"Misfire" on a diesel - possible cause?

"Misfire" on a diesel - possible cause?

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sunbeam_alpine

Original Poster:

6,945 posts

188 months

Monday 5th April 2010
quotequote all
Our trusty Fiat Ducato (2003 2.3 JTD) has developed an occasional "misfire". As it's a diesel it's probably not the right word, but what it does is like a misfire in a petrol engine - it "staggers" under acceleration.

It's only done it 3 times - twice on Thursday evening, and once today. Otherwise it's running and driving fine. It is regularly serviced. I changed the fuel filter yesterday (advice from the garage), but it is still doing it.

I'm worried it could be something potentially expensive like the timing belt. It was last changed 4 years (and about 80,000 km) ago, so based on the km it should only be about half way.

Can a timing belt slip and cause these symptoms? Ot is it something else?

Unfortunately the garage I normally use is closed all this coming week (otherwise I'd be there first thing tomorrow morning) and the only other Fiat garage in the area doesn't have a very good name. We bought the van from them, but it has since changed owners and has even lost the Fiat distributorship.

I know if I go there and mention the timing belt it will definitely need changing. If it needs changing - no problem - it's cheaper than a new engine - but I don't trust them.

I would also prefer to spend the money at the other garage (it's the son of one of our customers). I'm not however going to wait a week if there's the risk of serious damage.

Grateful for any advice/suggestions.

sunbeam_alpine

Original Poster:

6,945 posts

188 months

Monday 5th April 2010
quotequote all
Thanks for the replies so far!

Unfortunately my technical knowledge runs out at changing filters/oil/brakes bits etc.

For the guys who replied so far, I guess I need to know whether the faults you are suggesting can wait a week until my trusted garage is open again, or whether they could cause more expensive problems, in which case I'll bite the bullet and go to the other garage.

P.S. Not overly worried about just breaking down - we've paid for breakdown cover for the van since the Fiat cover ran out, and never used it, plus it's mostly used locally and we could probably recover it ourselves if necessary (Disco + car trailer).

sunbeam_alpine

Original Poster:

6,945 posts

188 months

Monday 5th April 2010
quotequote all
Bump...

sunbeam_alpine

Original Poster:

6,945 posts

188 months

Monday 5th April 2010
quotequote all
My KEY question is whether this is something which can wait until next week (when my garage is open) or whether I should go to a garage this week.

Can anyone rule out something like a slipping timing belt?

sunbeam_alpine

Original Poster:

6,945 posts

188 months

Monday 5th April 2010
quotequote all
It's only happening occasionally. On Thursday it did it twice, then ran faultlessly for more than 200km.

Having changed the fuel filter, the engine seems to be running a bit smoother, but it has done the "misfire" since I changed the filter.

As I said, the most important question for me is to know whether I can wait until my usual garage is open next week, or whether I should be going to another garage tomorrow i.e. can it be something which will cause more damage?

sunbeam_alpine

Original Poster:

6,945 posts

188 months

Monday 5th April 2010
quotequote all
odyssey2200 said:
sunbeam_alpine said:
It's only happening occasionally. On Thursday it did it twice, then ran faultlessly for more than 200km.

Having changed the fuel filter, the engine seems to be running a bit smoother, but it has done the "misfire" since I changed the filter.

As I said, the most important question for me is to know whether I can wait until my usual garage is open next week, or whether I should be going to another garage tomorrow i.e. can it be something which will cause more damage?
If you have a sticking injector, worse case scenario is that the high pressure fuel will cut a hole in your piston.

An occasional misfire is unlikely to cause that though.
Would this sticking injector problem show itself in any other way - for example higher fuel consumption?

sunbeam_alpine

Original Poster:

6,945 posts

188 months

Monday 5th April 2010
quotequote all
odyssey2200 said:
sunbeam_alpine said:
odyssey2200 said:
sunbeam_alpine said:
It's only happening occasionally. On Thursday it did it twice, then ran faultlessly for more than 200km.

Having changed the fuel filter, the engine seems to be running a bit smoother, but it has done the "misfire" since I changed the filter.

As I said, the most important question for me is to know whether I can wait until my usual garage is open next week, or whether I should be going to another garage tomorrow i.e. can it be something which will cause more damage?
If you have a sticking injector, worse case scenario is that the high pressure fuel will cut a hole in your piston.

An occasional misfire is unlikely to cause that though.
Would this sticking injector problem show itself in any other way - for example higher fuel consumption?
It would smoke like a train if you had a sticking injector.
It's definitely not doing that!

sunbeam_alpine

Original Poster:

6,945 posts

188 months

Tuesday 6th April 2010
quotequote all
Quick Update:

Went to the garage this morning. They connected up the computer, and it reported a problem with a crank case sensor (rev sensor). The guy said that it should be replaced, but that I could carry on driving, as they didn't have the part in stock.

Broke down 500 yards after leaving the garage!

sunbeam_alpine

Original Poster:

6,945 posts

188 months

Tuesday 6th April 2010
quotequote all
odyssey2200 said:
never known a crank sensor cause a misfire before.

Normally they cause a complete non start.
That's what I had this morning (see my post at 12:16) smile