STARTING PROBLEM - 1.4 Petrol

Hi Terry
The (G28) engine speed sensor is located on the bulkhead side of the engine. Its towards the gearbox end and directly under the banana shaped intake manifold. The connecting lead runs along the bottom of the manifold, almost to the front of the engine.
I've also read the engine will tend to stall if the signal from the speed sensor fails while the engine is running - so check for a bad connection or faulty wiring before replacing the sensor,

Cheers Spike
 
Hi Spike,

I am currently working away and will not have chance to get my hands dirty untill the weekend when i return home to the car but thank you for your quick reply.

The diagram you provided looks most helpful, do you think i should be able to get at the sensor from under the bonnet or will i have to get underneath the car?


Hi Sarge,

Thank you for bringing your 'how to fix' post to my attention, i will check this also.
Very helpful photos by the way.

Thank you both

Terry
 
Hi Terry
I think you will need to remove the undertray and access the speed sensor from underneath the car.
If you have the chance, a last minute diagnostic scan would be useful just to see if anything has changed since the last check.

Cheers Spike
 
Hi Spike,

I've considered the speed sensor, but how does the temperature issue supposedly affect the speed sensor. I've also tried to drive with the air-condition off for about 2 months, and I have not experience the problem during this period. I am able to use the air-con while driving as long as I switch it off before I stop the car (so it's off when I start the next time).

-P-
 
pgodoe said:
Hi Spike,

I've considered the speed sensor, but how does the temperature issue supposedly affect the speed sensor. I've also tried to drive with the air-condition off for about 2 months, and I have not experience the problem during this period. I am able to use the air-con while driving as long as I switch it off before I stop the car (so it's off when I start the next time).

-P-
Click to expand...

Hi P

The temperature issue is not directly related to the speed sensor.
I understand the problem is about cars which start fine from cold but are reluctant to start when warm. A faulty intake manifold or coolant temp sensor could result in the fuelling being too rich or lean for instant starting of a warm engine. Its possible either sensor could be way out of calibration in the mid range and unless it was completely dead, this may not trigger any fault codes.
Driving with the aircon off reduces the parasitic loading on the engine which will make it easier to start, again suggesting a mixture problem.
A poor spark or incorrect ignition timing could also cause the problem but its difficult to link these to starting issues with a warm engine only

Cheers Spike
 
Spike

Sounds reasonable. Where are the coolant temp sensors located? There are definitively something wrong with the mixture. The challenge is finding the source of the problem.

Thanks!

-P-
 
Hi guys, just a quick update for you.
Having realised my MOT is due this month i have been on the hunt for a different garage.

Found a VW/Audi speacialist "VeeW Services" in Bedminster, Bristol.
After mentioning my starting problem to them, they as good as ruled out my crankshaft sensor theory. As i think Spike has already mentioned, they said this is not temperature related and would cause problems all the time/ car wouldnt start at all.

They've suggested the problem probaly lies with an engine temperature sensor but will need to do a scan.

Have got my A2 booked in with them on Tuesday for the MOT and Scan.
I will keep you posted.
 
Sounds good. Had a talk to the local manifold expert, and he suggested the temp sensor as well. Going to change it tomorrow. very exited:)
 
Hi Pgodoe,

Looks promising, good luck for 2moro.
Hope to hear of you've had success, would be nice to go to the garage on tuesday with a little more knowledge/solution.

Are you attempting a DIY replacement?

Which sensor are you replacing exactly? Is it the Intake Manifold sensor??
 
Terry-A2 said:
Hi Pgodoe,

Looks promising, good luck for 2moro.
Hope to hear of you've had success, would be nice to go to the garage on tuesday with a little more knowledge/solution.

Are you attempting a DIY replacement?

Which sensor are you replacing exactly? Is it the Intake Manifold sensor??
Click to expand...

All sensors are fairly easy to replace:) Are replacing the coolant temperature sender/sensor. Replaced the MAP-sensor a while back with no luck. Hope this might be it:)
 
bloody A2!!!!

I have the same problem. Tried a new map sensor, problem still there, stripped all pipes from intake side of engine, checked for holes etc. Nothing. The problem goes away for a week or 2 then plays up for a few days. Starting problems when warm and epc and warning light comes on. The car runs fine though? Its driving me mad. Removed and cleaned fuel relay, changed the plugs. Still problem persists. Had it dioagnosed, it didnt give any clear faults that I could chase up. Has anyone fixed this problem yet?:confused:
 
hiya

i had a similar problem with my mum's 2002 polo bby engine.

After many many hours researching - the fix for me was to have the throttle body recalibrated.

You can do this on vagcom but i forget how - i used my mechanics snap-on scanner which had a sub menu just for this task.

Hope this helps

Kaz
 
The alternative re-calibration trick didnt work for me - i had to put it into a proper scanner to sort it out
 
I have the same problem too, i've had one coil pack replaced, electronic thermostat and now the crank sensor has been replaced last week. Got in the car today, weather really hot, 32.5c on the outside temp gauge so i had the air con on, drove 15 miles stopped the car, started the car about 10 mins later but the rev counter needle drops go back up then drops again and the engine cuts out, tried to start it about 5 or 6 times before it's ok. A2 is a 1.6FSi BAD engine. Back to the dealer on Saturday so they can have another look at it.
 
I still have the check engine light shining on me, but the drop out problem stopped after I changed the EGR valve, and got the mechanic to program the new one.

Cheers,

-P-
 
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