Any help or suggestions appreciated here. Have an 01 TDI ambiente that is running roughly when started from cold, like the timing is retarded and it is very smokey. Once warmed up it runs fine.

Have just changed timing belt, timing is spot on via VCDS and there are no fault codes coming up.

This is on the back of a turbo failure when the seal failed and the engine ranaway for 4-5 seconds before I stopped it. Have replaced with a new turbo. Any ideas for the rough running when first started? As i say it runs sweetly when up to temp.

firstly when you did the new turbo, did you also do the oil feed pipes.

In terms of cold, try double cycling the glow plugs to see if this helps, if it does you've found your culprit.

If not look at the MAF sensor and the temperature sensor. Either can cause the car to over/under fuel and run funny when cold. (or warm for that matter).

Other option could be a leaking head gasket, causing some water to creep into a cylinder after a period. How is your coolant level?

Otherwise I would go for CTS (as you have vagcom check the ECU output and see if it is sensible), and then MAF, assuming the timing is spot on (as you say).

Edited 19 December, 201114 yr by mbames

Thanks for your suggestions. I kept the old oil pipe as it was clear and in good condition. You've got me wondering about the head gasket now as it does run when cold as if the HG has blown. I'll keep an eye on the coolant however it does not seem to have gone down. I'll run some more tests this eve regarding the coolant sensor/MAF. It's probably nothing but I did notice a discrepancy in what the VCDS said the temp was and what the needle on the dash said, about 10 degrees out.

ok I've just measured the temp using VCDS, engine has not been run for 2.5 hrs and it's 7degs outside, temp sensor is showing 34degs. Does this look like my problem? The GP light just goes on for 1 sec even when it was minus 5 the other day.

[edit]

I misread your post and through the engine had been running for 2 1/2 hours and then you read the temp.

It will take sometime for the engine to cool, but I dunno how long, so that figure may well be reasonable.

Edited 21 December, 201114 yr by mbames

I've just checked it again this morning when stone cold and it's showing as 8degs, same as ambient temp so I guess that rules out the coolant sensor.

[edit]

I misread your post and through the engine had been running for 2 1/2 hours and then you read the temp.

It will take sometime for the engine to cool, but I dunno how long, so that figure may well be reasonable.

No worries, I thought was the case!

Unfortunately this is a bit vague as I'm only snatching 5 mins here and there to work on the car due to 12hr days at work and it being xmas etc.

The MAF reading when idling from cold this morning was a variable figure switching from 550ish to 300ish, should this be a steady figure? I haven't had chance to unplug the MAF to see how it runs without it yet.

Also I was wondering what effect not having a breather pipe to the intake system may of had, if it was not measured by the MAF how would/could this have affected running?

I know I really need top spend a oouple of hours on this but I don't have them at the moment and I really need the car running ok!!

Edited 21 December, 201114 yr by YHNW

If it helps, I can read some figures off my car tomorrow for you (in a cold state), if you tell me which channels, etc.

Looking at an old graph of mine when it was having turbo problems, the MAF seemed to read between 480 (idle) to 1000 (hard acceleration). I would expect a fairly even idle MAF reading (logically - at least in my mind). - see image below.

Without the crankcase to air intake pipe (or at least the hole blocked on the air intake pipe the car would have had more air then it knew about and thus might be under fueling a bit. To be fair mine ran like this for about a week when my "bung" well out. It still started and idled fine, but was lacking a bit of power. Registered as soon as it fell out that something wasn't quite right but it was a few days before I had a chance to investigate.

I had some cold starting problems and sorted them by changing the 109 relay. I noticed that often the glow plug light would only come on for one second or so even when it was very cold.

Also having changed the CTS I would say you may need to watch what the sensor is reading for a while rather than just snapshots as often they seem to read OK then go wonky for a while and then back to normal, so I wouldn't out the CTS yet. What happens if you disconnect the CTS?

ok I tried removing the CTS - made no difference. Tried removing the MAF made no difference - however readings are on VCDS anyway.

These are the only error codes that I got from those actions:

2 Faults Found

17552 - Mass Air Flow Sensor (G70): Open or Short to Ground

P1144 - 35-00 - -

17664 - Engine Coolant Temp Sensor (G62): Open or Short to Plus

P1256 - 35-00 - -

Nothing about glowplug relay - is this as it should be?

The MAF reading is what it should be...the EGR is around the 60% mark from starting.

These are the inj quantities - cyl 1 is notably different to the other 3?

Cyl 1 Cyl 2 Cyl 3 Cyl 4

TIME

STAMP mg/str mg/str mg/str mg/str

0 1.88 -0.52 -0.89 -0.49

0.36 1.86 -0.47 -0.89 -0.47

0.72 1.86 -0.47 -0.92 -0.47

1.07 1.88 -0.52 -0.92 -0.47

1.42 1.88 -0.52 -0.89 -0.47

1.78 1.86 -0.49 -0.92 -0.45

2.14 1.88 -0.52 -0.92 -0.45

2.5 1.88 -0.52 -0.92 -0.47

2.86 1.88 -0.52 -0.89 -0.45

3.22 1.88 -0.52 -0.87 -0.42

3.58 1.88 -0.54 -0.87 -0.45

3.94 1.88 -0.59 -0.85 -0.47

4.3 1.88 -0.64 -0.8 -0.49

4.66 1.88 -0.71 -0.71 -0.52

5.01 1.88 -0.75 -0.61 -0.52

5.37 1.88 -0.8 -0.54 -0.56

5.73 1.88 -0.87 -0.47 -0.59

6.08 1.88 -0.94 -0.38 -0.61

6.44 1.88 -0.99 -0.31 -0.64

6.79 1.88 -1.04 -0.24 -0.66

7.14 1.88 -1.08 -0.19 -0.68

7.5 1.88 -1.11 -0.09 -0.71

7.86 1.88 -1.15 -0.09 -0.71

8.22 1.88 -1.13 -0.09 -0.71

8.58 1.88 -1.06 -0.14 -0.68

8.94 1.88 -0.99 -0.16 -0.68

9.29 1.88 -0.96 -0.21 -0.68

9.64 1.88 -0.94 -0.26 -0.66

10 1.88 -0.92 -0.31 -0.66

10.36 1.88 -0.89 -0.33 -0.68

10.7 1.88 -0.85 -0.38 -0.68

11.04 1.88 -0.8 -0.4 -0.68

11.41 1.88 -0.78 -0.4 -0.68

Also what should the EGR be reading straight off from a cold start? 60% seems a lot.

I think the EGR recycles more gasses at lower engine RPMs, so that might be reasonable. A google on the subject may reveal more info.