missfire blues

[maxstu]

Hi all,
Newbie to the forum. However I have been reading and laughing along with the regulars for some time now. But thought it best to introduce myself with a wee problem.
My problem (misfire or fuel starvation perhaps?) occured again last night after about fifty miles of driving in the dark.
First, for your information....
1986 Pop top Bilbo's conversion transporter and we love her.
DG 1.9 petrol engine newly recond. Sept 2007. Just 3k so far.
5 speed gearbox
New battery
New leads
New plugs
Carb cleaned and reset
New waterpump and most hoses
New air, oil and fuel filters
Temp gauge runs just left of warning light.
No leaks.
New coil. I thought this had cured it initially but nooo.
New dizzy cap and rotor arm.
The problem occurs under load or going up hill. But not down hill or on the level. Also problem seems reduced if I turn vans LIGHTS OFF!!??(maybe?).
The van begins to suffer from a lack of stomp and judders or misfires. Sometimes so badly I'm expecting the exhaust to get ripped off!
I'm using the gears appropriately and if I stop, engage neutral, she revs freely as she should. No smoke or strange things coming out of her backside. And when runnng properly goes brilliantly. Lovely and smooth around 60-65mph. Yet we never get over 20mpg even at 55mph, even on a smooth motorway. The weekend before I did a 120 mile trip and she ran beautifully.
I really does feel something electrical is breaking down or fuel not getting to the carb. Not tested fuel pump though. How?
I use the van as regular transport...for short trips during the week and weekend camping..... and I know the problem is sporadic and never happens locally or during the day. She always flies up hills local to me and still causes me to grin from ear to ear when behind the wheel and a with bit of cranked up AC/DC. But a ten day trip to Spain is looming and I really want her in the best of health before starting on our BIG ADVENTURE.
This problem did happen before and I took it back to the garage that fitted the recon. And I must say they have been most helpful throughout. But the "stuttering" problem has reared it's ugly head again.
Can anyone help please. As you can see I spent quite a bit of hard earned readies on this van and we love her to bits. However the dosh pit is getting a bit barren!
Thanks and a big hello to Tracy & Marcus or MrsT25Vanspares.
maxstu (Maxine & Stuart)

[Fritz]

First of all your explanation of your problem leaves me almost guessing as you are,,,,,,,,Is it safe to assume the fuel filter has been changed recently ? and the vaccum advance on the dizzy is working properly ?

I have to agree it does sound like some kind of intermittent electrical fault, so if possible find your self a good new or used ignition ampifier (the black/ally bit bolted to the engine bay situated near the coil) to simply eliminate from the equation and while you are working in that area try a known good dizzy just incase the 'hall' unit is starting to fail.

Regards

Fritz,,,,,,,,,,,,,,

[maxstu]

Hi Fritz,
Thanks for the information and reading all of my long winded dilemma? Will try a new or sound dizzy and/or ignition amp as instructed.
Both fuel filters under five months old.
Not sure how to check the vaccum advance but am considering booking a tune up with a company in Bexleyheath, Kent call SANSPEED.
They were always spot on with my Fiat X1/9.

[VWCamperfan]

If you have a Idle Stabiliser unit attatched (little box usually near coil with 2 round plugs going into the bottom), try unplugging the plugs from the box and plugging them into each other. Sometimes this unit plays up a bit and can cause problems.
I would have suspected the coil espicially as the problem is under load. Make sure you have the correct coil for your ignition system as the wrong one can cause these problems.
Did you check the plug gap before putting the new plugs in, sometimes they may not be quite right and a plug gap that is too big would cause this as well.
Replace the rotor arm as well if you havn't already (cant remember!). They have an in-built resistance to prevent radio interference and this can break down causing a weak spark.

The reason why turning the lights off helps is purly because there is slightly more voltage running to the coil and ignition system, hence supplying a more powerful spark to the plugs.

Personally I would still suspect the coil, classic symptoms me thinks but try some cheaper things first.

Hope this helps!

[toomanytoys]

Also worth cleaning the earth strap mounting points and the small brown wire earth point on the left head.
Also ensure the ignition amplifier is mounted well.. (DO NOT overtighten screws..)

No ign stabiliser fitted to DG's..

[ermie571]

two fuel filters....I was told by several on here that there should only be one...just outside of the tank? If I remember correctly, I was advised to remove any filters in the engine bay.

oh - we have a 1.9dg sitting by the side of the road not doing much....but the electronicy gadgety bit was working fine if you want to pop down and try it? Got some nice hills to try it under load!!

Em
x

[ghost123uk]

Sounds like fuel starvation when under heavy loads for a longish period, like going up a long hill.

This is caused because at large throttle openings the supply cannot keep up with demand and after a while the float chamber on the carb runs dry = heavy misfiring.

Then you come off the throttle for a while, say ticking over, and the float chamber fills up again and all seems normal until next high fuel demand occurs.

Sciroccos and early Golfs are famous for this ( I know !!!!! )

The cause...

1 = A blocked strainer inside the tank.
2 = A blocked breather pipe on the tank.
3 = Blocked fuel filters.

If any of the above rings true and you need more help, just post back

[maxstu]

Hi again.
Many thanks and gratitudes to... Fritz, VWCamperfan, toomanytoys, ermie571 & ghost123uk.
Have taken all advice on board and decided to have a bit of a prod around the engine bay today after work. I'm not mechanically minded though so bear with me guys!
On VWCampervan's advice, I thought I'd start with checking the basics first. Cleaned plugs and gapped correctly according to handbook. All pukka here.
Tick list and move on.
Next, check all dizzy leads to dizzy cap. These are new CHAMPION SILICONE PERFORMANCE leads. Just five (3k only) months old, as is the dizzy cap too . However they differ in shape to the old 90% angled head leads I've kept as spares and I think here lies the problem.
The leads running to left hand side plugs are unsupported from dizzy to spark plug. I removed one of these leads from top of dizzy to expose metal end bit. Ooooh! Why is it all covered with aquamarine coloured powder!? So too the second lead???
IS THIS DISCOLOURING CAUSED BY ARCING OR POOR CONTACT ?? If so, I bet both leads at the dizzy end have worked loose, being unsupported, and resulted in poor spark to plugs, worsened when under load.
Have cleaned all lead ends and rerouted to support 'em too.
I've not tested yet but am most confident.
Hi Ermie571 and thanks for the offer. I may need to accept your invite to compare vehicles. We're always passing through to visit the Kent coast. I've got two filters. One under vehicle and another in engine bay. Is this excessive?
Hi toomanytoys Brown wire on left bank looks pretty naff. Will give that a refresh too.
Hi ghost123uk I too thought fuel starvation was the problem. So alway made sure I had plenty of fuel in the tank and intended to check fuel pump ata later stage. Will wait to test before diving in to that side of things. But many thanks for the pointers.
Heading to Bucks to see my sister at weekend and will report our findings henceforth. I've got a feeling this is another problem solved for the world
famous 80-90 gang
Many thanks too all.
Regards
maxstu