Flywheel ring gear

[johnb]

When you ask how the screw lines up -- you mean the relationship between the ref sensor pin and the ring gear teeth? Other than accommodating other models, nothing obvious comes to mind about the half-tooth delay. The phase seems to be fixed by the hardware, so I can't think up an scenario where it would change on a running car...? I'll have to read your write up to understand the other quirks you mention...

Yes that's what I'm asking.

I suppose the same Motronic system was used on other cars too, and maybe some of those cars has press-fit ring gears without any particular timing guarantee.

The diagnostic pin thing is interesting. Does that have something to do with that other sensor, with the connector on the back of the cam tower? I always wondered what the deal was with that. I tried checking it for a signal before and didn't get anything.

[Tom]

When you ask how the screw lines up -- you mean the relationship between the ref sensor pin and the ring gear teeth? Other than accommodating other models, nothing obvious comes to mind about the half-tooth delay. The phase seems to be fixed by the hardware, so I can't think up an scenario where it would change on a running car...? I'll have to read your write up to understand the other quirks you mention...

Yes that's what I'm asking.

I suppose the same Motronic system was used on other cars too, and maybe some of those cars has press-fit ring gears without any particular timing guarantee.

The diagnostic pin thing is interesting. Does that have something to do with that other sensor, with the connector on the back of the cam tower? I always wondered what the deal was with that. I tried checking it for a signal before and didn't get anything.

I'll take a look (and some pics) in the morning. Yes, the extra pin on the flywheel is for that diagnostic connector -- vestigial hardware of no use outside the basement of the Bosch diagnostic equipment museum...

[soxnail]

I am chasing an issue that has me pulling my remaining hair out....
Back ground: The car will get a tiny stumble while sitting at idle, in the dash I will see the rpm nudge down and then up (higher than idle) and then settle down.
It does it with or without the ICV being used to control the idle.

Here is a bench test pic of the idle timing for my DME.

Idle timing.jpg (140.95 KiB) Viewed 13 times

Sorry still trying to figure out how to embed pics with text...

[soxnail]

Now in the car I have been able to isolate this occurrence to an extra tach pulse showing up just before actual tach pulse, it also a lot shorter in time than the regular pulse. (just before the second tach pulse)

F0004TEK.JPG (135.41 KiB) Viewed 12 times

[soxnail]

My last post did not happen so here it is again.
This pic has the speed and ref sensor shown, I could not find any noise in those lines.
Any ideas would be helpful, Tia Sox.

Ps. sorry about the 3 posts trying to figure out how to get the in line pics to agree with the text.

Ign glitch.jpg (140.71 KiB) Viewed 8 times