106 Gti (tu5j4) Starting Problems

[number2301 1 1 Cars]

My other half has been having a few strange problems with her 106 GTi, basically it will always start but takes a while some of the time. Sometimes it'll start and run just fine, other times it turns over for ages before firing up. Sometimes when it won't start it will start turning over really slowly then start up, or even turn over normally, slow down, then speed up again. Often when it struggles to start like this it needs a bit of throttle to keep it going for half a second after starting up.

 

It does this at completely random times, when cold, after a run, when it's been sat, when it hasn't been sat etc which makes diagnosing it that much harder!

 

From speaking to a few people and having a read of the Haynes manual I suspect the coil, spark plugs or crank position sensor. Only problem being that apart from the spark plugs these aren't cheap items to just replace and see if it makes a difference.

 

So can anyone offer any advice based on the symptoms above?

[McDude 33]

From what you described my first port of call would be crank or cam position sensors. Try unplugging one and see if it does the start fault all of the time.

 

I'd also check that you have a good earth - the starter problems might be related to this.

[welshpug 1,622]

From what you described my first port of call would be crank or cam position sensors. Try unplugging one and see if it does the start fault all of the time.

 

LMAO!! unplugging the crank sensor would stop it from starting totally.

 

 

 

not too far off the mark though, they are a common failure on the TU engines.

[McDude 33]

LMAO!! unplugging the crank sensor would stop it from starting totally.

Not strictly true - there is no crank inhibit so the engine would crank. It might even fire depending how the maps are set up but it wouldn't move to a 'running' map - this is certainly the case with a cam sensor failure. My point here is that if this demonstrates is the described intermittant behaviour it will become the permanent behaviour until the sensor is reconnected.

[welshpug 1,622]

no, it wont fire at all, it will just turn and turn till the battery dies.

[Mikey S 29 1 Cars]

My other half has been having a few strange problems with her 106 GTi, basically it will always start but takes a while some of the time. Sometimes it'll start and run just fine, other times it turns over for ages before firing up. Sometimes when it won't start it will start turning over really slowly then start up, or even turn over normally, slow down, then speed up again. Often when it struggles to start like this it needs a bit of throttle to keep it going for half a second after starting up.

 

It does this at completely random times, when cold, after a run, when it's been sat, when it hasn't been sat etc which makes diagnosing it that much harder!

 

From speaking to a few people and having a read of the Haynes manual I suspect the coil, spark plugs or crank position sensor. Only problem being that apart from the spark plugs these aren't cheap items to just replace and see if it makes a difference.

 

So can anyone offer any advice based on the symptoms above?

 

 

how old is it? if its a later one a fault code read may throw up a few codes and give you something to go on.

 

crank sensors usually fire the plugs and cam sensors the injectors. in my experience if its a cam sensor at fault they will not start, ever.

 

a crank sensor can flag a fault code but the car will still be capable of starting.

Edited November 25, 2008 by pugger

[number2301 1 1 Cars]

It's a 98 (R reg), does that mean diagnostics would give something useful? I'll see if I can get at the crank sensor.

[projectpug 0]

Coolant Temp Sensor ?

[Mikey S 29 1 Cars]

It's a 98 (R reg), does that mean diagnostics would give something useful? I'll see if I can get at the crank sensor.

 

 

its on the changeover between obd (onboard diagnostics) and the earlier diagnostic plugs (usually green two pin plug).

 

if the sensor has flagged a code it will be stored in the ecu, so it could well give you something to look for instead of wading in blind so to speak.

 

my moneys on the crank sensor playing up.

[DamirGTI 323]

Coolant Temp Sensor ?

 

... after i fixed blown head gasket on my mates Citroen Saxo (same engine anyway ..) he had very similar problem with hard starting afterwards , so he came back to my place next morning , i did inspect few bits and bobs and final fixed that hard starting by cleaning up the CTS sensor and sensor plug contacts with contact spray (apparently there was moisture trapped on the sensor tip/connector plug while i've been cleaning the engine with water/degreaser ..)

 

Damir

[number2301 1 1 Cars]

Diagnostics machine said low battery and even showed the voltage drop from 14.odd v to 12v within minutes of it being sat, always start simple I guess!

 

On a side note, I was amazed by the output from the ECU, battery voltage, RPM, all sorts of stuff!