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BKC AUDI 1.9 SMOKING MISFIRE CONUNDRUM

5K views 22 replies 5 participants last post by  ukbob 
#1 ·
MOST OF THE TIME LOGIC AND LITERATURE GUIDES ME THROUGH. I have to admit to being on the edge of frustration.
2006 bkc engine smokes under load and stutters around 2k revs. over 2.5 k takes off and behaves normally.
With the vacuum hose to the egr valve blanked all is well. With the maf disconnected all is well. So I cleaned egr valve, no change, I tested egr valve operation, all good. I replaced maf sensor with bosch, no change. Hmmm I thought. I checked vacuum hoses with mityvac, all good. vacuum pump makes food vacuum. I checked boost hoses up to 1/2 bar positive , no leaks. I checked movement of turbo vane actuator whilst connected. seemed ok. I hooked it up to computer, with egr hose blocked boost actual matches boost expected. with egr connected normally it doesnt tally, less boost than expected. First I thought vacuum leak from belows in egr valve (causing vanes to open) as all hoses hold vacuum, but tests good. perhaps solonoid is playing around?
Is there any chance I am looking in completely the wrong place, I checked the camshaft lobes and injector loom. This on has got me.
 
#11 ·
Scanned with what a generic scanner?

You need to get your motor scanned (preferably with VAG-COM\VCDS) for any error codes logged in the ecu and post them, that will save a lot of guessing and check systems out.

Manufacturer: Audi, Date(s) Used: 02/2003-05/2007, Model: Audi A3/S3/Sportback/Limousine/Quattro, Engine Code: BKC, 77Kw, 105PS, 1.9 Ltr, 4 Cyls, Remarks: Turbocharged Direct Injection Pumpe Düse (TDI-PD), 8v Timing belt
 
#9 ·
It'll turn on a check engine light... basically look up black smoke remap and diy it... it's not that hard to do or expensive neither... just tell them you want them to map it out if you don't trust their maps... they do offer it as a service but you'd be better off reading about it on their website... you will need at least mpps v18 ( cheap chinese clone of ebay) to actually read the map save it and sent it to them by email.
 
#14 ·
Not yet, I am considering pulling the cooler and pipes to clean, the inlet manifold, the turbo to check the vanes. In the meanwhile I’m driving with the egr vacuum hose blocked, no smoke but a bit of a surge when the turbo kicks in around 2.3 k revs
 
#16 ·
By way of an update. Driving uphill with load the other day and suddenly lost a cylinder. Limped home to find electrical malfunction on no.2. I suspected that my overhaul of the injector wiring loom wasn't sufficient. I also feared an injector might be bad. Ordered a new loom and fitted. So far on a test drive, with the egr in circuit, misfire and smoke haven't re-appeared. So it looks like all the problems were from a faulty loom. Any further news and I shall report.
 
#17 ·
Nope! Not completely cured, definitely better since the new loom but still stutters under load until either, the turbo kicks in or the system closes the egr valve. I have seperated the exhaust from the turbo to have a look and to treat with chemicals.
The actuator moves fairly freely with a vacuum tool, starts moving around 5 and ends around 20. Holds pressure. ran a bit better after the treatment, time to think again.
 
#18 ·
On the turbo there is a little stop screw. It sets the initial point of the vanes position for full boost. If this little screw gets some wear on it and the vanes initial position is no longer correct you won't get boost from low down. Then it suddenly kicks in at higher revs.

How do I know this:

I got a turbo rebuild supposedly bench tested... they lied. Once fitted i had this black smoke... OK lots of black smoke on pull away with no power at all. Then suddenly the turbo kicks in, black smoke dissapears and car shoots off. It took me a long time... a visit to the turbo rebuilders who couldn't fix it.. lots of fiddling with egr valves etc etc. Nothing worked. Then I found the magic little stop screw on the turbo. You need a 4mm (i think from memory) ball head Allan key and 8mm socket for the stop screw lock nut. Unlock stop screw... turn the stop screw in a little bit in and re lock it. The stop screw sets the position of the actuator lever at full boost position. If its too far screwed out it does not work.

I have no idea how to set it correctly... but I know in my case just a half turn on that stop screw solved my issue.

Check it.

Sent from my SM-G980F using Tapatalk
 
#19 ·
Thanks for that y shall check it out, still not solved but the other day it suddenly got a little better! No idea why, I have put cleaner into the exhaust side of the turbo. I am about to put injector cleaner in the tank. Don’t drive it much so this is taking time.
 
#20 ·
I havnt ruled out the injectors yet, however I am leaning towards sticking vanes on the turbo, my understanding is that if they are not shutting down, resulting in low boost at low revs, then the engine wont be getting enough air. That would explain why at higher revs there isnt a problem. I am going to have another go with a chemical clean of turbo on the car before I bite the bullet and take it off for inspection cleaning.
 
#23 ·
Finally! After a lot of reading and help from "generous with their time" forum members I have had some success.
I got under the car and with the aid of a small socket set was able to access the stop screw. I screwed it in one turn. This action changes the position of the vanes at low revs. This is when full vacuum is applied. The engine at idle immediately felt smoother. There was no stutter or surge in power anymore during a 20 mile test drive. Thanks again to all that share their wisdom and experience online.
 
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