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Discussion Starter #1
Hi all,
2003, 1.8t Sedan

I replaced the motor mounts (Corteco), Transmission mounts (Febi) and the snub mount (Febi).

I still feel the engine vibration at idle. It is amplified at D and R as well as driving on highway.

I ran the engine before I tightened all the bolts, centered the snub mount bracket.

Replaced both axles with Raxles.

On a side note, I had a downpipe, from the flex pipe to the muffler, installed by a muffler shop.

How can I diagnose the problem?

Help is appreciated.
 

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You had engine vibration before replacing motor / trans mounts I'm assuming. Depending the severity of the vibration, replacing the motor mounts may or may not resolve the problem.
With brand new engine and trans mounts, seeing as they are so much newer / stiffer than the old worn out ones you just might be experiencing normal harmonics because of the new mounts.
If the vibrations increase with speed, then you've got tire balance, tire alignment, front / rear wheel bearings. Are you sure you installed the axles on the proper side of the vehicle?
 

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Discussion Starter #4
Thanks for the answer Andreas. What makes me think that it’s not the axles that is causing the vibration is I can feel it when the car is in P, simply idling. The vibration at P is worse between 1000-1500 rpm.
Would the wrongly installed downpipe cause vibration?
 

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Discussion Starter #5
Hi chief,
I installed the new tb about 2000 miles ago. I made sure the timing marks were aligned. I did numerous bag com tests for misfire and timing retardation. All came zero. Makes me think it’s not the timing.
 

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Thanks for the answer Andreas. What makes me think that it’s not the axles that is causing the vibration is I can feel it when the car is in P, simply idling. The vibration at P is worse between 1000-1500 rpm.
Would the wrongly installed downpipe cause vibration?
Honestly, if you've installed Raxle axles and the left / right are mounted properly I would rule that out.
Now that you've mentioned you can feel it in Park at 1000-1500RPM obviously the other stuff can be ruled out also, at least for this particular issue.
Unless the downpipe is physically interfering with something, I don't see how this alone could cause vibration.
Is it possible one of your fuel injectors is not working properly.
My thought is that you might have a single injector that is just slightly off from the rest of them. If one is slightly off causing a misfire it won't register on VCDS as a misfire.
The cars management system (and VCDS for that matter) don't get feedback from the injector itself so that's why I say this.
Obviously this also has to be within reason, if the injector isn't functioning at all then a lean condition code will be triggered and the CEL light will come on.
The easiest way to check the injectors is measuring the OHMs resistance on each injector.
I can't remember what the ohms spec is from Bentley Manual (somewhere around 14 ohms +/-.5 IIRC) whatever the case, when checking all 4 injectors they should all be within .5 ohms of each other.
Hopefully someone can chime with that spec.
 

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I forgot to ask in the previous post. Did you run a scan with VCDS?
 

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I would also lean towards the mounts being the culprit. As those mounts are not OEM do you know if they are still fluid filled? Many aftermarket mounts are not, they are just solid rubber. If they are not fluid filled, the vibrations will be more significant.

I went from OEM mounts to solid rubber mounts (on purpose) and while they do "break in" a bit they provide a lot more vibration at idle and part throttle.

Sent from my SM-G955U using Tapatalk
 

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Honestly, if you've installed Raxle axles and the left / right are mounted properly I would rule that out.
Now that you've mentioned you can feel it in Park at 1000-1500RPM obviously the other stuff can be ruled out also, at least for this particular issue.
Unless the downpipe is physically interfering with something, I don't see how this alone could cause vibration.
Is it possible one of your fuel injectors is not working properly.
My thought is that you might have a single injector that is just slightly off from the rest of them. If one is slightly off causing a misfire it won't register on VCDS as a misfire.
The cars management system (and VCDS for that matter) don't get feedback from the injector itself so that's why I say this.
Obviously this also has to be within reason, if the injector isn't functioning at all then a lean condition code will be triggered and the CEL light will come on.
The easiest way to check the injectors is measuring the OHMs resistance on each injector.
I can't remember what the ohms spec is from Bentley Manual (somewhere around 14 ohms +/-.5 IIRC) whatever the case, when checking all 4 injectors they should all be within .5 ohms of each other.
Hopefully someone can chime with that spec.
interested what results are regarding injectors, mine is progressively getting more vibration also, I do know this,when I put on my 16 inch rim/ tires for the winter I had less vibration than with my 17s do to taller sidewall...
 

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Here is the vag scan.

Well you obviously don't have any codes to worry about. I'm envious ;)
I would check the ohms resistance across the injectors to see if they are within spec and to each other. One injector that has a different ohm value from the rest will result in an unbalanced delivery of fuel hence some vibration.
I don't have my Bentley on hand anymore so I can't tell you what the parameters are supposed to be. That last figure I gave of 14 ohms is just a reference I remember seeing on VWVORTEX forum.

Don't know how much difference it would make, but have you checked your harmonic balancer (large serpentine pulley on crankshaft)? I know a few members here (PZ is one for sure) that have had the harmonic balancer come apart to some degree.
I have also heard that re-adjusting the motor mounts might help. If you've replaced your motor mounts, you'll know that there are some slots on the lower mount point (where motor mount attaches to sub-frame assembly). I don't know if I can 100% subscribe to this, but I have read in this forum and in some of the others that a few individuals have re-adjusted their mounts and it has improved.
Maybe others can chime in to verify or debunk this claim.
 

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Hmm...
I think you might need to check your CCT (cam chain tensioner).
The chances of your CPS (cam position sensor) going bad are slim but it should not be ruled out.
I'd check for wear on the CCT pads. My guess is that they are getting worn and or the CCT is having a slight malfunction causing your intake cam to be slightly retarded (static timing).
How long has it been since you've been under the valve cover?
 

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Discussion Starter #15
Thanks Andreas. I actually replaced the cct about two months ago. Made sure the marks were aligned. The old one was badly worn, the bottom pad literally fell off upon removing the tensioner from the chain. There was a chain indention on the of as well. The rattling is gone. The thing is the code was there even before I replaced the cct and the timing belt.
I had cleared the code after I sent the picture and it has been about 260 miles. No codes so far.
I feel no loss of engine power . The car reaches to 80mpg at no time.
I am gonna get a couple of sensors from the junk yard and try them.
 

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Hah, I had a hunch you were going to come back and tell me that you had already done that. Which is good. Unless the CCT is collapsed, which I doubt, I would rule out the CCT.
That brings us back to the injectors.
And maybe that adjusting of the motor mount claim. Still not sold on that one though.
 

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Discussion Starter #18
Do you think I should get some injectors from junk yard and try them? I m not sure how to check them tho.
 

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Discussion Starter #19 (Edited)
Thank you Tom. Getting down to the timing belt area is a dreadful endeavor although I have replaced tb 3 times on different b5 and 5.5s.
Is there any other way of checking the timing without pulling the front to service position?
 

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Thank you Tom. Getting down to the timing belt area is a dreadful endeavor although I have replaced tb 3 times on different b5 and 5.5s.
Is there any other way of checking the timing without pulling the front to service position?
Unless you have made some other mark on the crankshaft pulley referenced back to some other non-moveable point on the engine or covers, I don't see how it be done with absolute assurance that everything is correct.
But then again, I'm not savvy to the 1.8 like I am with the V6. When I rebuilt that 1.8t a few years ago, I don't remember anything that would allow you to check timing without pulling stuff apart.

I had wanted to ask, at what point in time did this code pop up relative to you replacing the engine and trans mounts?
And, is the code still present?
 
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