Recently Converted to EDIS, Now Mid-RPM Hesitation

73Inka2002 · Post by **73Inka2002** » Tue May 09, 2006 10:57 am

(MS-II, V 3.0 PCB)

Can anyone think of a reason why switching to EDIS would cause a mid-RPM (right about 3500 RPM) hesitation? Iâ€™ve tried different predictor algorithms and played with the predictor gain and next pulse tolerance values. Unfortunately none of my tinkering has eliminated the problem.

I purchased the EDIS unit from Boost Engineering and am running the â€œjunk yardâ€ wires that came with the kit. I may try new plug wires but I donâ€™t have a lot of confidence that this will fix the problem.

Additional observations:
* Iâ€™m having a lot of trouble getting the timing to be consistent over a range of RPMs. I keep adjusting the trigger offset but I canâ€™t get both the idle and mid RPMs accurate. If I get the timing set accurately at idle, it can be as much as 10 deg off at 4,000 RPM.
* Prior to converting to EDIS I had the distributor set to 16 deg BTDC and it felt OK. Now with EDIS it seems to idle much better with 20+ deg BTDC.

Any help would be greatly appreciated.
Robert Moylan

Bernard Fife · Post by **Bernard Fife** » Wed May 10, 2006 10:50 am

Iâ€™m having a lot of trouble getting the timing to be consistent over a range of RPMs.

Robert,

Thgat sounds a lot like what would happen if the VR sensor were backwards. Ia assume you had a complete harness, so this shouldn't happen, but I would check it in any case.

One thing that has tripped me up on EDIS is that a dial-back timing light doesn't work because of the wasted spark messing up the internal timing calculations. So are you testing the timing with a regular ('non-dial back') timing light, or keeping the timing light set on the base value and reading off the damper?

Lance.

73Inka2002 · Post by **73Inka2002** » Wed May 10, 2006 12:01 pm

Thanks Lance, very interesting stuff...

I'll check the VR wires. I had assumed the car wouldn't start if the wires were reversed. Oh, just as an FYI, the wires are not shielded at this time. I had planned to get it up and running and then shield the wires. Could that be the cause of the problem?

Your timing comment is very interesting. I'm using an adjustable timing light so I assume that's going to be a problem. Unfortunately my pulley only has a mark at 0 deg (because it was adapted from a different model year car) and I had to add the marking myself. I assume I could measure the markings on the original pulley and add similar markings to the new pulley...

Questions:
* Will an adjustable timing light work correctly if it's set to 0 deg?
* Can an adjustable timing light be used at idle or will it provide erroneous readings at any RPM?
* Is it possible that I've just got the timing set way wrong because of the timing light issue?

Thanks again. Just when I'm ready to give up cars for knitting or something, someone bails me out!

Robert

Bernard Fife · Post by **Bernard Fife** » Wed May 10, 2006 1:02 pm

Robert,

The dial-back timing light should be okay if it is set to 0 degrees. It should be accurate at all rpms then. Not having a marked pulley is a bit of a problem though, and you'll likely have to mark carefully it yourself.

Lance.

73Inka2002 · Post by **73Inka2002** » Wed May 10, 2006 8:17 pm

Ahhhhhhhh!!!!! Problem solved! Thanks Lance!!!

It turns out my only problem was that my trigger offset was off by 10 deg because of the wasted spark timing light conundrum.

Question:
* Is it OK to just double the values on a dial-back timing light? For example, if I'm trying to set the idle advance to 16 deg, can I just set the timing light to 32 deg? I'm planning on modifying my pulley with an official 16 deg mark, but I'm hoping to just ballpark it at this point.

Thanks again,
Robert

eliotmansfield · Post by **eliotmansfield** » Mon May 15, 2006 1:03 am

Ive got a very old timing light, so I just made a tape up that has the degrees shown on it that attached to my damper. Ive posted up the files to make your own one up at http://www.mez.co.uk/ms9.html

73Inka2002 · Post by **73Inka2002** » Mon May 15, 2006 10:14 pm

Thanks Eliot, I think I'm going to do something similar in Visio to accurately add graduations directly to my crank pulley. Thanks for the idea!

Unfortunately, after posting my success message above, I realized that I was still having some hesitation issues. In the process of just trying random stuff, I changed the Ignition Input Capture Angle from Falling Edge to Rising Edge and it made all the difference in the world. The car now pulls hard to redline and the hesitation appears to be completely gone. Can anyone explain why changing the Ignition Input Capture Angle would have made such a difference? Is it possible I have something wired incorrectly?

Thanks,
Robert