Compression query
Discussion
Really ? I'll certainly look into that !
If I could carry out some basic tests , that would be great , but I'm hoping to find a problem in one of the conductors which carries the trigger signal between the LT coil and the PCM.
I understand that certain resistance tests are not possible when using a multimeter to test electronics due to the amount of current applied by the meter , so I guess I'll have to do some research beforehand !
If I could carry out some basic tests , that would be great , but I'm hoping to find a problem in one of the conductors which carries the trigger signal between the LT coil and the PCM.
I understand that certain resistance tests are not possible when using a multimeter to test electronics due to the amount of current applied by the meter , so I guess I'll have to do some research beforehand !
Mark Hulme said:
I was wondering whether the fact that each wasted spark ( TDC on the exhaust stroke ) is reverse polarity would make a difference .
I don't know if these testers only work with the HT current flowing in the conventional direction.
I think I've heard of everything now!I don't know if these testers only work with the HT current flowing in the conventional direction.
I have now removed the ECU from the car and carried out some very basic circuit tests.
I identified the two pulse wires which run from the coil connector to the ECU (BK/GN and BK/OG ) which earth out the primary coil when required .
Having disconnected the 60 pin connector block from the ECU , I connected the two pin sockets for the two coil wires with a paper clip so I could conduct the test from the engine bay .
I disconnected the wiring block at the coil and put 12V from the (disconnected) battery on one wire and ran my circuit tester between the other wire and earth.
The test lamp lit , proving a complete circuit through the two wires.
I also tried slightly pulling and wiggling the wires where they enter the connector block but the tester lamp shone without any flickering , so my guess is that they are sound .
My next step now , I guess , is to get the ECU tested ,
Incidentally , I read that a fault code which puts an engine into ‘limp mode’ needs to be deleted from the ECU memory before the engine will return to normal , EVEN if the problem which caused the fault has been rectified ! I wondered if this could apply to my problem ?
Thanks in anticipation guys !
I identified the two pulse wires which run from the coil connector to the ECU (BK/GN and BK/OG ) which earth out the primary coil when required .
Having disconnected the 60 pin connector block from the ECU , I connected the two pin sockets for the two coil wires with a paper clip so I could conduct the test from the engine bay .
I disconnected the wiring block at the coil and put 12V from the (disconnected) battery on one wire and ran my circuit tester between the other wire and earth.
The test lamp lit , proving a complete circuit through the two wires.
I also tried slightly pulling and wiggling the wires where they enter the connector block but the tester lamp shone without any flickering , so my guess is that they are sound .
My next step now , I guess , is to get the ECU tested ,
Incidentally , I read that a fault code which puts an engine into ‘limp mode’ needs to be deleted from the ECU memory before the engine will return to normal , EVEN if the problem which caused the fault has been rectified ! I wondered if this could apply to my problem ?
Thanks in anticipation guys !
I can't see it being the ECU from what you say, if you have a spark the ECU output is more than likely correct, have you tried re-doing your spark test to see that what you saw isn't just a slight issue between the "testers"?
There could just be slight differences that make the sparks look better on one than another, do the test & then re-do it with the testers in different positions.
A simple & quick test that COULD mean you don't need to do the ECU.
There could just be slight differences that make the sparks look better on one than another, do the test & then re-do it with the testers in different positions.
A simple & quick test that COULD mean you don't need to do the ECU.
Well , with my ignition set up , inside the coil block is a primary coil and two secondary coils.
The primary coil has a conductor at each end which is connected to the ECU.
Depending on which conductor the ECU earths out , the HT is induced in the coil on that particular side. Each secondary coil is responsible for two spark plugs , 1 and 4 , and 2 and 3 .Each pair of plugs fire simultaneously . One cylinder will be at TDC on compression and the other , on exhaust, (wasted spark principal)
Having tested the ignition system from the plugs right back to the ECU several times , and finding that the two plugs affected are controlled by the same coil , I believe that the ECU is failing to earth down the LT on one side of the coil.
The primary coil has a conductor at each end which is connected to the ECU.
Depending on which conductor the ECU earths out , the HT is induced in the coil on that particular side. Each secondary coil is responsible for two spark plugs , 1 and 4 , and 2 and 3 .Each pair of plugs fire simultaneously . One cylinder will be at TDC on compression and the other , on exhaust, (wasted spark principal)
Having tested the ignition system from the plugs right back to the ECU several times , and finding that the two plugs affected are controlled by the same coil , I believe that the ECU is failing to earth down the LT on one side of the coil.
It's plausible, but if that was me I'd like to confirm that theory before spending potentially a lot of money repairing the ECU.
If you can exchange the connection between the two wires from the ECU to the coil LT circuit and then swap over the corresponding pairs of HT leads at the coil, if your theory is correct then the problem will still affect the same cylinders.
You could exchange the connection either by backing the terminals out of the connector housing and putting them back in the other positions, or using separate wires to make the connection between those terminals and the coil.
If you can exchange the connection between the two wires from the ECU to the coil LT circuit and then swap over the corresponding pairs of HT leads at the coil, if your theory is correct then the problem will still affect the same cylinders.
You could exchange the connection either by backing the terminals out of the connector housing and putting them back in the other positions, or using separate wires to make the connection between those terminals and the coil.
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