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    Thread: Golf Mk4 TDI - excessive smoke at cold start - possible MAF problem

    1. 02-13-2009 07:43 AM #1
      Mk4 Golf Excess smoke at cold start
      I have a 1998 Golf TDI Mk4 bought new and synthetic oil changed every 5000 miles. New air filter and fuel filter. Current done 64,000 miles and changed MAF at 52,000 (two years ago - not doing a big mileage).
      Just checked pipes around the inlet manifold and everything looks OK. Last I looked inside the inlet manifold it had no more than a light coating and certainly not clogged up.
      When MAF was last changed (genuine VW Part)there was a pronounced drop in performance, accelerating in particular. After changing it it drove like a new car.
      Recently started pumping out excessive smoke from rear exaust when starting from cold, but clearing as it warmed up. Disconnected MAF and started from cold - no smoke at all. Reconnected MAF and still no smoke.
      Reasonably confident fault lies with the MAF, or at least the signals it is giving to the Engine Management System. Have ordered a a new MAF. I do have access to VagCom but have not used it to diagnose this problem.
      Is this the right diagnosis?

    2. 02-13-2009 11:43 AM #2
      On reflection it might be that there was simply a bad contact on the electonic plug which was made good when the plug was removed and replaced. Watch this space.

    3. Member ejg3855's Avatar
      Join Date
      Sep 23rd, 2004
      Rochester, NY
      1993 UrS4
      02-13-2009 12:41 PM #3
      PSST..... post in the right forum and you wil get help

    4. 02-13-2009 02:13 PM #4
      I thought it was the right forum.? It says Mk4 TDI at the top of the page?.

    5. Member
      Join Date
      Apr 15th, 2004
      Hatfield, MA
      2010 Golf TDI 6M 2Dr
      02-13-2009 04:42 PM #5
      Your turbo seals could be bad or going bad.
      Where are you located? How's the weather? If you have one or two bad GPs, you'll get smokey starts.

    6. 02-14-2009 02:40 AM #6
      Thanks for your thoughts. I hope it's not the turbo. It was replaced when it was about 12 months old and I know how expensive they are. It is not using any oil at all so I tend to think (hope) that is not the problem. It's been cold but not extremely so.

    7. 02-14-2009 06:53 AM #7
      Vag Com showed only one fault "MAF - open or short to ground" Replaced MAF and there is no fault shown.
      Additional problem might be that the dynamic timing has slipped back (retarded) a little which might have result in overfueling at start-up. Will rectify in due course. Smoke problem has gone for the time being.
      Thanks for you interest.

    8. 02-21-2009 02:33 PM #8
      For information:
      The Mk4 TDI 1999 carries a MAF with a Part No. 06A 906461 (Bosch 280217121) for the European AGR engine (UK) as original equipment.
      This has now been superseded by VW Part 038 906 461 C, priced at £70.00 including VAT ($99.00). This part used to cost £190.00 (equivalent $270)as a VW part. Presumably this reflects all the problems that have been experienced and how the could the original cost be justified?
      I recently bought a new MAF on EBay for £30.00 with the exact part numbers shown in the first paragraph of this post and it works fine and no faults shown on VagCom.
      Now fitted the uprated VW MAF which is significantly different internally. VAGCOM before and after both MAFs and the readings are much the same. Smoke problem solved.

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