Yet another jimstim, ms3, secondary cam noob

[peterro]

Hi all,

I've assembled my ms3, ms3x, jimstim, and jimstimx and I'm having an issue with the cam input. At this point I'm only bench tuning/testing and it won't be on the car for some time. The intent is to have full sequential, coil on plug, 36-1 crank sensor and a CPS for the cam (it's a V8). Tuner studio says it has a cam fault. I think the problem may be with the jimstim but I'm not sure so here are the results of my tests.

I connected the primary tach signal to an iac led and then to 12v. With all dip switches off, I used the fine adjustment and watched the led blink slowly and faster related to the position of the pot.

I then switched to the secondary trigger and turned switch 3 on. The fine pot was all the way counter clockwise and when I slowly turned it up, the led came on and didn't blink in the same way. It was mostly on solid. If I watched the led carefully, I see a slight blink off that is barely noticeable and it would increase in speed as I turn the pot up though it would quickly become undetectable.

I then checked the voltage on all the chip pins. Apparently pins 1, 3, 13, and 14 should be 3.3v (depending on pot position) and the rest should be about 0. The 3.3v was correct for the 4 pins (13 and 14 varied with pot adjustment) though I noticed pins 15 and 16 were about 2v. Could this be my issue? If so, what should I be looking for? I've re-validated the solders though it's possible I've missed one/some. I don't feel any heat issues on any of the components.

If this is normal, where else should I be looking? Am I even on the right path? msq attached if necessary.

Thanks in advance
Ron

[Matt Cramer]

The cam blinks at a much lower speed in many output modes; I wouldn't worry about that.

[peterro]

Thanks. It's been a while but I'm getting some time back for troubleshooting. I don't know if it's a secondary cam issue or not but I did realize that I wasn't truly testing with the intended VR setup so I think going back to the basics is what I need.

On both the ms3 and ms3x, I've adjusted the pots fully counter clockwise as best as I can tell. There's no click so I don't really know when I'm there. I turned it a bunch hoping that I was going to the end. The Jimstim primary tach is on the VR setting. The jumpers on the bottom of the ms3 are set for VR. The secondary tack on the jimstim is jumpered to the cam input on the jimstimx. At this point I'm not getting any RPM sync. I was before but that's when I was using the jimstim non-vr setting. I'm betting it's something small I've overlooked but I'm not sure where to go from here.

What are the other basic settings I'm leaving out to get RPM sync? Is there a checklist of any kind? I've been reading lots of pages and I'm not making any headway. Also, which is the correct ms3 build doc? The one on megamanual or msextra?

I've attached a couple photos of the top and bottom of my ms3 in case there's anything anyone can see that I've mistakenly done. MSQ was previously attached.

Thanks again.

[Matt Cramer]

Can you attach a copy of your MSQ and a composite log? This will show what signal you are and aren't getting.

[peterro]

I've attached the msq. the composite log is empty so I don't seem to be getting any signal.

[Matt Cramer]

At this point, try the VR circuit bench test:

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

[peterro]

Thanks for the pointer, I think I'm going to make progress on this but I'm trying to dissect what's being said. First I'll let you know how I'm testing and what I've found and then any questions I have.

I'm down to the MS3 and Jimstim for testing. Power to the stim and a jumper from 5v to pin 24 (tach) on the stim. At this point on U7, there is .16v on pin 1 and 4.95v on pin 2.

When moving to gnd on pin 24, pin1 on u7 is 4.22v and pin2 is .91v

I believe r56 is the 10k resister on the edge of the ms3 board, true? I've tried adjusting it and the above values don't change though the value on pin3 of u7 does change. It does say that when grounding the input, pin2 of u7 should be between 0 and .7v. If it's significantly higher than that, q22 should be replaced. Do you think that's my issue? Am I having an issue with u7? If I have bad parts, how would they gotten this way? DOA or something I did wrong?

Thanks again. Let me know if there's anything else I can measure/find.
Ron

[Matt Cramer]

The voltages look within spec. You're checking to see if you can trigger the output, and it is.

[peterro]

That's great, though I'm not sure how I'd know it was in spec since my numbers didn't seem to match the ones on the troubleshooting page. In any case, what does this imply regarding why I have no RPM sync?

[Matt Cramer]

That the problem is not in the VR conditioner.

Are you using 5V or 12V pull ups on the JimStim?

[peterro]

An excellent question and one that led me to rpm sync. I thought I had done something wrong. I didn't have either pull-up on. Tried 5v and nothing, but 12v did the trick. Now I have engine speed.

Now on to tuning. Thanks a lot!