starting problems S2 3b

[nielsl]

Hello,

My Audi S2 3B has a starting problem, it takes around 5 seconds before the engine runs. When I crank the engine he doesn't sputters, but after 5 seconds he runs smoothly without a problem.


When I turn of the engine and start him after 1 minut, he starts immediately. When you wait 15min till 1 day, it takes around 5 seconds before the engine runs.

But it's my second car and i drive him once in a while, and when I don't drive him for several weeks, the engine runs directly after 1 turn the key.


I allready put a jumper i stead of the relais for the fuel pump but that did not make a difference.

Can someone help me?

[dr.strangelove]

I had a similar problem with my 3b. It turned out to be the plug wires. I used an ohm meter and tested them. Most wires read solid numbers, but the ones that were bad either showed irregular or inconsistent readings. This is an easy test to do if you have a multi-meter and costs nothing. Report back if everything checks out. I have some other suggestions too.

[nielsl]

I had a similar problem with my 3b. It turned out to be the plug wires. I used an ohm meter and tested them. Most wires read solid numbers, but the ones that were bad either showed irregular or inconsistent readings. This is an easy test to do if you have a multi-meter and costs nothing. Report back if everything checks out. I have some other suggestions too.

I've done a quick test and i checked 2 cables, but they mesure infinite. Is this possible? Or did i something wrong? When the car runs he runs good, and sometimes he starts good, sometimes I need to krank several seconds

[dr.strangelove]

Infinite resistance means there's an open circuit (no continuity). That is bad. It means that there's no electricity flowing to your sparkplug. However, the wires may just have backed-out of the connectors. Try pushing them further into the plugs on either end. If you still don't get a reading, pull the wires right out and see if there's corrosion on the tips or damage to the terminals on the ends. Clean/fix as required. If that doesn't solve your problem replace the wires.

If you're not igniting your fuel mixture your oil is going to smell like fuel. Take the oil fill cap off and have a sniff.

[nielsl]

Problem solved! It was the fuel pressure valve that was broken. The pressure was stil good, but there was a little leak to the vacuum circuit. And when the engine was not running, there was fuel that went in the vacuum line

[nielsl]

Now a new problem...
the car stood in my garage (20degrees), and i drove it to a friend. A couple hours later I wanted to go home and the car doesn't start. He does crank but the engine don't run. It was cold outside (2 degrees).

Then i towed him back home and pushed him in the garage, and the day after I tried and he runs again.
I tried a couple times and the always started, then I drove him outside (around freezingpoint) and waited 1 day and now he doesn't start again

I there someone that knows what could be the problem? I think he hates the freezing cold

[newsh]

There is a minimum RPM for starting.
Does the engine crank over slower when the car is cold?

How old is your battery?

Also, any time a 3B has trouble starting I always recommend checking the dizzy timing against the flywheel zero mark.

[K Simmonds]

As above the engine needs to crank over quite quickly to give the ECU the signal to start, so if your battery is lazy this is one of the first things to look at.

Also checking the timing is always good for piece of mind, talking about timing I've know hall senders that are dying and don't function when really cold, though this is fairly unlikely.

Given that your car starts fine at 20C in your garage and doesn't start outside in the cold then perhaps the temp sender on the back of the head is not giving the correct signal as it's that controls the warm up enrichment, easy to change and cheap.

[steve briance]

Weirdly had exactly this recently on my 7A... It happens most years when cold enough for long enough.

No start this morning at - 4deg c.

Get home and it's 0.5deg but maybe reached 2 deg during day.

Starts fine.

Last year when it did it, i got a fault code for crank position sensor. The sensor seems to have the correct resistance and was clean on the tip so you could say it isnt faulty. I guess it could be a fault inside it that is caused by very cold weather shrinking something so it loses continuity or, more likely a wirimg fault between sensor and ecu. Similar theory of a joint being affected by cold, maybe its damp and the ice expands it to lose continuity?

Im guessing as never found the fault and it always starts again when just over zero degrees.

Annoying and hard to replicate.

Have you pulled fault codes?

[nielsl]

I put a startjumper on the battery and he cranks fast, so that can't be the problem. Can the sensor on the back of the head make that he doesn't want to start? What resistance does he have when it's 20degrees? I can simulate that (thought it was 3,3k Ohm).

I don't checked the faultcodes.

[K Simmonds]

Pulling the fault codes would be really useful, it's kinda essential to have a ripped version of VCDS if you run one of these old beasts.

My RS2 is currently in my workshop at roughly 0C so it's pointless me measuring that sensor, however I'm about to put on a lot of cloths and go do a couple of hours work down there and I think I have a spare sensor on a 3B head I can remove and bring back into the house... It's 21C in here so if I can find it I'll put it in my pocket and test it latter to see what reading I get at room temperature.

[nielsl]

And what resistance does he must have at 0°C? That could be also usefull to mesure it. But I don't want to force you to do this now

[newsh]

https://forums.quattroworld.com/s4s6/msgs/20985.phtml

[newsh]

[newsh]

https://forums.quattroworld.com/s4s6/msgs/22625.phtml