Vacuum leak? I was having several cold start misfires lately and it turned out to be a broken check valve.

 

i replaced the entire vacuum system myself last year. including the main vac kit with the valves, and the hoses.

 

Scan it. Could be something as simple as a coolant temp sensor.

 

i will scan it today after work. i'm hoping its nothing serious. coolant temp sensor fairly easy to replace? whatever the issue is, im going to find the time to do it myself. i'm not letting any more mechanics touch my car. unless i have no choice.

 

Shaking and flashing CEL usually point me toward ignition problems. How recent are the plugs, wires, and coil?

 

the plugs i replaced about 2 years ago (about 35k miles ago) with bosch platinum.
the coil packs i never replaced myself, but im not sure if the previous owner ever did either.
never changed the plug wires either.

 

I had the same issue start 3 days ago but only on cold starts then the car runs fine. I have a 2002 1.8t and found a recall for faulty coilpacks on all 2001, 2002, and early 2003 1.8t and VR6 models. I called VW this morning and ran my VIN and they are honoring this recall for me over 10 years later with 150k miles. They also said they would replace my fuel tank heat shield under recall as well. Kudos to VW. I suggest giving your local dealership a call. A free replacement is always welcome, plus if that doesn't fix it, you just ruled out a pricey possibility.

 

Always a good idea to call your dealer to check for recalls. But - sorry to disagree on the coil recall you cite. Pretty sure they never did anything about coils on a VR6 B5/5.5, and reasonably sure it didn't apply to V6's, either. It was a 1.8T thing; two programs for that, IIRC.

 

I can't believe this needs to be said for a member with almost four years under their belt, but..

Scan it and post the exact codes.

 

the reason i didn't scan it in the first place is, because last time this happened i had over 10 codes show up. and none of which were the cause of the problem.
but i will scan it today. i just seriously didnt have the time yesterday as i was working almost 14 hours and was exhausted. i came home and went straight to bed. you know i'd eventually scan it and post the codes

 

ok fellas, just got home from work. scanned the car via a simple obd2 scanner i have. and the following codes appeared.

P0301 - cylinder 1 misfire detected
P0300 random/multiple cylinder misfire detected

and the code thats been there for a year and prob doesnt matter P0421 warm up catalyst efficiency below threshold bank 1

anyone?
thanks!!

 

First, after 35k miles I would expect those plugs are overdue, I would replace them with the VW recommended NGK BKR6EKUB plugs.
This might even fix the P0421 issue.

 

I wouldn't say the plugs are past due or necessarily wrong - but they're close enough to due that changing them is the least expensive next step, and you might as well use the correct ones as Tom suggests. One cylinder, intermittent... Past plugs, ignition wires and coil. I'm guessing wires.

 

Sounds like a cracked coilpack to me had the same problem with my Jetta. Condensation during the winter time causes the issue.

 

That is not likely the case here, on a V6 that would normally cause misfires on 2 cylinders.

 

i remember jay telling me he had the same plugs in his car for like 90k-100k miles and they were great.
i will replace them with ngk's and i guess i might as well get the cables too.
once i do that, i will swap the coil pack with another one and clear the CEL. if the code follows to another bank, then it is for sure the coil pack correct?

would cam chain tensioner being bad, cause any of this?
i know its probably due for replacing, especially at 135k miles.

 

i remember jay telling me he had the same plugs in his car for like 90k-100k miles and they were great.
i will replace them with ngk's and i guess i might as well get the cables too.

I would try one thing at a time starting with the plugs.
The cables may or may not need to be replaced.

i will swap the coil pack with another one and clear the CEL. if the code follows to another bank, then it is for sure the coil pack correct?

There is only one coil pack on the V6, and the coil pack almost never causes misfiring on only one cylinder. You could check that by swapping plug wires #1 & #6 at the coil pack only, if the misfire goes to #6 the coil pack is faulty.

A faulty fuel injector would be far more likely than the coil pack.

would cam chain tensioner being bad, cause any of this?
i know its probably due for replacing, especially at 135k miles.

You have 2 CCTs on the V6, and they are not at all likely to be causing your issues.
It might be good preventative maintenance to replace the pads if they haven't been replaced.

 

thanks! i have not done CCT jobs yet so this will be interesting.
the pads are plastic on them correct? is it only the pads that need replacing? i was reading that CCT on the V6 is a pain in the ass.
if its just the pads, it shouldn't be too hard.

i will buy some spark plugs today and see if that helps. thanks everyone!!!!

 

thanks! i have not done CCT jobs yet so this will be interesting.
the pads are plastic on them correct?

The pads are made of plastic. Replacing the pads would be just preventative maintenance, there is nothing to indicate a problem.
I didn't replace mine when I did the VCGs at 110,000 miles.
If you do replace the pads, you will need the 4 pads, 2 VCG kits with CCT gaskets, and a CCT compression tool.

is it only the pads that need replacing? i was reading that CCT on the V6 is a pain in the ass.
if its just the pads, it shouldn't be too hard.

On the V6, if the CCTs have always had good synthetic oil they should last the life of the engine, but of course anything can fail at any time.

i will buy some spark plugs today and see if that helps. thanks everyone!!!!

That will be a good start.

From Post #1: on cold starts in the morning, i hear a crank sound for just a quick second. maybe cam chain tensioner? its been ongoing for a year

Could you give a better description of a crank sound ?

 

My B5 2.8 Just did the same thing three weeks ago and it was the coil pack. Same codes, same behavior.

 

Are you saying you had these and only these codes.
P0301 - cylinder 1 misfire detected
P0300 random/multiple cylinder misfire detected
P0421
And the engine was running on 5 cylinders ?

When you replaced the coil pack, did you replace the leads or anything else at the same time ?

 

I just ordered the oem NGK plugs. They should be here Tuesday I hope

 

Replacing the wires will do a lot of good. If they are the original ones and have been taken off several times, they will break and start breaking down. I had similar symptoms on my 2000 v6, and I replaced the plugs, and it helped for about 3 days. I bought a new "coil pack" and it helped for a couple of days. I replaced the wires and the car has been fine since. It has been about a year since I changed everything. If you check your coil and it turns out bad, I have an extra OEM one in the garage I can part with.

 

Update:
I installed new plugs and cables and car is back to normal!
The cables were $160 but I'm glad I replaced them. As I believe they were original from factory.

Thanks everyone! I appreciate everyone's help.

 

Glad to hear you are back up and going.

 

Glad it worked for ya BEE. :thumbup: