Information HELP! A2 1.4 tdi smokes and dies when up to temperature.

C

chesteradrian

Member
Hi everyone,
I've had a couple of A2 diesels, and regrettably just wrote one off in a low speed bump, having spent a load on it Bah humbug.

Anyway, I just bought a Y reg five seater that was supposedly losing compression so got it for a reasonable price, thinking I could fix.

It was smoking fairly heavily and dying when warm.

So far......
1. Diesel purge to clear the injectors - helped with the smoke.
2. Change Injector wiring loom and harness.
3. Changed water temp sensor.
4. Changed fuel temp sensor.
5. Keep running VAG COM to check for codes - none showing.
6. Cleaned air mass meter with CRC

So, now, it starts instantly and runs smoothly from cold with no smoke.
As it gets up to temperature, it statrs to smoke, but only a bit running at 2,000 rpm or so. It starts to splutter as it gets to 90 deg c then splutters and dies.

WTForum is happening here boys and girls?

HELLPPPPP!!!
 
Have changed air filter but not fuel = will try that.
What is a wet and dry compression test? is it expensive?
Thanks and regards.
 
If you think you may have a compression issue, then a compression test will confirm/deny this.

Dry is just connecting the tester and moitoring the results.
Wet is adding a little oil into the cylinder and testing, (about 10ml (2 teaspoons)) of oil is all that's needed.
Do NOT use too much oil or further damage could occur.

If the dry test shows low compression then a wet test should be done to eliminate possible causes.

If compression increases with the wet test then the issue could be poor piston ring sealing or worm bores.
If the compression stays about the same then the issue could be poorly seated or burnt valves or failed head gasket.

Only use a compression tester capable of testing diesel engines and test via the glow plugs.

Jeff
 
For info the compression test pressures for TDi's are -

New engine - 25 to 31 Bar
Worn limit - 19 Bar
Max difference between cylinders - 5 Bar

Cheers Spike
 
Thanks for the suggestions, I've ordered a compression tester from the interweb.
What puzzles me is that when cold, fuel flow through the filter is absolutely fine, why would it be adversely affected once warm?
I can't help but think that it must be an engine management system issue, that for some reason cuts the fuel flow once it gets to temp.
When it's warm and I try to restart, it spins away as if no fuel is getting through.
It certainly isn't overheating in any way, any clues as to this?
I have a similar car for spares (write off) and can try changing bits over.
Thanks to all for assistance so far.
 
One theory on the fuel filter might be - You are assuming that it is related to temperature, but it could be that the filter is partially blocked and after several miles of more crud being sucked through it could block the filter further and so cut the flow?

Leaving it to settle allows the fuel to settle and for the crud to settle to the bottom of the filter?

Not saying that this is the cause, just saying that the symptoms COULD be due to a fuel filter that is clogged, although the symptoms would not be so predictable, sometimes it would run fine even after a few miles.

As for it being compression, I wonder why it would run better when cold? When warmed up metal expands and so would surely be less leakage? Or perhaps it is just the oil thinning out and reducing the seal.

You mention that you have changed the temperature sender, that would be a likely source of the problem, so unless you have managed to buy a faulty one (there are several on eBay that are faulty) it sounds like it is not the sender.


Steve B
 
What colour smoke is it when it's warm and then dies? Is it white, black, or oily blue? That might help diagnose if there's unburnt fuel going up the chimney (black), coolant (white) or oil (blue).
 
chesteradrian said:
Hi everyone,
I've had a couple of A2 diesels, and regrettably just wrote one off in a low speed bump, having spent a load on it Bah humbug.

Anyway, I just bought a Y reg five seater that was supposedly losing compression so got it for a reasonable price, thinking I could fix.

It was smoking fairly heavily and dying when warm.

So far......

5. Keep running VAG COM to check for codes - none showing.
Click to expand...

You mention you're checking for DTC's with Vag Com......are you using a generic code reader or genuine VCDS?.
Some DTC's aren't picked up with generic code readers, and clone VCDS cables are equally poor (plus this Forum actively discourages the use/discussion of such devices).

Cheers

Jeff
 
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