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Discussion Starter · #1 ·
Hello friends,

After swapping a 6G72 3.0 petrol engine on a 2008 Mitsubishi Pajero Montero due to overheating of the former one,
I found myself in front a crank no start issue,

I checked all the ignition system and finally found out that always I had without cranking 4.97V on all 6 trigger wires coming from ECU 8631A527.
The other pins of the coils are normal (earth on pin#1, 12V on pin#3).
I assumed that the ECU was bad and bought another one (second hand), but the result with it is the same.

Here is the only fault code that appears on the engine ECU
U1102 ASC / TCL / ABS timeout / Not equipped

As you can see on the oscillograms opposite, with the ignition on and when cranking, the crankshaft sensor CH1 and the camshaft sensor CH2 are working well
but the control signal CH3 and CH4 of two coils taken randomly does does not react properly..

So I am wondering how can the second ecu behaves just like the first one and all of them be bad.
I called the seller of the ecu and he confirmed the ecu was ok and picked from a working car actually broken

Is the guy right and his ecu is correct
or is the ecu bad and need to be replaced
If the 2 ecus are correct why does all the 6 trigger wires signal behave like that and how to fix it

Regards
 

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Have you worked through the steps in the factory service manual? Some of them may not apply if your 2008 ECM is different, but I would think the crankshaft and camshaft sensors would generate the same signals.

The FSM is at tearstone.com, and section 13B describes the signals from the camshaft and crankshaft position sensors. Maybe that will help.

Something else I've run across is that the distributor reluctor wheel has to match what the ECM is expecting to see. In the 3g, 2000-2002 has a one-tooth reluctor wheel inside the distributor, and 2003+ has four teeth. The distributors look the same on the outside but they're not interchangeable.
 

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Discussion Starter · #3 ·
Have you worked through the steps in the factory service manual? Some of them may not apply if your 2008 ECM is different, but I would think the crankshaft and camshaft sensors would generate the same signals.

The FSM is at tearstone.com, and section 13B describes the signals from the camshaft and crankshaft position sensors. Maybe that will help.

Something else I've run across is that the distributor reluctor wheel has to match what the ECM is expecting to see. In the 3g, 2000-2002 has a one-tooth reluctor wheel inside the distributor, and 2003+ has four teeth. The distributors look the same on the outside but they're not interchangeable.
Thank very much

I will have a look at it.
In the meantime I had a look at the timing belt and found that the belt was injured and had jump one tooth (as you can see in the timing images attached).
Can you confirm that is enough to send bad or no signal to trigger wires for ignition coil and prevent the car from starting?
Regards
 

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The last time I let a shop do my TB change, I later found that one of the camshafts was off by one tooth. The ECM gave a P0300 code, but the engine ran very well. The only reason I knew there was a problem was the code.

I can't tell from your pic if the belt is off the mark. I draw a line on mine with a white paint pen to make it easier to see the alignment.
 

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Discussion Starter · #5 ·
Hello

It is the same thing I did.

I drawn the same lines on each camshaft and as you can see each cam is off by one tooth.
Here there is no DTC.
From the explanation your DTC p300 (misfire) it is not directly relevant to the timing but its just a consequence. No doubt that if my engine started it would display the same fault.

What I also learnt from the history of this car (before i was invited to solve the crank no start issue) is that after swapping the 6G72 engine the car started and ran for 3 to 4mn and stopped and from that point did no more start untl now.
The timing or TB have not bee checked or adjusted either by the mechanic.
I'm the one checking and observing this as probably the reason for the no signal, no signal to trigger the ignition coil leads.
 

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Discussion Starter · #6 ·
Hello,

I have adjusted the TB and i still have a crank no start issue.
Finally I thing that there is an inversion of the polarity of the signal coming out from CMP and CKP.

Look at the polarity of my signals and the one from the good timing CKP and CMP signal mitsubishi pajero I got from Good timing-CKP & CMP signal-Mitsubishi-Pajero 2006– | ROTKEE
If you look at it carefully you will notice that when the good timing CKP or CMP are up (at 5V) mines are at 0V and vise versa.
So I think finally here is the solution of this problem
Any comments?

Tomorrow I will try it and report the update.
 

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Discussion Starter · #7 ·
Hello folks

Finally I will first change CKP and CMP
and see the result

Any comments?

Regards
 

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Try replacing the ignition module. MD152999(please verify) !Please don't use any brand electronics, recommended are; transpo, beckarnley or used genuine
 

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Discussion Starter · #11 ·
Hello friends!

I replaced the CMP sensor with abrand new one
But the CKP and CMP waveforms are JUST the same.
I dont have the Mitshubishi specification ration between the 2 revolutions:

2 revolutions of CKP = 1 revolution of CMP

So the problem was not the CMP sensor
And I still dont have synchronisation in order to produice good trigger signal on the coils and start the engine!

I'm exhausted
Help please

Regards
 

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I know what the oscilloscope signals from the camshaft and crankshaft should look like, but I don't know how to interpret the waveform you're seeing.

However, my best guess is still a problem with the reluctor wheels on the crank or camshaft, because they send the trigger signal. For example, the crankshaft reluctor wheel is connected to the crankshaft sprocket with a roll pin. If that came loose, it would match your symptoms (engine ran ok for a while then stopped, and won't restart.)
 
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