Megasquirt Car Starting Problems
 

Ok, so a few days ago I went about properly securing my megasquirt since it's just been taped to my stock ECU for a while. So I did that, and at the same time I cleaned a bit of surface rust on the floor in the car with POR15 so I had to let the paint dry for a day.

I went to start the car yesterday, and it fired up on like 2... maybe 3 cyl. It was hard to tell but it was definatley not running on 4 and ran like shit. The car would only stay alive with almost full throttle. I let the throttle off and it died.

Now to the frustrating part. I try to start it again thinking maybe the plugs were a bit wet and it needed to be cleared out. It turns over a few times... sounding pretty harsh and turning over slow. Then all of a sudden nothing. NADA. The starter is still trying to turn the car over but all I get is a "CLUNK" once... and the engine is not turning. I can hear the starter though so I don't know what's up.

I didn't make any changes to the Megasquirt, jsut unplugged it and plugged it back in. I'm super frustrated right now. I had to take fucking public transit to work. I DON'T take public transit. FML.

So what do you homos suggest is wrong?

did you swap the coils around somehow?

Nope. Running COPS... and I didn't move anything. Just unplugged the ECU... secured it to the foot panel that goes between the carpet and the stock ECU area and plugged it back in.

i misread. so the motor isnt spinning?

This same exact thing word for word happened to me a couple months ago, except I got a ride to work. I finally gave up diagnosing and put the stock ECU back in. My assumption was that I had a faulty microcontroller. When I get the MS2 chip I will find out for sure.

Correct. The motor WAS turning over... it ran for about 10 seconds. Then I let it die. Now it doest even turn over but the starter is trying to do it's job. When the starter ingages all I get is a CLUNK.

Word for word as in your engine "CLUNK"'d too? Did the engine end up being OK? I'm just worried that somthing similar happened to me that happened to Wayne_Curr not long ago. He ended up hydrolocking his motor from a faulty MS.

And this is not instilling confidence in Megasquirt for me right now. Since I have a brand new engine with Ocean being built right now the last thing I want is a faulty ECU damaging it.

Take a spark plug out to see if fuel is puddling in the cylinder, that could be why it doesn't want to turn over. It may be that the 2 cylinders that weren't firing got too much fuel in them.

edit: yes, that is exactly what happened to me. I tried everything to get MS to work again, and the only solution that worked for me was to put the stock ECU back in.

Now if that's the case, could that have damaged the engine?

You should be okay. I don't think the starter motor has enough power to bend rods or do damage if the cylinders are fluid locked.

If you have a stim, you can test MS to check your ignition. In my case it was only firing for one bank of injectors. I was unable to figure out why.

I don't have a stim... I may have to bust down to Bellingham and get wayne_curr to test it for me.

Check the connections at the patch harness. You probably have a loose wire or two. I've had that happen before where moving the ECU around cracked the solder joints and caused the car to not run.

I guessed that might be what's wrong. That was the first thing I was going to check but I ran out of daylight.

What happened to me had nothing to do with a faulty megasquirt. What happened is the TPS connector on the factory harness fell off causing the wires to short together. This tells the megasquirt to lock all the injectors open. I doubt this happened to you.

Its too hard to speculate on what went wrong without more troubleshooting. Unfortunately i'm working til 10:30 every night til my days off sunday/monday.

I thought you had another car...?

I do. My sister has been using it for the last month or so. Her car broke down so I lent it to her.

I'm going to check the connections on the sub harness tonite.

I would be pretty surprised if there was something wrong with that harness but you might as well check everything at this point. I guess I cant really imagine what else would be wrong at this point.

Did you bang the megasquirt around or drop it or something?

No I was very careful with it when I had it out of the car. Specifically because I didn't want to do anythign to it.

I did mount the box basically 180* opposite from before. So I had to twist the harness around 180* to match it. So who knows, something may have come loose.

Well I pulled the coils, plugs and unplugged the injectors and turned the car over.

You should have SEEN the amount of fuel that came shooting out of cyl 2 and 3. It covered my engine bay in fuel and half my driveway.

I'm letting it air out overnight. And will pick up new plugs tommorow.

I checked all the connections on the patch harness and they are all fine. No touching of one to another from twisting it.

So the only logical conclusion is a problem with the MS or two of the 4 of my coils happened to shit the bed at exactly the same time I did the re-location of the MS. I am trying to locate a local Stim and if I can't find one I'll head down to Bellingham and throw it on wayne_currs. Since 2 and 3 fire together (I think?) I'm guessing my spark output is messed up somehow.

Wow déjà vu. I'm not sure what coils you have, but if you have stock, using a multimeter you can check the resistance between the coil towers on the 2 coils. Resistance between the terminals should be 8.7k-12.9k ohms at 20 degrees C. I don't think that's your problem though.

I bet something is up with your spark output on MS. I wish I could help you but I possibly have the same problem myself. I have a thread about it somewhere, but I'm too tired to link.

I'm running Toyota COPS.

Your spark outputs are wired as 1&3, 2&4. Your fuel outputs are wired as 1&4, 2&3. Something is locking your injectors open. Check your TPS circuit.

Hmm, unplugged injectors (as not connected to the MS) and fuel flowing?
Would that not mean 2 injectors are stuck open, and a problem unrelated to MS or wiring?

Ok update. I let the car sit overnight and let the fuel evap. I put new plugs in and swapped a few coils around to see if they were the issue. I was wrong before. It's not cyl 2/3 it's cyl 1/3. I check the plugs after it had a hissy fit again. So it's running on cyls 2 and 4. I just pulled the MS out of the car... and am opening it up. Maybe I'll see something fried? Dunno...

I've ruled out that it's the coils... or the wiring (tested with a multimeter).

And Anton... it's not the TPS. It's well wrapped up and zip tied out of the way.

Ok well its definitely related to spark and not fuel then. I guess its possible that something happened inside the megasquirt though I'm not so sure you'll be able to tell anything at all. I think I'm just going to have to take a look at it in person.

In the mean time, reflash the firmware, burn your MSQ again and see if that does anything. I've had my firmware corrupt for some reason after moving the megasquirt around, unplugging it and plugging it back in, etc. Never caused 2 cylinders, but who knows. Gotta try the simple stuff first.

Main problem here is my laptop shit the bed last week and I don't have a copy of my msq anymore.

When is the soonest I can come down?

Shit.

Sunday is the soonest.

FML. I'm busy on Sunday. Guess I won't be AutoX'n this Sunday.

Well if you're busy Sunday then you dont have any time to autox anyway!

I meant I'm busy Sunday because I have to run the AutoX... just won't be able to drive.

How late on Sunday are you around? Are you not around at all tommorow during any part of the day? I'm off work.

No I work from Noon to 8:30.

How long is it supposed to take to hook up to the stim? Am I missing something here...

Yes I think you're missing something. What are you expecting to happen with the stim?

Anyway, forget the stim. It wont solve anything. What we need to do is plug it into my car and make sure its working or broken. Thats the first troubleshooting step then we can go from there.

Oh...

I though we just hook it up to the stim and see if it's actually the MS that's broken. I don't even know that for sure yet.

Let me know when I can come down. Is the evening tommorow OK for you? I can't miss th AutoX. It ends at 4ish.

Hey what ignition driver does my board have? VB921 IGBT or Bosch BIP373?

From some reading I've done it seems the VB921 has had problems before where it just gives up it's ghost randomly.

driving the cops directly from ms or do you still have them wired into the miata ignitor?

direct. and they haven't cause me any issues before...

I think I figured it out. A while ago Joe Perez posted the thread on dwell. He found 3ms worked better for him and that it is in fact actually 2.5ms because of a wierd calculation in the code. So what did I do? Changed my dwell to 3.0ms. And now this. And I found this thread to confirm my conclusion. Time to order a new Bosch ignition driver and set my dwell back to 2.5ms where it's been sitting happily for the last 8 mos.

http://www.msextra.com/forums/viewto...=36329&start=0

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How does this look? It looks nothing like the thread I posted? Could it just be fried internally?

...........

That TIP120 you're focusing on has nothing to do with your ignition drivers. That is your idle control circuit. I totally understand why you're confusing it though because on a standard build for most people that spot is used as an ignition driver.

The transistors I think you're looking for are in the proto area. Go find Joe's thread on the spark output mod and you can read all about them and how to build the circuit.

Well every other site I've been to says Q16 on the upper right with the 3 wires off of it control ignition. So now I'm confused.

Ok I will go look at his thread....

I just dug into my harness. Any particular reason my brown and white/green ignition wires are reversed at the stock ECU boomslang connection? According to Brains DIY post on how to build your own MS, the brown and white/green wires are in opposite spots than what my car has.

Anyone?

Are you actually tracing these back to the pins on the DB37 or just going by the colors of the wires? I might have reversed the colors of the wires but the pins should still correspond to the correct pin numbers on the DB37.

Essentially too much dwell fried the two NPN transistors in Joe's inverted spark out mod, and I just have to replace them and change the dwell back to 2.5ms? If so this will have to be logged in my epic fail book. :facepalm:

Nope. The car just fired up. I reflashed the MS and put my msq back on. And before firing it up I tested every coil with each spark plug at all 4 COP connections with my brother cranking the car. And they all sparked. It STINKS like fuel though... and it's running a bit rough. Time to go do an oil change and take the car for a drive.

I also set the dwell back to 2.5ms before starting it up.

Who knows what went wrong but it runs now so I'm not complainging. Must have been jostled a bit when I moved the unit and damaged something in the stofware.

Holy wow, I never changed the dwell from my base map. 5.5 cranking, 4.4 running :facepalm:

Like I said, i've had weird things happen when unplugging, moving and replugging in the megasquirt that were only fixed by re-burning the firmware and MSQ. I haven't had this happen in a very long time, but it happened a few times when I was first installing and troubleshooting my MS.

Glad to hear it wasn't hardware related.

Me too.. I had to wait for a buddy to swing by with his laptop. Inspires confidence back into the system :D....