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Discussion Starter · #1 ·
Hey all,

After working on my 2002 1.8t Passat AWM, I am about to throw in the towel and send it off to the shop. I have been working on it off and on for a couple months. Here is the original thread on the PCV system and VCG fix....

https://www.passatworld.com/forums/...il-spark-plug-wells-replace-pcv-system-2.html

Anyway, I have come to this point: After doing coils, plugs, New ECS PCV system (tubes and hoses/PCV valve) , and today the OEM Bosch Mass air Flow sensor, I still have the same dang misfires, on all the cylinders. I have checked vacuum hoses, replaced hoses, and made sure my hoses were routed correctly.

The car will idle but very rough. All the misfire codes are there, but now the "high voltage" (I think) MAF code is gone, as I replaced that.

Accelerates well, haven't had it over 3000, didn't want to "blow it up" lol.

I am assuming that the kit I bought from ECS is a good kit and nothing is bad there. I don't have access to the VAG system to truly analyze the system. I have the "dash cam" reader which will give me codes, but that's about it.

Typical misfire codes: P0300, Random/Multiple and P030X for cylinder 1, 2 and 3.

I really wanted to get this thing going as a goal, but I'm very frustrated. I can drive it 45 minutes to the shop (they will be doing my timing belt for $750 with German parts - and they are reputable). About to let them just fix it, but man I wanted this thing to run smoothly.

Thanks and Cheers!
 

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OK.

Do you have an android or iPhone? Get an ELM327 bluetooth (for android)or wifi (for iPhone) OBDII scanner. $15 on ebay or amazon.

Iphone apps:
Car Doctor or Car Scanner

Android app:
Torque Pro

Those apps will let you check sensor voltages and readings real time to see if anything it out of range or not responding.

Check every check valve for holes.
Any codes other than the misfire codes?
Look at the injector seals/o-rings. Cheap and easy to replace if needed or not.


Absent obvious issues, I start to check and clean sensors and throttle body. AIT, boost sensor in intercooler top, check voltage and physical condition of the crank sensor

There isn't much left.
 
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Considering all the work that you have done and VAGguy even makes statement about that, I would be suspect of the timing itself.
I would double check the static timing between the two cams, making sure the CCT is in proper working order. I would then check the timing belt to make sure everything is just right.
I find it hard to believe that, that many electrical components would be faulty all at once. Maybe a bad ECU but not very likely.
Through the years here I've seen some pretty strange mishaps with timing. Broken cams, loose cam chain sprockets and timing pulley(s) keys sheared off only part way that makes it look as everything is ok but it's really not.
 
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Check the wiring harness. The harness to the coils makes that 90* turn into the coils. That is a weak spot for wires getting hot/tired/split. take the connector off the coil, slide back the rubber boot and check the condition of the wire. If they're brittle, one seems smaller/bigger, have little bits of copper sticking out of the wire, it could be your misfire problem. I had this years ago, I knew timing was fine but couldn't get it to fire correctly. All those wires into the boots of the coil plugs were basically worn out (if thats a thing for wires), it gets hot on top of that head and they take a beating. The ground wires on top of the head are another area, could be a loose ground or those wires too could be shot.

I found another harness at the pick and pull, spliced it all together, do one at a time, don't want to mix wires up, then wrapped it all in heat wrap, not more misfires. You can get the generic connectors at any auto parts store but I was always skeptical.
 

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Discussion Starter · #6 ·
OK.

Do you have an android or iPhone? Get an ELM327 bluetooth (for android)or wifi (for iPhone) OBDII scanner. $15 on ebay or amazon.

Iphone apps:
Car Doctor or Car Scanner

Android app:
Torque Pro

Those apps will let you check sensor voltages and readings real time to see if anything it out of range or not responding.

Check every check valve for holes.
Any codes other than the misfire codes?
Look at the injector seals/o-rings. Cheap and easy to replace if needed or not.


Absent obvious issues, I start to check and clean sensors and throttle body. AIT, boost sensor in intercooler top, check voltage and physical condition of the crank sensor

There isn't much left.
Thanks! That's what I was thinking. I might have to pull the MAF off and send it back, as it only has 4 miles on it!!!

Unfortunately, my forte isn't in electrical diagnosis, and I bought a multimeter once that I blew up on the first try! And I don't do the volume of vehicles to have a "real computer!"

I am going to look at those programs, they look pretty cool.

I'll also check all the check valves, although they're pretty cheap.

I had the injector rail out with the valve cover gasket and intake manifold removal.I wondered about new/rebuilt injectors, but stopped there.
 

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Discussion Starter · #7 ·
Considering all the work that you have done and VAGguy even makes statement about that, I would be suspect of the timing itself.
I would double check the static timing between the two cams, making sure the CCT is in proper working order. I would then check the timing belt to make sure everything is just right.
I find it hard to believe that, that many electrical components would be faulty all at once. Maybe a bad ECU but not very likely.
Through the years here I've seen some pretty strange mishaps with timing. Broken cams, loose cam chain sprockets and timing pulley(s) keys sheared off only part way that makes it look as everything is ok but it's really not.
Yeah, I'm thinking it's something weird. I did not remove any cams, belts, and I even skipped the CCT gasket, as I didn't want to get that far involved. I did NOT do a timing belt on this job, although after it's all done and said, I maybe should have. However, I wanted to address the misfires first. Thanks!
 

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I had the same problem with the misfire on all cylinders. Took it a shop and all of the one way vacuum valves in the vacuum lines needed to be replaced. I also have lean on bank one and turbo underboost. Now I don't know if you have the same problem but you might want to check them. Just my two cents.
 

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Those check valves are flimsy and subject to embrittlement. Fortunately, they are pretty cheap and readily available online. Thanks for the reminder -- I have a couple of iffy-looking ones on the Passat and the A4. I think all are original, which means they are past their prime.
 
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