MSQ gurus please

kiwicar · Post by **kiwicar** » Wed Oct 02, 2013 10:52 am

Hi
Owing to the engine set up I have I need to be able to operate my megasquirt off the car to get anything usefull out of it beyond sparks, so I have been trying to find out what is out there, so far I have come up with Jimstim for the V£ board. . .er and hat is it really, looks nice but is it £150+ nice, and do I really need to ba able to simulate 200 odd triggerwheels? if I buy this am I going to end up with another item that has more features than I can possably use? I want to be able to get my rev counter going on the bence before I fit it to the car, sort out the two stage rev limiter so I can get it to stage on the transbrake on full throttle and operate a lean out valve on the line. Setting it up to log AFR and EGT on the bench would be good prior to fitting it to the car and getting it to fire off a shift light would also be good, although if I get the rev counter working that would sort that out.
So any ideas please, is this a usefull item worth £150+ of my hard earned cash or is it too complicated to be of practical use.
Please bear in mind I view MSQ as a part of a car not a hobby in it's own right.
Best regards
Mike

DaveEFI · Post by **DaveEFI** » Wed Oct 02, 2013 12:18 pm

The JimStim is a fine piece of kit - but it doesn't produce a waveform which is identical to say a VR sensor, so isn't going to be the total answer to what is a common problem - getting a solid tach signal from a VR sensor. In other words, you may still have to adjust the pots (or whatever) between it working on a JimStim and from the actual sensor.

For basic checking, you could use an ordinary Stim and alter your tach input via software to what it produces - a simple tach pulse, so from a coil or EDIS etc. The actual pulse a Stim produces is the same as a JimStim - but of course is constant, so not the same from as a missing tooth wheel. For the correct pulse sequence you need a JimStim. FWIW, I don't think it costs much more to produce with the ability to provide all those different tooth formats.

From DIYAutotune, a JimStim kit costs 59 usd. Pretty simple to assemble if you have any experience of doing this sort of thing. But of course there is also postage and import duty.

One of the most useful bits of kit I have for MS is a breakout board which plugs between the MS DB37 connector and loom or stim. Allows you to probe any circuit easily to measure voltages etc while it's working. There is also two rows of pin headers for all 'ins and 'outs' normally connected by jumpers. So you can remove a jumper and measure a sensor direct, and so on.

As regards your rev-counter - how was it originally driven? Ones which were triggered from the coil originally can be a right PITA to get working perfectly from, say, a 5 volt tach signal. But not always.

Eliot · Post by **Eliot** » Wed Oct 02, 2013 12:57 pm

I've got an ordinary ms stimulator which will simuate everything except for the trigger wheel which you can borrow.
On some versions of the code (PHIL help me) there was "stim for wheel" where it would accept ordinary signal from a normal stimulator and in the code it would convert it into a trigger like signal.

Of course there's nothing to stop you putting a real trigger wheel (or your whole damper) into a pillar drill. Variable speeds would be hard though.

Here's mine in the lathe:
http://www.youtube.com/watch?v=0g4Mocypxzo&feature=player_embedded

The stimulators are good though as they allow you sit down with a cup of tea and learn/test things on the megasquirt in a controlled and repeatable manner.

kiwicar · Post by **kiwicar** » Wed Oct 02, 2013 1:49 pm

Hi
I have a good triggerwheel pulse on the set up on the engine, the trouble with fault finding on the car is the 130dB in your ear from the open zoomies and the general level of part burnt methanol

. Thanks for the offer Eliot but I have a standard Stim somewhere at home and I found relay board from my original MSQ the other day. $59 from Autotune may be the answer, trouble is in that form it is one more thing that needs testing before I can get on with fixing things this makes the ready made ones attractive.
The rev counter is an aftermarket one from McGills, I bought a diferentiator spike generator thing (a choke and transistors) from Phil's mate and as yet it is not working, I however as yet do not know if that is because there is no output from the MSQ, that the spike generator is not giving big enough spikes or because the rev counter is not working, I have an osciliscope but as I said at the start of this post no way can I test it on the car.Pity you cant just tell the thing to pulse the revcounter output! hovever there are the other bits I want to do.
Best regards
Mike

DaveEFI · Post by **DaveEFI** » Wed Oct 02, 2013 2:06 pm

If you jury rig a stim ignition pulse output into your 'choke' rev counter adaptor and rev counter, you should get a reading of sorts.

However, Tuner Studio will tell you if you have a tach pulse or not - its revcounter dial will show it, and you won't get 'sync' without. If MS has a tach input, it will send out a signal to the rev-counter - if you have the software set correctly.

But as you say, it is so much easier to check all this sort of thing on the workbench first, rather than on the car. And preferably with an old desktop PC with proper serial port.

I've got a complete spare top end from an RV8 here, so can check an MS and loom on that before it goes near a car. But only obviously for my version of the injection. Probably overkill for most.

kiwicar · Post by **kiwicar** » Wed Oct 02, 2013 2:16 pm

Hi Dave
Ok that is a thought
really I need to try more basic ideas, I will still need to find out what is comming out the MSQ but I can do some basics. . .
Best regards
Mike

DaveEFI · Post by **DaveEFI** » Wed Oct 02, 2013 2:20 pm

kiwicar wrote:Hi Dave
Ok that is a thought
really I need to try more basic ideas, I will still need to find out what is comming out the MSQ but I can do some basics. . .
Best regards
Mike

Having a 'scope is very useful.

Eliot · Post by **Eliot** » Wed Oct 02, 2013 8:03 pm

What about making some auxiliary silencers that you could attach to the headers?

Where I used to live my neighbours were really pissy about the noise from my car - so I got an extra silencer that I put over the end of the exhaust to quieten it down

daxtojeiro · Post by **daxtojeiro** » Wed Oct 02, 2013 8:56 pm

If you have a tach adaptor and your not sure its working, you can test it without the MS ECU.
All it needs is the input wire tapping to a ground to make it generate a spike. So tap it onto a ground as fast as you can and it should move the rev counter.
If you send me a picture of how youve wired your MS to run the tach adaptor, I can soon tell you if it should work or not
thanks
Phil

kiwicar · Post by **kiwicar** » Thu Oct 03, 2013 7:25 am

Hi Eliot
I think I like your idea of individual silencers, however 8 silencers nay cost me more than the stim. I would also still have the part burnt Methanol issue, running it for any length of time means about 4:1 AFR to stop it over heating and that hurts the eyes

Phil
I will strip off the rev counter off the car in the next few days and see if I can get the rev counter to twitch.
I now have a Jim Stim on order from DIY Autotune $103 assembled including postage, it will probably come to £100 by it gets through customs but I think this will let me do most of what I want.
best regards
Mike

DaveEFI · Post by **DaveEFI** » Thu Oct 03, 2013 8:59 am

You can always flog it on Ebay when you are finished with it. But I'll guess you'll find it so useful you'll want to keep it.

One thing to note is if you use a spare car battery to provide the power for it in the workshop, do fit a suitable small fuse. If messing around and accidentally short something, it prevents doing damage. Or use a suitable power supply of no more than 1 amp.

kiwicar · Post by **kiwicar** » Thu Oct 03, 2013 10:29 am

Hi Dave
good point, I have a suitable PSU with a current limmit.
Best regards
Mike

SimpleSimon · Post by **SimpleSimon** » Thu Oct 03, 2013 10:41 am

DaveEFI wrote:You can always flog it on Ebay when you are finished with it. But I'll guess you'll find it so useful you'll want to keep it.

One thing to note is if you use a spare car battery to provide the power for it in the workshop, do fit a suitable small fuse. If messing around and accidentally short something, it prevents doing damage. Or use a suitable power supply of no more than 1 amp.

Yep those PP3 bats are a waste of time with the Stims

my IBM spare laptop charger gives a nice stable 14.7 volts