1.9 tdi won't rev, smoke, stalls

[Tangles553]

Hi all, please check all the dot points!

Per the title... I have a 2007 1.9L TDI Golf, BKC engine. It won't rev, if i hit the pedal it runs rough and will eventually stall out. It behaves like it's starved for air or fuel but as below I've done all the troubleshooting and everything seems fine. I'm stumped, please help! See videos below and note the engine bay smoke is from the exhaust, which was disconnected at the turbo.

For the first 20-30 seconds after cold start, it runs fine, boosts, drives normal - then like a switch was flicked, I get the below issue.

• hooked up VCDS - no codes

Checked fuel system:

• drained tank and filled with fresh diesel
• checked in-tank lift pump is working fine, it is, I used the pump to drain the tank
• checked pump primes with key-on (and checked that it does indeed flow out from the fuel filter)
• replaced fuel filter
• checked fuel lines have no leaks or splits
• have rebuilt the tandem pump, which showed no signs of wear or issues
• replaced fuel filter housing after finding an issue with it - fuel now flows correctly to tandem pump

Checked engine:

• checked 'intake flap' is open while engine running - it is
• checked EGR operates correctly, it does
• MAF reading seems normal, no difference at all with it disconnected
• Cam angle sensor reading normal - RPM is correct
• Crank angle sensor reading normal - RPM correct
• injector deviations all within spec
• checked exhaust not blocked - still happens with it removed at dump pipe
• checked turbo OK - have stripped and reassembled, no signs of wear (it's brand new) - still wouldn't explain the issue with it not revving even if the seals were shot
• checked for vac leaks - hard to check but I'm certain there isn't one
• checked and re-set engine timing - possibly need to do again with the proper tools but I'm reasonably sure it's not the issue as it runs fine for 20-30 sec
• inspected rockers and cam lobes - look fine, no signs of wear (new cylinder head)

I'm almost at the point of replacing injectors, there's not much else I can think of

Some videos of the issue. In both videos I'm planting the accelerator pedal and as you can see it won't rev. The second one highlights the smoke from the exhaust really well

VID 20200721 155744 - YouTube
VID 20200718 145837 - YouTube

Piccie of the beast for your enjoyment....

[Tangles553]

Bump... anyone here have any idea?

[Umai Naa!!]

Physically check the turbo itself.

These were known to break the shaft.

[Tangles553]

Physically check the turbo itself.

These were known to break the shaft.

Thanks, I have done. As above. Turbo is fine and even if it weren't it wouldn't prevent the engine revving in the way that it is

[Tangles553]

Bump...

Have stripped the tandem pump and reassembled with new seals, there were no signs of wear or perished seals so I doubt that had any issue. The internal mesh screen was totally clean also

I think diesel is coming from both the feed and return lines when the pump is disconnected and I activate the in-tank pump. Not sure if that is normal so will look a bit closer, hopefully there's just a faulty check valve or something to explain it

[Tangles553]

I think I have identified the issue. I disconnected the diesel fuel feed / return lines from the tandem pump and supplied power directly to the in-tank pump. Diesel came out of BOTH hoses at the same rate, which doesn't seem right. I joined them together by clear tube hoping to see the diesel correctly flow from the feed to the return, instead, I found that both lines were supplied the same pressure - so it leaked a little under my jury-rigged tube but just left an air bubble in the middle of it, ie. no flow.

I disconnected the lines from the tank to the fuel filter housing instead, and fitted my clear tube in between. I ran the in-tank pump again and lo and behold, the diesel flowed correctly from feed to return.

I took the top off the fuel filter housing (recently replaced fuel filter and seals with the correct kit) and couldn't visually see any issues at all, but something is definitely wrong inside the upright centre section of the housing.

I've fitted a small mower-style inline filter in place of the filter housing for now, it's probably not adequate at all, but it should be sufficient to see if I've identified the issue. Will report back how it goes

I can't find any reference online to disassembling that centre section of the filter housing to examine it for issues so I might just be looking at finding a replacement...

[Tangles553]

Welp, still doing it. Fine for 20 - 30 seconds after first start, revs, boosts, no smoke, can drive it up the street fine and it pulls like a train

Then, no revs, stalls after a bit.

I'm completely stumped and considering just finding another engine. Surely the injectors wouldn't cause this? That's all I can think that's left to swap out

[saabman]

Hi,

Ive got only a basic understanding of diesel operation - just never had to deal with them but strange problems interest me.

I would have thought if you have an injector problem than it most likely be one injector not all 4 causing grief and I understand the engine idles OK its just when you open the throttle it doesnt behave.

I just had a look at the video and WTF is the go with the smoke?? where is that coming from - reading your description I was thinking it was from the tail pipe but pouring out from under the bonnet??

Or was that with the tail pipe disconnected?

[Tangles553]

Hi,

Ive got only a basic understanding of diesel operation - just never had to deal with them but strange problems interest me.

I would have thought if you have an injector problem than it most likely be one injector not all 4 causing grief and I understand the engine idles OK its just when you open the throttle it doesnt behave.

I just had a look at the video and WTF is the go with the smoke?? where is that coming from - reading your description I was thinking it was from the tail pipe but pouring out from under the bonnet??

Or was that with the tail pipe disconnected?

That was with the exhaust disconnected at the turbo - I had it off to see whether it was blocked or if the turbo seals had failed.

I can't work out the smoke either. I have re-set the timing but didn't have the proper tools to lock the various pulley, just some I made myself, so I've ordered the real thing and will try it again. It doesn't make sense that it would run fine during the first 20 - 30 secs after startup if it had a timing issue, but I'm grasping at straws.

Oddly there is zero smoke during the first 30-odd seconds when the engine runs fine, it's only once something changes that it blows any smoke at all. That's leading me to rule out turbo or other mechanical failure due to oil. I'm no expert but it doesn't smell like oil either

edit: updated OP dot points to reflect most recent troubleshooting

[saabman]

Do you have a copy of the Funktionsrahmen for your ECU. I could only find the one for mine in German but worked through it using google translate enough to understand the basic functionality.

Blowing so much smoke looks like it running rich. In a petrol engine they run in open loop mode for around 90 seconds till the o2 sensors warm up and then switch to closed loop. I wonder if diesels do something similar?

[Transporter]

How was it running before it started to misbehave?


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[Tangles553]

This is where I'm at...



Had everything off to do timing, found I couldn't turn the camshaft at all with any sane application of strength. That didn't seem right, so i had the tandem pump off to see if it was binding. That was fine, so I figured I'd pull the rocker cover. Lots of condensation inside... Not sure how or why, although the sump oil looks fine there is milkyness under the oil cap.

I already had a spare head gasket and bolts here so figured it wasn't much extra work to simply do it and know it's done right (previous owner replaced the head and did a questionable job)



Took the injector rockers off and the cam spins freely so I guess the injectors just require a lot of torque to get pumping. I'm swapping them out so will see if there's any difference when it goes back together

Camshaft is like new, as it should be, it IS new

How was it running before it started to misbehave?

Running fine, then the turbo blew and the head was replaced due to it slowly using coolant. Put it all back together, now this.

[Transporter]

When you’re at it, before you fit the cyl. head back on, check the TDC of each piston making sure that all are at TDC.


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[saabman]

Just wondering if it appeared after having large number of parts pulled out to replace the turbo and do the head is it possible something as simple as a vacuum line is connected wrong?

I know I'm guilty of such mishaps

or parts from the disintegrating turbo lodging where they shouldn't?

[Tangles553]

When you’re at it, before you fit the cyl. head back on, check the TDC of each piston making sure that all are at TDC.

Do you mean check they all reach the top of the stroke? ie no bent rods?

Just wondering if it appeared after having large number of parts pulled out to replace the turbo and do the head is it possible something as simple as a vacuum line is connected wrong?

I know I'm guilty of such mishaps

or parts from the disintegrating turbo lodging where they shouldn't?

Maybe, I'm going to hate myself if I find something like that wrong haha but I have been over all that in detail and can't find anything wrong, although not that I am able to find a vacuum diagram for the BKC golf

Only the turbo seal failed, nothing broke