So I have a persistent jerk that is happening in my Fiat Punto 1.2 8v.

What seems to be happening is everytime I take my foot off the accellorator the car jerks about 2-3 times, everytime! It reminds me of being a learner driver

So far to try and resolve the problem I have had a:
major service
throttle body clean
Dogbone engine mount changed (the car also had a knocking when changing gear and from a previous thread I saw it suggested changing the mount)
A clutch change

It's really frustrating, I can't seem to isolate what is causing this fault... What is odd is that after the mechanic works on the car, there is no jerk for approx half an hour, and this happens each time he works on it lol! :bang:

I can't seem to attach the jerk to anything e.g. warm/cold engine

Any advice?

Thanks!!

I know the feeling I have this problem, yours sounds more severe though. Mine happens when I come off the accelerator in first gear mostly, I can reduce it by coming off the accelerator smoothly or by pressing the clutch in.

My first hunch is to say it is an air leak, and that Is what I would say to check, but as I have checked myself for this and can't solve it then I'm not sure (have a suspicion one of my lambdas has killed itself).

Do you have multiecuscan?

KRaikkonenNo1 said:

I know the feeling I have this problem, yours sounds more severe though. Mine happens when I come off the accelerator in first gear mostly, I can reduce it by coming off the accelerator smoothly or by pressing the clutch in.

My first hunch is to say it is an air leak, and that Is what I would say to check, but as I have checked myself for this and can't solve it then I'm not sure (have a suspicion one of my lambdas has killed itself).

Do you have multiecuscan?

Click to expand...

Thanks for the response, yes easing off the accelerator does sometimes ease the problem... or at least cause less jerking...

I have multiecuscan, I only have the free stuff... Any advice on what to check?

I do have a friend with a real code reader if need be...

Thanks

jedeacon94 said:

Thanks for the response, yes easing off the accelerator does sometimes ease the problem... or at least cause less jerking...

I have multiecuscan, I only have the free stuff... Any advice on what to check?

I do have a friend with a real code reader if need be...

Thanks

Click to expand...

Have you had a check on that to see if anything looks amiss? Maybe post some of the results up here, check lambda status, have a play and see what's what. See if any codes are thrown up.

Someone much more knowledge will probably be along soon if none of this helps :thumbup:

Sounds like you've done a lot to eliminate possible culprits, what about the injectors sometimes they can need a bit of a clean through, easily done with some Redex or similar, also have you driven then the car with petrol really low at all?, sometimes old sludgy petrol can get sucked up through the pump and give you similar symptoms, you sound quite close to a conclusion though, as KRaikkonenNo1 mentioned could be one of your sensors? Lambada? Pick one up from a scrappys cheap enough to rule out that probability

this happens to my punto when i use the crappy normal petrol when i put in the good stuff it goes away.

When clutch done was the gearbox mounting under the battery fitted correctly tightly and of course in goody goody yum yum condition?

s and b said:

When clutch done was the gearbox mounting under the battery fitted correctly tightly and of course in goody goody yum yum condition?

Click to expand...

The jerking was happening way before I had the clutch changed so wouldn't image this was the problem - plus a mechanic done the clutch so I hope so lol!

I'm gonna have a look in the haynes manual now re: lambda and fuel injectors... Also going to see if I can figure out how to use multiecuscan to run these tests as I have only used it for airbag light.

I always put decent fuel in and have tried mixing with redex too...

Hittinf a brick wall lol

Might have success!

Just unplugged lambda, car was running fine no jerking, i am going to leave it unplugged because as mentioned in the first post after working on it it's fine for the first half an hour lol!

Leaving it unplugged for the next day and will update on progress, what's strange is that no engine management light is popping up?

jedeacon94 said:

Might have success!

Just unplugged lambda, car was running fine no jerking, i am going to leave it unplugged because as mentioned in the first post after working on it it's fine for the first half an hour lol!

Leaving it unplugged for the next day and will update on progress, what's strange is that no engine management light is popping up?

Click to expand...

Hopefully this is the issue then, update back when you know anything further, sounds like my issue too!

jedeacon94 said:

Might have success!

Just unplugged lambda, car was running fine no jerking, i am going to leave it unplugged because as mentioned in the first post after working on it it's fine for the first half an hour lol!

Leaving it unplugged for the next day and will update on progress, what's strange is that no engine management light is popping up?

Click to expand...

(what's strange is that no engine management light is popping up?)

it will do after a few stop/starts.
you may find it will be drinking a lot more fuel too,

KRaikkonenNo1 said:

Hopefully this is the issue then, update back when you know anything further, sounds like my issue too!

Click to expand...

So lastnight the car was still jerky but there was no engine management light...

This morning I turned the car on, engine management light popped up instantly and there was no jerk at all, so I will let the drive home from work be the deciding factor...

Usually it happens all the time so for it to of only happened once now out of 3 drives I am pretty confident it is the sensor...

jedeacon94 said:

So lastnight the car was still jerky but there was no engine management light...

This morning I turned the car on, engine management light popped up instantly and there was no jerk at all, so I will let the drive home from work be the deciding factor...

Usually it happens all the time so for it to of only happened once now out of 3 drives I am pretty confident it is the sensor...

Click to expand...

Still hard to tell, as the lambda is unplugged, you would think this would cause a bit of rough running aswell (obviously the lambdas are there for a reason).

I suppose the only way to really determine if the lambda is at fault is to plug in either a new one or a known working 2nd hand one..although a code read should show up if there was an error with the lambdas/cat.

Gonna experiment with mine soon to see if I can cure this problem (will also monitor on multiecuscan aswell).

KRaikkonenNo1 said:

Still hard to tell, as the lambda is unplugged, you would think this would cause a bit of rough running aswell (obviously the lambdas are there for a reason).

I suppose the only way to really determine if the lambda is at fault is to plug in either a new one or a known working 2nd hand one..although a code read should show up if there was an error with the lambdas/cat.

Gonna experiment with mine soon to see if I can cure this problem (will also monitor on multiecuscan aswell).

Click to expand...

Just drove home, jerked once or twice but a massive improvement to the constant jerking. I did expect it to run poor as I had no Lambda plugged in so I am putting the rare jerk down to that.

Gonna buy a new lambda Monday and will report back - I think it is worth a shot... It's much cheaper than the mount/clutch and the rest of the work i've had done plus I can fit it myself lol!

Hope your problem is the same!

sorry but ithink you is wasting your money.

if EML was on and fault code directed me to a faulty lambda sensor,
then iwouid replace it..but sometimes wiring can be a miss making it look like a faulty sensor.. money lost here..so taking one from low mileage'd breaker in scrapyard is where id go first.

if you can get lambda sensors cheap from motorfactor..you can guarantee it will be a cheap moody clone from wrong kong

the real article is expensive's.

Just thought I'd update on my issue to see if it helps you..read my engine before using MES -- got code P1135, pre-cat lambda resistantce above catalyser. -- the description of the problem here suggests that it may be a wiring/lead issue, like oldhammer has said.

Next step for me is to remove the sensor and check the wiring.

Just thought I'd update as it sounds like a very similar issue to yours