strange no spark problem

ukmercman · Post by **ukmercman** » Sat Apr 21, 2012 11:24 am

Hi all.

1989 Mercedes 190e 2.5 16v.

Was running on megajolt a-ok last year.

Did a head gasket and some detailing work to the bay over Xmas and recently tried to fire her up. Initially, she almost went, but ran out of fuel, next day I returned with a Billy can expecting it to fire up - but no luck!?

Seems I have no spark at all - I actually checked a spark plug (all of them separately) by removing it from the engine and resting it against the block while cranking - nothing. Once, the plug gave off a little smoke like it was getting warm but certainly no decent visible spark and the engine isn’t kicking at all.

I have looked through the forum and tried the following:

Bench tested VR sensor - approx 400ohms resistance (I think, not 100% sure on reading the gauge but it showed some resistance). I tried picking up a steel washer and removing it quickly while checking for voltage - got between 1-3V so assume that means the sensor is OK?

Checked continuity of wiring between VR sensor plug and EDIS plug - all good.

Checked 12V at coilpack (pin 2) when ignition on – all good.

Checked 12V at EDIS plug (pin 8 ) when ignition on – all good.

Checked earth connections for EDIS and MJ – all good.

Tried swapping VR sensor and coil pack – no change.

Tried looking for voltage across VR terminals (pin 5 & 6) at EDIS plug when cranking – no voltage. This made me think it was the sensor hence swapping/testing as above but still got no voltage across VR terminals (pin 5 & 6) at EDIS plug when cranking? This seems particularly unusual as continuity of wiring between VR sensor plug and EDIS plug was OK and bench-testing VR sensor was OK?

I also checked the position of the VR sensor against the trigger wheel. You can just slide a 0.5mm blade between its tip and the tooth – again, this is OK?

EDIT: I just tried testing the VR sensor by picking up a steel washer and removing it quickly while checking for voltage BUT I did it with the VR sensor plugged in and looked for voltage at the EDIS plug and I got between 1-3V so assume that means the trigger wheel isn’t playing ball?? Doe the trigger wheel have to be bare metal – mine is painted satin black – could that be causing a problem??

END OF DAY UPDATE: I have 12v power to the EDIS unit and the coil pack with ignition on and while cranking the engine. I cleaned my trigger wheel tips and re-gapped my VR sensor to the trigger wheel and I now seem to have around 3V across VR terminals (pin 5 & 6) at EDIS plug when cranking. But still no spark at plugs?? Went to the breakers yard and grabbed another EDIS unit, coil pack and VR sensor and tried different combinations but still no spark at plugs!???

Thank and help!?

klivins · Post by **klivins** » Sat Apr 21, 2012 4:24 pm

strangely enough I have the same problem but totally different car
1990 Mini, 1275 cc
fitted MJ last year, but couldnt get round to sort out fuelling properly. After the winter was over and my broken ankle was healed I returned to the garage, and she sprang into life beautifully. Then I decided on head gasket swap.
Since then I have lost spark.
And have performed all the tests you have done. All good, still no spark. Got another EDIS unit from scrappie. No spark.
Ground good, power good, coil with corresponding ohms, VR sensor gives signal.
Any ideas?

ukmercman · Post by **ukmercman** » Sat Apr 21, 2012 5:23 pm

klivins wrote:strangely enough I have the same problem but totally different car
1990 Mini, 1275 cc
fitted MJ last year, but couldnt get round to sort out fuelling properly. After the winter was over and my broken ankle was healed I returned to the garage, and she sprang into life beautifully. Then I decided on head gasket swap.
Since then I have lost spark.
And have performed all the tests you have done. All good, still no spark. Got another EDIS unit from scrappie. No spark.
Ground good, power good, coil with corresponding ohms, VR sensor gives signal.
Any ideas?

well, i dont have any ideas - hence my post!

only thing i havent changed in the actual sparklpugs! might get a set tomorrow and see what happens.

klivins · Post by **klivins** » Sat Apr 21, 2012 6:18 pm

good luck mate

my concerns are: the VR signal is somewhat bigger voltage - 5 to 6 when measured with my low tech multimeter in AC mode; the coil pack shows 1.5 ohms both primary and 12.5 kohms both secondary coils. I suspected the equal numbers shows they are OK but I found info here the numbers should be 3-6 ohms and 13 - 15 kohms respectively. Can these figures mean the coil is buggered?

rewired both ground and power temporarily to the battery. No change there.
Any idea how to check Edis packs?

thanks and sorry if I hijacked your thread...

EDIT
went to garage and checked some soldered joints. Swapped over leads to coils, and hey presto - there was a spark! The joy was short lived. The spark disappeared again...

EDIT again

rechecked the EDIS module, had all connections soldered again. No changes there. Put multimeter across coil cable connections. When ignition on multimeter shows 12V, when cranking - 10V. When the coil is connected the multimeter does not register any voltage. What would that mean?

EDIT number last ( I hope!)

Report of what happened. When resoldering all wiring, I noticed small error where VR signal could have been touching the earthed screen. Fixed that. That seemed to be the cause of my initial problem.
The next problem was myself when in try to get better power source I wired all the loom into wrong fuse, the one what didnt have power whilst cranking. Took me a good while to find it out, but once I rewired the loom into correct fuse the mini sprang into light beautifully.

Post by **brentp** » Sun Apr 22, 2012 11:07 pm

That's great you figured it out! now enjoy your new system

ukmercman · Post by **ukmercman** » Mon Apr 23, 2012 2:19 pm

brentp wrote:That's great you figured it out! now enjoy your new system

Er, this was my thread and my system still isnt working!

After a frustrating day of testing, this is where I am:

When I bench test the VR sensor, it seems to be working, or at least doing something. Checking the terminals while holding/removing it from a small piece of metal produces a small voltage reading on my multi-meter.

I checked the continuity of the shielded wire that connects the VR sensor to the EDIS plug, all is good.

However, when I plug the VR sensor in and crank the engine, I don’t get a voltage reading at the VR sensor terminals on the EDIS plug?

I have checked the position of the VR sensor in relation to the trigger wheel and its all good. Centrally aligned to the correct tooth. I have tried spacing it to/from the trigger wheel with varying gaps between 0.1mm and 2mm. No change.

Am I right in saying that even if the trigger wheel/VR sensor was incorrectly aligned, that it would still produce a spark/signal albeit at the wrong time?

The coil pack plug and the EDIS plug are both getting 12v at ignition on and when the engine is cranking.

I have tried swapping the EDIS module, VR sensor and coil pack albeit for untested units from a breakers yard – I guess they could be faulty as well?

I have tried cranking with and without MJ connected – no change.

I had the car running on Megajolt (well!) last year and aside from the head gasket swap and moving the battery to the boot, the car is unchanged from the last time I drove it.

On this basis I can only assume that the problem lies with either the sensor (both the original and used replacement being faulty, possible I guess) or the shielded wire connecting the VR sensor to the EDIS module or the actual plug that connects to the VR sensor as I am unable to measure a voltage reading at the EDIS module from the VR sensor when cranking. However, my testing seems to have ruled these items out individually yet when they are all together nothing happens!!??

I guess the only other item to question is the actual trigger wheel however, this hasn’t been touched and it worked before!

Total mystery and my limited electronics skills are wearing out fast!

Any help/advice appreciated.

Thanks.

klivins · Post by **klivins** » Mon Apr 23, 2012 2:35 pm

sorry for bumping into your thread, I felt it was OK to do so as I had seemingly same problem, even the head removal!

My 2 cent worth of advice would be to check and double check the wiring. If you dont see the VR sensor giving any output on the EDIS pin, then frankly EDIS cant see it neither! I had the signal on EDIS pin on AC 200V mode of the multimeter it showed 5-6 V even with the signal shorting to the shield!

Good luck in bugs hunting!

toenee · Post by **toenee** » Mon Apr 23, 2012 3:33 pm

ukmercman wrote:
brentp wrote: I had the car running on Megajolt (well!) last year and aside from the head gasket swap and moving the battery to the boot, the car is unchanged from the last time I drove it.
Think this could well be the problem, have you used a common ground for all the megajolt/ford bits ?
Try running a wire from the negative earth on the battery to the earth of the jolt etc

Post by **brentp** » Mon Apr 23, 2012 3:52 pm

Whoops, apologies for not paying attention to who was posting what!

When cranking *and* the sensor is plugged in to the wiring harness, do you get a voltage reading at the sensor?

You might want to temporarily bypass the wire going from the sensor to EDIS module to see if you have a short there somewhere. I would have to double-check our test bench to see what voltage is being read on the sensor while connected. It should show some value at least.

ukmercman · Post by **ukmercman** » Mon Apr 23, 2012 9:17 pm

toenee wrote:
ukmercman wrote:
brentp wrote: I had the car running on Megajolt (well!) last year and aside from the head gasket swap and moving the battery to the boot, the car is unchanged from the last time I drove it.
Think this could well be the problem, have you used a common ground for all the megajolt/ford bits ?
Try running a wire from the negative earth on the battery to the earth of the jolt etc
Yes. I have one earthing point for the EDIS module and the MJ ECU. Its on the bulkhead near where the battery used to be and close to where the EDIS module lives. I guess the only difference is that the main battery earth is now further away? I used the earth point when I was testing for voltage and it seemed OK? If I re-route the earth cables, I could use the spot the battery earth orignally connected to - no harm in that I guess?

I'll try connecting the earth directly (might have to hook up a couple jump leads - its quite a distance!) during the next round of testing!

ukmercman · Post by **ukmercman** » Mon Apr 23, 2012 9:22 pm

brentp wrote:Whoops, apologies for not paying attention to who was posting what!

No probs - just glad you're here!

brentp wrote:When cranking *and* the sensor is plugged in to the wiring harness, do you get a voltage reading at the sensor?

Silly question: where do I take the reading from if the sensor is plugged in? Doesn’t the sensor plug cover the terminals on the sensor where you'd test for voltage?

brentp wrote:You might want to temporarily bypass the wire going from the sensor to EDIS module to see if you have a short there somewhere. I would have to double-check our test bench to see what voltage is being read on the sensor while connected. It should show some value at least.

This is the route I’m going down at the moment – I ordered a brand new VR sensor, plug lead and several meters of the shielded cable from triggerwheels.com – should be here in a day or so. I’ll go pin to pin from the (new) VR sensor plug to the EDIS module plug so it should solve the problem! I hope!

klivins · Post by **klivins** » Tue Apr 24, 2012 6:21 am

ukmercman wrote:
Silly question: where do I take the reading from if the sensor is plugged in? Doesn’t the sensor plug cover the terminals on the sensor where you'd test for voltage?

there are not silly questions but silly answers are possible!

Try this - sticking multimeter pins from top of the EDIS plug into orifices where corresponding wires disappear. Or test without the EDIS module in place - both should give reading for VR signal.