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Hi, im new in the forums but have been reading them for some time now. Im looking for some information on how to advance the timing on my a6 c4. its a 2.6 litre abc engine with obd 1. its a 95 mod. What i would like to get some information about is how to advance the timing for me to run 98 octane fuel and get dome more jiuce out of the engine as i feel it a bit sluggish. Best regards Aleks.
Pretty sure your engine has knock sensors...the timing is not really adjustable but the knock sensors will back the timing up if you get poor fuel and the engine starts pinging..contrary, the timing will adjust more advanced (within specs) with high octane fuel..the engine control unit will adjust itself for best operation with knock sensors. Don't expect immediate results with high octane fuel..it takes a few miles and starts to build a new control unit memory.
Thanks for a great awnser mate, really appreciate it. i will be testing it out with about 2 tanks of 98 octane and if i dont get any noticable result i will have to go with other upgrades like cams and polishing i guess..!
Be sure all your vacuum lines are in good shape. It is worth checking the big plastic cover that fits over the throttle butterfly(s) with a rubber band/spacer. A couple of 10mm head bolts hold it on up top and some plastic spacers which are easy to loose at the bottom on some alignment dowels.
Those plastic covers get loose on the rubber band, cause an air leak and create sluggish engine problems.
I used some screen door repair rubber stripes to tighten the plastic housing against the rubber band..there is a valley gap in the plastic you can thread the screen door rubber stripes into that tightens the fit on the throttle housing rubber band ...some use old phone cord..anything that tightens the fit helps.
Sorry..no exact pictures, but I did find these on the web.
This is the screen door rubber stripes in this picture..you don't need the other tools shown..the rubber length need to be right at 11".
The rubber stripes fit on the outside of the mouth of the plastic air duct..inside the gap, tucked inside the gap/groove to tighten the fit on the rubber band on the throttle butterfly housing..on this part here. You can't see the gap/groove..but once you have the part off the car..you will see what I mean.
Last edited by Rusty Spokes; Mar 20, 2015 at 06:24 PM.
Thanks. vaccum lines are in good condition but i will check the plastic intake housing for leaks! did not even know thoose were prone to leaking. Thanks for the walkthrough and pictures!
****...I've taken my plenum chamber off, but cannot recall having seen those plastic studs before. I'll have to investigate. And I'll do the phone cord mod for sure.....have been reading about the fabled phone cord mod for ages now, never seen a picture of it until now due to old threads with broken links.
****...I've taken my plenum chamber off, but cannot recall having seen those plastic studs before. I'll have to investigate. And I'll do the phone cord mod for sure.....have been reading about the fabled phone cord mod for ages now, never seen a picture of it until now due to old threads with broken links.
The studs are steel dowels...you can see in picture #2 one steel on the left and one of the two plastic bushings still sitting on the steel stub on the right.
The two plastic bushings are sitting inside the plastic manifold in the final picture #4
I was going to phone cord mod my 2.6 ABC... but NOPE. Plenum has no lip.
But I did measure a steady 18 inHg vacuum at the throttle body My engine can't be half bad. I wasn't able to provoke any change in rpm with propane. And unlike the 2.8, the 2.6 (ABC) has no MAF; no EGR; no vacuum operated flaps in the IM. = Less problems.
From what I've seen of 2.8 IM port polishing (VAPs IM workshop), I'd say my spare 2.6 IM has much finer finish. It looks factory honed/polished, unlike the 2.8 IM which has a gritty finish from sand casting.
The weird thing is that the 2.6 seem to get the same MPG as the 2.8.. so what you get is a car with less torque and 22 horses shy...
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ABC Advanced timing help
My engine can't be half bad. I wasn't able to provoke any change in rpm with propane. And unlike the 2.8, the 2.6 (ABC) has no MAF; no EGR; no vacuum operated flaps in the IM. = Less problems. 
