Car wiil not start? re-occuring problem - once in 7 months(so far)

[Jake242]

Hi guys, I hope you have some ideas on why my car won't start.

First time I had it(and there was nothing before) was 7 months ago, when leaving from a visit at my parents... the car would just not start.

The starter is running, turning the engine but it does not fire up... My dad, whos a truck mechanic by trade had a look at it and could not find anything wrong, he was testing that the spark plugs "sparked" and that there was fuel comming from the fuel rail... Everything worked... but no matter, it was not starting.

I had it towed to my Audi mechanic(official one) as I had some one year mobility service with them after a longlife service.

They told me when they had a look at it, that it just started up the first time they tried, they were running VAG-COm and it displayed no errors.

They suggested that it could be the immobilizer as the instrument cluster was faulty(they could not reset the service interval)

I was told on here(by you guys) that the immobilizer was not in the cluster until the FL cars(mine is a PF) so they had no solution to the problem... I picked up the car and drove off.

Now in the last 7 months, I have occasional(like one in ten) prolonged startups... where it runs the starter for maybe 15 secs, or where it needs several tries of 10-15 secs before it fires up... but it had so far ended with the car starting.

But yesterday... no more, it will not start(tried 15-20 times of 15-30 secs running the starter) and it will not fire up... it acts exactly as it did 7 months ago. I have tried leaving it over night... it will not start, taken the battery off and on again...nothing.

I have now taken the battery off and will leave it that way until tomorrow and then try again...

Is there anyone who has heard about something like this before. could it be a common fault?

Hoping for some suggestions, I would hate to leave it with Audi(as they clearly has no idea what they are doing)... ending up with a huge bill and still having the problem.

Thanks in advance guys

Cheers, Jake

[ainarssems]

2 common things for non start are immobilizer and crank position sensor but both of them result in no spark and no fuel.

[Jake242]

Thats the oddest thing... its almost like the car wants me to look like a fool, now it started! I tried with normal starting after re-attaching the battery... nothing

Then out of nothing I pumped the gas twice(like in old cars) and kept the accelerator planted to the floor.... all of a sudden it comes to life and revs to 5000 rpm

Even though this method of starting the car(with a thicker blend of gas to air) should not work on new cars... it did!

Dead for 2 days and now alive... its the oddest thing

I am happy that it now runs again but in fear of the next time it dies... maybe somewhere the car cannot stay overnight

Cheers, Jake

[PsYcHe]

The D2 has a cable throttle,maybe the cable is just a little loose for it, check for slack.

But mine did have a habit of not wanting to start if it had just been run for a few seconds before being turned off again.

[rs32]

(with similar problem)

after I left you guys in Littledean yesterday, the car has been stopped/started maybe 8 times.

all day yesterday, it was taking maybe 3-4 seconds to start.

This morning, cold start and caught within 1 second, cruised up to the office @ 65-ish for maybe 20 miles, parked the car, restarted to sort out crap parking and caught immediately / nice and strong.

I've done maybe 220 miles since collecting the car on Friday and overall the problem seems to be improving but it would be nice to solve it completely before we get to the winter again.

will report back once it's been properly looked at by my trusted tech.

[graynada]

Not withstanding your experience 7 months ago I would try and test the fuel pump, maybe a direct feed on to the pins and listen for it running.

[rs32]

have decided to start replacing stuff one bit at a time to see if the culprit can be found.

So engine speed sensor and engine temp sensor being done in succession next week. Then onto fuel filter if that makes no difference, then not sure after that !

[tonupkid]

Originally Posted by graynada

Not withstanding your experience 7 months ago I would try and test the fuel pump, maybe a direct feed on to the pins and listen for it running.

I'd look at the fuel pump too

[rs32]

had the engine (coolant) temp sensor replaced last week, still got the same problem although the sensor probe was corroded slightly so not a bad thing to have sorted out.

then this morning I've popped the relaly board panel off in the front footwell and replaced the fuel pump relay (Relay #6, grey type 372) and heard what I thought was a slightly different - more purposeful - fuel priming sound.

looking at the old relay - there was tarnishing buildup on some of the pins and also what looked like a current arc deposit around one of the larger pins where it enters the sealed case but that might mean nothing.

engine has caught better than normal with 2 starts so far but will just leave it for normal use as no point starting/restarting from cold repeatedly.

so far so good in that I haven't broken the car, but not yet conclusive on the warm starting problem.

[HPsauce]

Originally Posted by Jake242

Then out of nothing I pumped the gas twice(like in old cars) and kept the accelerator planted to the floor.... all of a sudden it comes to life and revs to 5000 rpm

I also have similar symptoms very occasionally. Always when the car is "part warm" having been left for maybe an hour or so after use.
Cold it's always fine. Used recently ditto.

And the "old school" "just floor it" trick always works if it won't fire after a few seconds of starter motor.

Spoke to a friend of mine "in the trade" and he reckons it's not uncommon and due to a slight fuel leak from the injectors into the cylinders, usually when/after turning off.
When cold it's not a problem as it needs to be richer and when hot it stays as a vapour.
Not worth bothering about he says, just floor it when necessary to get started.