1.6 GTi - warm/hot start issue

[danj.pdx 3]

Hi,

 

This is a 1.6 GTi in the US. Since buying the car 14 months ago, this issue has gotten progressively worse. Last month, I did a full service on the motor - plugs, wires, dizzy cap, rotor, injector clean/balance, fuel filter, fuel pump, ignition amplifier, tachy relay and fresh coolant/breather hoses, and fluids.

 

When the car sits for several days unused, it usually fires right up.

 

However - when restarting after the car is warmed up or has sat for just a few hours, it often (but not always) takes forever to start.

 

There seem to be too issues. The starter motor will spin, but often only briefly will it engage and spin the flywheel. More commonly, it will spin the flywheel for a second or two, then disengage and just spin the starter motor. Not sure why that is. Also, it may need to crank over for several times - cranking a few seconds each time. 

 

Related to the starter - is there some kind of switch that controls the bendix and needs attention or replacement? Again, the motor spins as it should. It just doesn't always engage and spin the flywheel.

 

Related to firing the motor - it always starts eventually and seems to run fine. Is there something else that needs replacement for the car to fire off right away? Note - I don't think there's a fuel pressure issue, at least there's no leak I can identify.

 

Otherwise once running everything seems fine.

 

Suggestions?

Thank you,

Dan.

[dt_ 7]

I had a problem like this on a car years ago, 100% fine from cold, but would sometimes be difficult to start from red hot, and was frequently hard to start when hot/warm (after 1-2 hrs sitting), it turned out to be the coolant temperature sensor breaking down.  I removed and tested mine with a voltmeter in a pan of water, and watched the resistance reading drop as the water boiled, was ok up to about 30-40 degrees c, but fluctuated wildly when the water temp was between 40-60c which would have caused the ECU to play hell with the fuel mixture (randomly thinking it's cold, hot etc) and causing the starting issue.  A replacement part shouldn't be too much

[danj.pdx 3]

Dan - thank you for the suggestion. I'll look into it.

Many thanks,

Dan.

[danj.pdx 3]

Hello all,

 

Well, the new coolant temp sensor hasn't helped solved the issue. From stone cold, the car fires up instantly. When warm, it doesn't want to catch. 

 

Any other suggestions?

 

Thank you,
Dan.

[jackherer 543]

Check the coolant temp sensor electrical connector and wiring is in good condition. The best way to do this is to measure the resistance across the sensor then plug it in and measure the resistance at the ECU plug to check it is reaching all the way there.

 

The CTS is on pin 10 of the ECU plug, I can't remember which ground it uses, either pin 5 or 13 I think.