Megasquirt.. No spark

[Jhonno]

Right back to my mates megasquirt issues now he's finished uni..

We've got fuel, turns over with plenty of juice, rpm reading on the laptop, apparently a good map uploaded to the ecu, brand new coil pack, plugs etc ok... BUT no spark

Where should he/we/i start?

[jaistanley]

Flint and a chisel.

[Jhonno]

[Speedtouch]

Does it have coil pack or conventional coil & dizzy?

[Jhonno]

Coil pack from a V6 Vauxhall

[Speedtouch]

Have you tried asking Flappysocks, he's an expert on these...
http://www.diyefi.co.uk/

I take it you've got an ignition map stored in the ECU?

[Jhonno]

I believe so..

Might be related.. But it came off the road as it broke down from lack of spark (or very weak), so my mate decided to M/S it.. Its got a new Crank sensor on there also

[Speedtouch]

How about the LEDs on the MS box - are they flashing to indicate the 3 coil outputs?

[Jhonno]

Yes..

[Speedtouch]

It's possible that the engine earth strap needs checking/replacing as a dodgy one may have caused the original weak spark problem.

Also have you checked the fuse to the coil drivers, and the state of the coil driver transistors themselves? It's possible that they haven't been insulated properly from the metal casing (assuming you used one) and that's causing them to short out. See http://wiki.diyefi.co.uk/Fairchild_ISL9 ... ion_Driver

[Jhonno]

Any way to check the earth strap? It does have a split casing i noticed earlier..

Will have a look at the fuses and drivers..

[d6dph]

Dan, I have heard of people using a jump lead to make a temp earth to test. If this solves it then fit a new earth strap.

[e30_Turbo]

Fit a new engine earth, even if the one fitted looks fine, change it.

Also MAKE SURE the earth point for the coil pack/ECU are separate and have EXCELLENT contact with the earth.

I cannot ever get across how many hours I lost of my life trying to get my F**KING coil pack to fire.

Have you specified the outputs in MS? Spark A, C, B?

You mention lights flashing on the MS, what version do you have? I ask as my spark outputs are X led outputs even on my V3.

HTH, Mark.

[Speedtouch]

A multimeter can be used to check the engine earth strap, by measuring the resistance between the engine block and a clean bit of bodywork. You are looking for a very low resistance, practically zero ohms. A continuity buzzer can also be used - try wiggling the earth strap and see if the buzzer cuts in and out (it should give a continuous tone.)

The problem with a manky old earth strap is that it may be breaking down under load or giving an intermittent connection, which plays havoc with ECUs.

Prior to fitting a new one if required, ensure that the termination points are cleaned with a wire brush or similar to provide the best possible contacts.

[Turbo-Brown]

Do you guys not earth your megasquirts directly to the battery?

The coil pack low-tension side shouldn't be earthed through anything other than the ECU.

[Jhonno]

Ive no idea how my mate has done it.. I wont have a chance to look personally till the beginning of next month due to work, but i can relay all this to him, even though it can be a bit of a spactard with cars

[e30_Turbo]

Do you guys not earth your megasquirts directly to the battery?

The coil pack low-tension side shouldn't be earthed through anything other than the ECU.

Ms Earth is on the front strut, the coil pack earth on the bonnet bracket, sandwiched in.

These were the best connection and stopped all the hassle I was having.

Having both together seemed to have issues also.

Alex, do you run yours all the way back to the battery then?

And have you changed mobiles? I tried to call you the other night and it didn't connect.

Thanks, Mark.

[Turbo-Brown]

Hmm, that's really odd!

On mine, one pin was connected to a 12v feed, and then the other three pins went to the coil drivers in the ECU which just earths to charge and releases to spark as necessary.

The only +ve output from the Emerald is for the tacho driver I think, everything else is an earth which is why I'm surprised that MS does it differently.

I did indeed run a big heavy cable all the way back to the -ve on the battery just to ensure the best possible earthing for the ECU.

I've not changed mobiles dude, think it's still working

[FlappySocks]

Hmm, that's really odd!

On mine, one pin was connected to a 12v feed, and then the other three pins went to the coil drivers in the ECU which just earths to charge and releases to spark as necessary.

The only +ve output from the Emerald is for the tacho driver I think, everything else is an earth which is why I'm surprised that MS does it differently.

MS does it the same way. On a Vauxhall/Bosch coil pack, pin 4 is +12v, and 1,2 & 3 are connected to the spark drivers, which in turn are connected to ground.

Regarding the problem. If it's not what has already been discussed, then here are a few thoughts.

The LEDs on megasquirt may flash, but that doesn't mean the spark drivers are working. Ideally you need a scope, but you can put an LED on the output of the drivers (the input of the coil) to +12v (use an inline resistor) and see if there is any flickering. It will mostly stay lit up, so flicking is very slight.

Check the spark output setting. Normal or Inverted. It should normally be Inverted (unless your using a 3.57 board, and not attached the drivers directly to the LEDs).

[hoshy]

Did you ever get this sorted Jhonno ?

[Jhonno]

Nope! Car ended up being scrapped..

I think it was chased to not being MS related though

[hoshy]

fair enough

[e30_Turbo]

Jhonno, did you get your clutch?

[Jhonno]

Turned up today..

[e30_Turbo]

You planning on fitting it soon? I'm popping past your car tomorrow sometime, may see you there.

[Jhonno]

It is already fitted.. The car is still there though, so I will be up again tomorrow