29 replies to this topic

[Wazzah]

 

 

Still haven't manage to get my ECU checked as we are still in lockdown. 

 

But when I start the car sometimes, it is ok with my current ECU. But sometimes it is running rough as no firing on lead 2 and 3.

 

 

Could this be a faulty crank sensor?

 

It will not be a faulty crank sensor as it is only effecting one side of your coil pack.

The MNE 101351 is a dual plug ECU.

The smaller plug has 3 wires coming out of it.

The 2 black ones are unused in your car.

There should be a single white wire with a silver trace.

It is in position 18 of the small plug and runs direct to the bosch junior plug under your coil pack.

Your fault lies somewhere in this single circuit.

Check this wire and it's plugs each end for good clean connection and continuity.

The bosch junior crimp connectors are a bit fragile.

I'd be tempted to pull the ECU out of its bracket, pull the little plug and test pin 18 out of the ECU whilst turning the starter over.

No signal would confirm an ECU fault.

Please attend to the simple non ECU things first.

If it is the ECU I may be able to assist in repairs.

I may have a spare MNE 101351 in the coming weeks if I finish my Haltech project.

Regards

Waz

 

 

I have checked the wiring seems all good. Then I have tried to remove the small plug from ecu and tested the pin 18 with test lamp seems no supply. Can this conclude the ECU at fault?

 

The engine still misfire with or without the small plug connected to ECU as well.

 

 

At least we've got to the root cause now.

Like me in Australia you won't have access to repairers in KL.

You could try David Ainsley in Japan for a replacement unit.

I had an open circuit on my ATS Pin 16 on the larger plug.

An internal dry solder onto the back of the pin tang.

Pulled mine apart and resoldered and has worked fine ever since.

Mine was a nightmare to get too being in the second row of Pins.

The MEMS ECU's have an internal amplifier on the coil circuits.

Either you have a dry solder connection or the amplifier is gone.

The coil wire in your Pin 18 on the small plug is on the bottom row of pins and easy to get to.

There are no other connections on this small plug.

Good luck.

[sonscar]

You probably know this and I do not want to cause any insult.The coilpack has a single 12v feed to both sides of the coil.This will be live when the ign is turned on and maybe only whilst cranking.If half of your coil sparks then it is reasonable to conclude that this is ok.The ECU sparks by earthing to charge the coil and disconnecting to fire it.It uses a system called "wasted spark" whereby it fires 1and4 then 2and 3 in pairs.Something affecting the 2and3 part of the circuit is faulty,If all the wiring is good then it is reasonable to suspect the ECU

I would remove the ECU and inspect the pin connected to 2and 3 and measure the resistance from the plug to the coil,comparing it to 1and4 and watching whilst moving the wiring.The coil driver transistor in the ECU may be failing.High resistance in the wiring and/or coil can increase the current it has to sink and lead to overheating and failure so it is important to verify the wiring.

Sorry to ramble,Steve..

[Wazzah]

You probably know this and I do not want to cause any insult.The coilpack has a single 12v feed to both sides of the coil.This will be live when the ign is turned on and maybe only whilst cranking.If half of your coil sparks then it is reasonable to conclude that this is ok.The ECU sparks by earthing to charge the coil and disconnecting to fire it.It uses a system called "wasted spark" whereby it fires 1and4 then 2and 3 in pairs.Something affecting the 2and3 part of the circuit is faulty,If all the wiring is good then it is reasonable to suspect the ECU

I would remove the ECU and inspect the pin connected to 2and 3 and measure the resistance from the plug to the coil,comparing it to 1and4 and watching whilst moving the wiring.The coil driver transistor in the ECU may be failing.High resistance in the wiring and/or coil can increase the current it has to sink and lead to overheating and failure so it is important to verify the wiring.

Sorry to ramble,Steve..

Hi Steve,

I had asked him to check continuity of his wiring in a previous post.

Assumed he had already.

Regards

Waz

[sonscar]

I noticed that you did but sometimes advice gets lost somewhere in the ether.I was confused by the engine still running with the coil power plug removed.I have no experience with SPI or MPI but I have wired several standalones onto old non EFI conversions.Electricity and EFI seem to be a magic art despite it being around now for decades.Just trying to be helpful,Regards Steve..

[mnr47]

I have tested the white silver wire from the ECU small plug end to the coil pack plug end, there is no breakage in the wire using a multimeter..

I tried to start the car with the small plug not connected to the ECU, the car starts and running without the coil 2&3 not firing..

I tried to start again with the small plug connected to ECU, the car still runs without the coil 2&3 firing..

That's when i used a test lamp, ground it to the block and while the car running without the small plug connected to ECU, i test the pin 18 of the small socket of ECU and notice there is no supply.. I assume the pin 18 should supply 12v and if the ECU is not faulty, the test lamp should light up..

Please correct me if I'm wrong as this is new to me..

[nicklouse]

Is this set up not wasted spark? 

[mnr47]

Is this set up not wasted spark?

It is wasted spark.

[nicklouse]

 

Is this set up not wasted spark?

It is wasted spark.

 

So if you swap the paired plugs over you get the same issue on 1 and 4?

Edited by nicklouse, 15 August 2021 - 06:18 PM.

[sonscar]

The ECU supplies earth to spark the coil.Steve..

[mnr47]

 

 

Is this set up not wasted spark?

It is wasted spark.

 

So if you swap the paired plugs over you get the same issue on 1 and 4?

 

 

Yes that is correct, I tried swap and same happen.

[mnr47]

The ECU supplies earth to spark the coil.Steve..

 

Means i cannot use the test lamp method as how I did to test as it will never light up as it supplies earth. right?

 

How can I test the ECU then? Sorry abit new here

[Wazzah]

I noticed that you did but sometimes advice gets lost somewhere in the ether.I was confused by the engine still running with the coil power plug removed.I have no experience with SPI or MPI but I have wired several standalones onto old non EFI conversions.Electricity and EFI seem to be a magic art despite it being around now for decades.Just trying to be helpful,Regards Steve..

Hey Steve, All good.

Been working on an ECU conversion and have just wired in a necessary ignition "igniter" between the new ECU and existing wasted spark coil pack.

The new ECU states that it cannot "drive" a coil pack which doesn't have an inbuilt igniter.

Our wasted spark coil pack does not have this and the MEMS literature states that the Rover ECU has a high output and amplifier to enable proper operation.

So much study for my 58 year old brain I think I misplaced how a coil actually works in a cupboard to the rear somewhere.

I think both ECU documents have got it around the wrong way.

Given your correct comment that the ECU earths each side of the coil pack alternatively I think it is better expressed that the Rover can accept a higher incoming current as it switches to earth.

Following on from that logic an 'igniter" is actually the opposite and "extinguishes" thus limiting the current switched internally to earth on my new ECU.

The ignition igniter is an unpowered device but requires a lead to ground to work.

I then assume that the Igniter has a couple of internal resistors that limit current flow back to the ECU.

You wait until I tell you about the stepper motor which is another head....f....ache.

Inputs, outputs, switched earths, switched positives, 4 wire conversions and sequences depending on polarities.

Regards Waz

[nicklouse]

 

 

 

Is this set up not wasted spark?

It is wasted spark.

 

So if you swap the paired plugs over you get the same issue on 1 and 4?

 

 

Yes that is correct, I tried swap and same happen.

 

What do you mean same happened? It failed on 1 and 4 or it failed on 2 and 3? And how did you test the result?

 

on line diagnosis has to be exact. 

[mnr47]

 

 

 

 

Is this set up not wasted spark?

It is wasted spark.

 

So if you swap the paired plugs over you get the same issue on 1 and 4?

 

 

Yes that is correct, I tried swap and same happen.

 

What do you mean same happened? It failed on 1 and 4 or it failed on 2 and 3? And how did you test the result?

 

on line diagnosis has to be exact. 

 

 

The same 2 & 3 failed. 

How I diagnosed: I start the car and while it is running, I pull the leads 1 by 1 and notice the difference in engine idling and also I ground the lead to the engine block and observe the spark. 

[nicklouse]

 

 

 

 

 

Is this set up not wasted spark?

It is wasted spark.

 

So if you swap the paired plugs over you get the same issue on 1 and 4?

 

 

Yes that is correct, I tried swap and same happen.

 

What do you mean same happened? It failed on 1 and 4 or it failed on 2 and 3? And how did you test the result?

 

on line diagnosis has to be exact. 

 

 

The same 2 & 3 failed. 

How I diagnosed: I start the car and while it is running, I pull the leads 1 by 1 and notice the difference in engine idling and also I ground the lead to the engine block and observe the spark. 

 

have you done a compression test?

 

what i am reading is that it is not an electrical issue.