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Old 06-22-2008, 02:50 AM   #1
N3v
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Default tried to install megasquirt, now won't run on stock ecu

I tried to plug in my megasquirt on my boomslang harness (megasquirt and harness made per braineak's instructions) and I couldn't get it to work, but that's not really my big concern. I had a couple of friends over and I'm sure I missed a step tuning the megasquirt. Anyway, couldn't get the megasquirt to start, so I attached the stock ecu to the stock harness agian, and it would just crank, no start. I pulled the injector fuse and cranked it, then put it back in and cranked again and still nothing. I pulled the plugs and they were dripping in fuel, so I dried them off and gave it another shot, nope. I checked all of my fuses, the ones under the hood on the left side and also the ones next to the clutch- they all looked good. Is it possible to somehow blow the ecu, or would I blow a fuse somewhere first? I feel like it's probably not blown though cause it still injects fuel. I dunno. I just gave it up for tonight and threw a few back instead. I'm totally out of ideas. I feel like it's probably not sparking, but what can I do to check/fix that?
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Old 06-22-2008, 03:04 AM   #2
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Welcome to the "correct" forum. It's unlikely that the ECU is damaged. Power to the coils comes directly from the keyswitch through the 80A main fuse, and if this was blown, you'd have no ECU power. I'll copy and paste my response from your post at M.net below:

If the ignition polarity was reversed (either in hardware or software) or the MS was connected to the ignition coils during a firmware flash, then it's possible that the coils have been damaged. Specifically, the coil triggers being left on for an extended length of time causes the coil primaries to conduct continuously, which can lead to the overheating and failure of the igniter section of the coil.

I'd suggest that, with the stock ECU connected, you test the coils while cranking. You can remove one spark plug, ground the body securely to the head, and plug the wire into it, then have a friend crank the engine while observing the gap. Take whatever precautions you feel appropriate to deal with atomized fuel flying around during this test.
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Old 06-22-2008, 03:25 AM   #3
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what do you mean by ground the spark plug body? I think I know what you're talking about but I just don't want to electrocute myself. I was afraid it'd be coils. That sounds like the most likely diagnosis, and those are kinda expensive aren't they?
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Old 06-22-2008, 03:42 AM   #4
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Just pull the spark plug out of the head, stick it in the plug wire and place it next to your engine hoist mount so that it will sit in place. Then let go and crank the car or let someone else do it for you while you watch. Do that to determine if you're getting spark from both coils.
Grounding the plug body means put the threaded portion on something metal.
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Old 06-22-2008, 02:44 PM   #5
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did what you said, no spark. So does that mean it's the coil pack for sure? I only tested one of them, but if the other two sparkplugs were getting spark, wouldn't it sound like it's about to start or even start and run like hell? It just cranks for me and gives me no sign of anything. It sounds the same with or without wires. I suppose I could test the other ones but I already removed the coil pack. About how much is a new coil pack gonna run me?

Edit:
Also, since I presumably blew my old one because of my failed megasquirt wiring and/or tuning, what precautions can I take to not blow my new one besides double checking everything?

Edit 2:
my huge problem is that when I bought the boomslang wiring harness equipment, I have a 97, so I needed the middle plug, and according to onlinecomponents.com it's on back order for 8 weeks. waiting 8 weeks is out of the question, so I decided to see if I could get it started by crimping/soldering the contacts onto the ends of the wires that should plug into the plug, then plugging them into the stock ecu one by one, pin by pin, after wrapping each one in heat shrink. Kinda dumb, i know, but it's all I could think of. That might have caused a problem as far as grounding out and such. Is there a better solution?
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Old 06-22-2008, 02:45 PM   #6
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New coil packs from the dealer are like $300 aren't they? If you end up needing new coils I suggest you look into Toyota COPs. We have a well detailed FAQ and writeup on how to complete this swap.
Are you sure you don't have any blown fuses?
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Old 06-22-2008, 02:55 PM   #7
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Quote:
Originally Posted by cjernigan View Post
New coil packs from the dealer are like $300 aren't they? If you end up needing new coils I suggest you look into Toyota COPs. We have a well detailed FAQ and writeup on how to complete this swap.
Are you sure you don't have any blown fuses?
I checked them all last night, but I'd definitely want to double check them before spending that kinda cash. What fuses could mess with the ignition? Ecu is presumably performing as it should because I'm getting the engine check light with the key in the ready position.

Toyota COP's seem like a pretty cool solution, and that would even yield a slight performance gain, wouldn't it?

Edit: Is there a way to test the coil pack besides the spark plug test? Like, outside of the car? I just really would want to make sure my issue is with my coil pack before I consider trying COPs so I don't compound one problem with another.

Edit 2: in the meantime I'm trying to figure out what's wrong with my megasquirt and thinking it'd be less of a headache to run full standalone. With a boomslang harness the megasquirt should function normally with the stock ecu not plugged in, right?

Last edited by N3v; 06-22-2008 at 03:32 PM.
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Old 06-22-2008, 03:37 PM   #8
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What year is your car?
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Old 06-22-2008, 04:35 PM   #9
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Quote:
Originally Posted by cjernigan View Post
What year is your car?
He's got a '97. And I don't think it's fuses. The only fuse between the coils and the battery is the 80A main fuse, and he'd know if that was gone.

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Edit: Is there a way to test the coil pack besides the spark plug test? Like, outside of the car?
Yes. With regard to the factory colors, apply +12 to the Blue wire, ground the Black wire, and, with two plugs connected and their threaded bits grounded to one another and to ground, quickly tap +12 onto the Brown or Brown / Yellow wire. This will fire the plugs. You must have both plugs connected to do this, as they are series-wired on the coil secondary.

Quote:
With a boomslang harness the megasquirt should function normally with the stock ecu not plugged in, right?
It depends on the wiring. It's quite probable that the +5 Vref signal to drive the TPS comes from the ECU rather than the MS. And you won't have any idle control. And your temp sensors won't read properly, if at all.

You're right however about standalone being easier.
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Old 06-22-2008, 10:28 PM   #10
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I tested my coil pack. Yep, it's blown. Gonna go over to toyota coil packs this week. I even plugged a volt meter up to the coil pack plugs in the car and cranked it to make sure it was sending out a signal across the signal line.

Being a noob at megasquirt (but apparently pretty experienced at ******* up my car, it seems) I have a couple of questions. please don't hate me for just mulling it all into this thead, but

1. i've been reading about those toyota coil packs and theres a signal for tach output, but my coil pack was only plugged into two plugs, each plug has 3 wires going into it, ground, positive, and signal. wheres this tach thing go?

2. what about those other 4 wires from the megasquirt wiring harness that don't go anywhere? :E

Thanks guys. sorry for being a tool.
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Old 06-22-2008, 10:48 PM   #11
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Don't 96 and up get their tach signal from the stock ECU?

What other 4 wires are you talking about.
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Old 06-22-2008, 11:29 PM   #12
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Quote:
Originally Posted by cjernigan View Post
What other 4 wires are you talking about.
If you wire up all the wires from the bundle to the DB37 like this:

And then follow this:

you'll end up with 4 extra wires coming off the DB37 that aren't connected to anything. There's an extra green/white, a blue/white, and two others I forget. I kinda had the same question, but I just got my MS installed today and my car runs without them, so they can't be that important, right?
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Old 06-22-2008, 11:32 PM   #13
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I'm guessing, most likely 2 are for IAC outputs, 1 for 5vref, and the last one for...
When you end up with left over wires post what pins its on and i'll tell you what it goes to.
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Old 06-23-2008, 01:21 AM   #14
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Solid gray labeled TPS VREF (pin 26?)
Solid green labeled F IDLE (pin 30?)
green/white labeled IAC B (pin 29?)
blue/white with no legible label, another IAC output? (pin 27?)

Those pinouts are based on the wiring diagrams and my recollection, because it's too dark & rainy for me to go out and verify it with a multimeter in the car. The labels are definitely right though, and I'm pretty sure those are the correct pin numbers.
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Old 06-24-2008, 01:14 AM   #15
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Pins 27 and 29 are I/O for w/e you feel like using them for. Fidle is for the idle control valve. Tps Vref is for people running standalone, it provides 5 volts for the circuit.
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Old 07-04-2008, 11:15 PM   #16
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Alright, after lots of work, I'm about to finally get this thing going. I've got a couple more questions though. Before I get started, I've modded my MS for full standalone, which means I've done the idle control mod and the fan control mod.

1. my megasquirt is being kinda weird with the AIT sensor. On the stim, it will change the value of it, but super slowly. like if I have the pot set on a middle value, the temp gauge on megatune will go from 200+ down to the temp that my pot is set at slowly. Then If I change it up or down, it will take a minute or more for the value to crawl in that direction. Is that normal? will it do the same on my car, or is it just a stim issue because of something else?

2. my ecu is acting all funny on the stim when it comes to idling. I think it's probably due to the MS controlling the idle though. I know i need to wire in a diode to my IAC wires when its installed in the car, so I'm assuming that it's just the stim causing it to act funny. My 'warm up' LED on my MS blinks as rapidly as the ignition light. weird. Also as I raise the coolant temp now the 'IDL' light on my stim just gets dimmer as the CLT gets hotter until the 'IDL' LED finally turns off

3. I'm running ITBs with a IAC valve from a 94. I have a plug that goes to it, and it's only two wires. one wire is thicker than the other. the thicker and thinner wires are respectively white/red and yellow/red. can anyone tell me which one I need to wire to pin 30? don't I need to run the other one to +12v?

4. Where can I get 5 volts for the vref wire? Can I splice it into some wire on the stock harness?

5. last time I tried to start my car I think it was responsible for blowing my coil pack. I've retuned it completely from the ground up for standalone and I know that all of my basic engine constants are correct. With all the basic engine constants correct (i.e. number of cylinders, injections per cycle etc) there is no way it should blow my coil packs is there? What should I make sure to do so that I don't blow anything?
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Old 07-05-2008, 03:28 AM   #17
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I'm not sure if it's an issue on the 97 but on the 1.6 we need to remove the ST SIGN fuse before using the MS. It would need to be replaced to return to using the Factory ECU.
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Old 07-05-2008, 03:42 AM   #18
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okay, I've got an update:

Tried to go ahead with the install without the idle control yet; I figured if I could at least get the engine to fire then I'd be clear of 90% of the problems. I've got spark, but no fuel. It seems I've got no pressurized fuel in the lines either. My megatune says fuel pump is on for about 3-4 seconds after i turn the key to the ready position, then it says that the fuel pump is off. When I crank it it says the fuel pump is on, but afterwards goes back to saying it's off. I'm pretty sure the fuel pump is the culprit, i've got spark, and my fuel injectors click like they should. Advice?
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Old 07-05-2008, 05:42 AM   #19
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Quote:
Originally Posted by StarGehzer View Post
I'm not sure if it's an issue on the 97 but on the 1.6 we need to remove the ST SIGN fuse before using the MS. It would need to be replaced to return to using the Factory ECU.
That's only for the 1.6, and only for the MSPNP.

It's because the fuel pump turn-on wire in the 1.6 does not hit the ECU directly- it's driven by the AFM. To get around this, DIY rigged it such that the 1.6 MSPNP back-feeds +12 into the start signal wire, which turns on the fuel pump relay in a sort of roundabout manner. It's a clever solution to a wierd problem. Pulling the fuse isolates the rig from the starter itself.

Those of us doing regular standalones on 1.6 cars generally either tap the light green wire on the circuit opening relay and use the MS's stock fuel pump driver (a closure to ground) or just hard-wire the pump on. Thus, the fuse can stay in.
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Old 07-05-2008, 05:54 AM   #20
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Quote:
Originally Posted by N3v View Post
1. my megasquirt is being kinda weird with the AIT sensor. On the stim, it will change the value of it, but super slowly.
It does not sound normal to me.
My 'warm up' LED on my MS blinks as rapidly as the ignition light.
In the MegaTune Output functions screen, what is LED18 set to?

3. I'm running ITBs with a IAC valve from a 94. I have a plug that goes to it, and it's only two wires. one wire is thicker than the other. the thicker and thinner wires are respectively white/red and yellow/red.
ITBs with an IAC valve? Interesting. White/Red is +12 (White/Red is always +12 under the hood- it's the switched Main Relay output). On a '94, the wire from IAC to the MS should be Blue/Orange. Yellow/Red is the color of the negative wire from the charcoal canister purge valve.

4. Where can I get 5 volts for the vref wire? Can I splice it into some wire on the stock harness?
+5Vref is an output of the MS on pin 26. It is provided for you to power your TPS with. On a '97, this should feed into the factory harness on the light green / white wire at 2K, where it then goes to both the TPS and the EGR position sensor.

5. With all the basic engine constants correct (i.e. number of cylinders, injections per cycle etc) there is no way it should blow my coil packs is there? What should I make sure to do so that I don't blow anything?
Unplug the coils anytime you're doing a firmware flash or have the bootload jumper installed. (not an MSQ from megatune, but an actual reflash from EasyTherm or the command line uploader)
I've got spark, but no fuel. It seems I've got no pressurized fuel in the lines either.
How have you wired the fuel pump relay?
My megatune says fuel pump is on for about 3-4 seconds after i turn the key to the ready position, then it says that the fuel pump is off. When I crank it it says the fuel pump is on, but afterwards goes back to saying it's off.
Yes, that's normal. It's only on when cranking, when running, or when priming at initial turnon.
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