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Old 09-09-2010, 01:20 PM   #1
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Default 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 ****. 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 ******* public transit to work. I DON'T take public transit. FML.

So what do you homos suggest is wrong?
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Old 09-09-2010, 01:31 PM   #2
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did you swap the coils around somehow?
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Old 09-09-2010, 01:36 PM   #3
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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.
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Old 09-09-2010, 01:37 PM   #4
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i misread. so the motor isnt spinning?
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Old 09-09-2010, 01:41 PM   #5
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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.
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Old 09-09-2010, 01:43 PM   #6
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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.
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Old 09-09-2010, 01:51 PM   #7
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Quote:
Originally Posted by Cococarbine3 View Post
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.
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.
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Old 09-09-2010, 01:51 PM   #8
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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.
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Old 09-09-2010, 01:55 PM   #9
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Now if that's the case, could that have damaged the engine?
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Old 09-09-2010, 02:12 PM   #10
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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.
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Old 09-09-2010, 02:29 PM   #11
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I don't have a stim... I may have to bust down to Bellingham and get wayne_curr to test it for me.
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Old 09-09-2010, 02:31 PM   #12
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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.
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Old 09-09-2010, 02:33 PM   #13
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I guessed that might be what's wrong. That was the first thing I was going to check but I ran out of daylight.
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Old 09-09-2010, 03:03 PM   #14
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Quote:
Originally Posted by falcon View Post
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.
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...?
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Old 09-09-2010, 03:05 PM   #15
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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.
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Old 09-09-2010, 03:12 PM   #16
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Quote:
Originally Posted by falcon View Post
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?
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Old 09-09-2010, 03:14 PM   #17
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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.
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Old 09-10-2010, 12:23 AM   #18
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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 **** 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.
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Old 09-10-2010, 05:29 AM   #19
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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.
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Old 09-10-2010, 12:56 PM   #20
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I'm running Toyota COPS.
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