80, 'N' reg - acceleration and smoke problems

[xylophone]

I have an Audi 80 1.9 TDi, 1995, 90bhp, 222, 000 miles. Serviced and maintained on the dot, latterly by an excellent Bosch franchise, Volksparts, Durham. Never had what I would call major problems. Next major service due about now.

During last 7 days touring Scotland, heavily laden. Checked oil beforehand, level above line, topped up with small amount. Noticed she was not accelerating properly up steep hills. This got progressively worse, ending with same symptom on any hill, and sometimes on the flat. I put in Reddex thinking of the injectors, but no discernible improvement. Sometimes she would go up any hills without a problem, 75 mph, say, but that rare.

Coincidentally, perhaps, she has been emitting smoke in a manner I have not experienced before. Started with occasional cloud of dense black smoke we are all used to, which appeared to happen also at times when changing gear. Difficult to be sure in rear view mirror. That stopped, then noticed a thin, vapoury, whitish/darkish smoke, and that this happening when going up hills. This got worse. Not belching smoke, just thin clouds.
Exhaust is the original. Volksparts said several years ago, outer skin perished, but inner ok. They have only ever replaced a clip.

I am a member of the IAM, so I don’t drive fast or, I hope, badly so far as the car is concerned.

Re the lack of acceleration, I had the same problem, more or less with the car, five years ago, when I kept a record of what happened, as follows:

“Car not accelerate beyond 70

Main dealer advised as follows:

1. Turbo valve sticking - £35 valve + 20 minutes. Mechanic can tell just by taking on road

2. Cat - £100 - £300 + 2 hours (I think he said 2 hours) Diagnostic while on road

3. Flow meter -£100 + 2 hours. Diagnostic machine would tell, expensive

They leaned towards 1. Seemed confident that was it. If 2, would lose power across range, i.e at any speed.

In end, Volksparts, Bosch people, fixed - pipe/hose frayed so hole, stopping enough air into engine, you understand. To look at, hose very similar to bicycle pump connector. Car transformed. Might not be answer, they said, but seems so. £62 including £40 diagnostic test.”

Car not losing power at any speed, so not 2.

So seems this hose business may be the answer. I seem to recall being advised this is a known problem with the car.

On that basis, I am more concerned about the smoke. Volksparts, I assume, will do a smoke test. But I would appreciate any thoughts/comments from you guys here.

This has been a wonderful car. I intend to replace it with another one, an A4 Avant of some kind.

[jonathan_dyane]

Hello,

OK, simple things first. How bad was the car smoking? If the car is generally used fairly gently, soot will lodge in the cat and intake system. A long trip with lot's of hills will serve to get the car good and hot, and it would be perfectly normal to see this soot expelled as smoke; it's almost like the car giving itself a decoke!

On the power issue, you are quite right in that a split hose would cause these symptoms. If I were you, I would buy a couple of yards of 'diesel injector leak off pipe' and use this to replace all of the old vaccum piping you can find under the bonnet. Cost is pennies, and you may find the problem will be solved. The large diameter piping can be checked physically, but splits here may also be betrayed by whistling or sucking noises as the engine is revved...

Good luck,
Jonathan.

[xylophone]

Thanks, Johnathan

Its the whitish/darkish smoke that worries me. Personally, no idea what that might be - broken exhaust, broken cat, cylinder head gasket (God Forbid!)

Re the lack of acceleration, the damaged hose must be a candidate.

I think I'll get Volksparts to do a diagnostic test, their forte, which should indicate the true problem/problems. Could be any of a number of things.

If the hose is shown to be a problem, couple of quid and Bob's Your Uncle.

Wish me luck

[jonathan_dyane]

Don't worry about the grey smoke at this stage; if your problem was caused by the head gasket permitting water to enter the cylinders you would certainly have noticed either coolant loss or pressurisation.

Grey smoke can be caused by poor combustion which could well be caused by perished or damaged vaccum piping...

The cat *could* cause lack of power, but I too would expect this to manifest itself gradually and progressively rather than on an intermittant basis. Incidentally, the car does not need the cat to pass the MOT, so if it was to need replacing due to blockage I personally would cut it out and replace it with a straight piece of pipe. This has the added benefit of making the car slightly more responsive, and improving the MPG...

Good luck,
Jonathan.

PS, other than blockage in the cat as discussed above, it is unlikely in the extreme that the exhaust is at fault; as the silencer is behind the cat and obviously is less restricted the cat would choke first... The EGR can and does cause the inlet manifold to choke up, but again I would expect it to manifest itself gradually and progressively.

[xylophone]

Jonathan

Thanks again. You know your stuff!

Will keep you posted as to how I get on, as you have been good enough to help.

Do you say what you say as you are perhaps a mechanic or otherwise a car person of some other sort?

[jonathan_dyane]

No problem! I'm not a trained mechanic, just a keen amateur, who takes pride in the fact that he has never yet had to pay anyone to fix his car! (Fitment of new tyres excepted...)

[xylophone]

Thanks.

Re "Grey smoke can be caused by poor combustion which could well be caused by perished or damaged vaccum piping...", I don't understand what piping you mean here - what it does - and why it perishing could be connected with the smoke

[jonathan_dyane]

If you examine under the bonnet to the driverside of the engine, you will find various runs of small diameter tubing. The easiest to spot immediately are relating to the egr, and attatch to two small plastic bobbin-looking things which are sensors mounted on the inner wing.

A similar pipe on many TDI 80s also connects through the bulkhead to the computer. There are also more, but without looking under the bonnet I can't picture them all...

Running with damage to any of these pipes will cause the car to run incorrectly, as it will mess up the information regarding that item which the computer uses to adjust it's settings.

It is then quite possible for an engine running in this state to have intermittent power loss and/or emit smoke due to the system being unable to correctly interact with other mechanical units/sensors...

I hope that isn't confusing; I seem to be getting the flu, which is impairing my own functioning ;-)

[xylophone]

Rang Volkparts this morning, this afternoon took car in, diagnostics test, nothing, except big slit in hose, showed me, something to do with a manifold, I think - about 6" long. curved, thick rubber, original part, £17 to replace - advised this causing both lack of acceleration and the whitish smoke, "blueish", they said. When replaced, major ejection of soot, covering big part of garage!, but after mile or two testing on road, all clear. Total cost. £61

Thanks again. You did a good job there with advice and ideas.

[jonathan_dyane]

It's a pleasure! Hope the 80 gives you many more years of fine motoring!

J.