Engine Bucks On Light Throttle

[KRISKARRERA 2 1 Cars]

If one applies light throttle opening at low revs the engine likes to buck a little. Kind of a gentle kangarooing that slowly subsides over a few seconds or goes completely if the throttle is then opened more. And it does the same when you come off the gas. It's similar to on the old carb engines when you'd boot the accelerator, nothing would happen and then suddenly the car would take off like a scalded cat! It's like having it running on jetronic!

 

Any ideas what causes this? Can't be low octane fuel, it's got V power in there.

Edited May 21, 2008 by KRISKARRERA

[saveloy 8]

Can you explain it again please Kris. But this time, think, write it down, read it twice, then hit the 'add reply' button. And some plain English would be a bonus.

[Goliath 94]

when i had this it was the casing of the throttle cable moving causing a kangarooing action, at the tps end of the throttle cable take the metal clip off and move it up a couple of notches until it is tight but not too far for the TPS to click!

[KRISKARRERA 2 1 Cars]

Thanks for the suggestion Goliath but I've already checked that, it's spot on.

 

Another example, which may help in diagnosis: When I start the car first thing and accelerate a few yards to the junction in 1st gear I obviously take the foot off the accelerator to allow "engine braking" to slow me down, and as the revs drop the car jolts once, violently as fuel injection is restarted (- You know, how injection of fuel is restarted after it is cut on the "overrun" because the revs are dropping near to idle)

Edited May 21, 2008 by KRISKARRERA

[jackherer 543]

Fit a new fuel filter if you haven't put one on for a while.

[welshpug 1,636]

check your engine mounts, don't forget that though being Motronic its still AFM equipped Kriss so the kangarooing is amplified if its not secure or being moved about.

[NeilGTi85 5]

Might also be worth checking your lambda sensor if you have one,

 

Neil

[Phil H 16]

Have you tried changing the antifreeze.

[saveloy 8]

Have you tried changing the antifreeze.

 

Huh?

 

Kris, are the plugs OK? And it could be the AFM arseing about. It could also be dirty fuel injectors.

Also, have you considered God's influence in this matter?

[KRISKARRERA 2 1 Cars]

Hehe it's funny that you should dig this up because what with petrol now being more expensive than gold I'm doing my best to feather the throttle but the car's having none of it. It just wants to kangerooooooo all the way.

 

Plugs are brand new. If it's the AFM that means both my AFMs have the same problem. Injectors... hmm could be. Some times the car is very slow to start and when it reluctntly fires up you can smell fuel. (So either flooding in fuel or weak spark. Oh the joys).

 

I'm sure Phil's antifreeze suggestion was a joke. I hope

 

I asked God but there was no reply. Typical.

[Phil H 16]

Hehe it's funny that you should dig this up because what with petrol now being more expensive than gold I'm doing my best to feather the throttle but the car's having none of it. It just wants to kangerooooooo all the way.

 

Plugs are brand new. If it's the AFM that means both my AFMs have the same problem. Injectors... hmm could be. Some times the car is very slow to start and when it reluctntly fires up you can smell fuel. (So either flooding in fuel or weak spark. Oh the joys).

 

I'm sure Phil's antifreeze suggestion was a joke. I hope

 

I asked God but there was no reply. Typical.

 

I assumed it was a rhetorical question type of thread !

[tagy 1]

Fit a new fuel filter if you haven't put one on for a while.

 

^agreed, try that.

[dch1950 37 1 Cars]

God's a Mercedes dealer.!!

[djinuk 2]

i get this problem aswell, i cleaned out all my breathers, and also i found a tiny tear in a breather pip, so for the moment this is taped up and it seems to have helped, although ive only drove it for about a hour, so i might be eating my words