kgbeh

I have a Audi A6 C-4 1995 year car and the problem is that after moving the car and later stoping it for at least half an hour I find it difficult to start the enging . At the same time the enging will shake like running in 3 cylinders. After a while it will be ok. Can i know what is the problem as i have already changed the fuel accumulator, fuel injectors, spark plugs, distrbutor cap,fuel filter,temperature switch. So can I know what is the problem then . Thank you.

The_Hamster

I am guessing you have a European version with a 4 cyl engine?

kgbeh

I have a 5 cylinder engine.

austinado16

Back in the day (mid 1980's) the Audi 5000's in the US were well known for their poor starting. It was found that heavy carbon build up in the intake and on the backs of the intake valves was acting like a sponge and soaking up the fuel from the fuel injectors.

Some dealers.....or most dealers had a walnut shell blaster that basically sandblasted the intakes and backs of the valves in car. This and fuel injection cleaner cured the problem.

For your car, I would recommend an induction service using the 3 can system sold by BG44K. You can find the 3 can kit on ebay for about $25. One can sprays out the throttle body. One can goes in the fuel tank. One can is run into the engine, while the engine is running by letting a hose from the intake manifold suck out the contents of the can.

This should cure the problem.

DaveInSaltLake

Is the car throwing any codes?

kgbeh

Thanks for your advice, but I still have the same problem stating the car after following your advice to clean the carbon in the intake system.My problem happens when I switch off the enging for at least half an hour. And the difficulty to start begins. After it starts after 3 times the enging will not be running smothly for a while. But it gets better after a while like say 10 to 20 secs. Could it be the fuel distributor as most people have been saying.Thank you.

austinado16

Does this car have some version of K-Jetronic (CIS) fuel injection? Fuel distributor with the woven stainless injection lines and injectors mounted in the cylinder head with rubber o-ring?

If so, there is a laundry list of items that will cause your symptoms, some of which you say you've addressed, but I'll list them anyway.

1) Fuel system check valves are leaking down instead of holding system pressure.

2) Fuel accumulator has failed

3) Fuel injectors don't spray properly at idle

4) Fuel injectors drip after engine is shut off

5) Carbon built up on backs of intake valves and in intake runners and plenum

6) Air leaking past bad injector o-rings

7) Air leaking past bad injector bushings

8) Vacuum leak at intake manifold-to-head gasket

9) Fuel distributor piston hanging up

10) Air flow sensor plate hanging up/dirty

Those are just some off the top of my head.

If this were my car, I'd test for vacuum leaks, then I'd pull the injectors and lay them on the valve cover and watch how they spray at idle, then I'd do a control pressure and system pressure test, then I'd see how long the system held pressure, and how much pressure it held.......and keep moving toward the more complex solution from there. CIS is very easy to work on, so it shouldn't be too much trouble to sort this out.

kgbeh

Thanks , well the mechanic used some kind of equipment to pump a kind of chemical to clean the throttle where the fuel injector are.For your information , I have already changed the fuel accumulator, fuel filter, fuel injectors.I have also checked the fuel pressure and it is ok.I have changed my fuel pressure pump some years back, I did not change now becos the pressure is ok. Can it be totally caused by the fuel distributor. Yes`my car is K-Jetronic. Where can i find a used fuel distributor and how much? Thank you.

austinado16

With K-jetronic, you have to look at several pressures.

1) The control pressure. You have to see what the control pressure does, from cold start, all the way up through normal operating temp. These pressures are adjustable.

2) The system pressure. You have to see what this pressure is, both cold and hot, and you have to see how long the system is able to hold pressure once you turn the engine off. If the system does not hold pressure, then the car won't start or won't start right....or if it doesn start, it won't run right until normal pressure is achieved. With K-jetronic, low system pressure means super rich fuel mixture. So if you have a system that bleeds off pressure after the engine is shut off, then when you start you don't have any fuel in the injectors, and then you have a super rich mixture flooding the engine. The result is what you have....hard starting, and poor running for a few seconds.

There are typically several check valves. One is usually just before the fuel filter. A second one is usually at the output of the fuel pump. But yours may be set up differently, so you need to look at a service manual, find the exploded views and locate the check valves.

The other thing that you may have on your model is an electronic control at the fuel distributor. These can go bad and cause running problems too.

A good service manual will go into great detail about all this, so take the time to read through it.

I wouldn't recommend just throwing more parts at the car.......as you've found out already, that usually doesn't work. Diagnose the problem, then fix it. And if you can't prove that something is bad, then make everything else prove that it's good.

kgbeh

Thanks again, as i agree with you to diagnose the correct problem.One question , can we find out whether the fuel distributor is not working well or not? I am living in Malaysia and the mechanics here are just trouble shooting for me.