Club G40 Forum

Technical => Engine and Transmission => Topic started by: packers on November 14, 2010, 08:42:17 PM

Title: Eratic acceleration
Post by: packers on November 14, 2010, 08:42:17 PM
Odd fault with car. starts and runs ok allbeit with a high tickover accelrates fine untill you go above 3000rev  then come back to tickover and try to accelerate again engine cuts briefly
the comes back fine jerking the whole car this kangarooing continues untill the ignition is briefly turned off then back on.driving my mad any ideas ?
Title: Re: Eratic acceleration
Post by: scotsjohn on November 14, 2010, 09:15:37 PM
Any odd noises from the fuel pump?
Title: Re: Eratic acceleration
Post by: packers on November 15, 2010, 01:30:47 PM
No and is fine on full throtle
Title: Re: Eratic acceleration
Post by: hardchargin40 on November 15, 2010, 10:42:09 PM
hall sender.
Title: Re: Eratic acceleration
Post by: Turbodaily on November 16, 2010, 12:04:05 AM
Get a code reader on it. The 2 plugs are under the glove box area. Have you done any work on it all? check all the connections are the right way round, as there a couple that can fit the wrong way, like co pot and knock sensor.
Title: Re: Eratic acceleration
Post by: scotsjohn on November 17, 2010, 05:34:55 PM
Hall Sender sounds good to me too.
Title: Re: Eratic acceleration
Post by: packers on February 12, 2011, 07:23:04 PM

Hi again just started work on the car again  after allthe bad weather checked all plugs etx also changed hall sender from a spare dizzy i had but fault still persists any ideas guys.
Title: Re: Eratic acceleration
Post by: hardchargin40 on February 12, 2011, 08:19:49 PM
Wiring to hall sender  ;D  Multimeter time! :D
Title: Re: Eratic acceleration
Post by: PeteG40 on February 12, 2011, 08:23:33 PM
how old is the coil?
Title: Re: Eratic acceleration
Post by: packers on February 13, 2011, 04:49:49 PM
Original as far as i can tell
Title: Re: Eratic acceleration
Post by: PeteG40 on February 13, 2011, 05:01:28 PM
i'd get a new one as a matter of course then to rule that out
Title: Re: Eratic acceleration
Post by: ereeiz on February 20, 2011, 10:48:31 AM
Loose inlet manifold/ air getting in/ out somewhere?

A dodgy cable that's breaking connection under engine load perhaps?
Title: Re: Eratic acceleration
Post by: packers on February 20, 2011, 04:12:53 PM
Exchanged coil no diff. out of desperation  disconected vacuum feed to ecu and blocked off feed to maintain vacuum  think it solved problem but engine ran so badley difficult to be certain anyone local got a spare ecu to use as diagnostic live in north sheffield
Title: Re: Eratic acceleration
Post by: G40supercharged on February 20, 2011, 10:30:56 PM
Vacuum feed to ECU sets fuelling when on boost so it will run very lean on full throttle. I wouldn't try driving it like that too much as you may damage the engine. It will also run rich off boost.
Title: Re: Eratic acceleration
Post by: samg40 on February 20, 2011, 11:01:39 PM
How erratic is the cutting in and out? My car was really badly jerky at one point when I had a bad connection to the knock sensor, it was awful to drive.
Title: Re: Eratic acceleration
Post by: packers on February 21, 2011, 04:33:42 PM
drives fine if you stay below 3000ish revs and avoid hard acceleration .drives fine on full throtle problem only occures after you accelerate up to speed then settle down to cruise at say 1500revs .every 2-3 secs engine cuts very briefly and then comes back causing all the car to jerk this continues untill you turn  ign off and back on
Title: Re: Eratic acceleration
Post by: packers on February 22, 2011, 09:45:06 PM
Tried disconecting knock sensor did not seem to make much difference to engine performance neither did it cure problem.
Title: Re: Eratic acceleration
Post by: packers on August 27, 2011, 07:01:02 PM
Finally sorted turned out to be a break in the white lead coming off loom end of knock sensor plug so sam was in the right area and it might explain why it made no difference when i pulled knock sensor plug . you live and learn as they say hope i dont have too many more faults like this one again.