Intermittently Losing Hall Trigger Signal

[fakename]

I'm intermittently losing my hall sender trigger signal inside my ecu, my car will randomly die and I will see no rpms while cranking. After a minute or so it will start again. This has not been an issue until about 6-8 months ago and has gotten increasingly worse and more consistent (every drive).

I have read multiple threads about similar issues but none seems to match my ecu wiring schematic. I'm noticing some wiring/jumpers in the hall circuit on my board that aren't in the assembly steps. If you notice something that may be contributing to losing my hall signal, that's really what I'm trying to troubleshoot. Thanks.

VW 16vt distributor/hall sender (tried multiple hall senders with same results), ms1 v3 board, squirt and spark. msq and datalog attached. Below is a pic of the jumpers under my board.



Here are some of the wiring anomalies:
I don't have a 1k resistor inline from optoin to 5V in the proto area.
I don't have a jumper from xg1 to xg2
Found a post from Matt Cramer "Jumpering XG1 to IAC1A would make pin 25 a tach input" which is how my board is wired, doesn't sound like it's a normal way to wire it (?)
"If you have a Hall sensor or optical sensor, do not install D1, put a jumper in its place." Same step says roughly the same thing about D2 but says it's ok to solder the diode and jumper between it's leads essentially shorting it out. This is how both D1 and D2 are wired.

Thanks.

[Matt Cramer]

This is a weird way to mod the board and is not using the usual tach input on pin 24. But the board looks like it's got a lot of flux on it. Try cleaning it with rubbing alcohol.

[fakename]

It does seem unconventional. If I understand correctly, on my board pin 25 is my tach input and pin 24 is supplying 5V to my hall? I haven't traced my wires yet to confirm this. It's been working up until now but would it be wise to rewire it in a way that is more standard?

I'll give cleaning it a shot, thanks Matt.

[Matt Cramer]

Yes. For some reason, this used to be pretty common in the VW world, mostly with V2.2 boards. I'm not sure why.

[fakename]

Oh ok. And just to clarify, is that 'yes' about my pin configuration or 'yes' that rewiring it would be a good idea? If it was pretty common, I feel a little better about it. Like I say, it's been working so far, I just wonder if wiring it true to the schematics is known to lower noise or something more beneficial.

[rickb794]

Looks like someone was battling noise demons!

Might just be the sensor failing?

[fakename]

Yes, the noise mods actually were done by me, I installed a high pressure fuel pump and my s*** went all wacky in boost.

Sensor issue is unlikely because I've had the same result with two different sensors. Certainly a possibility though. I've cleaned the board and I'm going to take a test drive tonight. If all of my issues are still there, I'm going to unwrap my harness and check my wires. If problems are still there I'm going to start testing individual components on my board. Expect a lot more questions if that happens...

[fakename]

Cleaned the board and updated firmware. It's still having these random events but the nature of them has changed, I've attached a new datalog. Please let me know what you guys think.

I believe the ms is now losing power randomly. If the rpms are above idle, it seems to recover before it stalls, if it's idling, it generally stalls when this happens. In either case, I can hear my fuel pump relay click on and off at the same time as I lose connection with my computer and the ecu. When it stalls, fuel pump kicks off immediately and then a few seconds later it kicks on, pump primes, and then it kicks off again. The relay has not had this behavior until tonight's test drive.

Any thoughts?

[Matt Cramer]

You are at the very least getting processor resets - the MS might not be losing power, but it's getting things interrupted to the point the processor restarts itself. See this link for more info. http://www.msextra.com/doc/ms1extra/MS_ ... htm#resets

[fakename]

Am I right that these processor resets are an exclusive symptom of noise? Or could there be other causes like a bad processor?

I'm going to test my relays and recheck and clean all of my grounds. Last time I was dealing with noise I added a few capacitors under the board and moved my megasquirt grounds to the head and both of those solved my problems. When I read the suggestions about how to deal with noise on my board, it seems like I have either already made those mods or my wiring doesn't match the mold.

[DaveEFI]

IMHO, you don't generally need to sprinkle caps around an MS - it's already been done where needed. Best to make sure your supply is as clean as possible (direct from battery, via a relay and fuse) and the grounds are good too.

[fakename]

Can't remember where but placement of those particular caps was recommended I think in the manual or maybe just on another forum. But it makes sense that if I've got clean signals, I shouldn't have to add them. Matt has mentioned that my board is wired in a peculiar way, I'm wondering if that has an affect on my level of noise. What's curious, though, is that it was driving fine without issue and that this problem has gotten slowly worse-which does seem to indicate to me that some type of component may have been slowly dying. Last time I dealt with noise, it was directly after an install of a high current pump but this time, there's really no change in my setup.

[slow_hemi6]

IMHO, you don't generally need to sprinkle caps around an MS - it's already been done where needed. Best to make sure your supply is as clean as possible (direct from battery, via a relay and fuse) and the grounds are good too.

I agree with Dave. More so you have reset issues and you have also installed a green cap to the reset pin(6). Maybe try clipping that cap off and seeing if things improve or not. Seems like a good place to start.

[fakename]

I can find continuity from 6 to SPR4 but then I'm not sure where SPR4 goes and which capacitor it corresponds too. Similarly, I'm trying to trace my pin 25 'tach in' input and I have continuity to XG1 but not sure where XG1 goes from there.

[slow_hemi6]

Not pin6 of the DB connector. Pin 6 of the processor socket is the pin that resets the proccessor. You have soldered one leg of a green cap to it. Pin 25 goes to XG1 and then XG1 goes to the opto isolators cathode. This setup is for open collector (ground switching) hall devices and the little led inside the opto is switched on when pin 25 is pulled to ground. You don't need a pullup with this type of triggering. I trigger this same way(XG1) using pin 24 and a diy hall sensor and 36-1 trigger and have done so for too many years. Spins to 6k redline fairly often.

[fakename]

Thanks, that's really helpful information.
So I have continuity from pin 25 to the opto isolator. I'm going to try grounding pin 25 and see if I get a signal. Looks like I can also test the opto isolator this way too by looking for 5v off one of it's pins (correct me if I'm wrong).
If adding that capacitor to pin 6 helped isolate noise previously, why do you suggest removing it now? I'm not saying it's a bad idea, just trying to understand.

[slow_hemi6]

It could be faulty. Caps don't always explode when they are faulty. Be extremely careful probing around pin 5 of the opto. It's directly connected to the processor. No oopsies! You should see a change of state when grounding/releasing pin 25. Probably a bit less then the full 5v but a logic high and low condition anyway.

[fakename]

When I check impedance on those green caps at 20k, I get .7 in both directions on all caps except the pin 6 cap where I get 15.45 in one direction and no continuity in the other direction. Think that means it's no good?

[slow_hemi6]

Maybe but testing in situ, the results are influenced by other seen and unseen components in both parallel and series connection. Results can vary wildly.

[fakename]

hmm, ok. I was just bench testing it while my box was unplugged from the car so it had no power. Is there an ideal way to test it?

Also, I tested voltage at my hall sender wires. Key on, I'm getting 4.95v at the positive, 4.2V on my tach in wire (going to pin 25), and continuity to ground on my negative. Voltages didn't drop during cranking. Spun distributor by hand, I got a pretty consistent spark. Pulled the hall plug, ground pin 25 and got a consistent spark (and led indicators on ecu). I think this means that my hall circuit is in working order and that opto isolator and voltage regulator are in good shape.

But I'm still getting no/intermittent trigger signal when I put it back together and cranked it. Occasionally the led will show a rapid flicker for about a second or two and then pulse slowly about once per second.