RS2 Stopped! Ignition point sensor (g4) ?

[quattrojan]

Yesterday on my way home entering the highway i emptied 2. gear and went into 3rd and got full boost when i heard a "thump" and the revs felt down to about 4500 so i shifted to 4th and all the power was gone.... I could barely get her home by just being easy on the throttle, more then 10% and sounded like she was drowning in fuel and the revs would fall...

So got her back to the house driving really slow, popped the hood and the turbo and manifold was slightly glowing even is she was driven like a baby

Let her cool down then shut her down and started investigating, found nothing, all the hoses are where they should be. Then i was going to drive he into the garage, bu no way she would start....

Got the vag-com thingie out today and it reads:

Ignition point sensor (g4) No Signal
Engine Speed Sensor (g20) No signal

is the G4 the one on the camshaft?

The G20 error are from what i remember just cause the engine isnt running?

If its the one on the camshaft, where to buy online? the stealer wants my body and soul!

[S2central.net]

I'd suggest it is G4 (reference signal on the crank) or G40 (behind cam pulley) - if either of these is missing then engine cannot start.

Also check that the flywheel pin for G4 is still there - only way to test the G4 sensor properly is with an oscilloscope, but you can use a 5V test lamp/LED across two pins of G40 while cranking to see if you get pulses... one pulse every 2nd crank rotation

[quattrojan]

Thanks! i reeeally hope its not the pin on the crank thats gone missing, prob wont have time to change that one before 2013

but i have a few of those sensors for that pin lying around, so i might do that first

[UrS4boy]

A non-starting engine will typically throw a bad engine speed (G28) sensor and *might* throw a bad crank position (G4) sensor code:

Here is some G4 and G28 crank position and engine speed sensor info that might be useful:

http://forums.quattroworld.com/s4s6/msgs/20986.phtml

There is more AAN electrical info here that might help you with your ADU problem:

http://forums.quattroworld.com/s4s6/msgs/22625.phtml

Definitely check your G4 sensor and the absense/presence of the reference pin.

[bernsaudi]

so whats the score with the glowing manifold /turbo then? I had that on a 5.9 rpi range rover once that did that...scared the bejeezuz out of my wallet...I had to get it home at 10 mph too. fitted an msd blaster 55kva kit and it went away for ever. Has anyone fitted an msd system to the audis before?

[quattrojan]

Thanks for all the input. Gonna have a look at it tomorrow just to see if the pin is still there, is she's gone tha car can live in the garage until next year No time at all to take out the engine now

About the glowing, i think that is caused by the g4 sensor(or pin missing) error causing the timing for the ignition to be way off since its lacking that signal when running. giving it loads of pre-ignition(or what its called in english )


Anybody tried changing that pin without removing the gearbox or engine? i doubt it....

[Jamo]

Thanks for all the input. Gonna have a look at it tomorrow just to see if the pin is still there, is she's gone tha car can live in the garage until next year No time at all to take out the engine now

About the glowing, i think that is caused by the g4 sensor(or pin missing) error causing the timing for the ignition to be way off since its lacking that signal when running. giving it loads of pre-ignition(or what its called in english )


Anybody tried changing that pin without removing the gearbox or engine? i doubt it....

Yes it's been done a few times by removing the starter motor to get access

[UrS4boy]

Yes it's been done a few times by removing the starter motor to get access

Agree. A friend with an UrS4 lost his reference pin and was able to make a new one (square bar stock) and weld it onto the flywheel through the starter hole. It did require some skill (his father's) but it can be done. (IF that is the issue)

[quattrojan]

Removed the sensor today. Had the engine on tdc mark at the crank (front) and couldn't find any pin.......... nice! Turned the egnine by hand a few times just to make sure, and never felt anything resembling a pin..

So i'm gonna try to remove the starter next week to see, and as some of you say, it seems like there is hope

[GT500]

Agree. A friend with an UrS4 lost his reference pin and was able to make a new one (square bar stock) and weld it onto the flywheel through the starter hole. It did require some skill (his father's) but it can be done. (IF that is the issue)

did mine on the UR, I must be skilled! i'll tell the wife!

[A80Avant]

thats what they did on my 7A flywheel to get it to work with VEMS.... stresfull days...

[EspenW]

Glowing manifold probably due to massively retarded timing, causing EGT to skyrocket.

[quattrojan]

Agree. A friend with an UrS4 lost his reference pin and was able to make a new one (square bar stock) and weld it onto the flywheel through the starter hole. It did require some skill (his father's) but it can be done. (IF that is the issue)

This seems to be what i need to do i'm afraid..... Took the starter ot today, turned the engine and i could clearly see that there 1 or 2 pieces of metal missing, they are(used to) sitting right over each other. At least thats what it looks like

I could try to weld something back on, but i'm not sure that my welding skills are that good

Anybody with eny good advice?

[90/90qs]

I have bought one of these "pins" from the dealer for my 7A. The pin they gave me was actually a piece of spring steel tubing with a cut down the side so that it could be pinched and slid into the hole. - the cut was actually toothed like so: /\/\/\/\/\.
The difficulty with putting the new one in is you need to pull the flywheel and remove the broken stub.
That means removing the ring gear (I used an oxy acetylaine torch), and drill a hole through the back of the flywheel, then push the stub out.
Lots of work, but not too bad if you have the tools on hand

[UrS4boy]

...and i could clearly see that there 1 or 2 pieces of metal missing, they are(used to) sitting right over each other. At least thats what it looks like. I could try to weld something back on, but i'm not sure that my welding skills are that good Anybody with eny good advice?

Sorry for your loss (pun intended). You might try to fish down in the bell housing with one of those magnetic wand things to see if you can retrieve the missing "pin" (square bar stock).