Boost stops at 1.4bar - N75?

[hunker7]

I did zip tie it, but i didn't have second pair of hands to help me, so it might have jumped a tooth.

And thanks for the timing info

[UrS4boy]

I thought i didn't touch timing belt, but i needed an access to cam sensor, so the pulley was off, maybe it did move by a tooth. Will check tomorrow definitely.

When you do the cam sensor alone, without renewing the timing belt, you *should* zip-tie the belt to the cam pulley, or mark the position of the belt on the pulley with white-out or the like, to prevent moving a tooth or too. All that said, it is probably difficult to move a tooth because the cam belt is captured strongly by the crank cog and is very unlikely to move down there, even if you tug on the belt up at the cam.

HOWEVER, you have now broached the topic and need to check the cam timing against the crank. *IF* you were out by a tooth, it would definitely explain why you can't get the proper boost (assuming everything else, e.g. N75, is fine and there are no boost leaks).

Cam timing post:

http://forums.quattroworld.com/s4s6/msgs/136943.phtml

G40 cam sensor replacement DIY by Nate P. (Imquattro):

https://plus.google.com/photos/104138090013789212848/albums/5227437779355510001?banner=pwa&gpsrc=pwrd1#photos/104138090013789212848/albums/5227437779355510001

Photo showing cam belt zip-tied to cam sprocket (note: broken magnetic bit of the G40 stuck to the inside of the cam position shutter wheel.)

[hunker7]

And that also could be why it's vibrating at idle

[hunker7]

??
And check timing marks!

I thought i didn't touch timing belt, but i needed an access to cam sensor, so the pulley was off, maybe it did move by a tooth. Will check tomorrow definately.

[newsh]

And do the check where you run it with the N75 disconnected so you get an idea of how much boost control the ECU is actually doing.

??
And check timing marks!

[hunker7]

my display shows 2.2 bar maximum too . .

Don't you have a picture too, or maybe a video that shows how quick your car is?

[geneandbolly]

Ooops It would be nice to keep it simple and just read it the way Audi intended by reading the LCD display.Use that as a datum?

that's over educated boffins for you, mark!! always showing off that they know more than you do . .

[geneandbolly]

my display shows 2.2 bar maximum too . .

[Vorsprung durch Technik]

Ooops It would be nice to keep it simple and just read it the way Audi intended by reading the LCD display.Use that as a datum?

[UrS4boy]

The best you should be getting is 2.1 - 2.2 somethings amiss mate.

Mark: You're talking absolute pressure. I think he is talking relative (=absolute-1.01 Bar).

[UrS4boy]

Just did a 50-100mph in 4th gear, and I got 0,8 bar. But when I was going to work I just floored it in 3rd and got 1 bar. Is that normal, or still something ain't right?

Closer but still not normal, even for a stock AAN ECU. You should be able to get about 17.2 psig (just less than 1.2 Bar) max.

I'll try making a boost test thing this weekend and do that again

YAY!!

[Vorsprung durch Technik]

The best you should be getting is 2.1 - 2.2 somethings amiss mate.

[hunker7]

Just did a 50-100mph in 4th gear, and I got 0,8 bar. But when I was going to work I just floored it in 3rd and got 1 bar. Is that normal, or still something ain't right?

I'll try making a boost test thing this weekend and do that again

[hunker7]

And do the check where you run it with the N75 disconnected so you get an idea of how much boost control the ECU is actually doing.

Will do

[newsh]

And do the check where you run it with the N75 disconnected so you get an idea of how much boost control the ECU is actually doing.