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NEED HELP! Misfire only when Hot!

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Hi,
I have a 1993 Turbo, runs fine when cold but as soon as it gets hot runs like a bag of nails...
The best way to describe it, its as though its fuel starvation. Say at 40 in 4th it judders and jucks as though running out of fuel or not fireing on all cylinders. But if you floor it it coffs and splitters until about 3-4k RPM then pulls away fine...ish, i.e. not like it does when cold....still missing a little bit..
I've checked all leads, connections, disy cap rotor search the net etc........I'm at a loss!!!

Mods include for your info:-

Induction Kit.
Fabspeed Exhaust inc cat bypass

More anoying is I thought Id found the fault as a 30amp fuse had blown and guess what some muppet previous owner had done?, yup a bit of wire under the blown fuse....but alas, this made no differance...


PLEASE HELP!!
 
Hi Rossy I didn't reply because I'm not Turbo specialist especially not 993 but from what you describe I think like you that an electrical component is breaking down under load. If you've been through every aspect of the electrical system that you can then it's probably time to take it to someone with Bosch testing gear or similar and try to trace the fault that way. Perhaps before that contact Maurice Piper or post on the 993 forum as apart from the turbo the cars are all pretty similar.
 
Cheers, just at a loss.

Could it be Fuel Filter? My guess is that more fuel would get to the engine when cold than when hot, if it was trickling through..?
 
Idle seems fine......another one for you...the O2 Sensor is unplugged, I have the end that leads to the sensor but can not for the life of me see where the other end goes???
Was told that it may have a loop out mod, but want to check that out too in case its the problem. Seemed to happen after a service, the garage says just need to rich the mixture using alan key....ummm rather find out what the problem is 1st...
 
Two thoughts:
1) Contact Bob Watson, Turbo Register technical specialist 01869 340814, but...
2)...as intermittent electrical problems are notoriously difficult to diagnose ( especially over the phone ) go to your nearest independent Porsche specialist with 911 turbo experience, and ( ideally ) a rolling road, so that problem can be replicated and treated.
Good luck.
 
Rossy if the 'garage' is saying you just need to richen the mixture when you 've explained you have a hot running issue I'd consider trying someone else and wire the o2 sensor up. If the car was running fine before and suddenly it misfires when hot it's unlikely the mixture has suddenly weakened, however weak mixtures produce lousy running so maybe they backed the mixture off at service , I think you really need expert advice and Bob Watson is reputed to be great with Turbos if you are near.
 
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