Running on 3 cylinders?

Post by **rodmonty** » 01 Jul 2008, 21:16

Help appreciated with the following problem that has just occurred on what has been a very reliable and sweet 1.9 petrol camper.

Whilst driving the other day I felt the camper suddenly lose power as though it was running on 3 cylinders or there was fuel starvation due to a blocked filter or such like. The engine still runs and revs but obviously struggles as it's not running on full power.

Today I decided to tackle what I know (could) be the cause;

Took apart carb, cleaned and rebuilt with new gaskets

Checked all vacum hoses, electrical connections, etc

Replaced plugs, dizzy cap and rotor arm

replaced air filter

None of the above has made any difference, she still runs as though running on 3 cylinders. Whilst the engine was running I removed each HT lead from the plug with the left hand cylinder making a noticeable difference to the running of the engine when disconnected. When I did the same for the right cylinder there was hardly any change in the engine note which leads me to think there is a problem there, not fuel or ignition.

I'm thinking that maybe a valve clearance has closed up but couldn't get to Halfords in time to get a compression tester.

Bit of a long post but would welcome any thoughts on what it could be? I guess my next course of action will be to check clearances?

Just to re-iterate, the camper has always run fine and not has any recent work to alter things.

Cheers in advance
rod

Post by **gally** » 01 Jul 2008, 21:31

did u try new plug leads?
gally

Website · Post by **syncrosimon** » 01 Jul 2008, 22:48

Wet the exhausts when cold, with a watering can or similar, dont get the plugs wet, fire up the engine with the help of an assistant, and watch the exhaust carefully. The misfiring cylinder will burn off the water slower.

It does sound like a HT lead problem. You can sometimes hear a ticking, which is the faulty lead arcing out, you can sometimes see the spark in the dark, so go and do it now.

Post by **Poseidon** » 02 Jul 2008, 06:52

Also replace the inline fuel filter... sounds dumb, but it's fixed poor running for me a number of times...

Post by **rodmonty** » 02 Jul 2008, 08:40

not convinced about the HT lead problem as when I pulled them from the plugs with the engine running there was a nice juicy spark, but I guess replacing them wouldn't hurt.

I'm going to have a proper look again tonight and will report back.

thanks for the replies so far

Rod

Website · Post by **syncrosimon** » 02 Jul 2008, 08:43

Try checking fuel pump output. If it was low output though you would only notice when you are flooring her, she would pootle along fine. You got nice fresh petrol in there??

Post by **rodmonty** » 03 Jul 2008, 06:26

So took a trip down to Halfords, bought a feeler gauge and workshop manual all ready to adjust valves and lo and behold I find out the valves are hyrdaulic and don't get adjusted....DOH!

I was convinced that the tappets had closed up and adjusting them would solve the problem

So I guess the only things left to do are as suggested, new fuel pump and HT leads. If that doesn't work then I haven't got a clue what it could be. I'm pretty sure there are no air leaks, I've had a good poke around all hoses and whilst engine is running too all to no avail.

Wild crazy guesses welcome in this hour of desperation now........

Post by **Mocki** » 03 Jul 2008, 07:08

with it running, spray wd40 around the inlet manifold gaskets and vac hoses....... if the revs raise just moments after spraying around ( one area at a time, starting with the suspect side) there is a air leak........

Post by **rodmonty** » 03 Jul 2008, 19:15

This one has got me really puzzled now as so far I have now replaced or done the following;

Took apart carb, cleaned and rebuilt with new gaskets

Checked all vacum hoses, electrical connections, etc

Replaced plugs, dizzy cap and rotor arm

Replaced air filter

Replaced HT leads

Squirted WD40 on over inlet manifold and any pipework

Check fuel delivery from pump which was fine

Compression check showed all cylinders to be running virtually equal pressure!

What on earth could this be???? Remember the camper has always run perfectly and has not been modified or played with.

HELPPPPPPPP!!!!!!!!!

Post by **unhappy camper** » 04 Jul 2008, 15:27

Hi,I had a similar problem. I put the old rotor arm back in and cured my miss-fire.It is worth a try.

Post by **phade** » 04 Jul 2008, 16:20

Silly question, have you tried removing the air filter unit and revving the engine up and down whilst your hand is over (leave a small gap to let some air in) the top of the right hand carburettor?

The engine should sound like a lawn mower whilst you are revving the engine up and down and should force out any crap within the carburettor's air and fuel circuits. The engine should sound normal again once the blockage has been cleared.

Post by **rodmonty** » 07 Jul 2008, 10:27

Finally sorted the probelm

Or rather sorted the problem out and then caused another. Let me explain.

After much head scratching I finally took the car to a VW specialist and told him of my woes. Got a call an hour later saying it had been fixed. What ??? I spend 3 days and he solves it in under an hour?

So when he tells me that 2 plug leads were on the wrong way round I almost laughed

Apparently in taking apart the carb and half the ignition system I had solved the original problem of the misfire BUT when putting the whole shebang back together I inadvertantly switched HT lead 2 with 1. DOH!

So, I'll never know what caused the original misfire although I suspect it was crud in the carb but what I do know is that check the basics has got to be stamped on everyones heads when looking at things like this and sometimes it's easier to get a fresh pair of eyes to look at things.

I was moments away from blowing £300 on a new weber carb.......

happy again though