Hi guys,

I have a 2000 Audi A4 B5 1.8i with 105000kms. I bought the car second hand recently and have found since that if I run the air conditioner on high or have the key in on position and use the electric windows, the car will turn over for 5-10 seconds before starting. However, if I don't have the air conditioner on before turning off, the car starts easily the next time I try to start it. So its seems to be as if the electrical instruments drain the power quickly.
With the key in on position the battery shows 12V and when the car is running shows about 14V but closer to 13V when the air conditioner is on.

Do you have any ideas of what it could be?
Any help is appreciated.

 

I'm not sure about the electrical relevance of your issue, but I had a new fuel pump put in my car when I had it tuned and unfortunately, the fuel pump came with a defective diaphragm. When the car sits for any period of time, the fuel will slowly drain back into the tank. When I try to start it cold, it takes the same amount of time as you're saying yours does (way too long). When it's hot, it fires right up, which tells me that I'm right about the pump.

What's odd though, is that I can turn the engine over once or twice (real quick) when it's cold, then turn it off and try again and it fires right up. It has nothing to do with the priming of the pump either. I've already ruled that out.

I always keep pretty much all of my electrical components on at all times (climate control, radio, headlights, fog lights (both during the day and night). They don't seem to affect anything.

Try what I do before you begin throwing your money and time into this. Just bump the key for a second or two, then turn the ignition off and try again (regardless of electrical load).

G/L

 

I might try that quick key turn-over idea next time. But it's definitely not a heat related issue because I live in Australia and it's about 35C - 40C in the day at the moment. The issue had't happened in a while but today I put the key in on position to get the windows down, then took the key out. I tried starting it later and it really struggled but eventually got there. Then I let the car idle for a minute before turning off. Later on (couple hours later) it easily started.
I'm thinking at this point that the battery is weak, so I'll go to get it tested soon.

Thanks for your ideas though. I'll post if the battery is the problem.

 

Good idea. Have the entire charging system tested. It could be a single dead battery cell, which could be slowly killing your alternator.

 

If I crank my A4 up and it doesn't fire immediately (2-3 seconds), I turn the key off and try again. It seems to always fire the second time. I've had some problems with my cam position sensor, and read somewhere that if the CPS is 'bad' (I've replaced mine twice) that the car won't start easily, if at all. but if you stop cranking, the ECU will make an educated guess as to the correct cam position on the next try, and it usually gets it right. Sounds crazy, I know.

2000 atw 220,000 miles

 

See my posts four posts above this one. (Post #2)

I bet that's your problem, because coincidentally: I've replaced my Cam Positioning Sensor twice as well (But I replaced mine twice because I needed a VSS and people kept telling me that the CPS is the VSS, when in reality, they're two different sensors.

If you've replaced your CPS twice, it's most likely fine. Do as I suggested above and you'll find out whether or not it's the fuel pump.

G/L

 

after reading your post I'm sure we are both guessing. nothing wrong with that. as long as my 16 year old heap starts the second time while cranking, I aint spending no more money on this little problem. Something big will break real soon, I'm sure. I'm saving for that.

does the fuel drain from the fuel pump up into the tank? I've changed my fuel filter, but is the pump up above?

 

Unfortunately, it's the pump. There's a diaphragm built into the pump that's supposed to keep the fuel from flowing backwards (into the tank).

I hoped and prayed that there was a valve under the hood somewhere, but I'm 100% sure it's the pump, because my problem didn't start until the day I put the new (defective) pump in and I talked to my Audi guy about it and he knew right away what was going on and told me that he's had to replace pumps for guys because of the same thing.

I'm not going to pay for the labor to have a new one put in, even though the pump is under warrantee. I just live with it.

It's just one of those terrible ******* ideas one of the engineers had. Nothing we can do about it (besides replacing it).

.