3.2 Carrera won't start when warm

[clarkeyjnr]

Just got my 3.2 back after new clutch and gearbox and low and behold......another problem.
As always, she starts fantastic when she's cold, but after she's been running for a bit and then turned off, she won't restart! Just keeps turning over like there's no fuel getting through OR she's flooded....... Wait until she's cold again and she'll start perfectly. Is the Engine Temperature sensor to blame, or is it something altogether more horrid? Any ideas, fellow 3.2 owners?

[andy tims]

Sounds like starter motor problems if the car starts OK when cold, but not when hot.

[Raven Flyer]

Almost certainly Engine Temp Sensor, from how you have described it.

[clarkeyjnr]

Thanks for the advice. Doesn't make sense does it? Starts perfectly from cold, but once engine has been running for a while, it wont start again. It just sounds like it won't 'catch' - if that makes any sense. I don't think it's possible to flood it so I figure either there's no fuel to ignite, or no ignition to spark the fuel. Would the engine temp sensor tell the Bosch Jetronic system not to fire up, if it's faulty and thinks tehh engine is too hot? Where does the engine temp sensor reside? I can get to the plug on the n/s of the engine, butheaven knows where the wire goes to that's connected to the sensor. Not sure if its the starter motor as it sounds like its truning over prefectly, just not roaring to life.......!!!!!

Thanks for the advice!

[rubystone]

Are you sure it isn't just a faulty DME relay - they play up in all sorts of silly ways - I'd heartily recommend buying one for £40 or so and fitting it - easy job,just plugs in under the passenger seat. I always kept one as a spare after having one fail on a test drive - needless to say the eager buyer didn't buy the car!!!!!

[clarkeyjnr]

I've got a spare one (from when the link to the fuel pump died once - and I thought it was the DME......even though it wasn't) - I'll give it a go! Thanks!

[clarkeyjnr]

I've got a spare one (from when the link to the fuel pump died once - and I thought it was the DME......even though it wasn't) - I'll give it a go! Thanks!

[philly]

I had this problem a few weeks ago but it was cured when I fitted a new battery.

Sounds strange, but I guess that with the old battery the voltage was lower and this had an effect on the DME?

Anyhow, maybe check the battery is in good condition as a simple start point.

[Raven Flyer]

Engine Temp sensor tells the ECU whether or not it needs to use cold start routines. For a warm engine, this will result in far too much fuel going in.

[burriana]

here's another vote for the DME relay!

[clarkeyjnr]

Oh Lordy......It won't start at all now!!!!!!!!

Tried a change of DME Relay. Checked battery. Checked connector plug for Engine Temperature Sensor. Taken out the Motronic 'Brain' and cleaned all contacts.....now all it's doing is turning over and not firing into life when it's cold either......

Could it be plugs, leads or coil? Fuel pump is whirring so I know there's fuel being pumped into the mix.

AAARRRRRGGGGHHHHHH!!!!!!!

Any more ideas, anybody? Anybody? Somebody.......?

[h_____]

I too would have thought a DME relay, but you 've tried that. Are you a club member? If so ring the 3.2 Tech advisor, always helpful on this kind of stuff. Alternatively call a friendly indie, where do you get your car serviced?

[lemon yella rs]

try working your way back a little. Did you put the original dme relay back in after you tried the new one? if not do so. Do you have a spark? take a lead and plug out and test? no spark work back etc.Do you actually have fuel (silly i know but its easy to overlook) Do you have an alarm or immobiliser if so check around that and around battery for loose connections. Check you've not blown a fuse whilst you were cleaning etc. Check all plugs and sockets in the engine bay are sound (distrubed by the clutch change?) also double check everything else you have touched!!
When you get back to the warm start fault start to check all things associated with warm start NTC (you can check it with an ohm meter) fuel pressure if you have the correct equipment etc.

[SP_CS]

clarkeyjnr said:

Oh Lordy......It won't start at all now!!!!!!!! Tried a change of DME Relay. Checked battery. Checked connector plug for Engine Temperature Sensor. Taken out the Motronic 'Brain' and cleaned all contacts.....now all it's doing is turning over and not firing into life when it's cold either...... Could it be plugs, leads or coil? Fuel pump is whirring so I know there's fuel being pumped into the mix. AAARRRRRGGGGHHHHHH!!!!!!! Any more ideas, anybody? Anybody? Somebody.......?

Do the ignition lights turn on when you turn the key?

If not, i had similar probs once, let me know

SP

[911mot]

Have you fiddled with the connectors for the CHT, Speed and Reference sensors? (3 in a bracket)
It's very possible to get the speed and reference plugs swapped over - and it won't start if you do...BTDT

[clarkeyjnr]

Top man! It was the Speed Reference Indicator Plug (on the n/s rail) that wasn't connected quite as flush as it should have been. Bit of trial and error but we got there in the end. Running sweet as a nut...and I've just sold my Boxster tonight as well. Now just need to sell the Carrera and I'm shopping for a 996 C4! Hurrah!

Thanks for all your help and suggestions - but 911MOT wins a beer because he was the only one to diagnose.

Nothing to do with DME/Battery/Temperature Sensor et al, Cheers!

[lemon yella rs]

Ahem ahem, i did say check all plugs and sockets in engine bay are sound (and not disturbed with clutch change) 911 mot was however more specific