2.6i ignition timing

[silverbullet]

Hi All,
Not been on here for a good while, the Microbus has generally been pretty reliable so nothing to report! However, I have been thinking that the performance is a little "flat" and the motor won't really pull much over 4000 rpm after I changed the distributor.

How can I check if the ignition timing is correct and does anyone know of the timing procedure and data for the early 2.6i (it's 1995)
I run it mostly on lpg but the system is being reworked, so it's back to petrol for a while.

I would run it on super unleaded (97 or even 99 Octane if I can get it) but if it has to be 95, I think there is a modification to put a resistor across a couple of terminals on the diagnostic plug, which retards the timing? Something like 500-1k Ohm?

Thanks in advance,
Ian

[syncromad]

is your dizzy pirate/aftermarket or genuine?

i have new genuine if you need a new one, pirate ones don't work properly.

stuart

syncro hospital

[silverbullet]

Genuine VW dizzy. It wasn't part of the old running problems (butchered loom, now all fixed) and I still have the original.

Just need to know how to set up the timing correctly.

[syncromad]

cool, just checking before you move anything and cock it up more,

in the diagnostic plug with the groove facing down ward, from the left side, 2nd and 4th pin(pin no 2 and$ on the plug) need to be looped/joined, while connected to the VAG set up, this locks the ecu timing movement, ie ecu does not adjust the timing, then set the timing at 6 degrees, not sure if it works without the VAG connected but should, also no one must be on the mark on the dizzy.

also check cam timing, one tooth can make a huge difference on these motors, use no1 cyl to get TDC, not the mark on the pulley as these sometimes move on the rubber damper.

[silverbullet]

Thanks a million! I replaced the cambelt about 20,000 miles ago, I will re-check the cam timing from #1 at TDC, never thought about the timing mark drifting if the rubber damper is suspect.
Any idea how much 6 degrees looks like when measured around the pulley circumference from the TDC mark?

[syncromad]

no idea, but have you not got a timing light with a settable degree value, set to 6 degrees and then the marks line up, you may need to make your own marks if the pulley has moved, white marker works well, we use a correction pen for this

[silverbullet]

Unfortunately it's just a basic Xenon tube gun with rpm compensation.

I have now measured the pulley flange nearest the timing coverand it's about 135mm dia, so 6 degrees works out at 7mm by my maths:

135 x 3.142 = 424mm circ.

424 / 360 = 1.18 mm per degree.

At least I will be able to see if it's close or miles out.

Thanks again.

[silverbullet]

Stuart you hit the nail square on the head! The cam was advanced 1 tooth...the bus did have a replacement head some time before I bought it and when I did the cambelt I was very careful to put it back exactly how I found... That must have been the big mistake!
Pleased to say that it now pulls quite happily past 5k in 4th and the new 0.77 5th gear makes for slightly more relaxed cruising.
The engine no longer pinks under load either

[syncromad]

Great news Ian

glad it was an easy solve, very easy mistake to make.

[silverbullet]

PS I had a look at the ignition timing too. It looked to be circa 10-11 degrees so I knocked it back to half that (all on diy timing marks)
This resulted in a drop in performance just like the camshaft error and it popped and crackled on the overrun like some boy racer car! Plus it was very lazy to start...
So i put it back as before.
Starts on a flick of the key and pulls like a train on 99RON, no pinking and its been pretty hot here (for the UK) pushing 30*C so I guess the motor is happy!