Odd BRM Behaviour 2006

[tassolake]

I'm having an odd BRM issue with the car dropping into partial limp mode (It's not full limp mode). I've owned this car since new and replaced the lifters / cam / tandem pump / turbo / lift pump / timing belt / cylinder head all in the last 100K km (60K miles). Car now has 320K KM (200K miles).

Symptoms:
Lots of white smoke on start up.
starts and idles great
During hard acceleration the car appears to drop into limp mode (minimal power), continue to gently accelerate and the car then behaves normal again (without turning ignition on or off) and will get upto 130km/h (80mph), whereas in the past limp mode would limit me to 80km/h (50mph). Sometimes on the highway it loses power, then regains it.
VCDS does not show any error codes (other then AC compressor sensor shorted to ground).

Checked the Cam and Lifters last night (they appear good with a very slight flat spot on 6 of the 8 lobes). Lifters do not appear to be dished.
Group 13 shows the following injector deviations, 0.00mg, -0.28mg, -0.89mg & 1.15mg (cyl 1 - 4).

Are those flat spots on the cam enough to cause this issue?
Could this me a leaky injector issue (suspect cyl 4)? causing the O2 sensor to back off the fueling when it detects it being rich? Is there something else I should check?

Any guidance would be much appreciated.

 

[tactdi]

Sticky Turbo Vanes?

Try the Tie Wrap Mod to keep the Turbo Vanes out of the worn spot.

http://forums.tdiclub.com/showthread.php?t=309554

 

[tassolake]

The turbo is less than 40K old, but I just tried the tie wrap mod, with no change, I also did the turbo test on Gp11 of the engine module basic test. The test ran great and pressure moved from 980mg to 1244mg. Could the slight wear on the cam cause this issue? I cleaned off the lifters and they all looked good but some of the cam lobes have a slight flat spot?
Anyone have picture of a bad BRM cam? My last one I replaced was gouged because of a failed lifter, this is not the case today.

 

[Carlos_TJ]

How is your injector deviation data in vcds?

 

[tassolake]

The results of the deviation test from Group 13 shows the following injector deviations, 0.00mg, -0.28mg, -0.89mg & 1.15mg (cyl 1 - 4).

 

[Carlos_TJ]

You have something going on in cyl #4.
General consensus is that anything over 1.00 will have driveability issues. (0.84 for #3 might be related to #4 being above 1.0)

How are cam lobes for #4 compared to #1?
(#1 being closer to the cam pulley and #4 closer to the tandem pump)

BTW, the o2 sensor in these TDIs is used to control the EGR cycle, not direct fueling. (However if o2 fails the car turns into a dog because excessive egr but you get CEL)

 

[tassolake]

Thank you Carlos, I relooked at the cam and those two lobes are the worst of the lot, but still look okay. I'll head out and pick up a new cam and replace in the morning. will post the results.

 

[Carlos_TJ]

One last question? How does your engine sound if you remove the air filter? Or better yet, the hose before the intake? Do you hear the uneven-sound of three cylinder firing and one dead cyl engine or you hear the even sound of a 4 cyl all firing up?

If your cam is worn enough you will hear the uneven sound.....



I am also curious about what engine oil you use, i can see on your original post you already replaced the cam once. At what mileage was that? What cam did you use as a replacement and what waa your break in method?

Sorry for many questions. I am also on my 2nd cam..
I now use 5~40w rotella t6 and i add some drops of zdp every month.

Good luck

 

[tassolake]

Carlos, the new cam and lifters did not solve the issue. The cam I removed today looked fine when inspected out of the car and lifters had normal wear. I put in new cam and lifters and the deviation is now 0.00, -0.89, -0.87, 1.76 (1-4), which is worse than before. Could this be a bad injector? Compression? The torsion value did improve from -1.0 to -0.5 after the change.

It is idling nicely in the driveway (same as before).

As for maintenance I have owned this since new and have maintained it as per VW specs with fresh oil every 5K Km. Oil is Total 5w40.

 

[Carlos_TJ]

Yes, a bad injector could cause this.
Have you ever diesel purge your car? I am talking about feeding liqui moly directly to the tandem pump, not dilluted in the fuel tank.

It might be possible your injectors need rebuild due to your mileage.

Compression is also a player, but unless an abnormal event happened, its unlikely as the tdi bottom ends are sturdy and long lasting. You might want to test it for peace of mind.

 

[tassolake]

Good suggestion, i have never diesel purged the injectors. I will try that monday. I have also reached out to the local community for a compression test. Oil consumption has increased (1 litre per 2000K km), so may be the compression is failing.

Eitherway the old cam and lifters looked quite good when I removed them. I shall keep everyone posted on the results.

 

[DidJettarun]

I know this sounds silly but have you changed the fuel filter lately? Dirty filter will not allow good fuel flow at higher power and give you the sensation of "limp" mode. White smoke at start certainly suggests under fueling. I realize this is a longshot given the #4 injector data. I agree that a proper diesel purge is a reasonable next step but find someone who has a proper diesel douche rig to keep recycling purge through system

 

[Carlos_TJ]

I tought White smoke at startup means raw fuel (on a cold engine). Op did not state if the smoke has strong diesel smell.

Mine did it when i had a severely worn cam and i could not stand to be behind the car exhaust. The diesel smell would make your eyes water..