Weird Starting Problem

[Pugdaddy 0]

I've lived with this for six months in the hope that I'd fix it without a plea for help. So I've read loads of starting problem threads and tried a few things but all to no avail. So hoping I'm not the only one who has suffered from this annoying and repetitive habit of my 1.6 Gti (I've owned since 1996 so know it well!).

 

If I go to start the car I have about a 1 in 3 chance on a non-start. Without touching the throttle, the car will catch and then immediately die. If I try to use a bit of throttle on the first turn of the key, when you're on a non-start 1 in 3, the revs will rise momentarily and then the car dies. All takes a fraction of a second. 2 out of 3 times, it starts perfectly (although I have to hold on revs for first 30 seconds until the SAD does its job - I don't think I'm alone here).

 

After a non start, if you try a 2nd time immediately the car will just turn over but not fire. The sensation is as if the car is flooded. I know this glitch so well now I know exactly what the drill is. Wait 10 minutes and try again = damn good chance it will burst into life as per the 2 in 3 starts. Wait less than 10 minutes and you get another non-start, sometmes a lumpy attempt to fire but with no throttle response. If you cock up a second time, the routine starts all over again. Wait at least 10 minutes and give it another go. Patience is definitely a virtue here but my wife, son and I are running out of it and get bored of hanging around in Tescos car parks!

 

So what have I tried, swopped and changed:

1. Ignition coil

2. Ignition amp

3. AFM

4. Leads

5. Spark plugs

 

1 to 3 all with used but working parts, 4 and 5 new. I'm confident enough to believe that none of these is the culprit. The spark plugs all look perfect on inspection so that's not helped. Compression test results and leak down test all OK. One cylinder slightly worse at between 5 and 10% leak but that's been the case for the past 5+ years and this starting problem is relatively new.

 

Things I know that aren't perfect but I'd be surprised if they have any bearing on things. My SAD is pretty knackered and on my wish list for replacement. I've had more mayonnaise in the oil breather cap over the last few months than previously but this could be due to daily use to and from work which is only 5 minute drive away (until last year I only used the car at weekends and occasional weekdays but now daily driver). There's no mayo on dipstick and I loose only the slightest amount of coolant over time - I've been monitoring this and reckon 1 cm drop in header tank for every 500 to 1000 miles.

 

I'm not going to speculate on what's causing the problem as I simply don't know. It can get expensive replacing parts even second hand in the hope of fixing it so I'm going to ask for your help before going down that route anymore.

 

Look forward to your thoughts and ideas. Many thanks in advance.

[large 33]

If you have changed all of the above I would go the full hog and change the Dizzy Cap and Rota arm

 

What does the car start like when warm?

 

Another component that gives starting/running problems is the ECU temp sender. I would check the connection on the plug and that one of the 2 wires from the plug has a good earth.

[GLPoomobile 958]

Easy way to tell if it's flooding - when it next fails to start, pull the fuel pump fuse (I'm afraid I can't remember which one it is though) and try turning it again. If it's overfuelling it should (hopefully) fire up after a few turns and run for a second before dying.

 

ECU temp sensor would be my first port of call if it's overfuelling. Cheap and easy to replace. If it is that, then it's odd that the problem is intermittant, but stranger things have happened (and my parents had an intermittant failure with the temp sensor on their corsa). I'd also thorougly inspect the plug and wiring to the sensor, as a loose connection or broken wire could account for the intermittant nature. Knackered AFM could also cause overfuelling.

[Pugdaddy 0]

Easy way to tell if it's flooding - when it next fails to start, pull the fuel pump fuse (I'm afraid I can't remember which one it is though) and try turning it again. If it's overfuelling it should (hopefully) fire up after a few turns and run for a second before dying.

 

ECU temp sensor would be my first port of call if it's overfuelling. Cheap and easy to replace. If it is that, then it's odd that the problem is intermittant, but stranger things have happened (and my parents had an intermittant failure with the temp sensor on their corsa). I'd also thorougly inspect the plug and wiring to the sensor, as a loose connection or broken wire could account for the intermittant nature. Knackered AFM could also cause overfuelling.

[Pugdaddy 0]

Sorry, ignore the last post - hit the button in error.

 

I forgot in original post to mention that I have replaced ECU temp sensor a couple of months ago with a new one from peugeot. I'd hoped that might sort things but no (getting 33mpg though so quite happy with that). ECU sensor wiring could be the problem so will explore that, thanks.

 

Will try the fuel pump fuse removal after next non-start (last one on right I believe) to see if flooding and also try cap and rotor arm.

 

Seems no one else has had the exact same intermittent problem? Also forgot to mention that it can happen when engine is cold or hot, althought most often happens when engine is hot. Say 15 minutes after last driving it - that's the classic time when I feel least confident and when I get the non start most often.

[feb 47]

Did you manage to sort this out and how?