Solutions for VR-signal dropouts?

[MrBill]

Right.
36-1, mounted on the front with one of dale's pulleys and a ford sensor.
Hyundai coil packs
MS2e, 3.0 board

The car will physically rev to 7000+ RPM, even under light load, but the second you really "GET ON IT" and the injector pulsewidth gets over like 5.5/6ms (1000cc injectors) the computer loses sync and it does consistently until you drop off the gas again.

I isolated the wiring from the rest of the harness.
Tried changing the location of the sensor (i don't think this is the issue since it revs freely)
Played with the pots on the 3.0 board.

I haven't tried the older MS2e code.
Haven't tried another sensor

What else is there to do? I've read people put resistors or something somewhere or caps or what.

ideas?

[kildea]

i had similar issues, in my case there were a couple of sources.
firstly there was a groundloop issue in my case - i had the ms box bolted to the body - so i'd suggest first isolating the box to avoid that issue.
i did find that the same (this one was funny to find - it turned out that i was getting the rpm dropouts all the time before fixing it, but they got really bad when i had the tuning cable connected - and it was resetting like mad when i had the cable coiled-up and connected, kinda funny, but makes perfect sense in retrospect) issue persisted after this, though it took more romping to get it to occur so it was not a huge deal at first. further improvements came with resistor plugs (copper buggers) gapped down really skinny (23 thou-ish).
after the plugs i found i had to monkey with the tune a bit (start-up in particular) but once it was all ok the thing revved freely.

another way to buffer some of that rf noise (from the spark event) is to solder capacitors from the coil positive poles to ground, i did not do this, but it was the first thing that my antenna engineer buddy suggested. he said to get the cap as close to the coil as possible, and to go to a real ground, not just the negative line - you want the cap circuit to be parallel to that ground circuit (to the coilpack) to a chassis ground by being parallel to the spark at an engine ground.

[Karl Buchka]

Do all the stuff kildea suggested. It took his car from being pretty fun to being absolutely brutal.

In any case, I think your trigger is fine. It sounds like an ignition problem.

[Lord Tentacle]

Right.
36-1, mounted on the front with one of dale's pulleys and a ford sensor.
Hyundai coil packs
MS2e, 3.0 board

The car will physically rev to 7000+ RPM, even under light load, but the second you really "GET ON IT" and the injector pulsewidth gets over like 5.5/6ms (1000cc injectors) the computer loses sync and it does consistently until you drop off the gas again.

I isolated the wiring from the rest of the harness.
Tried changing the location of the sensor (i don't think this is the issue since it revs freely)
Played with the pots on the 3.0 board.

I haven't tried the older MS2e code.
Haven't tried another sensor

What else is there to do? I've read people put resistors or something somewhere or caps or what.

ideas?

I had same issue on the tentacle wagon
I gave up went from the MS2 chip to the MS1 chip and its worked effing perfectly since

the MS2 chip just seams super sensative for VR work

the every tooth decoder is a blessing and a PITA all at the same time

[2fast242gt]

i never had a problem... i have ms2v3.57 i also think its a ignition issue like karl said. pick up a new sensor and try it. if it doesnt work just return it. problem may lie somewhere else.

[kildea]

i never had a problem... i have ms2v3.57 i also think its a ignition issue like karl said. pick up a new sensor and try it. if it doesnt work just return it. problem may lie somewhere else.



... or who knows, just try the plugs ... like i said above i do have some experience with this, skip the new sensor your problem is with rf noise in the system, try to quiet that before wasting time with a sensor or returning the box :e-shrug:

[DNAsEqUeNcE]

too much RF

[MrBill]

okay thanks for the suggestions :nod: I'll try to look into this next time.

Question: on MS2e, there is a gauge that is labeled something like "lost sync counter" and that's how I ASSUMED the VR signal was the issue.

I can see why noise could be the culprit, but (and i'm just thinking) why would there be more ignition noise during load vs not during load?

[kildea]

...Question: on MS2e, there is a gauge that is labeled something like "lost sync counter" and that's how I ASSUMED the VR signal was the issue.

i think that you have made the correct assumption - the rf noise issue impacts the system via the vr sensor signal.

I can see why noise could be the culprit, but (and i'm just thinking) why would there be more ignition noise during load vs not during load?

that's a good question, i don't know.

maybe it's a combination of things, the injectors are staying open longer, the ignition events are more frequent, the vr swinging events are more frequent, the fuel pump is doing its thing full tilt, and i bet there are some other noisy things happening. as the rpms go higher the vr signal itself may be getting clipped (as the amplitude is sensitive to the rate of missing tooth passing events), there's probably a sensible culprit that incorporates a combination of these circumstances and others?

although - also - someone had a problem like the one you have and the one i had, and he found the trouble to be related to his software settings/setup - triggering on the wrong side of the wave or some such thing - there was a discussion in here and he did post exactly what he had to do to get it right, though i don't recall what it was at the moment - it's in this subforum somewhere, he worked it out last winter i think.

if you find that the plugs don't change anything (they had to get gapped really tight in my case) then you may find this to be more hassle than its worth, since you've mounted the wheel yourself you could always swap in a hall sensor and do away with the whole conditioning circuit altogether - that may get you there quicker

definitely worth figuring out though.

[2fast242gt]

i still think trying a new sensor is worth a try. my car missfired with a old sensor. worst case you return it saying you dont need it. otherwise do you have sheilded vr wires? mine arnt sheilded and are ran right next to the rest of my ms wires and i have no problems. but thats not to say your car is working the same.

[MrBill]

I have another sensor I got from 500dollarmatt friday night. It's some LH sensor, or a regina sensor, or an ABS sensor, I can't remember...

Hopefully I'll get to try it over the long weekend :nod: I really need to get this car going. I've been contemplating putting together a t3/t4 with a spare .63 hotside on my 7- series DD just to get some sort of satisfaction :-(

Also, will the hall work exactly the same as the VR..with the toothed wheel?:omg: I didn't know that...

[kildea]

Also, will the hall work exactly the same as the VR..with the toothed wheel?:omg: I didn't know that...

well yeah, you'll need to modify the megasuirt though, but that poart where you had to choose between the conditioned input and the hall sensor input - that's it.
switching it to hall input is easy, just go back to the build manual and look for that series of steps.

also make sure the sensor is not too close to the wheel, the clipping i mentioned earlier could be caused by that.

[MrBill]

we've adjusted the sensor gap a million times, no dice there.

Yeah I originally had a 2.2 distributor and used the hall input. It wasn't until this most-recent build that I went with the crank-mounted trigger (in prep for a 16v motor without distributor)

Okay so any suggestions on a hall sensor? I know the distributor has one I can try to mount that guy up...
I guess I can use the same method wiring it up as I did before, with a 370ish ohm resistor from a 12v source and a 10ohm for the power.

*fingers are crossed*

[kildea]

we've adjusted the sensor gap a million times, no dice there.

Yeah I originally had a 2.2 distributor and used the hall input. It wasn't until this most-recent build that I went with the crank-mounted trigger (in prep for a 16v motor without distributor)

Okay so any suggestions on a hall sensor? I know the distributor has one I can try to mount that guy up...
I guess I can use the same method wiring it up as I did before, with a 370ish ohm resistor from a 12v source and a 10ohm for the power.

*fingers are crossed*

just check the megamanual, if you build the circuit as described you should be fine.
i'd try gapping the resistor plugs down first though, i got that from one of kenny's threads and it fixed everything.

[WeezilUSA]

I'm guessing you have checked all of your wiring and the grounding of your shields?

[MrBill]

I'm guessing you have checked all of your wiring and the grounding of your shields?

vr signal line - not shielded... I suppose that's a bad thing (facepalm?).

i used the diy autotune harness that has some coaxial cable. a shield on the outside I put to (-) and the other wire was (+)

I do have some 1553 bus cable from work's dumpster that I've been wanting to try. I'm a bit weary of tearing apart my DIY autotune harness to un-solder the cables and re-solder them, but I guess it's important.

1553 bus cable is mil-spec twisted pair with a nice braided stainless line around it. If it's good enough for a helicopter, good enough for me

[2fast242gt]

vr signal line - not shielded... I suppose that's a bad thing (facepalm?).



yeah i did tell you to try sheilded wires many times now.. it very well could fix everything.

[MrBill]

yeah i did tell you to try sheilded wires many times now.. it very well could fix everything.

it's just an epic pain :lol:

okay I'm gonna do it. I PROMISE. shielded wire first.
resistor plugs next. (even though that's a pain and I gotta remove the manifold :-()