Juddery car.

[Jimmy Filth]

Hey guys I have a rather frustrating issue with my car at the minute.

Basically, it is damn juddery when driving, completely randomly.  Some journeys it'll be fine, other times it feels like the engine is trying to break free.

At first I thought (hoped) it may just be crap in the fuel filter so I changed that and no change.  Next guess was an air intake sensor but I got it checked on a computer and it showed no faults.  Finally I thought it may be the slider valve on the intake but on that being taken out and inspected it was working correctly.

I can't think of anything else it may be.  The car drives fine, regular services blah blah blah other than this.  Engine is completely standard although the exhaust is blowing slightly.

[rob.043]

Water getting into the fuel? Duno really.

Can you attribute a common condition to the symptoms?  High engine load, speed, temperature, weather, twisty bits or motorway, etc....

[Jimmy Filth]

It doesn't seem to happen on an particular style of driving, sometimes it'll start happening as soon as I pull of the driveway, sometimes I'll be able to do a half hour drive and it'll happen once, sometimes I'll get 15 minutes down the road and it'll feel like it's coming apart around me.

Weather doesn't seem to make much difference and engine temp makes no difference.

I'm flummoxed really.

[snifferdog]

First things Id look at - get the exhaust blow sorted - this fixed my judders and also try changing the coil pack, could be a slight misfire. Try checking everything under the bonnet and coating in wd40 incase moisture has gotten in somewhere!

[Jimmy Filth]

Cheers for that, i'll give it a shot. 

My big worry is a MAF sensor.

The only other issue, that I forgot to mention, is that the rocker gasket is shot, I think, as oil gets into the spark plug holes.  It doesn't reach the spark end, just pools a little in the holes.

[Seanl]

I always seem to answer the same thing when this happens, even though lots of different things cause similar symptoms. But yes I would check the MAF sensor. When I first bought my car, this was what was happening and again it was random, but always around 3k rpm, and it was more often than not happening. I was told by the guy that it was the coil, so changed that. Made no difference, so after joining here, checked the MAF out. I just used some contact cleaner and a cotton bud and very very gently gave it a good clean. At the same time I bought a used one just to check, (just over a tenner including delivery from fleabay) but the original turned out to be fine after that. 8 months on, apart from the oil cooler which killed the engine, it has been good as gold. I suppose it makes sense that if its dirty, it randomly reads airflow accurately but most of the time cant take a reading as its covered in sh!te. Hope this helps mate. 

[rob.043]

If you have a poor rocker cover gasket there could be more air being drawn in through this and in to the breather pipe, thus pulling loads of grunge into the throttle body etc. Replacing the gasket and cleaning the throttle body would be a very good start. If there is excess oil residue reaching the combustion chambers, that could certainly create some judders and naff combustion.

The MAF sensor cleaning sounds like a good idea too. On that note what type of air filter do you have? In reasherching K&N and other cotton filters I read about them letting in larger particulates than paper filters, which can damage air flow sensors. Could be a factor in dirtying your sensor, besides the 20 years that is. After reading about this I realised that the on two K&N equipped engines known to me, both went through a air fow sensor! So I switched back to regular changes of paper filters.