RS2 Cam Timing

[nilo]

Hello guys,

I´m having a rough time reassembling my ADU after changing the head gasket. When reassembling it, I verifyed the both marks on camshafts aligned, as well as the sprocket mark with the head. After haveing all those aligned, I moved the sprocket one tooth in retard, so as should be in ADU, right?
Doing that, I´m getting G40 Hall sender mechanical fault on the diagnosis, and the car won´t start. I tryed, then, aligning the mark on the sprocket with the head, and I can get the car to start, but I start getting fault signal from G28.
I have tried looking for threads on this subject, for I sure I´m not the first one asking about this, but the info seems to be conflicting. Plus, many times, people refer to AAN, and we know ADU has different timing complications, right? Please, any info on thet subject will be most appreciated, for I really seem to be out of options here.

Best regards from sunny Rio

[stocious]

Why not leave the engine timed as it is supposed to be?

[nilo]

That´s the whole question! How is it supposed to be? For all I have known, it is supposed to be on tooth off, or am I getting something wrong? I just want it to be the way it is "supposed to be", really.

Regards

[AndyP]

Have a read of this

http://www.s2forum.com/forum/showthread.php?t=21353&highlight=rs2+timing

[nilo]

Ok, Andy, thanks for your answer. On my car, all mark are aligned, then I take the sprocket one tooth to the left, right? In this way, I get the hall sender fault msg. is it really one tooth, or slight less than one? I´ve seen people mentioning half a tooth or something.

Best Regards

[UrS4boy]

Have a read of this

No offense to you Andy but I call "BS" on this one tooth to the left business. I just checked a copy of the RS2 ADU Workshop manual and there is NO reference to this. Just a reference to the AAN manual with a note for pg. 15-1 that is not related to cam timing. The factory RS2 exhaust cam sprocket (034109105B) is already modified to take care of the 10 deg difference in the cam lobe advance/retard relative to the AAN and ABY exhaust cam specs. Line up the two O's, O---O, should be good.

Naturally, I will change my mind if somebody posts up a factory document that details the one-tooth to the left requirement.

RS2 Cam sprocket (Note the B)


Photo courtesy of Tom S.

[stocious]

I thought the cam sprocket was different for this reason also.. Unless the chain wheels are on a different phase also?
Interesting thread !

[spink]

Defo not 'BS'

[george21]

maybe a stupid question,but, are you using 150 tooth rs2 belt with 26 tooth rs2 water pump?
or it will not work i believe.

[twoqu]

http://www.s2forum.com/forum/showpost.php?p=624042&postcount=15

That shows the accepted evidence based setting.
Audi were too lazy to even do an ABY factory manual let alone an ADU one!
As to the theory behind it, might be better to start another thread.

[robo]

No offense to you Andy but I call "BS" on this one tooth to the left business. I just checked a copy of the RS2 ADU Workshop manual and there is NO reference to this. J.

If you had no Rs2 you will not know, (even the stealer has no clue) If you do one tooth before the mark the car may not boost.
Just align everything and then move the cam wheel back 1/2 tooth back.

[UrS4boy]

Defo not 'BS'

More like myth then. If you repeat the myth for long enough, does it become reality??

(Why is there no factory documentation on this somewhere?)

This photo that twoqu pointed me too shows a cam sprocket aligned a bit to the left. It doesn't document why. (No offense meant twoqu)

[twoqu]

Well according to parchments at the time the Earth was flat!
If there is not something funky about the RS2 vs ABY/AAN then why is there a different cam pulley?
It appears they had to reposition the rotor for the hall sender on the RS2 to take account of the different pulley position when timed correctly. Unless you have another explanation backed by factory documentation for the change, which of course you will not.
I have personally corrected an RS2 myself and there is a wealth of others experience on here to document the same.
If you time it up using the factory mark you get the hall sensor fault code and lower boost.
Whilst it does appear to be counter intuitive, it is not documented officially. It is only through members experiences that it become to be noticed.

[UrS4boy]

...If there is not something funky about the RS2 vs ABY/AAN then why is there a different cam pulley? It appears they had to reposition the rotor for the hall sender on the RS2 to take account of the different pulley position when timed correctly.

I know that the G40 cam position sender shutter wheel on the RS2 Exhaust cam sprocket 034109105B has its opening 10 degrees different than the AAN/ABY exhaust cam. This is because Porsche adjusted the intake cam timing by 10 degrees (but still wanted the ignition spark to occur at the same basic time as the AAN/ABY). The mark on the chain drive sprocket on the RS2 exhaust cam should be 10 degrees away from the equivalent AAN/ABY exhaust cam mark.

Cam specs:

Intake

AAN, ABY, 3B_ Opens 3° ATDC, closes 25° ABDC, duration 202°, lift 8,3mm
ADU__________Opens 13° ATDC, closes 35° ABDC, duration 202°, lift 8,3mm?

Exhaust

AAN, ABY, 3B_ Opens 42° BBDC, closes 9° BTDC, duration 213°, lift 8,6mm
ADU__________ Opens 24° BBDC, closes 1° ATDC, duration 205°, lift 9,5mm

Intake cams:

AAN, ABY, ADU 034109021AN (after mid-Feb.1991, 021AQ)
Opens 3° ATDC, closes 25° ABDC, duration 202°, lift 8.3mm
Note: installed, the ADU Opens 13° ATDC, closes 35° ABDC, duration 202°, lift 8.3 mm (because the RS2 cam sprocket is "turned" 10 deg)

Conclusion: The one tooth trick must be because, somehow, the Porsche engineers Fk'd up.

[twoqu]

I guess this method was down to cost on what was really the end for the line for the I5. So rather than manufacture a new correct cam pulley they took the cheapest option, making use of bits that already existed. Just like the water pump really. It was just the same for a lot of the other RS2 bits which look like they come from Porsche parts bins, some modified, some not.