Technical Violent jerking/shuddering when accelerating

[KRaikkonenNo1]

Hi, ive tried reading other similar posts about this issue but theres not a clear solution. Basically my car has started to violently jerk, jump and shudder at pull away speed in first gear. I thought it did it when it was just cold on first start up but the other day it did it all day when it was warm. The last couple of days its been really violent with it forcing me to dip the clutch further in to avoid it from stalling!

So I was just wondering if any one could help with this? My car is a 1.2 8v 2001.

Thanks.

 

[Most Easterly Pandas]

Sounds like a possible misfire. It's either coil pack failure, or more probably HT leads have had it.

Have you checked to see if the leads are arching?

 

[Ziggy122]

Is it a misfire or a sudden case of violet clutch judder?

Does the shuddering continue once the gears are fully engaged? if it does continue its not clutch judder

If so
Follow down the route of checking for sparks and coil pack signals

Ziggy

 

[KRaikkonenNo1]

Ok, and yes the shuddering does continue once gears are engaged. Sorry if this is basic but how do you go about testing the leads, etc?

Also just now I have used the diagnostic software and it has detected a misfire in cylinder 3, what should be done now?

 

[s and b]

you give it a proper upper engine service of consummable parts and hope you havent blown the ecu
is the first thing to do
assuming its not been serviced since it was built?

 

[KRaikkonenNo1]

Well since I got it 3 months ago, I've just done the basics, oil change, gearbox oil, oil filter, air filter, spark plugs, few little bits.

 

[s and b]

Well since I got it 3 months ago, I've just done the basics, oil change, gearbox oil, oil filter, air filter, spark plugs, few little bits.

pulling old leads off can create your problem as they are old and brittle

 

[KRaikkonenNo1]

So would you suggest replacing the leads?
What is the way to test if they are fried?

 

[Most Easterly Pandas]

Here's what you'll probably see with arcing HT leads.

http://www.youtube.com/qjYW8i8JiDE

 

[fingers99]

Yep. Leads are cheap. Hurn into the bin, one at a time, replacing with new in between hurls.

Of course, it could be a combination of clutch slip, misfire and knackered rear gearbox mount, but I'd start with the leads.

 

[KRaikkonenNo1]

Ok I think I will check the leads, and that and probably replace the leads very soon

Thanks

 

[KRaikkonenNo1]

I was also just wondering if this could have anything to do with the cat? I'm thinking this because MES brought up the code P0420 yesterday saying catalyser 1

Also the last couple of days there has been a strange, well all I can say is a sort of burning, eggy smell

Could anyone shed some light on this?

 

[Most Easterly Pandas]

The code will be because of the misfire. You shouldn't be driving it ATM because if you haven't already you'll kill the CAT!

 

[fingers99]

A misfire will dump a lot of unburnt fuel onto the cat. That's probably what the smell is.

Cat itself won't cause misfire.

 

[KRaikkonenNo1]

So now my attention has turned to the CAT, should I just totally stop using it until it is fixed?

Also does this mean that I will need a new CAT?

Thanks

 

[Most Easterly Pandas]

So now my attention has turned to the CAT, should I just totally stop using it until it is fixed?

Yes!

Also does this mean that I will need a new CAT?

Possibly.

 

[KRaikkonenNo1]

Ok so I will not drive it, and how much am I looking at for a new CAT?

 

[fingers99]

A fair bit, unless you can find a good s/h one.

But I'd worry about that only when you've sorted the misfire. It may be OK.

Mr Cat is a pretty good source of new ones, if that's what you need, or try CES.

 

[Ziggy122]

2 things
Why look at the cat when the misfire is the problem

Dont replace the cat, it might survive

An easy way to tell is to ask local friendly MOT man to put it on gas tester

Ziggy

 

[atom0007]

your car will still go with a broken cat. It just won't pass an emissions test.


FYI, my cat smelled a bit eggy before it died; I had no misfires.