Mi16 No Spark

[cybernck 402 1 Cars]

ok this is a half-rebuilt DFW mi16, using the loom the came from another DFW mi16

and ECU of yet another DFW mi16, but that shouldn't make any difference really .

 

 

at first i didn't have both fuel pump running and the coil sparking spark so the TDC

sensor was the likely suspect, but today i fitted another TDC sensor (still no joy)

and later found out that it was a dead fuel pump relay fuse that was preventing

the fuel pump from running (although the fuse looked ok ) - success .

 

still no spark ofcourse, so first i tried with a spare coil - no difference. ignition amp

(Bosch MTR01) was previously tested and working ok so i didn't suspect it but also

tried a Magnetti Marelli one (also MTR01) just for the heck of it - still nothing.

btw, ECU is working fine too, tested on another engine.

 

as it stands, ECU relay is working fine, ECU has got the power, ignition amp is getting

the power (orange wire, from pin #27 on ECU - "engine control relay"), coil has got

power too, purple wire between ignition amp and coil is fine...

 

 

the remaining few things that spring to mind are:

 

- green wire #101 coming from ECU to ignition amp pins 5 and 6 is supposed to have

5V and 30Hz od idle and 5V and 100Hz on 3000rpm. no info for during cranking, but

i got only about 2.5-3v there during cranking. battery was on the way out though.

 

- yellow wire on ignition amp pin 3 - i take it this is earth? it goes to the loom so i assume

it's earthed through the loom, as this amp was running fine (on a 605) without even

being fitted onto the metal plate. maybe there's something wrong with it's earth then.

 

- pins 2 and 3 on the coil (2 being +ve and 3 being -ve, the purple wire) both have +ve

on ignition on, though pin 3 starts changing once cranking and pin 4 (rev counter wire)

goes from zero to something, which i assume is the correct signal for the rev counter,

which i don't have connected so not sure if the needle actually bounces or not.

 

 

any ideas welcome!

 

 

thanks.

[pug_ham 245 3 Cars]

I was fixing an Mi recently (BX loom) & found the same as you for the coil plug pins 2 & 3 but since found out that pin three is the rev counter so it must be a pulsed 12v to give the rpm signal.

 

On the BX loom I have here pin 3 on the ignition amp is empty but pin 2 is an earth that is a short wire with a ring termnal on for bolting to the chassis.

 

Only thing is mine's a two row ecu & you are working on a three row one so it could well be different.

 

Graham.

[pug_ham 245 3 Cars]

Also looking at the Haynes it seems that pin 5 on the ignition amp is the earth (M3), it is on the Jetronic plug for the 8v (yellow wire with green stripes an inch apart).

 

If it is earthed properly checked the pins on the amp plug against the engine / ecu loom earth you are using & you should get continuity.

 

Graham.

[cybernck 402 1 Cars]

- yellow wire on ignition amp pin 3 - i take it this is earth? it goes to the loom so i assume

it's earthed through the loom, as this amp was running fine (on a 605) without even

being fitted onto the metal plate. maybe there's something wrong with it's earth then.

it came down to this scenario .

 

it's grounded through the loom, but not on the main engine ground. it goes to the multiplug instead

and gets it's ground from there. with it connected, i got a nice spark instantly and also the engine

started soon after .

 

now i have to see why is the engine running rough, but the main problem is solved .