7mge comp log, NOW low cranking rpm signal loss

[nathaninwa]

Can someone look over this comp log. This is my first time setting up the pots for a vr sensor, and it didn't take much adjusting. I had to turn counter clockwise to get it to read down to 250ish rpm.

This an MS3X setup using a 7mge distributor 24/1 trigger Im using a drill on the bench to spin the distributor so I sweep from 0 to 3000 and back to 250 and stop It looks funky

[Matt Cramer]

I'm seeing a lot of noise on the 2nd trigger. Primary trigger looks OK.

[nathaninwa]

Is that just a pot adjustment on the 3x card? I've tried rising and falling edge. If I spin the dist backwards the cam tooth looks fine.

I had actually took a log spinning it backwards and loaded it, then realized I had it backwards so loaded the new one

[Matt Cramer]

Correct, there's a second set of trim pots on the MS3X.

[nathaninwa]

Does one pot have more impact on the signal over the other pot?

[nathaninwa]

I got the signal cleaned way up, now with the second trigger working properly, I can only rev down to 325rpm for cranking. Is there a way to get it to read lower? Ive adjusted the main board pots a lot and can only get it to read 0 then 325rpm. Im not sure if this is enough rpm, or what the 7m cranks at

[Matt Cramer]

Does one pot have more impact on the signal over the other pot?

We have an in depth article on adjusting the trim pots here:

http://www.diyautotune.com/tech_article ... _index.htm

It looks like it may need a little more adjustment, but you should be able to come up with a setting that works across the rev range.

[nathaninwa]

Thanks for the link Matt. I'll use that after we get it wired and fired up

Lastly, I can't seem to find a ge msq, what's the common trigger offset when using g1 cam sensor, and well be using spark a on the 3x card to drive the stock igniter, is that rising or falling for the output?

[nathaninwa]

Ok, bump on this thread. The truck is about 2 hours from house and is being trailered to me my buddy says. I went there and wired it and did all the testing I could, when it came time to start it be was not getting any rpm signal. I was afraid the engine might not crank fast enough, so I had him pull the dizzy and adjust the pots and he is able to sync at 125rpm now, but when installed and cranked over there is no rpm in TS. I've gone over several things with him and beleive the problem is a ground issue since the battery is now in the bed

He has verified the dizzy spins while cranking

So when it gets to me, anything besides tidying up on the grounds properly should I be looking at?

7mge, ms3x, stock dizzy 24-1 vr crank and cam sensor

[nathaninwa]

I had a chance to mess with this last night. Grounds are fixed but still no cranking rpm. Seems like I get instable rpm around 125 then it doesn't actually start in cranking mode till about 300. This seems to be the low rpm limit of the sensor. I was able to use another Toyota dist and can get about 290rpm before falling to zero.

I don't have any fancy testing equipment so my plan tonight is to measure the AC voltage and see if its dropping off the sensor or not. I was able to test with a turbo cas, and with the pots adjusted for 300rpm I get a stable 190rpm So this is telling me it's something to do with th crank vr. I tried gapping and any closer or farther from a .010 gap the rpm only rose to around 400 before it would pick it up

Any tricks to get a vr sensor to read lower? I've tried shunting with a 1k and installing a 10k inline but nothing seems to clean the low limit of the signal up

[nathaninwa]

Update, wired the dizzy into a Pro I have for another project and it syncs at my drills 65rpm now without issue. So looks like a dual vr board is in my future. I have one in my car for vss sensors so I'm pulling it for testing

[nathaninwa]

So wired in the 2.1 vr board and no rpm. Still able to get 300 with just the dizzy hooked up. So not wanting to adjust pots I wired it into a truck I have that runs a 24-1 hires wheel in a Dsm cas and using the dizzy and the 2.1 board I'm not getting any rpm input. I tried shunting and using some pull-ups on the out going wires, any ideas?

[racingmini_mtl]

Can you test the dual VR board on a stim? It's rare that you get nothing at all on the output especially on different setups.

Jean

[nathaninwa]

I don't have a stim board. I did measure voltage on output 2 and it's at 5 volts all the time, output 1 was 0 volts and tested at 2.5 while spinning. Then i swapped back to the 3x setup and each output measure 5v.

[nathaninwa]

I see, cam signal sits at 5 volts and drops to about 3 when it crosses and the crank signal sits about 1.2 and drops down to about .8 when it crosses spinning by hand

[nathaninwa]

Got this working. Took a different ge distributer with different style vr sensors. Now the motor cranks on its own around 170rpm