Car slowing intermittently - Audi 80 Cabriolet 2.0e 1996
 

My cabriolet has developed a strange fault, it slows right down to 2000 rpm and then in some instances has slowed to a stop.

I've replaced 3 vacuum hoses and checked all the other hoses, but its still happening.

I've been advised to check the oil for yellow gunk. But I am well and truly stumped.

Fuel starvation? Is the pump still running when it happens ?

John

Good question. I'll have to check. It would be weird for it to happen intermittently no?

I agree with JB. Sounds like fuel starvation, and the pump/wiring/relay/fuse are good places to start.
If you remove the rear seat, can you hear the pump while inside the car? I have done that on a B2 80 before.

Has your fuel filter been changed? On my Avant is was the original from 1994!
Its so inaccessible on the Avant, no one had ever changed it.

on my ur it was from 1988, when there was still a West Germany...
I have new ones now available in my hand. I would advertise in the For Sale section and have upgraded, but its not working yet.

Even being difficult to get at is no excuse.

Over the weekend my patience was severely tested by removing the heater motor on a 2010 fiesta, pollen filter looked like it had never been replaced and had burnt out the motor because it struggled to draw air through. Changing pollen filter took two minutes and 7 quid....

Knowing the importance of good fuel pressure on these I'd be tempted to start there

John

agree :nod:

Relay 30 is a common failure on the 2.0e ABK cars. It’s a relay for the ecu and when it fails it can cause misfires and cutting out

Fuel filter acquired. We shall see how this goes.

Change the fuel filter yesterday. What an awful job that was. The smell of the petrol even in a well ventilated garage was truly terrible.

There were some bits in the petrol but not alot. The inside of the filter didn't look dirty at all.

All sorted now then?

We shall see this evening. i need to put some petrol in it

Success! Drove to work today. No problem.

Thanks for all the advice and help it's very much appreciated.

Disaster - had the same problem on the drive to work. It slowed to nothing, wouldn;t go over 3000 rpm then 1000rpm and died.

No idea what's wrong with it, plenty of fuel.

I had my foot jammed on the accelerator, it would move over 1000rpm.

Could it be a belt?

Belt? no.
Try Mikes suggestions of relay 30, and mine of..
"I agree with JB. Sounds like fuel starvation, and the pump/wiring/relay/fuse are good places to start.
If you remove the rear seat, can you hear the pump while inside the car? I have done that on a B2 80 before."

Are the plugs looking wet/black (form excess fuel-suggesting ignition is dying)or white (from insufficient fuel, suggesting fuel supply problem).
Good luck-and its the weekend now so plenty of time to fix....

Any idea of the part number for relay 30. I've found a couple of different options from googling relay 30 audi 80

I think it's 165 906 381 but I'm having trouble confirming that.

Or could be the fuel pump has its last days since the filter been changed.

165906381 is correct. The relay in the car may have a different number

Last resort - check the fuel tank breather vent. The vent on my rally car got blocked and wouldn't allow more than a minute or so running before it just petered out. The vent pipe exited just above the back wheel and got blocked with mud and all sorts and caused a vacuum to develop in the tank. To test the theory, drive the car with the filler cap off so it can breathe.

Does it have fuel filter/mesh in the tank?

Turns out it was low on oil.

So the engine was seizing?
How low on oil was it?

It was very low. When the guy from the AA checked it, he said there NO oil on the dip stick. I had put 1/2 litre that week. It must have been very very low. Such a rookie error.

Oops! Hope no damage was caused :shocked:
It will be a good idea to change the oil and filter and check for any white metal.

That's a good shout.

I'm going to change the oil and filter this weekend.

There must be an oil leak somewhere. There's no oil on the garage floor, so how would it be losing oil?

Any smoke from the exhaust?
Any oil in the water?
Most likely rings and you are burning oil as you drive.

Piston rings? Sounds like a job too big for me

You can do a compression test to check. Very easy.
It is quite a big job. You would possibly need a 're bore depending on the bore wear and if you have run it with low oil the big end bearings will also probably be shot. It's the parts list that makes this job expensive.

can you see actual heavy blue smoke coming out of the exhaust? Like a badly tuned diesel?
If not, just buy cheap oil....
I have a 2.0 A3, and the engine in these is known to burn oil. (Edit-but my exhaust pipe is not oily, and no marks of oil on my car, and no blue smoke)
I top it up as needed between oil changes, and carry on as normal.

No, no heavy smoke at all.

Then I'd certainly change oil and filter, and do a compression test out of interest, but shy away from a rebuild unless necessary-unlikely if the exhaust is not oily

Maybe post the compression test readings on here and get a consensus.

Others may have other valid opinions!

Just another thought. What oil were you using? These old Audi don't like thin oil.

I think I went for 10w 40 in the end.

I'm considering doing an engine flush. Good idea? Or not

10/40 is ok.
A flush can't do any harm. I prefer to use flushing oil. Some use the additive you put in the old oil first. Personal preference I suppose.
Have you done a compression test yet?

Not yet. Need to buy the kit first.

I'm happy to report the oil change wen well. I couldn't see anything alarming in the oil.

This pay day I will be treating the car to a new exhaust and gear mounting as the gear box seems to tip back and forth slightly and it looked quite worn.

All seemed well until this afternoon. Drove home to walk the pooch, the car just suddenly started losing power. The revs stayed at about 3000rpm but eventually dropped and the speed slow to about 10mph. I stopped for a minute and revved the engine. It revved fine. Started off again and eventually got home.

Cue the return journey lots of exhaust smoke, which eventually subsided. Drove back to work. within a mile, it started to slow again. Slowed, then went up the gears. By 3rd gear it seemed to be working as normal.