Jerking problems

[miren]

JERKING

hi people, my problem is that my car jerks.
it started this winter, on my to the mechanic when my car started to jerk constantly.
i push the accel and hold it steady, the revs keep jumping and idle is 4-5000 and sometimes cuts out. and the exhaust keeps popping or backfiring. sometimes it takes about 20-30 mins before it stops and is fine again. this only happens when it is really cold.
i changed plugs and leads not sure what it could be.
could it be to do with fuel pump or filter,
cos when it jerks there is no response from accelarator, push it down and no revs so have to pump it to catch revs

thanks
please! any help appreciated (new comer to site)

[Martinaston]

Check the crank position sensor and the wire from it.
It runs across the front of the engine and sometimes comes loose and rubs on the water pump pully until it cuts through it.

[miren]

cheers mate!
so its definately to do with fuel or air problems.
i had a look and cant see what im looking for.
you wouldnt be able to show a pic or specific description of part (where it is located and looks like)
its a 318i M40
thanks
m_shah83@hotmail.com

[dobbie82]

when my other halfs m40 was running like a turd, he had to change the "pulse generator"... but where it goes is a mystery to me

[miren]

cheers
did ur other halfs have the same problems as i described so i can go to the mechanic if could be a solution

[Martinaston]

The heads off this one but the wire your looking for is the single one on the left with the sensor hanging loose on the end.
When it's attached properly it runs across the timing belt cover behind the water pump pully, but the plastic clips break allowing it to move forward and touch the pully. This then earth's the wire giving the ECU a false speed reading.

[E30BeemerLad]

the symptoms don't sound the same and I don't know what your car is fella, but on my 325 i had a problem with it developing a lumpy idle where it would "hunt" up and down the revs, but nothing drastic. It would also jerk like a bugger when on very light throttle, say driving in urban traffic at say 30mph in third, it would kangaroo and made me look like a right spastic.

Turned out i had a leaky inlet manifolg gasket, with the car running spray some carb cleaner or WD40 around the inlet manifold where it bolts to the head. If normal idle is restored then odds are it is your gasket. Check other plumming for splits too and general electrical connections. Also your throttle position sensor on the throttle body, a click should just be audible on the slightest opening of the throttle
just some suggestions

[dobbie82]

Hi if you want to check the pulse generator it runs off number 1 lead and runs round the back of the water pump pully and sometimes wear's awa, But my other half spent 18months running with an eplate 318 that ran like a japanese nappy (full) and it was only after visiting 6 diffrent garages that he found out the fuel pump was on its way out but your problem sound's about the same.
Hope this been of help
Hannah

[miren]

cheers people
your help and advice is appreciated
taking it to the mechanic 2moro, will print of the advice and see if they know what would work
if this dont work will post again.

any other advice welcome

thanks