Does rpm gauge show rpm whilst cranking ?

Patriq · Post by **Patriq** » Tue Nov 09, 2010 10:03 pm

As the topic description says - does the rpm gauge show rpm whilst engine is cranking ?

I'm trying to find a fault with my engine. It suddenly stopped running, and I'm suspecting no spark.
It's a V3 MJLJ with v.3.3.2 Configurator. It communicates nicely with configurator, confirms TPS is working, temperature etc. Set up downloads from MJLJ to Configurator.

BUT, when cranking rpm gauge shows zero. I seem to recall that rpm gauge only works when engine is actually running - but I might be wrong.
But, if it is supposed to be showing rpm also whilst cranking - it seems I have no trigger. And that would narrow down things for me.

Post by **brentp** » Tue Nov 09, 2010 10:49 pm

The smallest RPM the megajolt can measure is about 450 RPMs- so it will typically not show RPMs on the on-screen RPM gauge ::while cranking::

Patriq · Post by **Patriq** » Wed Nov 10, 2010 8:02 am

Ok.

I turned on digital rpm gauge too, just to possible see any movement. But I guess it is around 300-400'ish whilst cranking.
Any other way to confirm that either EDIS or MJLJ is recieving trigger from the trigger sensor ?

I unplugged the cable coming from the sensor and confirmed that the sensor is generating small amount of AC when spinned. But, if the cable is somehow broken from that point and up to the EDIS unit I still wouldn't get spark.

So, any way of confirming that EDIS is recieving trigger ?

david_594 · Post by **david_594** » Tue Nov 23, 2010 6:02 pm

If you have the coil and wires connected, then just hook up your timing light quick and see if your getting spark.

Patriq · Post by **Patriq** » Tue Nov 23, 2010 7:40 pm

david_594 wrote:If you have the coil and wires connected, then just hook up your timing light quick and see if your getting spark.

No spark, that's why I'm trying to narrow down why. But is it the Edis Module, the trigger signal, the coil, or the HD leads......

NITROPIXIE · Post by **NITROPIXIE** » Wed Nov 24, 2010 9:18 pm

You maybe able to test the the signals between the EDIS and the coil pack by removing the coil pack and putting LED's (with protection resistors) in place. Then turn the engine over and confirm they flash off (it maybe just a flicker).

I have not tried this method and I'm not completely sure how successful this would be.

If it is not obvious then you may have to use an oscilloscope to fault find, if you can get access to one.

Post by **brentp** » Thu Nov 25, 2010 12:09 am

On top of the other suggestions, try reversing the connection to the VR sensor- it is polarized. If it is connected backwards, no spark will be generated.

Patriq · Post by **Patriq** » Thu Nov 25, 2010 9:14 am

brentp wrote:On top of the other suggestions, try reversing the connection to the VR sensor- it is polarized. If it is connected backwards, no spark will be generated.

Well, the installation have been running stable for quite a while. The car suddenly stopped, I'm trying to figure out why.

I've tried, and there is AC coming from the sensor up to a plug I have at the end of the sensor cable. Then there is the female plug to that plug connected to the EDIS harness. I there was a break in one of the leads from the plug up to the EDIS - it would not fire.

The MJLJ itself is running and registering TPS and engine temp. (but no rpm at crank as I initally mentioned)

I tried giving the engine startup-gas and cranked. Since it didn't fire on that I'm pretty sure there was no spark. (Although I haven't tried with a timing light yet) All plugs were clean at the moment I tried with startup-gas.

I've checked all other leads, including ground,to EDIS and coil - and they all seem intact and in place.

DannyP · Post by **DannyP** » Thu Nov 25, 2010 4:31 pm

Patriq, on my install I did a separately relayed and fused power supply for the coil, did you do the same? I know it is overkill(mine) but I did it anyway! Remove one fuse and the car is deader than dead!

Patriq · Post by **Patriq** » Thu Nov 25, 2010 6:51 pm

DannyP wrote:Patriq, on my install I did a separately relayed and fused power supply for the coil, did you do the same? I know it is overkill(mine) but I did it anyway! Remove one fuse and the car is deader than dead!

No, I took the old power lead (positive) for the coil as supply for both EDIS and MJLJ. Both ground at the same point, as well as the coil. So, there is a fuse for this supply - but the fuse is intact.

NITROPIXIE · Post by **NITROPIXIE** » Fri Nov 26, 2010 11:44 am

First of all take all the spark plugs out of the engine, rest them on the engine block, then turn the engine over and look for sparks. If there are sparks then the problem isn't ignition. If there are no sparks then obviously the problem lies here.

Then take the connectors off the edis and coil pack then continuity test the wires between the both connectors.

Also test your getting 12V (battery voltage) to the EDIS and coil pack.

Then test the earth of the EDIS connector and battery negative terminal.

Did you say you used the cars original coil power lead, is this resistive??? If not sure the only way to check is to use an Ohm meter across it.

The reason I ask you to test the continuity of the above is just to prove that everything is wired correctly and there aren't any obvious problems there.

If this doesn't throw up anything then suspect a component failure. The are a couple of basic tests you can perform on the coil pack to make sure it hasn't gone wibble. The EDIS will be a bit more challenging and may require an oscilloscope to properly test signal coming in and out.

Out of interest what spark plugs are you using?? Are they resistive??

Hope this helps

Ryan

Patriq · Post by **Patriq** » Sat Jan 01, 2011 5:31 pm

NITROPIXIE wrote:First of all take all the spark plugs out of the engine, rest them on the engine block, then turn the engine over and look for sparks. If there are sparks then the problem isn't ignition. If there are no sparks then obviously the problem lies here.

Then take the connectors off the edis and coil pack then continuity test the wires between the both connectors.

Also test your getting 12V (battery voltage) to the EDIS and coil pack.

Then test the earth of the EDIS connector and battery negative terminal.

Did you say you used the cars original coil power lead, is this resistive??? If not sure the only way to check is to use an Ohm meter across it.

Sorry for late respons. Got so much else to tend to. There is no spark when I turn engine over. No matter what way the VR-sensor is polarized, and as I've mentioned I'm getting AC from the sensor at the end of the sensor cable. Power leads are original EDIS ones that came with coil pack and EDIS-unit. I will recheck connectivity over the EDIS-coil pack cable, ground etc.

NITROPIXIE wrote:
The reason I ask you to test the continuity of the above is just to prove that everything is wired correctly and there aren't any obvious problems there.

If this doesn't throw up anything then suspect a component failure. The are a couple of basic tests you can perform on the coil pack to make sure it hasn't gone wibble. The EDIS will be a bit more challenging and may require an oscilloscope to properly test signal coming in and out.

Out of interest what spark plugs are you using?? Are they resistive??

Hope this helps

Ryan

Spark plugs are Golden Lodge 2HL's. It's the most frequently used for this motor type, although others off course are used. To be honest I don't know how resistive they are. But as I've mentioned the car has been running this setup stable for a while now.

Thanks again for splendid input. I shall continue checking, including all your other points above and report back.