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Juan Crespo
Juan Crespo, ASE Certified Technician
Category: VW
Satisfied Customers: 1526
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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2003 VW 2.0L NON TCEL - flashing codes generated PO304

Customer Question

2003 VW 2.0L NON TCEL - flashing codes generated PO304New timing bet /valve job / water pump / gaskets @ 109,000 milesproblem started at 118,000 miles a week ago since the I've been throwing partsNew parts in last weekcoil pack
O2 sensor16.1 ohm on #4 injector
118 lbs compression on #4Im lost and can't think on what other issues can cause this to be on only #4
Submitted: 1 year ago.
Category: VW
Expert:  Juan Crespo replied 1 year ago.
Hi there.At 118 psi, compression is borderline for that cylinder. If the other three were up to spec at 160 psi, then the PCM might be seeing that cylinder as not contributing enough to turn the crank at the same speed as the others and setting the code. How is the engine running otherwise?
Customer: replied 1 year ago.
runs great above 2k rpm shuttering at idle , no cel when above 2k
Customer: replied 1 year ago.
Also runs idles good at initial start up while blower? pump is active
Expert:  Juan Crespo replied 1 year ago.
In that case, you might want to check timing. Which 2.0L engine are you working with, AVH or AZG?I'm sorry but I don't understand what you mean by "Also runs idles good at initial start up while blower? pump is active".
Customer: replied 1 year ago.
AVH - on cold start up it'll run and idle without stumbling and shaking while the blower is forcing air into intake but once it cuts off the shaking missing begians
Customer: replied 1 year ago.
If are going to guess around for my 24 bucks I should of just not asked i didn't get an answer there for I'm dissatisfied
Expert:  Juan Crespo replied 1 year ago.
Ahh, thank you for that clarification. The AIR pump has no bearing or effect on how the engine runs; its only job is to pump air into the exhaust system to dilute emissions during cold start.I would also recommend doing a leak-down test on cylinder 4 to see if we have a valve not seating properly, in which case I would recommend checking that timing right away.If at any time you think my answer is not satisfactory. Please contact customer support.

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