Loss of power again!!

[itchyfeet]

Ours has magically gone away today.

magically intermittent faults are often electrical

[300CE]

As Kev says, check the coil & maybe see if you can swap one over to test. I had problems when the van was warm, no power at all unless I floored it. The coil had gotten extremely hot & conked out after being stuck in traffic (was a cheapo new one I'd bought). When van had cooled down it started fine until it warmed up again. Luckily I'd kept the original Bosch coil, swapped it over and it's been fine ever since. Also check & clean the connections going onto the coil as the metal on mine had gone green.

[mike9009]

I have had 'similar' issues which I hope are now solved. Mine was running lumpy when cold, then would start loosing power when getting warm. It would eventually just slow to a halt. Ten minutes later I could start it again and continue the journey.... Revving the engine at all times when warm, did help. It would also backfire quite well....

I thought, it was either choke related or carb related. Eventually turned out an earthing strap was corroded/ loose and there was an intermittent spark. (I cannot take credit for this, local VW specialist helped me out once I managed to get the van there.......)

Seems to be running much better now - although it slightly misses sometimes at low revs under load. Must get to that..... Any ideas?

Mike

[SamsBus2012]

Thanks everyone for your comments - just got back from a week away with the kids -unfortunately without the van - plan b was the roof box on the car! The coil was changed for a cheapo year before last as part of a routine service I did. I too have the original bosch coil in the shed somewhere so I'll see if that makes a difference. I'll run the van up first to see if the coil gets hot.
Cheers for now. Phil Davies in plymouth is a good call too.

[edwyn]

I generally do not add any input on Forums but, having diagnosed faults on Golfs and T25 for over 25 years I can possibly provide some guidance for this one. Invariably because of the attempts at rectification of a power problems over a period of time, people lose the correct base point in order to correctly diagnose where the real problem lies. Central to the correct operation of your engine is the carburettor and unless you confirm that you have a correctly operating unit in the first instance, then, you are completely wasting your time in searching for anything else. Get your carburettor correctly sorted by a professional and don't faff around with it yourself. You will undoubtedly compound the problem

[SamsBus2012]

I generally do not add any input on Forums but, having diagnosed faults on Golfs and T25 for over 25 years I can possibly provide some guidance for this one. Invariably because of the attempts at rectification of a power problems over a period of time, people lose the correct base point in order to correctly diagnose where the real problem lies. Central to the correct operation of your engine is the carburettor and unless you confirm that you have a correctly operating unit in the first instance, then, you are completely wasting your time in searching for anything else. Get your carburettor correctly sorted by a professional and don't faff around with it yourself. You will undoubtedly compound the problem

Thanks for the reminder. I have been considering sending the carb to Bromyard VW for a repair/refurb. I was trying to get the van through the summer first. Got some time with the van today so will try the coil before I accept the inevitable!

[SamsBus2012]

Latest update: The cheapo coil I had fitted a couple of years ago was not getting hot but I changed back for the original bosch anyway. Van started on the button and warmed up nicely revs building etc etc, after a minute or so, the autochoke went off and at this point the van stayed running but noticeably lumpy - intermittent drops in rpm. Took him for a short run and still experiencing coughing and spluttering on initial acceleration. Running up through the gears each gave a little falter then settled down as revs got high. Gave the van the full beans down a long straight and it seemed to pick up. Went home and had a cup of tea. As i needed some bits from B&Q I took him for a run down the A38 to plymouth and back (about 25 mile round trip) - all good at high speed, cruising nicely up to 70. The van is still lumpy on tick over and is a little hesitant in the lower rev range but is running!!
I've decided that this will do for now and see how we get on through the summer. Money and time permitting, I think I will seek some professional help, hopefully nearer to winter time.
Thanks to evryone once again for your input and help - really is much apreciated.

[kevtherev]

Idle speed circuit is a tad weak.
Can you get it on a gas anyliser?

[SamsBus2012]

Idle speed circuit is a tad weak.
Can you get it on a gas anyliser?

Not easily but could ask my freindly garage! I've got ythe printout from the MOT somewhere - is that any use?

[kevtherev]

You'll need the full read out
CO, CO2, O2 HC, Lambda on a warm engine.

while it's idling you could adjust the mixture...should it need it.

CO = 1.5%
CO2 = erm..
O2 1% ..(if this is way up you have an air leak)
HC less than 350 ppm (is awsome)
Lambda = 1 or as close as you can

[SamsBus2012]

Ok, so looking at the emmissions results for the mot (end of april) I got the following:
CO - 0.89%
HC - 84 ppm
No CO2 or lamda.
Both are about the same as the 2013 results. I know the tester so I'll ask him if he can stick the van on his machine for a full set of results.

[kevtherev]

bit weak that .89%
any kind of air leak will make the engine run lumpy.
even a pin hole.

[T25Convert]

Evening,

You say you have checked / replaced all vacuum pipes - does this include the brake servo pipe? Often a culprit in lean idle running, they can go porous under the old fabric wrap and often get overlooked.

Cheers,

Alex

[SamsBus2012]

Got a replacement from Brickwerks but it seemed really loose on the unions so currently reusing the original with the ends trimmed back a bit and whole wrapped in self amalgamating tape. Liberally sprayed the pipe with carb cleaner whilst running without noticeable change in engine note.
Currently sourcing another replacement.

[kevtherev]

if you have a leak when idling it is quite difficult to find.
I prefer the sherlock method.
elimination.

however you mixture may well be just badly adjusted.