Testing the SAW signal output from MJLT

attack chicken · Post by **attack chicken** » Fri Apr 11, 2008 1:19 am

Hey everyone, is there a way to check/test the output of the SAW port? I can see the tach.,the ka, and the timing, all these show what's going on BUT there is no adjustment at the EDIS. Even though it shows 15-20-25-30 degrees there is no change at the crank pulley with a timing light and it runs like it is at 10 drgrees. I just wondered if there was a way to test it without swapping the EDIS module or the Megajolt unit. Also I can remove the ground wire without having any effect on anything. The tach. still reads and there is no change in the timing at the crank pulley. If I pull the power wire everything shuts down.

that is everything Megajolt, the car still runs on the EDIS. Anyone have any ideas? Also how do I figure out which wire is positive on the VR sensor and what happens when it is reversed?
Thanks.
Rick.

Post by **brentp** » Fri Apr 11, 2008 1:42 am

Rick, For testing the SAW output, you should be able to see an voltage on the MJLJ while the engine is running. It should be observable using a stander volt meter. If you confirm a signal on the MJLJ connector, you can then trace it back down through your wiring harness to the EDIS module SAW input pin.

Regarding the VR sensor- the EDIS module will not function with a reversed connection to the VR sensor. Since you're engine is running, you have the polarity correct.

attack chicken · Post by **attack chicken** » Fri Apr 11, 2008 1:54 am

Thanks! Thats what I needed to know. I have no idea if the EDIS module is bad OR if I jacked something up on the Megajolt build. Ill try this tomorrow.

DannyP · Post by **DannyP** » Sat Apr 12, 2008 12:05 am

I have a similar setup to yours, Rick. It has yet to run, but soon, hopefully. 2165cc type1, dual 44 IDF, 911 fan conversion, in a 550 Spyder replica. The engine had 170 hp with an 009 dizzy, but the timing was all over the place, +/- 5 degrees!

If the engine is running, the EDIS is fine. You must have a fault in the wiring, in the soldering, or are getting interference on the SAW or PIP lines. I don't know if it is possible for an EDIS module to be bad(not change timing) but still function for limp-home mode.

If you have access to an oscilloscope, you can figure it out quickly. It sounds like the SAW isn't getting back to the EDIS, if Megajolt displays a timing change relative to rpm, but it just doesn't physically happen.

How did you do your plug leads?

attack chicken · Post by **attack chicken** » Sat Apr 12, 2008 1:56 am

I got it sorted out today. I tested for voltage at the SAW pin of the Megajolt and did find that there was a very low but changing voltage out in time with engine rpm. Plugged the SAW wire back in to Megajolt and it was on! I could hear the engine speed change. I checked with the timing light and all is well. It drove pretty good, now I just have to fine tune the map. I mounted the coil pack low in the center of the firewall, almost on the fan shroud and ran the plug wires down and accross to the plugs from behind the intake runners. I had a set of wires from a 4.6, if you have ever seen them you know they are several feet long and can be shortened for a perfect fit. I wanted a clean look and the less that can be seen the better...but it must work great!

Any ideas for a map? I looked but didn't find one in the library for a ACVW.