Jerky engine, bad earth??
 

Hi,

I've owned a modded uk turbo for two months.

Since i bought it it has had an occasional jerk under power.

I've just noticed that the rev counter will dip when it 'coughs' and on the way homejust now it was particularly bad.

Also sometimes it the startermotor will stall when starting, before carrying on.

It seems to me to be an electrical problem>?

do they have a known earth strap problem ?

Where are the main earth straps for the engine?

btw the car has a gems ecu mapped by steve simpson, don't think that will be the prblem will it??

any help would be much appreciated.

thanks

klunk

I've got a classic and if you follow the starter motor wire off the battery im sure the earth comes out of that and goes to the starter mounting bolt.

thanks i'll have a look.

do you know of any other earth straps?

Two that I can think of.
A tiny one from under the centre of the intercooler from the block to the bulkhead (the bit that juts out to take the top stabiliser bar)
and the main one from a bracket that is attached to the block by the top starter motor bolt straight back to the battery.
If both of those come off you'll soon know about it as it fries the throttle cable. :D

Andy

andy,

have you had any earth problems?

does my problem sound earth related?

paul

Had some electrical problems recently but it wasn't earth related.
Check those leads and then you can then discount your earthing problem idea.
The trouble with the net is you'll get a million and one different ideas to check from the MAF to rear wheel bearing :lol1: and you'll be no further forward in truly identifying what it is. Your best bet is get someone who knows what they are doing to actually look over the thing. (especially as it's non standard)


Andy

sounds like good advice, i do tend to try and solve things myself when half an hour with an expert can sort most things.

thanks mate

paul

i have just cleaned up both earths.

there was only two, one for the engine that was corroded, and one for the body earth that was very dirty and clogged with crud.

Have cleaned both to bare metal and secured.

Will post an update in case in helps others in the future.

Paul

well no difference engine still intermittent jerky.

off to an expert i think.

Could well be a faulty MAF sensor mucking around with the fueling. I've got a similar problem at the moment with my v4 STi (holding back and jerking occassioanlly during acceleration).

I'd check your fault codes off the ECU first, that might well tell you what it is :)

i'mnot sure but i think the gems ecu bypassesthe MAF although it is still present?

someone more knowledgeable may know more.

paul

sorry mate thaat cameout wrong, meant more knowledgeable than me! :brickwall

No worries lol, will be more knowledgeable than me too as I have no idea about Gem ECUs :D Will be interested to see what the problem is anyway, never know it may help me solve mine as well :)

Hi,

quick update went to simpson motorsport turned out to be wrong spark plugs set at too wide a gap,

the spark was literally being blown out under boost.

school boy error !! you live and learn


paul.