500 96 rough running

[911gary]

Last run out 2 weeks ago ran perfectly,this time after a few stop starts being moved around in workshop but not driven feels fluffy on one maybe two,pulls cleanly but feels down on power rough on idle,did have a plug foul on r/h rear cylinder so pulled that plug thinking it was the same issue but was fine,checked manifold temps first two were 320-340 both banks 3rd cylinder in both banks 191-201 rear two 320-340,surely not another cam as had an MC1 fitted about 20k ago ? Can only see a lobe as the connecting factor? What do we think?

Edited by 911gary on Monday 6th February 10:25

[TV8]

Plug extenders?

[911gary]

all 8 replaced.

[carsy]

Could those lower temps on the manifold be correct for no bang at all in those 2 cylinders and heat just transferring to it from the other 3 good firing ones ?

I`m just thinking if there`s no bang your cam could be good and its a spark / fuel problem. Plus the issue did come on all of a sudden didnt it. Cam lobes dissapearing would be more of a gradual decline over time.

Check fuel and spark first but failing that could well be the cam. Plenty of chocolate cams have been produced over the years for our engines.

[911gary]

Thanks for reply my only wory was the lobe is the only common item as both opposite cylinders were cold will get into it shortly will be so pissed if its a cam!!

[QBee]

911gary said:

all 8 replaced.

That's probably your problem.
The replacements are rubbish.
I had a new set March 2016. 6 failed within 6 months.

Try connecting the leads direct to the plugs without extenders and see if it solves it

[QBee]

If it does solve it, either fit fibreglass heat proof socks (on the plug leads, not your feet), or change the plug leads for a set with ceramic caps.

Or I can send you a couple of old extenders, or a set of heatproof socks, if it would help. My leads have been upgraded to ceramic recently, so the aforementioned are spare.

[911gary]

Thanks for the tip fair shout will get a set of leads and ive seen the protectors you mentioned thanks for the offer too its really appreciated wasnt a nice run home after paying good money getting outriggers done!!

[911gary]

I set of ceramic leads fitted now all fine what a joke those exstenders were, expensive but still crap only had them 3 months

[QBee]

Send 'em back - you may well find that the supplier is aware of the problem, but doesn't know which sets are faulty until the customer complains. It's not their fault, but your contract is with them and theirs is with their supplier.

[bomb]

I had the very same issue with my car a couple of years ago. Original plug extenders were replaced with new ones. The car ran OK for a short while, then became 'rough running'. The new extenders were rubbish, and I went down the route of heat protective wrap over the leads, and then socks on top of them.

Been running great ever since.

[911gary]

Ah must be same issue all good now thanks for reply