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Please HELP ASAP! Random stumble after major overhaul. No CEL.

1752 Views 12 Replies 3 Participants Last post by  05_r6
Ok, where do i begin. My sister owns a 2002 Passat 1.8T FWD. Last year because of her negligence, the timing belt snapped. She never changed the oil and it never got serviced properly. Its had little to no preventative maintanace performed on it since my father bought it for her in 2007. It had over 105,000 miles on it when it snapped. So, she had it serviced at a local speed shop in West Chester, Pa and they replaced the water pump and timing belt and removed "some" sludge. I have been told they changed the HG on it but its debateable. The paperwork was lost (imagine that...) and a few family members say it was. Are the stockers MLS?

Anyway, the pcv system was hosed and they didnt take care of it last year. They also had cut the vacuum line to the diverter valve and various others, and ran a bunch of tees and capped them with bolts. There were like 4-5 tee fittings under the IM when i witnessed it about 5 weeks ago. I couldnt believe what i witnessed. I fixed those and set it up properly. I changed the oil and ran some seafoam throurgh the car. This was 5 weeks ago. Well she drives it for a 1.5 weeks and then starts having problems. I guess during my cleaning of the engine bay or work, i sturred up the problems to manifest themselves.

I drove down to West Chester and saw how it was driving and it was bad. It could barely drive 40 mph. Stumbles nearly 100% of the time youre driving it. Leaking oil, cj joints were also bad and those were clicking and knocking. It was bad. It threw the P0411, P0300, P0301-4. And i believe another code too. So i try changing the spark plugs and the cam angle sensor and check the coilpacks. No go. I tell it needs to come home for me to fix it. I knew it was gonna be bad. I didnt realize it was this bad.

She gets it home by some miracle. I find literally everything is wrong. LITERALLY.

PCV- clogged, coked, brittle, most importantly not working
VC- coked, black
cylinder head, some sludge, turbo turds everywhere, coked
kombi valve- clogged, would not crack open
IC- filled with oil, oil stained and thick on the temp sensor? in the IC
Cam chain tensioner- clogged i believe, not working.
Oil pan- coked with oil, turbo turds, some sludge.
Pick up tube- nasty
Oil pump- prolly bad
Oil filter housing- nasty
Leaking oil from VC
Coolant was ugly!
Suspension- 4 blown struts
Motor mounts- both bad
Trans Mounts- both bad
Cj joints- both bad

So over the last 3 weeks I've literally fixed all of that. The engine bay is mint. Everything thing has been repaired. I rebuilt the turbo, took everything i could to the machine shop to clean, replaced the cam chain tensioner, replaced nearly all the gaskets in the car, cleaned every part of the car, everything. There is just too much to go over. I overhauled the car. I did even more that whats in the list above like clean the injectors and replace the o rings replace 60% of the hoses, and rebuild the pcv system...just too much to list. It was a 3 week fix! Regardless, the car looks great now. So i got it finally finished tonight. I had one minor leak with the coolant feed to the turbo while filling the coolant, but that was fixed. I havent seen another leak yet on the car. I cleared the ECU (unplugged the battery) primed the oil for over a minute with the fuel pump fuse out. Got the car running and no CEL's!!! Holy crap i was excited. Still no leaks! But, i was getting a STOP light that my coolant level was low. Forgot to plug in the sensor on the bottom of the expansion tank. Restart the car and now it is starting to stumble randomly. The SAIP was checked as well as the relay and fuse and i heard those run and it went off. Ive ran it for about 7 minutes with the heat on high and it will just stumble randomly. NO CELs. What could it be? Please someone help.

Heres a few photos from the overhaul.

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So what your asking is why is it stumbling randomly? How long did you drive it with no CEL. Have you scanned the modules for faults with a VAG/COM?
Did you clean the TB? Check for vacuum leaks?
I think a generic obd2 reader may display pending faults if there is any. Did you try adapting the throttle body?
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