5000CDQturbo

5000 CDqt 1987
Well last week it was cold in Canada, surprise, surprise ... -27 in the nations Capital. In US terms about - 3 .
Here is my problem and temporary emergency fix.
During the resent cold snap this car has been wonderful ... it starts every time !!! I came home from work and was about to go to the ski hill and the car wouldn't start .... it would turn over no problem , but wouldn't catch. ( now the car is still warm after the drive home. ) So standing there in the freezing cold I thought of an idea ? If I used the OUTPUT test for this car I could try and get all the solenoids to function. This way I could get the cold start valve to
pump some fuel into the intake manifold and see if that would work. Car started right away !!!
Anyone now what the possible problem is when it is warm ? Fuel related
regards
David

5000 CDqt 1987
Audi V8 1993
Corvette st. 1974

out put test , how to ?
- ignition is off
- turn ignition on
- open hood
- open fuse box
- get a number 10 fuse ( red )
- 1)place fuse in top of relay for 4 seconds, then pull out ...you will hear the fuel pump actuate.
- 2)place fuse in top of relay for 4 seconds, then pull out ?? wastegate soilinod
- 3)place fuse in top of relay for 4 seconds, then pull out ??
- 4)place fuse in top of relay for 4 seconds, then pull out, this time it will activate the cold start valve.

now car starts

audiqv8

Ok, I'll bite. There were two things that you did on the output test that appears to solve your hard starting when warm/hot.

1. You ran the fuel pump to pressurize the system. Could be a bad check valve at the fuel pump.

2. You activated the csv. Could be a bad engine coolant temperature sensor (ECT).

My guess would be the fuel pump check valve not maintaining residual pressure. Perform a pressure test to verify if this is the problem. Or the next time when you get a no start condition, just run the first test to pressurize the fuel system.

thanatos

fighting the same problem on my200 T 1990. The check valve would also make a cold start hard ?wouldnt it? Heard about thermotime switch for cold start valve- where is it ? is this the one (one prong)on the coolant flange (coolant temp. sensor ?)

audiqv8

try this link<ul><li><a href="http://www.sjmautotechnik.com/10vcoolt.html#coolt">Engine coolant temperature sensor</a></li></ul>

birdmanmt

when the engine is cold the cold start valve sprays enough fuel to get the engine running and get the system primed, if it's not retaining pressure, ie...bad check valve. If the engine is warm the cold start valve doesn't fire and the system isn't primed enough to start just from cranking because all the fuel drained back to the tank. And it will crank and crank and crank with out firing or anything. I went thru this last summer.....cold starts were great, warm start?! Ya right, never happened until i changed the little $20 bastard check valve. Then it started fine.

HTH
Jeff

thanatos

That's depressing because it sounds right-although it starts cold perfect- will have to reegzamine the check valve ( bosch which is just 40 k old). Until now I've been swapping warm up regulator, replaced the temp sensors, injectors,swapped fuel accu, warm up reg, and adjusting fuep press reg - no avail. I t may be just stuck, some sand grinding in it. God how I hate to dip my hands in the fuel by minus twenty !!! wanted audi ? suffer- be a man!thanks for this simple reminder.

5000CDQturbo

thanks it is number two 4 sure ... thanks for your imput.

myangle

2. You activated the csv. Could be a bad engine coolant temperature sensor (ECT).


I have a 1999 A4 B5 2.8L V6.
Was giving me the heebee jeebee's. Every time the car was warm it wouldn't start.

After reading all the forums here I thought the easiest and most likely was replacing the ECT. Yep! that'll fix it. AU$90 from Audi Centre.

Myangle

dkarten

I read these posts because I'm having a warm start problem with my 5K, so I went out & replaced the check valve with the one on my last fuel pump which I saved when it started buzzing but thats not my problem, tried to go to the link provided about ECT but it was not active, does anyone think the MFTS can cause warm start issues?

briangates

This post 17 years later just saved my ***! i couldnt figure out my hot start issue i was having for the last few months!!