[Alex B]

I know this is long winded and I don't know if anyone here will be able to help but it's worth a shot.

Quick run down of the specs:

Volvo 2.3l DOHC inline-5,
Megasquirt'n'Spark-Extra 029v on a Version 3 pcb,
dual trigger setup with 60-2 wheel + VR on the crank and 1 tooth wheel + hall effect sensor on the cam.

I set it up to drive 5 COP ignition coils with built in ignition modules that fire when pulled to +5v.

I've been having nothing but trouble with the rpm signal from the 60-2 wheel. The tooth logger function in the Megatunix tuning software has been showing some very strange trigger events. The norm seems to be I crank the engine over and I see what appears to be the missing tooth, then 4-10 regular teeth, one more long tooth time almost exactly the same as the first one, 4-10 regular teeth, then one more long tooth, then anything from 30-80 short ones, then the insanity starts all over again.

I've reflashed the Megasquirt probably 5 times just to be sure I got it right, I have also gone over the settings for the wheel decoder 10 times and I'm very sure I have trigger times and such set right. Sometimes during cranking it will read a clean missing tooth and start firing the plugs in the exact right order (verified by someone standing next to the engine bay looking at exposed spark plugs grounded on the engine), then the goofy sync behavior starts and the spark will drop out or behave erratically.

The VR and hall sensors are stock, in a completely stock configuration exactly as Volvo arranged them from the factory. I have triple and quadruple checked all the wiring to the sensors and I'm positive it's correct, I've also swapped all the sensors for other known good ones with no differing results. I've verified the function of the additional opto-isolator circuit for the second trigger and it delivers a perfect squarewave 0-5v signal to JS8 on the V3 pcb.

I wired up 6 LED's on the case of the Megasquirt; one connected to the output of the opto-isolator so I can see when the tooth is under the cam sensor and 5 more connected to the ignition outputs arranged in firing order so i can clearly see which outputs are working.

At first I thought it was cross talk between the wiring so I ran a new shielded wire from the VR to the MS outside the car, as far away from the other wires as possible, this made no difference.

I borrowed an old tektronix analogue scope from a friend to see what the signal looked like. I had never used a scope before but after some stumbling around I got the hang of it. The raw VR signal from the sensor looks proper and I can clearly see the missing tooth in the wave form with no apparent noise. I also scoped the signal coming out of the VR conditioner on the pcb and it looks very good, once again the missing tooth is clearly displayed with none of the strange behavior noted in the tooth logger.

I attempted to fiddle with the cut-off and hysteresis trim pots to see if it would make a difference. I know a friend of mine is running Megasquirt on a similar engine with an identical VR/wheel arrangement and he said leaving the pots turned fully CCW gave best results. After looking at the signal on the scope I agree with this. Turning the lower pot more than 3 turns made the signal vanish completely and turning the upper pot (closest to the FET's) had no noticeable effect.

I've verified all the components on the pcb are correct according to the assembly instructions and bill of materials. I'm really at my wits end here. Any advice is appreciated.

[offroadin]

Jeepers. Sound's like you in deep. I've read up a bit on the megasquirt setups, tuning and such. But sounds like you know more than me. Have you asked on the megasquirt forums? Or maybe email the guys who make it?

Since you're showing a good signal and the Megasquirt isn't working with it, my guess would be the problem is somewhere in between (assuming everything on the board is assembled correctly).

Personally when i run into problems like this where everything seems to be setup right. I'll usually just forget about it for a day or two, then come back at it with fresh eyes. Could be something really simple. I don't know how many times you've done this, but go back and recheck every single connection one by one, don't just look at it and say, that looks right. I mean actually check the connection, trace the wire (proper color code) etc.

Sorry i can't be of any more help, but there are some smart guys on the MS forums.

[Alex B]

Any advice is appreciated. I went over all my wiring and nothing is out of the ordinary. I thought it was a firmware issue so i flashed the MS with some different versions and messed around for a while. This proved to be fruitless but it did lead me to believe the cam trigger stuff was messing everything up.

Luckily I have a spare engine on a furniture dolly I could roll out and check trigger stuff on. After reading the cam trigger documentation VERY closely a few times over I realized the stock positioning of the cam trigger wheel is completely wrong. I fixed the cam position wheel to the best of my knowledge (can't see the crank wheel in relation with the tranny installed) and it's working better but not great. I got it fired up and i could rev it pretty well for a while but it's still dropping the sync signal every now and then.

Gotta mess around some more tomorrow.

[offroadin]

Right on. Sounds like you're making some progress. I wish i could help more, but my knowledge is mostly Ford EEC-IV with a dab of other things here and there.

This might be a stupid question, but is it necessary to run the dual trigger 60-2? Is there any way you could swap to something more common? This is a 4cyl motor correct? Maybe email the MS guys and ask them if there is any compatibility issues withe the 60-2 wheel. Just keep plugging away at it. I had a project where I wired an EFI 2.9L v-6 into an non EFI bronco. Took me a couple months to get everything sorted out. After i got it running, it ran ok for a while, then just died. wouldn't fire, i thought i had screwed up something and fried it. Yeah..the tank was empty DOH!!!!!!!

[offroadin]

Im guessing you've read this site many a times?

Distributor Pickups

Are you running a VR and a hall sensor? You should only need one correct?

Maybe check the polarity on the VR as well as the capture edge. you may have a correct signal, but are picking up on the wrong crossover.

[Alex B]

I built the 3" downpipe last night so now i can verify air/fuel with the wideband, but first i have to solve the current problem. I got the damn thing to start but it's randomly dropping the cam sync signal and misfiring. This makes the engine backfire and shoot flames which is cool in itself but doesn't really help me.

Originally Posted by offroadin

Right on. Sounds like you're making some progress. I wish i could help more, but my knowledge is mostly Ford EEC-IV with a dab of other things here and there.

This might be a stupid question, but is it necessary to run the dual trigger 60-2? Is there any way you could swap to something more common? This is a 4cyl motor correct? Maybe email the MS guys and ask them if there is any compatibility issues withe the 60-2 wheel. Just keep plugging away at it. I had a project where I wired an EFI 2.9L v-6 into an non EFI bronco. Took me a couple months to get everything sorted out. After i got it running, it ran ok for a while, then just died. wouldn't fire, i thought i had screwed up something and fried it. Yeah..the tank was empty DOH!!!!!!!

It's an inline-5 cylinder engine. This is the main reason why It needs to have the dual trigger setup. The 60-2 is how the engine came stock and is a very very common crank wheel arrangement. I know the VR signal from the crank is coming in clean as a whistle. The problem lies with the cam sync right now. I corrected the cam wheel positioning error (to the best of my knowledge at least) but it seems to be losing the signal every other rotation or so.

Basically here's a quick rundown of how the Megasquirt handles dual triggers: The 60-2 crank wheel is used to calculate ignition advance by counting trigger teeth that pass under the sensor. The "-2" part means it's a 60 tooth wheel with 2 missing teeth, so effectively 58 teeth. The missing teeth act as a synchronizing point for the MS. You give the MS software a bunch of constants regarding the position of the crank wheel in relation to the position of the cylinders when at TDC.

When you set up Megasquirt to run in a wasted spark arrangement it only needs to keep track of the crank wheel for 360 degrees of crank rotation, so every time it sees the missing tooth it just resets the tooth count and goes on it's merry way. This applies to all even fire engines with an even number of cylinders.

On for ex. a 5 cylinder which for certain reasons HAS to be run in a sequential coil on plug arrangement, MS has to keep track of the engine for 720 degrees of crank rotation or there is a big chance the engine will end up being out of phase when you crank it over. This is where the cam trigger comes in, you set it up to trigger 40-50 degrees BEFORE the missing tooth on the crank, this tells MS that the next missing tooth coming up is when to start counting. MS then counts 120 teeth (60-2*2) so it can fire all the plugs in correct order.

My engine is messing up since it's losing this cam sync signal and goes haywire for a full cycle before catching the cam sync signal and recovering. This is very frustrating and i'm going to look over my wiring later today.

[offroadin]

AH, i was wondering why the dual trigger. I understand the 60-2 wheel setup. Wasn't sure how common it was though. Hmm, can you monitor the trigger while it's running shitty? Maybe more like near the MS end rather right at the source since you've verified it is working correctly.

[Alex B]

I'm pretty sure i've got it figured. The idle is all fucked up and it dies if i let off the gas (fuel and spark maps only go down to 500rpms) so i need to fiddle with the cranking settings, afterstart enrichment and probably move the lowest rpm column down 100rpm's just to be safe. It does fire every time I crank it though, so the dropping rpm signal is most likely fixed. If i get it above ~1000rpm it really revs nicely with the fuel and spark maps i conjured out of my ass.

Turns out the problem was being caused by the opto-isolator circuit i built to filter the cam position signal. I realized there was a completely reliable one already built on the MS pcb (duh) that i could easily wire up, that solved everything pretty well.

Had some issues with the wideband today that require a trip to radio shack *shudder* so I mounted the shift knob instead. Came out pretty nice if I may say so myself. Kind of visible here:



The interior is a mess but that'll all be fixed before the first drive.

[offroadin]

Sounds good. By the way you talked i knew you knew enoguh to solve the problem. 8 ball shifter...that shit is wack. Where did you get your wideband from and how much if you don't mind me asking.

Curious about how this thing turns out as you slowly tune it. This motor is Turbo'd right? I'm assuming there is timing settings in relation to boost.

[Alex B]

The eight ball is a real one i got on ebay for $10 shipped, just drilled a hole in the bottom and pressed in a nut, then i threaded the shifter rod i made and jam-nutted the ball on there.

The wideband is a Just Another Wideband from 14Point7. Not the most accurate or feature laden unit available but for $55 shipped and another ~$45 for the sensor depending on where you get it, the price really can't be beat.

The engine is a 2.3l turbo inline-5. It was rated at 225bhp stock from volvo with 7psi or so of boost. The turbo on there is good for ~20psi so that should put me in the 300bhp territory if i tune it right. Megasquirt is referred to as a Speed/Density ecu because it mainly uses engine rpm and manifold pressure + temperature to calculate the amount of fuel to inject. Coincidentally manifold pressure is directly related the engine load so this works out nicely. You just connect a vacuum hose to the onboard pressure sensor, no mass air meter is required.

The fuel and spark maps are 12x12 tables with rpm on the x-axis, manifold pressure on the y-axis and volumetric efficiency in percent entered into the cells (z-axis).

[offroadin]

Jeez that is cheap for a wideband and sensor. Has it been fairly accurate for you so far?

My parents used to have an old 740 turbo, and it went pretty decent for a little motor.

I'm well versed in SD engine control as my mustang uses this system. I'm thinking about going to Mass Air thoguh because any cam with more than 224 duration and less than 114 lobe separation and the vacuum at idle throws the stock EEC way off. I could get a tweecer for the SD ECU but at 500US, i think i'd rather swap to MAF and let the stock computer handle it. I think the newer MS setups can run MAF as well.

As far as tuning the fuel maps for MS are you using a program to calculate it for you or are you manually entering a bunch of sets of values for certain points? Is there a different map for the ignition advance, vs load vs rpm boost?

[Alex B]

Yeah it's worked really well so far. It's got some pretty sweet data logging functionality and two completely programmable 0-5v outputs. It's not quite as accurate as, say, an Innovate LC-1 due to how it actually computes the oxygen content of the exhaust and how it heats the sensor (and some other stuff) but it's still perfectly acceptable for anyone but a dyno room operator.

MS can utilize a MAF now but it's kind of experimental and will most likely stay that way until MS-2 Extra comes out of beta stages. The MAF support was actually developed specifically for one guy who was trying to MS a banshee quad and having big issues with a MAP signal that was all over the board.

On your engine you could use a feature of MS called Alpha/n for fueling. Alpha/n disregards the MAP signal and uses throttle position and rpm to calculate how much fuel to inject (i think SDS efi uses this, as well as some magneti marrelli stuff). It's very handy for engines with a hot cam or ITB's where MAP signal at idle is very bad or non-existant. The drawback is that sometimes RPM and TPS voltage don't paint the whole picture of what the engine is doing so it becomes impossible to tune certain load areas correctly.

It's basically impossible to tune "on the fly", manually changing cells while driving. You can only do that during idle and that's it.

I personally like to use something called MegaLogViewer. It's a bad ass piece of free software that was originally only designed to just display data logs but eventually turned into a full tuning solution. You pretty much just drive around for 15 or 20 minutes, letting it data log everything. Then you hit a button in MLVW and it analyzes the logs and makes a new map based on what it's seen during the logging. It works fucking awesome for fuel and makes it a snap to get things dialed in (this is assuming you have a wideband o2 sensor).

There is a separate 12x12 spark table with rpm vs manifold pressure and the cells are in ignition advance in degrees BTDC. To tune spark well you pretty much either need a map someone else made that you know works, or dyno time. It can be hard to get a spark map right on the street, but you can get it close.

[offroadin]

Yeah I've read about the alpha N, and it sounds like its more for race/WFO applications mostly. Not the street. Like every other fool out there, I want a streetcar that drives like a streetcar, but can haul ass when i want as well.

The Stock EEC-IV seems to work well in the MAF configuration, although there is almost more power/drivability to be had with some tweecing/dyno tuning.

People say that to run the stock SD system, i'd have to stick with a cam with no more than 220 duration or less than 114 lobe separation. As it sits, the stock HO cam is very well suited to the stock heads/intake. Torquey as hell for a stock smallblock.

MS seems to be very popular for people running turbo setups on their mustangs. I'm just a poor college student right now, but when the time comes, i will build something similar to what you're doing except a mustang