Engine problem when hot, Chim 400

[Fatboy chim]

After replacing the temp sensor(SNB 802) and cleaning the stepper motor and checking plugs /leads are secure its still not right. When cold its fine, then once up to about 90C it starts stuttering at low revs (under 2500) with part throttle, with full throttle it clears and picks up ok.
Is there anything else fairly simple i can check/ replace before i take it to a specialist?
Is it possible for leads or coil to misbehave once hot?
I would really appreciate some help/ suggestions with this.
Thanks
Andy

[Ballistic Banana]

Looking The Bible www.t-v-r-services.co.uk/tvrbooks/faq_buying.html

A few possibilities are

Faulty or missaligned Throttle pot
Faulty Lamba sensors
Faulty Temp Sensor
Faulty Injectors

Also have you tried resetting the ECU just to see if that sorts it

BB

[fatboy chim]

Ballistic Banana said:

Looking The Bible www.t-v-r-services.co.uk/tvrbooks/faq_buying.html A few possibilities are Faulty or missaligned Throttle pot Faulty Lamba sensors Faulty Temp Sensor Faulty Injectors Also have you tried resetting the ECU just to see if that sorts it BB

Cheers BB, As ive changed the temp sensor i guess it cant be that, the other stuff is beyond me i fear.I might try the reset. Incidently, i looked in the bible ( ignition section) and couldn't find symptoms that matched mine. Did you look elsewhere?

[GreenV8S]

If I were you and I wasn't afraid to get my hands dirty I'd put a passive strobe on the king lead and confirm the spark is still strong, check the ignition timing is about right, and check the water temp sender by measuring the resistance at the ECU plug with the engine at temperature (this way you include all the wiring and connectors in the check). Also switch off while the engine is showing the fault and see what state the plugs are in (I mean switch the ignition off while it is stuttering, not stop the car switch the radio off check the mirrors then finally switch the ignition off). This will give you a clue as to whether it is over or under fuelling.

On second thoughts I take that back. If I were you I'd take it to a professional to diagnose, it will be safer, quicker, easier and probably cheaper in the long run.

[fatboy chim]

GreenV8S said:

If I were you and I wasn't afraid to get my hands dirty I'd put a passive strobe on the king lead and confirm the spark is still strong, check the ignition timing is about right, and check the water temp sender by measuring the resistance at the ECU plug with the engine at temperature (this way you include all the wiring and connectors in the check). Also switch off while the engine is showing the fault and see what state the plugs are in (I mean switch the ignition off while it is stuttering, not stop the car switch the radio off check the mirrors then finally switch the ignition off). This will give you a clue as to whether it is over or under fuelling. On second thoughts I take that back. If I were you I'd take it to a professional to diagnose, it will be safer, quicker, easier and probably cheaper in the long run.

Cheers Peter, I think i'll have to take the advice of your last paragraph, dirty hands ,no worry, insufficient knowhow though may be my problem.
Do you think that a weak spark fault would show itself in low revs/light load situation as my car seems ok when pressed harder?

[HarryW]

Given your symptoms I'd go for a lambda sensor, easier and best diagnosed by an expert though. If you change every thing recommended here you'll have a new engine before you know it .

Harry

[julianhj]

I had similar issues with the Griff, twice. First time was new lambda sensors, second was the injectors, all but one were clean ultrasonically - felt like a different car!