried new camshaft position sensors and a new MAF sensor, as well as replacing the vacuum lines. None of that helped at all.
Submitted: 1 year ago.
Category: VW
Expert:  gomi_otaku replied 1 year ago.

Have you read faults on it? You can get them read for FREE at Autozone or other large parts stores if you don't have a scan tool of your own. It would save you from just throwing expensive parts at it. Let me know if you have fault codes and I will help you figure out what is the cause, and what codes are just peripheral because of the main fault.

In the meantime- have you listened for a vacuum leak, since the brake pedal is assisted by manifold vacuum? Try removing the oil cap with the engine running to see if there is a vacuum on the crankcase, indicating a failure in the PCV system

Customer: replied 1 year ago.
Yeah, I scanned it. It just picked up the camshaft position sensor and the MAF sensor, so we changed those. Now it reads multiple random misfires as well as misfires on all cylinders.But yeah I'll try checking for leaks again.
Expert:  gomi_otaku replied 1 year ago.

Are you able to read fuel trims short term and long term on your scanner?

Customer: replied 1 year ago.
No, I don't think so.
Customer: replied 1 year ago.
What exactly was I looking for when I took of the oil cap?
Expert:  gomi_otaku replied 1 year ago.

Does it suck down hard? (if you put a piece of paper over it, would it suck flat, or does it pulse in and out) Or is there pressure pushing out?

Customer: replied 1 year ago.
It steams out.
Expert:  gomi_otaku replied 1 year ago.

Does it change the idle issue at all to have the oil cap off? If you pull the vacuum hose off the brake booster, is it pulling any vacuum at all? Check at the ports at the back of the intake manifold as well

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