911 3.2 - Ignition cutting when warm. Any tips?

[LBEEMING]

Hi Team,

Second issue with my 911 this year and seems to be another electrical one.

Situation: When cold, car runs well. As it warms jerking starts to appear. Once engine gets to temperature I get heavy jerking above 3k rpm. It feels like the ignition cuts for a split second and it comes back alive with a massive jerk forward. It keeps doing this as the rpm climbs further. Indicated RPM doesn't react to the jerk, they climb like they normally would.

It was late when I got back so I only tested the coil. Comes within range but at the lower spec. I have heard they can still show within range but still be bad and need replacement. Before I buy the part I thought I would reach out and see if anyone has experienced this.

FYI - I replaced the flywheel and ref sensor a few months ago (first issue that left me stranded).

I searched the forum but most engine cutting issues seem intermittent compared to my experience.

Thanks!

[ant7]

Check the simple things first ie; vacuum leaks, also the AFM tracks being worn can also cause the issue you describe, I have also experienced an ECU [Motronics unit] that does exactly as you describe, these are just a few suggestions, I am sure there will be others along shortly with their own.
Ant.

[wazzz]

Also check the CHT as it could be failing open, in which case the engine runs well when cold but mixture becomes too rich once engine is warm.

[mysocal911]

Originally Posted by wazzz

Also check the CHT as it could be failing open, in which case the engine runs well when cold but mixture becomes too rich once engine is warm.

Right! Then just jumper the temp sensor with a paper clip when warm.

[Cairo94507]

When I had an '87 3.2 in my car, I experienced similar issues. Finally, on a trip home from LA (400 miles) the coil died on Hiway 5. Turns out I had the wrong coil with the 3.2. Replaced with proper coil and all was right with the world again. I have never had a coil die before.

[Duc Hunter]

I ordered my clutch and flywheel from Patrick MS. They balances the entire assembly as a unit. Great unit, great clutch.

[Schulisco]

Originally Posted by LBEEMING

Hi Team,

Second issue with my 911 this year and seems to be another electrical one.

Situation: When cold, car runs well. As it warms jerking starts to appear. Once engine gets to temperature I get heavy jerking above 3k rpm. It feels like the ignition cuts for a split second and it comes back alive with a massive jerk forward. It keeps doing this as the rpm climbs further. Indicated RPM doesn't react to the jerk, they climb like they normally would.

It was late when I got back so I only tested the coil. Comes within range but at the lower spec. I have heard they can still show within range but still be bad and need replacement. Before I buy the part I thought I would reach out and see if anyone has experienced this.

Carry a can of ice spray with you on your next test ride. If car starts jerking again, pull over and cool down the coil, but do not flash freeze it... Does the jerking go away?

The coil may seem to be okay electrically when being cold, but heat can make the difference...if its proved by this test, replace the coil. Not so uncommon on Carreras.
How old are the ignition cables, rotor and distributor cap?

Thomas

[LBEEMING]

Thanks everyone for your inputs. Just my luck, the new speed sensor I installed was at fault.

I bought a BMW one, really not sure what went wrong but it's working again fine.

[ant7]

Good news, However; did you make sure you gapped the sensor correctly ? If not, then you may end up with the same issue again.
Ant.

Originally Posted by LBEEMING

Thanks everyone for your inputs. Just my luck, the new speed sensor I installed was at fault.

I bought a BMW one, really not sure what went wrong but it's working again fine.