smackhead999

iTrader: (5)

i bought it second hand muy... the vr circuit was there and not finished. i got a missing tooth cas with tthe ms. so i went with the missing tooth since this is how the previous owner was using it on his 7.

i also dont have a way to test continiuty, so i tested resistance between the pins and ground. pin7 cas- got minimal resistance with ground... should be normal. but pin 24 got 174ohms with ground. so they are connected some way. the long way i presume with the resistance tested. or there is something in the way. i looked over the board and i dont see any bridges or missing components. its ugly but i think its all there, i think. this is why i was asking about where pin24 signaled to. so i could follow the path out. i really feel right now like maybe i have a missing component or something is fried. my professional opinion says to strip it and rebuild it or start out fresh. but you already know what my pockets say.

muythaibxr

pin24 should go through the TACHSELECT->VRIN jumper inside the board... from there I'd have to look at the schematic to tell where it goes.

174 ohms to ground is probably just the resistance of the VR sensor itself assuming you had it hooked up when you measured...

What's the resistance from pin 24 to ground when not hooked up?

Ken

smackhead999

iTrader: (5)

pin24 to ground has no resistance or cont. with. vrin is jumped to tachselect. and tsel to vroutinv. i turned my pots up higher to like 6 turns. i will still have to test on the car at the jumper. but i get rpm signal with the stim on.

smackhead999

iTrader: (5)

i retested the ms on the harness with the pots turned up to six clockwise turns. no help. is it possible that part of the 1st vr circuit is shorted or broken internally? or perhaps the processor chip? somethings going on here.

toplessFC3Sman

iTrader: (1)

I tried to look thru the circuit diagram in the VR section of the MS extra manuals, but its design is a bit beyond my rusty electrical engineering knowledge. However, it could help if you went through and checked the direction of all diodes and capacitors on the board itself (if you havent already). The capacitors should be pretty easy, on the V3 boards there is a "+" silkscreened on next to the hole for the positive lead (usually marked with a + on the cap itself too). The diodes, depending on how far off the board you mounted them, may be easy too, but if not you can compare them to the circuit diagram that shows up in the upper right corner of the assembly page here. I also installed one of the chips backwards (U4 IIRC), but it didnt pass the communication test that way, and i was able to de-solder it, flip it, and re-solder it in correctly (altho it was a real PITA to do). Good luck man!

muythaibxr

Assuming you're using ms1, you could turn on "stim for wheel," disconnect your injector fuse or fuel pump fuse, and unhook your ignitors from the MS, and then pull the CAS out of the engine and spin it. Make sure the pots are all turned fully counterclockwise (until they click). IF you get rpm in this situation, then the VR conditioner circuit is working, and the problem is settings. Otherwise you've got a wiring problem from the CAS to the MS, or the MS itself has a problem.

Ken

smackhead999

iTrader: (5)

ive been through the layout of the board a couple times to see if it was all there and in the proper orienation. i will do it again with a magnified lense and a light bulb, or flashlight.

and i will try the stim for wheel cas method. i assume disconnect the ignitor wires at the harness? is it bad if i dont? i guess only if there is fuel in the engine. which there hasnt been for 6 months.

i hope this test will show some results. i have tested many things many times with no suffice. thanks guys

muythaibxr

Well, if you don't get RPM with stim-for-wheel turned on then you at least know where the problem is.

Ken

smackhead999

iTrader: (5)

look over the board again and all seems well. went out on a limb today and pulled the cas. before i had hand spun the cas slowely, less than 200 rpm. and then i had tested at cranking speed. both times i had done so in both stim for wheel and no stim for wheel. either time i had no rpm.

so today i went ahead and pulled the cas and then attatched my dewalt 18v drill. and i spun the cas at several rpms through the range limited by the drill... from 0-16000 rpm. and i got some readings. finally.

i tested both in stim for wheel and no stim for wheel. in either case, i got rpm with my drill. although the rpms only showed above 400 rpm. and when i got above 400 and then went below, it got jumpy for a split second and then goes yellow and does a peak-hold effect in megatune.

this is def. a settings thing now right? although i tried adjusting cranksettings to have a variety of rpm limits, nothing changed.

muy what do you make of this? its not reading rpm low enough to pick up on my cranking speed. this must be a bad parameter or something of that nature.

smackhead999

iTrader: (5)

ps my crank speed is approx. 250 rpms

rx3_pp

have you turned both pots counter clockwise till they click and then spin the CAS ?

smackhead999

iTrader: (5)

yes.

muythaibxr

If it won't read rpms below a certain value, it could be settings or it could be that you need to adjust the gap in the CAS (unusual though, unless someone tampered with it).

Ken

smackhead999

iTrader: (5)

i searched but cant find any info on any parameter setting for the rpms. when i tested with the stim i could get readings as low as like 30 rpms or something like that. so i would say that the vr pickup isnt close enough to the teeth. but i adjust that when i started having this problem. i tried as close as possible and far away. if it were an issue with noise... i would more than likely be getting some kind of signal be-it erratic or not. again rpms above about 430 but not below.

muythaibxr

Can you post your latest msq? I should at least be able to verify that those settings should work.

Ken

smackhead999

iTrader: (5)

yeah... itll take a bit
my laptop isnt online anymore

smackhead999

iTrader: (5)

ok here's the link to the msq
http://www.mediafire.com/?81s3het6p9n

muythaibxr

Alright, I'll take a look after work tonight.

smackhead999

iTrader: (5)

dude. did you have a chance to look at it?

muythaibxr

Nope, was at work until 11 PM the last few nights (70-80 hr work week)... work has been crazy... I'll look at it now.

Ken

muythaibxr

Second trigger active edge is wrong. This *could* cause a problem, but you should still get RPMs.
You have your fixed angle set at 0... that should be -10 until you're ready to check your timing. When you check timing set it to -5, then check, then set it back to -10. This won't cause the problems you're seeing.
Your running dwell is way too high, but that won't cause the problems you're seeing.
Cranking RPM should be 300 or higher.

There's nothing in there that I can find that should be causing you to not get RPMs... This is a problem with wiring or the conditioning circuits. The fact that stim for wheel gives the same behavior as not having it on is odd... you have the setting there set to 4, which should be 2. Try it with that and spin the CAS.

If you still have the same problem then, then I'm confident that you have a wiring issue or a bad CAS, or the built-in VR circuit on that board is messed up.

Ken

smackhead999

iTrader: (5)

thanks for checking that. WORD to the hours. i work 12hrs at dupont nylon. if i was to replace the vr conditioner circuit... what would i need to replace, be liberal, to ensure that it wasnt overlooked. and how could this have "gone bad" . wire swap?

i changed up all those settings you mentioned, when i realized this problem previously. tinkering with things trying to get a positive result. i will reset them all and try the #steps in the wheelstim menu.

is there any chance that firmware or software may be to blame?

the cas has the same pickup that this car and harness ran with 6 months ago. i really think this part is ok. although i think i will replace with new twisted, shielded cable.

muythaibxr

For the VR circuit, you'd probably want to try to only replace what's broken. I doubt anything there is broken though, except maybe the transistors that are in that circuit (Q22,Q23). People sometimes overheat or bridge them when soldering them in. You'd probably want to check the section for building that circuit at www.megasquirt.info to find out what else is in that circuit.

The software is not to blame. I've had that running for a very long time with no problems.

smackhead999

iTrader: (5)

i hate to keep bringing this thread back to the top, but i have no other source for information.

i have not replaced any of the vr circuit yet because it just doesnt make sense.

i have fixed the setting to muythaibxr specifications on a previous post. with the #steps set at 2 instead of 4 i did get rpm readings while spinning the cas by hand, about 100rpms lower than before. previously i would get no rpm readings unless i went over 400 or so rpms. now i get them at about 300. and once i get 300 and then slow to below 300 i can get them all the way down to something like 24 rpms. the gauge display on megatune being yellow below 300 rpms i think. as long as i dont restart megasquirt i can stop spinning the cas and begin turning again as slow as i want and get a rpm reading. once i reset megasquirt, i have to achieve 300 rpm again before i can see rpms on megatune. and i reset spark settings to -10 and crank rpms to 300

its hard to count with the eyes but it looks like my starter is turning the car at about 180-200 rpms now. might need to recharge the battery alittle but i still wont see 300 rpms on crank. and i have a 900cca battery.

in stim mode, with igniters unplugged, i can spin the cas and rpms are more sensitive. if that makes no sense i mean at about 400 rpms with no stim mode on, stim mode is seeing like 1500 rpm. its like a 3x or 4x actual rpm, which makes it hard to spin at rpms less than like 500 consistantly.

so i put ithe it back in no stim for wheel mode, put the cas in the motor and crank and get nothing even after i spun it by hand to achieve rpms over 300 and didnt reset megasquirt befor i reinstalled.

and i see my cas spinning about 1.5 turns every second...("one thousand one, one thousand two..etc") so that should be about 180 rpms right?

im thinking if part or all of the built in vr circuit was faulty i wouldnt see any rpm at any range or atleast a large part. but i do. just not at cranking rpms.

wtf?

smackhead999

iTrader: (5)

well i guess the only way to know for sure is to buy a new megasquirt and see if my situation changes. start fresh. what a nightmare.