New B5.5 wagon with a problem

[zzdiesel]

So, we just got a good deal on this wagon(my wife is a good bargainer). That is it is a good deal if the problem can be cured.

It is all standard, 130000 miles.

When accelerating or using power, it shudders. If I floor it it seems to smooth out. It drives very well, handles nicely. I had it over 95 mph, briefly, as I fear de cops. The tranny seems good, shifting properly.

There is no check engine light on. VCDS shows no engine faults. The tranny had a convertor fail to lock up code. I cleared it and it did not return on test drives.

The injestor quantaties at idle appoximately had 1 0.16 2 -40 3 0.0 4 .1

PD injection valve status, all 4 similar.

Timing 1.6 BTDC Torsion 00

Idle at 1500 having intermittant slight shudder. Injectors 1 2.99 2 1.2 3 .14 4 -1.86

The car shows no smoke under heavy acceleration nor at start up.

The car made 43+ MPG according to the display on my 2 1/2 hour drive at about 70 with lots of accelerating etc. trying to get a handle on the shudder problem.


Does any of this makes sence to anyone. Where to start?

Thanks
Mark

 

[mozark]

First thing I'd check is if the transmission is bolted securely to the engine. If it is I'd then start checking for loose bolts elsewhere in the drivetrain.

 

[zzdiesel]

A good suggestion, I hadn't thought of that.

Though I am fairly sure it is fuel related, engine missing at times. But I have no idea where to start.

 

[zzdiesel]

One other thing. The previous owner recently replaced the battery(Walmart) and the alternator(some aftermarket one).

Could the torque convetor non lockup be caused by low voltage? Also there were several comfort module related codes. They also may have been due to low voltage. Everything related seems to work now.

 

[afarfalla]

when you talk about TC lock-up problems your talking new transmission, the comfort module is most likely swimming under your seat

 

[zzdiesel]

I cleared the comfort module codes and they didn't return.

 

[borninabus]

@ 40+ mpg under those conditions, i would have to think that you are having a fuel delivery problem of some kind.

 

[zzdiesel]

I have never had to deal with a tandem pump. Could it cause this sort of problem? I do think it is fuel or injector related somehow. ECU?

 

[oilhammer]

Well you need a torque converter, but that is likely not the source of your issue. I'd replace the fuel filter first, cheap and easy, and chances are it has been neglected (most are it seems) and the PDs have no tolerance for that.

May also take the EGR valve off and see if it is really gunked up, and that it is closing all the way. Another odd thing that happens on the BHWs is that the CKP sensor in the block gets "pushed" away from the tone wheel on the crank due to rust building up underneath it. This can cause some "skips" or "hiccups" from time to time. Take the sensor out, clean up the block and the sensor, and slide it back in.

 

[zzdiesel]

Thanks Oil hammer. I changed the fuel filter 1st thing, but I will check these others.

 

[zzdiesel]

So I removed and cleaned up the CKP sensor. It wasn't bad. No change. I removed the EGR valve. It was only lightly carboned, and looked closed. I hooked it up to one of the other Passats. It did open briefly and close.

So, what else? Possibly a new CKP sensor, as a fault in that seems like it could cause these symptoms.

 

[Tom in PT]

Clean your MAF sensor. Did the car sit for a long time? Snow screen plugged?

 

[zzdiesel]

I don't think lack of air fits the symptoms. No smoke.

No, it did not sit long, that I know of. It was currently licenced and driven.

 

[tdi_my live]

The timing belt is 1.6 in the late direction. Better would be 0 or minus 0.6. What I once experienced is that the tensioning pulley on the timing belt was relaxed and the car started badly, ran restlessly in idle state and only had power at a later rpm.

 

[zzdiesel]

Yes, I should check the torsion value. I am currently doing the timing belt on my wifes Passat. Ist try it was about 3.6 and barely started. I did get it to -0.5 It completely shredded the serpentine belt, nothing but strings. That was at 40 miles before I was going to bring it in for the timing belt. Near right on to 80000. I am wondering why. Everything seems to turn fine.

 

[zzdiesel]

Set the torsion on the wagon to -0.5. No improvement. Still shudders under acceleration.

 

[tdi_my live]

Is this about a BEW? Does the car have a tuning? In my experience, there are uncomfortable vibrations if the SOI was programmed too early. Do you have VCDS and can log MWB04? MWB03-04-08 together is fine. WOT so that the vibrations are simulated.

 

[MOGolf]

It's a BHW engine.

What do you see for injector balance values?

Have you taken off the cylinder head cover and looked at the cam followers and cam lobes? Worn out? I know it you posted 130K miles, but if the previous owner(s) didn't use the correct oil they may have premature wear.

And the torque converter might be locking/unlocking rapidly. Any signs of fluid leaks? Perhaps a fluid and filter change might be in order too.

 

[zzdiesel]

I just checked codes again with VCDS. There were no engine or transmission fault codes. Since I do not know the cars history the plan is transmission service, timing belt, and probably a balance shaft delete, as well as an inspection of the camshaft.

There are no typical symptoms of a cam failure.

I have ordered a new crank sensor, which should be here in a few days.

I did list some injector values in the initial post. They are meaningless to me as has been others post these about other problem cars. Perhaps they make more sense to others with more experience.

Where is the MAF located? Is it up by the air box?

 

[tdi_my live]

Yes the MAF is by the air Box.
This is the Number 074906461B

 

[MOGolf]

"The injestor quantaties at idle appoximately had "
1: 0.16
2: -40 <---- really? negative 40? not missing a decimal point? A -40 would be way out of balance with the rest of them.
3: 0.0
4: .1

Also consider a diesel purge procedure to potentially clean out the injectors a little.

Has this car been tuned or is it stock VW programming?
Was the car sitting around for awhile or used a reasonable amount by previous owner(s)?
I wouldn't complain about 43+mpg in the driving you described. It might be worth putting up with shudder to keep that mpg.

 

[zzdiesel]

I will have to check injectors again as the values were rather meaningless to me.

The previous owner drove it somewhat regularly. I don't know how long he owned it but not more than a year or so. He said bought it at auction and it had the shudder from the start of his ownership. No known history, but it looks well taken care of.

 

[zzdiesel]

So I ran a liter of purge through it. No improvement. It seems the stumble and shudder only occurs in the midrange power band. At consistent driving on relative flat it is unnoticeable.When I floor it it doesn't happen.

Next I will replace the crank sensor, the 1st part I am throwing at it.

 

[thundershorts]

Have you tried unplugging the maf yet? Unplugged it will cause light to come on but that will rule out that the maf is bad. If maf is good, it will run the same plugged in or unplugged. I had 3 bad maf's so I unplugged it and drove if for 4 years.

 

[zzdiesel]

So what is the MAF for if it runs as well unplugged? What are the symptoms of a bad MAF?

 

[thundershorts]

It measurers incoming air, mass airflow meter, maf. disconnected, the ecu uses a value range that allows engine to run. Hope that helps.

 

[thundershorts]

On the maf, look at the 2 antitamper screws, 5 point torx, to see if they have been replaced. There have been lots of phony mafs sold on ebay that look like oem but are not. VW last time I checked only sold them as rebuilt for about 200. They are very specific and can cause running as you describe. Bad/wrong ones may take some time to trigger a cel. My old bhw is still running fine 6 years later after maf was dead.

 

[zzdiesel]

Thanks for the suggestion Thunder. I tried it with the MAF unplugged, no change and the check engine light did not come on.

 

[zzdiesel]

So, I replaced the crank sensor,as expected, no improvement.

I did find the sleeve for the cam sensor had been opened. The red and green wires spliced. Nearby the sleeve for the alternator wire had a melted hole, and the sleeves for two glow plugs had heat damaged spots.

Would it be possible to damage the sensor or the ECU if those two wires shorted together?

Might a damaged cam sensor be my problem?
































wou

 

[Kravt]

I doubt a shorted sensor would have much chance of damaging anything. Weirder things have happened, though. If you see damage on the cam sensor it is definitely worth looking into.

Something else you might try is letting it idle and -lightly- wiggling all the visible connector wires in the engine bay. If your problem is vibration/rpm-dependent it can sometimes be the wires degrading to the point of shorting inside the insulation.

Also, could you describe the shudder in a bit more detail? Is it pretty violent, rattling the interior? Or is it more of a heavy buzz?