boost lag and fuel economy question

[hunker7]

Going over Dave's G39 links I've realised why lambda seemed not to be working. Because I thought lambda plug is the one with 2 pins, and heater is the round one, so I was unplugging that, thus is wasn't running differently.

So nothing has really changed (glad I got lambda quite cheap) so I'm still where I was before whole lambda thing.

I will call Automark and see what he says, as Spink hasn't got back to me.

[newsh]

Good news on the compression test

Only time I feel something is off is when I'm requesting full boost..

Describe what happens when you request full boost.

[UrS4boy]

I think Dave is back from holidays.
Isn't there some way to test the lambda and it's connector, on the loom side, to check all is as it should be ?

http://forums.quattroworld.com/s4s6/msgs/28107.phtml

Check through his link and see what you can find

If you're talking about me, I am still on holidays. In sunny Nice at the moment. Back home mid-week, in the meantime, I have no access to any of my resources, including the G39 O2 sensor FAQ post (the link you gave is for some climate control issue). If you can, please give Janis the G39 link. (I can't (tablet with no mouse/no copy/paste)

Dave F.

[hunker7]

Checked compression on both positions this morning and it didn't change at all (10,5 to 12bar) so I've left the timing at half a tooth before the V and it runs pretty good.

Only time I feel something is off is when I'm requesting full boost. Could N75 be playing up? It looks like it hasn't been changed.

[macspring]

I think Dave is back from holidays.

Isn't there some way to test the lambda and it's connector, on the loom side, to check all is as it should be ?

http://forums.quattroworld.com/s4s6/msgs/28107.phtml

Check through his link and see what you can find.

[hunker7]

I did the same method with my red S4 when lower pulley failed. Had it resting on the ground and then did the bolt up, had no issues.

Both new pulley and the bolt were ordered straight from Audi as I've said before, so I doubt it's "faulty" part.

I am being open minded, I have genuinely checked all the piping, all the clips and I see nothing wrong with it. What bothers me is that car doesn't seem to run worse with unplugged lambda.

I will measure compression tomorrow on both positions for the timing ( i.e. half a tooth out 1/4 out) if timing is out compression should be down.

[macspring]

lower pulley was Audi genuine part.

Whoa Janis, you're in trouble now with this many of us on your case trying to help you.

Looking at the photo of the tool you used to hold the lower pulley, it doesn't look correct to me. Shouldn't the tool be connected to the engine only, and not the front 'crossmember' in the photo. To me it seems like when you tightened the nut real tight that the engine would have twisted / moved a bit with the slack in the engine mounts / gearbox mounts, and this may not have been good for the keyway in the pulley ?

Others might consider this point and let me know either way if I have a point or not, as the case may be ?

Was the new pulley an oem one or one of the aftermarket strong steel ones ?

You've gotta be open minded and allow us to help you, or give it to Automark and pay a bill.

[hunker7]

Haven't checked PN on cam pulley, and lower pulley was Audi genuine part.

[newsh]

Did you check the part number on the cam pulley?

[hunker7]

I've checked the cams, if I position the cam mark on the V on rocker cover, the marks inside rocker cover line up perfectly.

Regarding timing mark on the flywheel, I had my brother turning the engine and I was looking at the marks, and there is only one mark I can see (that line I mentioned before) and it appears when cyl 1 is TDC. When I align it cyl 1 is TDC.

I will check compression with timing as it is now, theoretically it should be down. Then I will move timing back to (half tooth out) and check compression then.

Then report back.

[newsh]

I really don't have a clue if it's right or not..

The flywheel needs to be at TDC with the cam pulley on the mark and the marks on the back of the cam wheels lined up correctly too. I don't believe you've checked the cams, even though I've suggested it a few times. Because you don't seem to have the correct flywheel mark it's a bit difficult to say, the only way I know how to check is with the "chopstic" method, I guess you could do it with a dial gauge on no.1 piston.

In any case, there's no fault code so a mechanical problem is most likely.

[hunker7]

Should I put timing back?

[newsh]

Do a compression test, just to be sure.

[hunker7]

I will put the timing back tomorrow and see how it is. Leave it at that and look into something else.

[hunker7]

I've checked the valves in PCV before I put them back on, and as for piping I used all Daves diagrams and at the end of the day it isn't rocket science.

Yesterday the only bad thing I noticed was a slight judder when going high speed, at low revs it felt pretty good. Could it be some sensor (don't know which just suggesting) that is playing up?