toyota 24 tooth dual wheel CAS wheel, but no RPM signal help

Eugene · Post by **Eugene** » Sun Jul 22, 2007 1:17 am

Hello, i need some help with my setup,

I am doing a blacktop 20v 4age toyota 1600cc into my toyota trueno ae86 since my old engine was a bit worn.

the detail of the megasquirt and spark setup that i am using is:

code 029v
tuning using megatune 2.25
on V3 board and ms1 chip
i also bought Glens Garage's extra board to build the extra vr conditioner and also some other extra functions.
I am also running 2 vb921 driving mitsubishi coils. (wasted spark)

i setup my system to run dual wheel trigger using the stock CAS. The stock toyota CAS only goes in one way and i was hoping that i could crank it with the vr pickups at just any random position, and when it idles, i will tune it with a timing light.

Anyway, its all wired in now and i cranked it on a full battery, but there is no RPM signal.

i did the wiring my self and i tinned all connections and checked it with a multimeter for continuity.

i also built the ms myself, and used shielded wired for all the signal wires.

Anyway, Any suggestions will be great.

photos of my transplant here, i'll reorganise the photos when i get some time.

http://www.photos.86factory.com/v/BT/

cheers

Eugene

rb26dett · Post by **rb26dett** » Sun Jul 22, 2007 2:25 am

one thing i'll add that i didnt say via pm is that you can take that approach, but keep the fuel out of there until you have setup the timing... you can use a timing light during cranking to check/set it up.

fred.

rb26dett · Post by **rb26dett** » Sun Jul 22, 2007 2:27 am

the relevant part of my pm for others to pick apart and add to :

you are right that you need an rpm signal before it will start. it sounds like you have done a good job on the wiring at least routing and materials wise.

one thing is certain here, there is either a dry joint, how long have you been soldering? do you flow both parts, then join? did you build the ms unit yourself? or a jumper wrongly placed, or a wire on a wrong pin on the plug, or the polarity backwards for the vr, or a software config issue on which pins you are using for inputs, or or or... you get the point.

ie, check, check, double check everything. and then do it again.

as it stands, i cant really help you. you have to narrow it down somewhat by trying stuff, and measuring for ac voltage at the vr inputs etc.

fred.

Eugene · Post by **Eugene** » Sun Jul 22, 2007 3:41 am

Thanks Fred,

I'd since trace all my jumpers and tachin was connected to VRin and Tsel was jumped to VRoutINV. so the jumpers seem right

however, i did notice that on the MSNS board, there are 2 VR conditioners and i'd connected the outputs from P5 on this board (pin 1 to 4) to both the dual wheel on the cas. Come to think of it, if i am using V3, does this mean that i should be just using the VR 2 + and - only on the ms board, ie only connect pin 1 and pin 2 of P5 on the msns board?

I didnt hook pin 2 and pin 24 of the DB37 to anything, as i thought the VR circuit on the V3 board is internally wired to P5 of the msns board somehow. I cant seem to find the circuit diagram of the msns board to check this.

i have not tried measuring the AC current yet as i am doing this alone. Will do so when i get a friend to help out.

Megatune seem to be reading my oem sensor after easytherm calibration well. i am not sure if the o2 sensor is suppose to read 10.2 AFR or not on the megatune, but on the logworks it reads 20.9 AFR. I checked my grounds and there are continuity with the chassis. The LC1 ground is soldered to the megasquirt ground.

Will crank and adjust the timing with the injectors unplug tomorrow when i get someone to help me.

Thanks for the help so far Fred. i'd inserted the link now.

rb26dett · Post by **rb26dett** » Sun Jul 22, 2007 6:47 am

cool car! good to see one without excessive "bling", i hate bling...

the other one with the 2j sounds even cooler, you can thank me with some pic/vids of that

i didnt entirely follow all that you said about the inputs, but as far as i understand it you want the following :

both VR sensors wired to a VR conditioner each (preferably the same type) and both outputs wired with the same polarity to the correct pins on the cpu for input. what these are depends on cpu type and code and is in the docs in each case. after that, you need to ensure that the polarity is correct from the vr sensor, and that there is a signal there, the polarity is hit n miss, but the signal should be able to be seen on a meter as a low ac voltage while cranking circa 1v. you also need to ensure that the 24 teeth are hooked to the primary input, and the other to the secondary. then you need it configured correctly in mt. mops will be onto it in no time. just watch he doesnt drool into your intake manifold ;-)

i hope that helps somewhat. show this post to mops and he will either tell you that i'm a idiot, but a mad bastard, or that i'm onto it. either way second opinions are always a good thing.

fred.

mops · Post by **mops** » Sun Jul 22, 2007 9:58 pm

ITB's

yeah, i'll drop in tonight and have a looksee ;)

Eugene · Post by **Eugene** » Mon Jul 23, 2007 4:59 am

Still no joy with getting any RPM signal.

i swapped polarity on the VR sensors and still nothing

i rewired the VR sensor so that the first VR sensor- (main wheel) is hooked up to ecu ground and pin 24 on the megasquirt DB37, effectively using the vr sensor on the V3 board.

As for the second VR, i used the megasquirt and spark board from Glens garage (errors board) and used the conditioning circuit on it, but still no joy.

However, when i check the signal from the cas by changing the megasquirt to trigger by distributor, when cracking, the dials on megatune detects something. I guess this means that there is signal going though the pin 24 at least.

Myself and mops swapped polarity and crank and still nothing.

Anyway, we thought it might be the CAS as since it is a dual wheel, it has 4 wires, G- ( which i assume is the common ground for the VRs,) G1 and G2 which are the pickups for the 2nd wheel, and NE, which is the pickup for the main wheel. i wired g1 and g2 together to form VR+ for the second trigger and used NE as the VR+ for the first trigger. Can anyone tell me if this approach is flawed or not please?

Anyway, the mind boggles.

Cheers

Eugene

mops · Post by **mops** » Mon Jul 23, 2007 1:21 pm

ok, ok.
I'll just make it clearer.

with 24 tooth wheel (1 sensor) with mt set in dizzy mode we get rpm signal in megatune just fine.

However, the setup of that particular engine is:
I has cas sensor only. Cas sensor has two toothed wheels.
One wheel is 24 tooth and has 1 sensor over it.
Second wheel have 2 teeth, 180 degrees apart and *the wierd thing* it aswell has two vr sensors, aswell 180 degrees apart. Eugene connected them both to one line, and I think that's not right (as their signals *may* be canceling each other). basically we get no rpm in wheel decoder mode.

I'm not too familiar with ms1/extra, so here are my questions:
1. since it is 24 tooth cam wheel, ms1/extra shoul be configured for 12 tooth wheel (no missing teeth), with 1 tooth sync ?
2. I'm not sure about the wheel decoder settings
3. Eugene is using Glens Garage daughterboard. The vr signals are supposed to go through glens daughterboard and be 'conditioned' prior to reaching ms board.
4. is sensor polarity important ?

I'm just not familiar with ms1/extra and was hoping somebody will help us with the trigger settings and stuff...

thechuckster · Post by **thechuckster** » Tue Jul 24, 2007 12:22 am

if you want to use both G1 & G2 sensors (that look at the single-tooth wheel) then you need something like:

From http://megasquirt.sourceforge.net/extra/wheel2.html

... circuit [at top] also show how two inputs may be mixed prior to conditioning as the input resistors tend to isolate each of the VR coils

cheers,
charles

Eugene · Post by **Eugene** » Tue Jul 24, 2007 3:35 pm

i thought that was refering to the situation when a second conditioning circuit is not built, and hence they use this circuit as conditioning.

I'll try to put some resistors on the G1 and G2 to isolate signal from G1 and G2, not too sure at what stage the diagram you posted becomes the conditioning cct.

i am using V3 board and also the Glens garage extra board, which has the second VR conditioning cct, i thought it was just a matter of hooking it up as per their instruction, thanks for pointing this out.

thanks

Eugene

Post by **muythaibxr** » Tue Jul 24, 2007 3:44 pm

To run wasted spark, you actually have to run both G sensors together... the G wheel actually only has 1 tooth, and the 2 G sensors together make it look like a 2 tooth G wheel if you have them wired together....

Then in order to use the G wheel, you have to run a resistor from each G wire (low resistance... 330 ohm maybe) to ground, which should keep the Ne signal from interfering with the G signals.

While you're at it, since the G signals aren't used for timing, you could add a capacitor from the G signals to ground to further reduce noise.

It would be easier to wire the Ne wheel's VR sensor to the main board as well since it comes with a VR conditioner.

Also, what are your settings? can you post your msq? Getting RPM is going to be largely dependent on your settings.

Trigger settings are going to depend on how everything looks on the wheel when the dizzy is stabbed as stock.

IE, what is the angle of tooth#1 after the extra tooth when the engine is at TDC?

Ken

mops · Post by **mops** » Tue Jul 24, 2007 4:29 pm

I'm working on this with Eugene....

he said it's 2 tooth wheel with 2 sensors over it, which i thought it's strange at the time. 2 sensors with 1 tooth makes more sense to me.

i's hard to pull that cas sensor out because it's jammed between the engine and firewall, and basically reauired undoing the engine from mounts (and tranny and driveshaft) to move it so it can be pulle dout for inspection.

another key factor is that Eugene is using Glens Garage daughterboard. I'm not sure exacly what this board does, but it has two vr conditioning circuits, and accouding to Eugene, he cant get any rpm signal though it - even at dizzy mode.

Eugene · Post by **Eugene** » Tue Jul 24, 2007 6:22 pm

Thanks for the awesome reponse.

Since my last post, i'd looked at a friends tooth wheel, and there is indeed just one tooth on the second wheel. however, there is a spiral step leading to it.

I'll get some resistors and capacitors and try them tonight and see how it goes.

Pulling the CAS is as mop said, really involved. From looking at my mates tooth wheel, it seems that it only goes in one way. its a shaft with flats though it, not gears like the others that i'd seen. I was hoping i could get at least some RPM reading and from then, with the injectors disconnected, i'll scope it while cranking and rotate the CAS housing, which should line up the sensors.

As for the MSNS board, from looking at the connections, it seems that when used with V3 board, VR conditioning circuit 1 is not hooked up to the main board, which explains why there are no RPM signal.

VR conditioning circuit 2 is hooked up to JS8, which is also used for sequential shift light, so i need to check my software settings when i get home to make sure i set it right. I'll post up my MSQ when i get home.

thanks for the suggestions, i'll implement them and see how far i go.

Post by **muythaibxr** » Tue Jul 24, 2007 9:53 pm

odd how difficult it is to get that dizzy out of the engine...

The project car I work on (belongs to a friend and I) is a 1985 Corolla GTS with a Silvertop 20v 4age, so it should be about the same setup (only I cut 2 teeth from the wheel and used it for wasted spark... I need another dizzy so I can set up for COP)... Admittedly it's a pain to get out of there, but I can get it out without loosening the engine mounts.

I hammered back the firewall a little before installing the engine however.

Ken

Eugene · Post by **Eugene** » Wed Jul 25, 2007 4:54 am

Hello,

i wired up some resistors as per the sketch below. Let me know if its wrong, its a mix of the circuit posted a few post back and circuit recommended by Ken.

cranked it and still no RPM signal (refer datalog). I'd also put a multimeter on it measuring alternating current, and there were no signal between the VR2+ and G- (ground) ( i switched the polarity and still nothing.) i checked continuity in the wiring, and the wiring is good.

I checked the VR1+ while cranking and there were up to 50V AC. When i set it to msns distributor mode, it reads the fake rpm, please refer to the attached datalogs.

i'd also attached my MSQ for anyone that might want to check my settings.

I didnt bash my firewall and i still have my heater setup in my car, hence there is no space to pull the tooth wheel out.

Running out of ideas now. i double checked my VR conditioning circuit on the msns board and its hooked up to js8.

thanks for your help

Post by **muythaibxr** » Wed Jul 25, 2007 12:46 pm

Will take a look tonight if I get a chance, otherwise tomorrow.

Ken

lmr052 · Post by **lmr052** » Wed Jul 25, 2007 6:31 pm

I believe these distributors are like 3SG(T)Es and can be a real pain to work correctly, primarily for two reasons.
1. Common ground for the 3 VR sensors - and the associated cross talk from the NE (24 tooth) sensor on to the signals the G1/G2 (single tooth) - hence the loading resistors
2. The shape of the single tooth is odd. My personal view (at this stage) is the shape of the G1/G2 tooth is a major problem for reliable triggering - it doesn't swing negative very much and may not trigger zero crossing point conditioners reliably.

The conditioning circuit above is the one I used but it has an issue around 2500 rpm due to the trigger point of the G1/G2 signal (or so I believe). I interfaced them to the main MS V2.2 both via the transisor of opto couplers - one on the V2.2 board for the NE and an off board coupler for the G1/G2.

I have not had any success using the conditioner circuits as per the V3 PCB to get good RPMs on the bench (I have a spare distributor). It sounds like you have a problem only with the G1/G2 feed.

In my limited spare time, I am investigating using LM1815s with adjusted RC values to get the trigger point correct, especially for the G1/G2.

Sorry I can't be more help other than give you a snap shot of my experience and thinking.

Regards, Richard

thechuckster · Post by **thechuckster** » Wed Jul 25, 2007 8:59 pm

fwiw: i use the VR sensor out of an earlier 22RE and it's proved quite reliable with a LM1815 interface - i made my own board rather than use one of *errors. I

never bothered with adjustable input control after initial testing (driving dizzi with a drill) showed a clean output on a scope and and hand turning of dizzi showed good rpm signal to MT/MTunix.

Would be a lot of work, but could you get the trigger wheel off and remove the ramp?

... or punch off 2 teeth from the main wheel and single trigger wasted-spark? Your ignition is already wasted spark ?

Eugene · Post by **Eugene** » Wed Jul 25, 2007 10:07 pm

Well, I'll wait till Ken have a look at my MSQ, and there's no obvious fault, i think the only option i have is to take the engine out and pull the tooth wheel/VR pickup assembly out and grind off 2 tooth, and run it as 12-1.

I could machine out the ramp that tapers up to the G tooth, but its a lot simpler pulling out the G sensors and grinding the tooth i think. Yeah, my ignition is setup as wasted spark

I had a look at Ken's Xanga site about his tooth wheel mod because i am running out of options, i might try that.. but it seems that the photos that was once there is missing. There used to be a good "how to" guide on club4ag too, but that's missing now

Can anyone tell me if MS2 extra work with my setup without encountering the problems i am having? or does this seem more like a tooth wheel design issue and it is signal strength dependant? i am considering this because after reading Ken's Xanga site, it seems that ITB is hard to tune with speed density, i was not aware of this previously.

This is really awsome, learnt so much just by posting here. Thanks guys.

lmr052 · Post by **lmr052** » Wed Jul 25, 2007 10:28 pm

thechuckster wrote:Would be a lot of work, but could you get the trigger wheel off and remove the ramp?

That would be tricky and tedious

thechuckster wrote:... or punch off 2 teeth from the main wheel and single trigger wasted-spark? Your ignition is already wasted spark ?

That would appear to be the simplest fix in this install.

For me, I want to be able to revert to OEM by just swapping the ECU - my MS is built into an OEM ECU case and connector... hence I am able to fiddle and play to get it just right.

Regards, Richard