Would VCDS help?

**daf95** · 14-10-2016,09:06 PM

Hi all,

Seems I only post when I have a problem!

Looking for some advice about VCDS - assuming I can find a local member who could help . . . My daughter has a '54 plate Polo 1.4 Tdi (fitted with the AMF engine.) It has 125,000 on the clock; I did the timing belt, water pump and idler two years ago at around 90,000. Also did engine service - oil, filters etc. Ran fine until earlier this year when daughter told me (in her own special way) that it was misfiring, mostly on hills. We've got a lot of those here in North Wales . . . I took it for a run and it was indeed misfiring, but I'd already exhausted my knowledge of more modern diesels so looked for some kind of specialist, but first changed the fuel and air filters in case it was being starved of fuel or air.

Having been recommended someone I phoned and described the problem. He stopped me halfway through and said it would be the injector harness so I booked it in to be fixed. £300 later she had the car back and it seemed OK. Couple of weeks down the line it started misfiring again so she phoned and told him, when he said it 'might' be injector seals - back it went . . . Another £300 and she had the car back, going OK for a while until it started misfiring again. This time it 'might' be injectors - at £1200 . . . That's probably more than the car is worth so she decided to live with the misfire - but a bit later it started getting hard to start as well. She did phone the garage and was told it might be glow plugs, so I changed them myself but it made no difference.

Eventually the performance got a lot worse, the car was laying a trail of blue smoke as she drove and got to the point where she was unable to overtake a tractor and trailer on a hill on the dual carriageway. Then she noticed the water temperature was through the roof and had to stop to give it a rest . . .

Various people have suggested that it's the turbo, EGR valve, injectors and anything else they could think of. Not qualified people, just folks whose uncle once had a diesel . . .

Getting to the point, if I could find a member who had VCDS near to us, would it be able to pinpoint the problem or is it really just a case of throwing money at the car by changing parts until we stumble on the solution?

**Gizmo68** · 15-10-2016,08:59 AM

VCDS will only tell you of a problem if the item in question has either a sensor on it or has a wire connecting to it.

From what you have described (especially the overheating) I would be looking at the head gasket, check for coolant marks between the head and block, oil in the expansion tank or coolant in the oil.

Blue smoke is oil being burnt off, usually caused by one of the following:

Valve seals (usually when you put you foot down)
Head gasket (normally white smoke from the coolant burning off... steam, but can also be blue if the oil is going into the cylinders, this would also cause a misfire)
Turbo (loads of blue smoke)

You really need a mechanic (someone who can diagnose what the fault is and it’s likely cause) to look at it rather than a ‘fitter’ (someone who just replaces parts)

**daf95** · 15-10-2016,10:01 AM

Thanks for your reply. I'm no mechanic and don't pretend to be - I've usually done what work I can on my own cars but the cars used to be simpler back then (points and condenser ignition, carburettors, naturally aspirated diesels etc . . . )

I did check the oil and it doesn't appear to have water in it; the water doesn't appear to have oil in it and the level in the header tank hasn't dropped. So yes, I agree - we need a mechanic, which is what the first guy claimed to be (diesel injection specialist, if you will . . . ) To be honest, I've lost faith in the way he appears to approach the job - 'could be' doesn't instill much confidence. Surely, if it 'could be' an injector the injectors could be tested?

Ironically, the car was booked into an independent VW specialist for the beginning of the next week when it died. We can't get it there now as (1) she had to buy a replacement car PDQ just to get to work, leaving the Polo with no insurance and (2) I'm not convinced it would make it the 20 miles to the garage. That's why I was wondering if VCDS would actually help in this case. And she's trying to assess whether the car is worth repairing, hence the need for accurate diagnosis before throwing more money into the pit IYSWIM?

Now to find a mobile mechanic who knows VW diesels . . .

**golfmk4owner** · 26-11-2016,10:27 AM

Hi,

I imagine you're probably sorted by now?, and I don't immediately know the answer, but might it not be worth running a live scan of your vehicle whilst you're driving it? Analysing the data from that, might assist in determining the root cause of the problem?

Just a thought!

**daf95** · 26-11-2016,11:31 AM

Thanks for the reply. No, the problem hasn't been resolved yet - we're still trying to find someone who has VCDS and knows what they're doing to look at it.

The battery ran down a bit from standing with the immobiliser on so I went to my daughter's house, removed the battery and brought it home to charge it. When I took it back I checked the levels - the oil level is still well within tolerance and so is the water. Had a good look again and there's no oil in the water, nor is there any water in the oil.

I've only had my daughter's description of the faults to go on previously (for example, she described the original misfire as 'slipping . . .' ) and although she said it was smoking she couldn't tell me what colour the smoke was. Thought it might be blue or white . . . And on close questioning under bright lights I'm told that the temperature gauge only reached the middle of the scale before she stopped and let it cool down, so maybe no damage to the head gasket

I started the car when I'd checked the oil and water and it feels to me as if it's only firing on one or two of its 3 cylinders - definitely way down on power and really lumpy; not wanting to rev. It also gave me the opportunity to experience the smoke, which was indeed blue but reeked of diesel (of the variety that comes out of the pump at the garage, not the usual diesel exhaust smell) suggesting to me that it's unburned fuel getting blown out of the back.

Thanks too for the suggestion of running diagnostics while under load, but I still don't have access to anyone with VCDS. I do have a cheap hand-held OBD scanner for VWs but I don't think it would give enough information to be of use in this case. Plus of course, no insurance so can't drive it either.

At this moment all she wants to know is if the car is worth repairing or should she sell it with all faults. Obviously if the repair bill exceeds the value of the car it's a no-brainer.

**golfmk4owner** · 26-11-2016,12:32 PM