Jetta stumbles-Out of ideas

rc_y2kws6ta

Well-known member
Joined
Jan 26, 2007
Location
Folsom, CA
TDI
2002 black Jetta TDI Auto
I need help please!! I am out of ideas on what is wrong with my 02 Jetta A4 with 83k miles.
Any help would be greatly appreciated. It just seems to not adjust the pump timing correctly (or momentarily lose air) at low RPM’s and under load.

About three weeks ago my Jetta started to stumble and hesitate upon acceleration for a stand still. It would hit about 1800 RPMs and stumble. I would give it more peddle and it would then stumble a little more and finally accelerate with a dark sooty cloud.

I have isolated this behavior.
1) It runs perfectly fine after a cold start for about 30 minutes. After that, its starts to run bad.
2) The idle is fine.
3) The power is fine (once I get the RPMs up past the stumble point)
4) When its fully warmed up, the engine does not like to be at 1800 to 2500 RPMs. It will stumble and blow dark smoke.
5) Accelerating and accelerating under load seems to be the biggest problem.

I have checked the car over with a couple of TDI friends with a VagCom.
1) Check all the hoses and vacuum lines (Replaced suspect lines)
2) Check all the sensors (MAF, EGR, N75, needle lift etc.)
3) Checked the function of the actuator on the turbo.
4) Intake and EGR was cleaned 10k ago along with TB, and fuel filter.
5) Cleaned snow screen, air filter good.
6) Played with the IQ and pump timing. Moving them up seemed to help, after a day the problem came back.
7) Injection pump seems to be in great shape. (no leaks or bad noises)

My next steps are to…..clean the EGR again, replace the relay 109 and have the ECU scanned and sent to a tuner.
 

wolf1477

Well-known member
Joined
Jun 21, 2007
Location
Tony,WI
TDI
2000 Golf
Stupid question: When you replaced your fuel filter did you replace the o-rings?
 

rc_y2kws6ta

Well-known member
Joined
Jan 26, 2007
Location
Folsom, CA
TDI
2002 black Jetta TDI Auto
Yep. I replaced the fuel filter 10k ago, with the supplied O-rings. I was careful with the pastic T as well.

I did check the boost with a VagCom (w/ a TDI friend). The boost was coming up fine.

I did find one fault code tonight and cleared it. Any insight on this fault code? A bad 109 relay?
17978/P1570 - Engine Start Blocked by Immobilizer

Possible Symptoms

  • Engine starting but stalling immediately
Possible Causes

  • Key(s) not matched
  • Instrument Cluster not matched
  • Engine Control Unit (ECU) not matched
  • Engine Control Unit (ECU) Power Supply faulty
Possible Solutions

  • Match Key(s)/Instrument Cluster/Engine Control Unit (ECU)
  • Check Engine Control Unit (ECU) Power Supply (Relay)
Special Notes

  • If no other immobilizer related fault codes are stored and the immobilizer related meas. blocks are fine except Engine Start not allowed, try cold-booting the car. Remove both battery cables from the battery. Short the battery cables together (away from the battery) for about 15 seconds. Reconnect the battery.
 

rc_y2kws6ta

Well-known member
Joined
Jan 26, 2007
Location
Folsom, CA
TDI
2002 black Jetta TDI Auto
Really need help....
Intermitted Hesitation starting at 1800 RPMS accompanied by black smoke...

New sympton: The idle holds for the most part until I put it in drive or reverse...It will dip for a split second and recover....only does it two or three times
 

alphaseinor

TDI Innovator, Gone but Not Forgotten
Joined
Jul 30, 2006
Location
Denton, TX
TDI
'03 Jetta TDI 780,000 miles (totaled out), 01 Audi TT 225 Quattro 230,000 Miles (runs great!), 00 Cabreetle Beetle dash, ALH & MK4 harness Swap
Turbo actuator is leaking... that's what mine was...

Could be the problem... I think someone was thinking about ice crystals or something...
 

rc_y2kws6ta

Well-known member
Joined
Jan 26, 2007
Location
Folsom, CA
TDI
2002 black Jetta TDI Auto
Eck and I tested the actuator with a mityvac. It appear to move well and hold vacuum.
Was the the correct test?
Can I buy an actuator without the turbo?
Maybe it losing a fine movement, can it be cleaned?
 

rc_y2kws6ta

Well-known member
Joined
Jan 26, 2007
Location
Folsom, CA
TDI
2002 black Jetta TDI Auto
I gave a the EGR a detailed cleaning and put it back on.
I noticed the turbo air intake pipe's spring clamp was about a 1/2 of an inch off, so I centered it back on. Are those really sensitive? I am wondering if it is a contributing factor to the hesitation.

I still need to drive it to see if its running better.
 

bob022004

Well-known member
Joined
Jun 13, 2007
Location
Monroe, LA
TDI
2010 Jetta TDI
I'm running across the same problem myself. if i happen to figure something out i'll post up. just recently did the intake cleaning....the fuel filter isn't very old, i use bp diesel, brand new MAF sensor.
 

rc_y2kws6ta

Well-known member
Joined
Jan 26, 2007
Location
Folsom, CA
TDI
2002 black Jetta TDI Auto
Thanks. I cleaned the ERG again and found a spring clamp on the turbo was slightly off. I lined it back up and throughouly checked all the hoses and piping. No Change.....

Visually, maintence schedule and on the vag-com my Jetta is in great running condition. I am going to switch out the injections with some new injectors, having a tuner verify the current programming, and upload a new tune. I am going to run somemore logs, just in case something changed or I missed something previously.

One good thing is...when your car puffs out some black smoke, nobody tail-gates you!!
 

bob022004

Well-known member
Joined
Jun 13, 2007
Location
Monroe, LA
TDI
2010 Jetta TDI
You're right about the smoke....funny stuff.

I'm thinking maybe the cat might be clogging. thinking of getting a test pipe when i get a chance. I'm out of town right now.
 

rc_y2kws6ta

Well-known member
Joined
Jan 26, 2007
Location
Folsom, CA
TDI
2002 black Jetta TDI Auto
I THINK I FOUND THE PROBLEM! >>>MAF or MAF wiring
I figure I must have missed something and so I started testing everything over again.

We were driving it this weekend and it hit a dead spot where it wouldn't accelerate, started to stumble, then told off with a puff of dark smoke. During that time, the MAF reading would start low then jump high and continue to jump all over.
I unplugged the MAF and the car has not sumbled or hesitated since. It drives alot better with the MAF unplugged.

I will either order a new MAF or borrow a friends for testing.

I think test pipes are around $200. You might want to unbolt the exhaust after the turbo, hold it up with a hanger (if needed) and test drive. Unless of course you are just going to run it without a cat.
 

alphaseinor

TDI Innovator, Gone but Not Forgotten
Joined
Jul 30, 2006
Location
Denton, TX
TDI
'03 Jetta TDI 780,000 miles (totaled out), 01 Audi TT 225 Quattro 230,000 Miles (runs great!), 00 Cabreetle Beetle dash, ALH & MK4 harness Swap
"test pipes" are about $20 + $40 to weld them in...
 

bob022004

Well-known member
Joined
Jun 13, 2007
Location
Monroe, LA
TDI
2010 Jetta TDI
I'll test my MAF by disconnecting it and driving it but i just replaced it not two weeks ago so i doubt mine is the MAF. also the way that the exhaust soot has been going out has been awfully lazy looking which is why i'm suspecting a clogged cat.
 

bob022004

Well-known member
Joined
Jun 13, 2007
Location
Monroe, LA
TDI
2010 Jetta TDI
the test pipe is on and the MAF is still plugged in and the battery has been disconnected and reconnected. things have improved but i'm still going to try a set of nozzles and see what happens from there.
 
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