Sudden Onset: Rough Idle, Jerking and Sputtering Under Acceleration, white/blue smoke

Hey Everybody,
Here's the deal, I drove my car to work the other day and all was well. I went to leave for lunch and as I was leaving the parking lot, the car was sputtering and jerking and would not accelerate beyond say 30 mph, also creating some white smoke. I am looking for help diagnosing the issue.

I immediately went to the forums and started searching those symptoms and figuring out what to do. Later that day, after car cooled, I started it (starts with no trouble) and noticed a slightly rough idle that smooths out as the temps came up. Drove around the parking lot again with same jerking issues.

After browsing forums related to my symptoms it appears common causes are injection issues (timing; quantity; quality; etc.), turbo issues (boost leak?), or compression issues. I do have a vag-com which I purchased back when I did the timing belt about 45K miles ago, so that will come in handy, I just don't know all of it's capabilities.

Observations/findings/fixes so far:
1) To address injector concerns, I performed a diesel purge (Liqui-Moly straight into IP) and replaced the fuel filter (fuel filter was last replaced same time as timing belt) - outcome: no improvement (figured this would be beneficial regardless of outcome)
2) I checked injection timing in Vag-Com and it was dead-on where it needed to be.
3) I performed a compression check (engine cold - immediately following oil change) - readings: 470-510-500-505 (1-2-3-4)
4) I disconnected lower intercooler pipe to check for oil and only a few drops came out (hopefully that rules out a blown turbo)
5) Also checked for fault codes - no codes
6) Regarding the smoke; produces white/blueish smoke at idle; smells like diesel to me (sweet-like; doesn't burn eyes); seems to dissipate as temps come up and idle smooths; though lots of smoke when trying to accelerate.


Btw, once the engine is warm (idling smooth), and in neutral, the engine will rev smoothly and I can hear the faint whine of the turbo...so I hope that means the turbo functioning properly.

Plan/Next steps:
1) remove valve cover to inspect things from that perspective
2) if all is well under the valve cover; continue to troubleshoot intake/turbo system (boost leak test?; vacuum problems?)

Am I on the right track? Anything else I should check right away with Vag-Com? Any recommended next steps? I'm trying to start with the simplest and least expensive fixes and keep going til I find the root cause.

The car:
2002 Golf w/ 295K miles; purchased the car with 245K miles; changed timing belt at 250K; regular OCIs (though my last oil change was 10K overdue); no problems/symptoms leading up to this, seemed to start acting up out of nowhere. It is my commuter, commuting 70 miles round trip 5days/week. Fuel economy has been steady around 47-48mpg.

Me: a do-it-yourselfer with some mechanical inclinations; no reservations attempting any repair as long as I have the right tools/guidance; like my 3yo son says, "I do it myself!" (that is unless I don't have the tools or until I'm getting nowhere)

I had the car towed home, it's currently in my garage. I will be on a business trip for the next 10 days, so I won't be able to do any immediate work on the car, but I can at least interact on the forums and refine my action plan for once I get home.

Thanks in advance the help!

One more thing: I did check the IQ and it was right at 3.0

Did you try unplugging the MAF and see how it runs?

I'm always watching these type of threads. My '98 did the same thing leaving the lot a while back. I was getting on it a bit more than usual but nothing serious since the motor was cold.

Had similar symptoms to yours. At the stop sign after about 50 yards it stalled. Started right up and has been normal ever since. Been looking for insight on this.

I had similar issues in my 2003 golf. Try unplugging the EGR valve vacuum line and see if it helps. My issues were very similar to yours and I diagnosed it as a faulty EGR spring. Vcds what is commanding a certain setting and adjusting the fuel for it but in reality The egr valve was doing what It wanted to and it was causing it terrible Idle issue when it was cold.

Someone correct me if I'm wrong but doesn't your EGR valve stay closed for the first so many minutes once you start your car. And if it is not staying closed going to give you all kinds of problems

Along the lines of what Sttb is suggesting, it pretty much sounds like a temperature instigated issue.

I wonder whether a flaky CTS could also cause this?

I'm really not wanting to say this, but... this also sounds like an IP starting to go bad.

Sttb said:

Someone correct me if I'm wrong but doesn't your EGR valve stay closed for the first so many minutes once you start your car. And if it is not staying closed going to give you all kinds of problems

Click to expand...

It's actually open for the first couple minutes. At exactly 2 minutes, the EGR valve snaps shut...you can hear it if the hood is up. If the hood is closed, the idle sound changes anyway, so you will hear that regardless.

As far as causing problems...I dunno. A lot of people have disabled them in one way or another...

Alright, I finally got back under the hood tonight. Too much other stuff going on lately. But I digress.

KLXD said:

Did you try unplugging the MAF and see how it runs?

Click to expand...

I started car, let it run a few minutes, and unplugged the MAF sensor. There was immediate change in the idle...not any smoother. I plugged and unplugged a couple times to verify the idle change. So that's working?

Sttb said:

Try unplugging the EGR valve vacuum line and see if it helps.

Click to expand...

I didn't know exactly which vacuum line to unplug, but as I was pulling one, it felt like it separated underneath the braided outer cover (and I was pulling with very little force). When that happened, I noticed a slight change in the idle. Now I have at least one vacuum line to replace.

UhOh said:

I'm really not wanting to say this, but... this also sounds like an IP starting to go bad.

Click to expand...

Any way to diagnose/test this?


I proceeded to take the car out in the cul-de-sac and although it idles fairly smooth (only a little hiccup now and then), it simply does not want to accelerate. Not as jerky as before, but less acceleration.

I did take a look under the valve cover to rule out anything major there.
looks good...can't figure out how to upload pic.

I hooked up the VCDS again to check codes (CEL came on at startup). I'm wondering if any of these were triggered by the MAF sensor (when I unplugged it) or the vacuum hose I may have damaged. they are:
P1563 - Quantity Adjuster (N146): Lower Limit Reached
P1354 - Modulating Piston Movement Sensor (G149): Electrical Malfunction
P0183 - Fuel Temp. Sensor A (G81): Open or Short to Plus
P0216 - Commencement of Injection Valve (N108): Circuit Malfunction

(I double checked the injection timing and it is right where it needs to be)

Any ideas what to do next? Thanks again!!

Unplugging the MAF should have set a Code for that.

All four of those Codes are for components inside the pump. I'd be looking for wiring issues on the pump harness. Maybe the connector on the pump.

^^^ Folks need to become accustomed to thinking this way as these cars age- wiring is aging and insulation is starting to break (and there's also chaffing occurring INSIDE of wire looms! - given a long enough period of time all that flexing that goes on the looms will break down the wires!)

Wiring or DMF may be where this is going, BUT FIRST
Sounds like you have the original vacuum tubes on the car. Renew them all.
If you look around the forum you'll find the lengths and sizes. Go ahead and do the viton hose as well (injector drains). Also an alternate source for he one-way valve, if you need one (OEM is stupid $).
Check supply air, check anti-shudder valve operation, check if turbo vanes stuck, actuator operating.

jdodson21 said:

.................
P1563 - Quantity Adjuster (N146): Lower Limit Reached
P1354 - Modulating Piston Movement Sensor (G149): Electrical Malfunction
P0183 - Fuel Temp. Sensor A (G81): Open or Short to Plus
P0216 - Commencement of Injection Valve (N108): Circuit Malfunction

Click to expand...

When you start with the wiring diagnose, there is a bundle of wires passing close to the starter and under the battery containing wiring for these devices, unwrap and inspect

KLXD said:

Unplugging the MAF should have set a Code for that.

All four of those Codes are for components inside the pump. I'd be looking for wiring issues on the pump harness. Maybe the connector on the pump.

Click to expand...

Thought so. I will inspect the wiring.

UhOh said:

Folks need to become accustomed to thinking this way as these cars age- wiring is aging and insulation is starting to break

Click to expand...

Yep, that has been in the back of my mind.

BobnOH said:

Sounds like you have the original vacuum tubes on the car. Renew them all.

Go ahead and do the viton hose as well (injector drains). Also an alternate source for he one-way valve, if you need one (OEM is stupid $).
Check supply air, check anti-shudder valve operation, check if turbo vanes stuck, actuator operating.

Click to expand...

Thanks for the list. I will make replacing the vacuum lines my next priority. Can you provide more details on the "one-way valve"...which one would that be? And what about the turbo vane actuator (I've read about this but I'm not sure where or how to check that)

I'm going to put the DMF possibility on the backburner for now. If problem persists after vacuum line replacement and wiring inspection, will the next step be Injection Pump?

Thanks again for the patience and assistance!

Resurrecting an old thread...didn't get things worked out back then and with baby #3 arriving soon, I had to sideline the project until recently. I'm ready to get this commuter back on the road, so here's where I'm at now...

While troubleshooting and going through processes of elimination, I pulled the EGR valve and discovered the fabled intake manifold buildup, a LOT of buildup. So even if those weren't the culprits, they needed to be replaced. So that's done, new EGR valve AND intake manifold.

also replaced all vacuum lines. pulled vacuum on the VNT actuator and the rod goes through full motion, doesn't seem to stick, but it's not holding the vacuum like it probably should (tried with old and new hose), it slowly leaks down.

Having done those two things, original behavior still persists, though not quite as bad as at first. Jerky at low RPM out of the gate. Turbo seems to kick in (not jerky) near WOT. Slow to moderate accelerations are more problematic (jerky). Runs extremely rich.

I cleared codes after replacing the EGR/manifold/vacuum lines and drove ~40 miles before CEL returned. New codes:

2 Faults Found:

16485 - Mass Air Flow Sensor (G70)
P0101 - 35-10 - Implausible Signal - Intermittent
16786 - EGR System
P0402 - 35-10 - Excessive Flow - Intermittent

Drove home and logged some data with VCDS - https://www.dropbox.com/s/30azrcahmhlgffd/LOG-01-003-010-011.CSV?dl=0

At this point, I want to check the following:
1 - MAF again (what's the best way to diagnose? can I clean it?)
2 - Vacuum Pump (make sure it's pulling consistent vacuum)
3 - VNT actuator (any way to test this with VCDS? or is manual test best?)

Where else should I be looking? EGR components? I'm happy to collect more data.

thanks in advance for your interest/advice/guidance
https://www.dropbox.com/s/30azrcahmhlgffd/LOG-01-003-010-011.CSV?dl=0

Because the actuator leaks down--doesn't hold vacuum-- that could be one of the reasons you really don't get any power until the higher RPM range, you don't have enough vacuum at the lower RPM's to make the actuator pull all the way in. To check the vacuum pump there are a couple of different orders of the same tests and here is where I suggest starting: at the nipple attached to the brake booster check the amount of vacuum at idle with only the vacuum gauge attached; it should pull up to 25" but if you get 22" you are still in good shape. If vacuum is in the 10"-15" range your vacuum pump is likely losing vacuum at the seam between the two halves of the pump housing. There are threads to fix this problem for less than $10 with a new o-ring. If vacuum is good at pump nipple go to N18 solenoid and check the vacuum there; if vacuum is less there than at the pump nipple you may have leaky solenoids causing the loss of vacuum to accumulate the farther away from the vac pump you get. If the pump is good, test each item from driver's to passenger side until the culprit(s) show them selves. In Vag-Com in Group 3 there is the option of lowering the percentage of EGR % to a very low number and that usually stops the EGR error message. Do you have any dielectric grease? Lots of people use that on the MAF connector to help clean the pins and improve conductivity. There are MAF cleaner sprays that may work sometimes for a long time and sometimes not at all, but a can of cleaner and a tube of grease is a LOT cheaper than buying a new Bosch MAF. I have been through all of this personally, myself, so I can give my experience on this issue. My IP has thrown IQ errors and cold start/injection timing errors, and since the pump that I now have is from a vehicle I have no history on, I am biting the bullet and getting a resealed and tested IP from a reputable source (DAP). If you have access to Bio-D a quart (or more) of B-99 per tankful of fuel helps to keep old pumps happy. There is always Power Service as well, but it is a bit more costly per tankful. If I can be of any more help, PM me.

you did diesel purge in step 1.... but did you rig it up so you could drive it on the can of diesel purge or just idle in lot?? i drive the car on the little can as then it replaces all but the pump from the fuel system.. as to me.. it sounds as if its got a air/fuel issue.. but that test seems to give tons of info.. why i ask... if runs same not in the fuel system unless the pump..

you cannot do this with that powerservice **** they sell... even mixed with fuel i had it down to 9 parts diesel 1 part **** and it would still lock the injector pintels open hydro locking the engine on fuel.. so ill say never use that **** as it no way adds lube the ve is seeking... 2oz of 2 stroke oil per gal of diesel fuel does do wonders on injector noise though.. adds the lube the uls fuel stole and makes the pintals quiet... why bio helps as it adds lube ulsf lacks.. only try stuff like this on proper running car..

Nevada_TDI - thanks for the guidance. I'm gonna swap my MAF with a known good one from a friend and try to rule that out. Then I'll move to testing the vacuum pump/solenoids. Then to the VNT actuator. I'm mentally preparing myself to replace the actuator. Hope to get on that this weekend.

CRSMP5 said:

you did diesel purge in step 1.... but did you rig it up so you could drive it on the can of diesel purge or just idle in lot?? i drive the car on the little can as then it replaces all but the pump from the fuel system.. as to me.. it sounds as if its got a air/fuel issue..

Click to expand...

I did the diesel purge at idle. definitely an air/fuel issue...but I'm becoming more convinced the source of the problem is either MAF, vacuum, or VNT.

Here is a screen shot of live data recorded while driving steady at ~60mph and 2000rpm+/- (right before it went into limp mode). The yellow line is MAF (actual), you can see that it drops off regularly and a more throttle brings it back up temporarily. My question is what is triggering the drop in MAF? if the VNT is leaking down (effectively a vacuum leak), that would restrict the turbo and not deliver the air required to match the fuel delivery, therefore creating the rich fuel:air ratio. is that right?



FWIW, the car runs fine in limp mode. Smooth running "non-turbo" diesel. I also found this out by accidentally leaving a vacuum hose disconnected after replacing the EGR/manifold (the one connected to the black side of the check valve). The car ran very smooth, just no turbo. That tells me that injectors, IP, or timing issues are not the issue.

Image doesn't appear...here is a link
https://ibb.co/jnKWqQ

I'm having similar problems: "missing", heavy smoke, a stall now and then.
2000 Jetta, approx 278K miles. I started inspecting the vacuum tubing and have replaced some that were quite hard (probably leaking). I've also got a NEW N-75 valve on the way. From other posts in this forum, they DO age and malfunction.
I also am replacing the fuel filter as the symptoms sorta make me think of water in the fuel and the filter is OLD.
My IP is nearly new tho, had it rebuilt last year by the folks in Oregon.

OH YEAH...If you've been running with the turbo disconnected, BE SURE TO DRAIN THE INTERCOOLER before putting the turbo back in service. There's a bunch of oil collecting there and you could have a runaway when the turbo starts working again.

Swapping the VNT actuator

jdodson21 said:

Nevada_TDI - thanks for the guidance. I'm gonna swap my MAF with a known good one from a friend and try to rule that out. Then I'll move to testing the vacuum pump/solenoids. Then to the VNT actuator. I'm mentally preparing myself to replace the actuator. Hope to get on that this weekend.

Click to expand...

It is a super easy job to do as there are only two 10mm bolts holding the actuator to the manifold. Remove the "E" clip, it's more like a horseshoe clip from the actuator arm and slide out the vacuum pot.

Fueling problems

Warthog said:

I'm having similar problems: "missing", heavy smoke, a stall now and then.
2000 Jetta, approx 278K miles. I started inspecting the vacuum tubing and have replaced some that were quite hard (probably leaking). I've also got a NEW N-75 valve on the way. From other posts in this forum, they DO age and malfunction.
I also am replacing the fuel filter as the symptoms sorta make me think of water in the fuel and the filter is OLD.
My IP is nearly new tho, had it rebuilt last year by the folks in Oregon.

Click to expand...

Missing and heavy smoke and sometimes a stall can be caused my the fuel pickup line in the fuel sender in the tank being partially plugged. It happened to me, and after testing everything else, when I drilled out the pickup tube the problem went away.

That's a new thought, Nevada. Now if it will only happen again, I will try to SEE how the fuel line looks (It's clear). Last time (8/2/17) I was in traffic but the car kept going...

The only negative thing about this idea is, heavy white/grey smoke usually suggests too much fuel and not enough air, like a cold morning start.

Update: Today I removed the EGR and the elbow tube under it. WHAT A MESS! I started cleaning it but finally just ordered a new one.
I'd say the bore was 2/3 clogged maybe more. No wonder my mileage was going down, the engine was starving for air.
I "think" particles may have been breaking off and going into the intake...
More later.

Have removed the intake manifold following deffbug's instructions (see "stickeys"").
It was pretty nasty...Now have to clean it. Lots of carbon shook out tho, so it's not as badly coked-up as some others I've seen. One so bad the Owner just replaced it!! I guess they drove sporty-like a lot.
I have some comments about the instructions so will go there next.