Not firing on all cylinders. Motec M48

#21
It is the same dissy that was in the car with the single throttle body. It has come out and gone back in so I would assume the crip angle has definitely changed. I'm aware it prob needs fixing but when I was running the self learning ecu and the 8579 (mag pick up) the crip angle wouldn't have played a part? Correct but for the Motec it will make a difference

Do the efi dissy's need to be put in a special way (the mag pickups) or do u just need to know which tower is at tdc for cylinder 1?
No special way but No1 dissy tower needs to be correct. Turn the motor over to TDC on No1 (compression) and use the tower in line with the rotor button for No1 cylinder. then place the other leads in firing order sequence counter clockwise from there.If there is a reference mark on the block and base of the dissy, then align them.Assuming there was a refence mark made before removal originally. If the marks are not correct try rotating the dissy each way a little until the motor smooths out. That will get the CRIP close but you still need to check with a timing light and with the Motec ignition locked at say 10degrees to set the correct CRIP value in Motec (or rotate the dissy until the timing corresponds to the locked value in Motec)

Another thought, did the original TB use MAP referencing for load via a vacuum port? if so do you have a good vacuum setup on the ITBs via a common port. You will also probably see a little less vacuum on an ITB setup as well.
 
#22
You probably want to clean or replace your spark plugs too if it has been as over fueled as mentioned. They are most likely well and truly fouled by now as well.
 

Ian Anderson

Member
Lifetime Supporter
#23
In my post 11 above, third link, have you run out of tuning time and need to send it back to the store to get it allowed again.

Ian
 
#24
In my post 11 above, third link, have you run out of tuning time and need to send it back to the store to get it allowed again.

Ian
I didn't know this was a thing. I'm not sure. Its allowing me access to it so id assume not. how does it calculate it and how much do you normally get?
 
#25
It is the same dissy that was in the car with the single throttle body. It has come out and gone back in so I would assume the crip angle has definitely changed. I'm aware it prob needs fixing but when I was running the self learning ecu and the 8579 (mag pick up) the crip angle wouldn't have played a part? Correct but for the Motec it will make a difference

Do the efi dissy's need to be put in a special way (the mag pickups) or do u just need to know which tower is at tdc for cylinder 1?
No special way but No1 dissy tower needs to be correct. Turn the motor over to TDC on No1 (compression) and use the tower in line with the rotor button for No1 cylinder. then place the other leads in firing order sequence counter clockwise from there.If there is a reference mark on the block and base of the dissy, then align them.Assuming there was a refence mark made before removal originally. If the marks are not correct try rotating the dissy each way a little until the motor smooths out. That will get the CRIP close but you still need to check with a timing light and with the Motec ignition locked at say 10degrees to set the correct CRIP value in Motec (or rotate the dissy until the timing corresponds to the locked value in Motec)

there is a reference mark on the block and I have the dizzy in at 10 deg btd. I've tested the injectors and they are all in the correct location. I will upload some pics I took of the software. the car is cold and off but it might show something I'm not seeing. in regards to the plugs I have been constantly removing and cleaning. I've done one oil change and will probably do another to be on the safe side.


Another thought, did the original TB use MAP referencing for load via a vacuum port? if so do you have a good vacuum setup on the ITBs via a common port. You will also probably see a little less vacuum on an ITB setup as well.
Yeah the other system was using the MAP which went straight to the ECU. Currently Ive got it running to the MAP sensor. From what I understand there is a plenum in the middle of them to allow vacuum but I'm not sure how efficient it is. I'm guessing it would be quite different compared to the old setup, will this make a big difference in the tune to cause the problem? running the old self learning system the plugs would get soaking wet and very black, the plugs the other day with motel system seemed a lot better. id say this is from having a tune already installed on it.
 
#27
The fuel mapping will be different if there is a big change in vac. Should still run, but either rich or lean depending on vac. Once running reasonably well you could globally trim the fuel table a bit to stop way over or under fueling until you get a proper tune.

In the original setup (with the single TB and Motec) was MAP or TPS being used for load sensing / fuel mapping? I ask because in the second image it says "TPS retune" in the file name at the top of the Motec screen.

The 20 degrees of base timing looks about right for idle with ITB's but the additional combined 10 degrees of trim looks a lot for a cold start. If the car ran nice previously then don't worry about it.

The dwell value looks high to me. It may be right for your coil (s) but I would have thought around 4.5mS would be plenty for most coils so as to not overheat / cook them.

I am also assuming "sync error status" on the Diagnostic page is only because the motor is not running.

Have you checked the timing with a timing light while the motor is running to check for alignment to Motec (with the ignition advance locked in Motec)?

In your first post you say "firing on 1,2,3,5,6". and "seems to have spark and fuel" - Are you getting spark at the non firing cylinders? You should in a dissy setup but have you checked? Pull the fuse on your fuel pump so when you crank the motor to check each cylinder you don't continually shoot fuel into the cylinders. It might save some time cleaning plugs and minimise fuel washing the bores too.....

Start from the basics. You have a Motec that is mapped. If it is timed correctly to the motor, has spark at all cylinders and has fuel, it should run. Maybe rich or lean, but it should run. That is so long as there are no failures in sensors or wiring broken, etc during the removal / refitment.
 
#29
The fuel mapping will be different if there is a big change in vac. Should still run, but either rich or lean depending on vac. Once running reasonably well you could globally trim the fuel table a bit to stop way over or under fueling until you get a proper tune.

In the original setup (with the single TB and Motec) was MAP or TPS being used for load sensing / fuel mapping? I ask because in the second image it says "TPS retune" in the file name at the top of the Motec screen.

Im not sure which one it is actually using however I did have to retune the TPS as its on a different mechanism to control it.


The 20 degrees of base timing looks about right for idle with ITB's but the additional combined 10 degrees of trim looks a lot for a cold start. If the car ran nice previously then don't worry about it.

Yeah it ran fine and I have not touched this setting yet


The dwell value looks high to me. It may be right for your coil (s) but I would have thought around 4.5mS would be plenty for most coils so as to not overheat / cook them.

Im not quite sure what dwell time is. (still new to this stuff but will definitely check it out with some research)


I am also assuming "sync error status" on the Diagnostic page is only because the motor is not running.

Yeah I thought this was a problem too however it turned out it was just the eco disconnected from the laptop :D


Have you checked the timing with a timing light while the motor is running to check for alignment to Motec (with the ignition advance locked in Motec)?

No I have not. next time I try to start the car I will check the timing to see.


In your first post you say "firing on 1,2,3,5,6". and "seems to have spark and fuel" - Are you getting spark at the non firing cylinders? You should in a dissy setup but have you checked? Pull the fuse on your fuel pump so when you crank the motor to check each cylinder you don't continually shoot fuel into the cylinders. It might save some time cleaning plugs and minimise fuel washing the bores too.....

Yes we are getting a spark on all the "non-working" Cylinders


Start from the basics. You have a Motec that is mapped. If it is timed correctly to the motor, has spark at all cylinders and has fuel, it should run. Maybe rich or lean, but it should run. That is so long as there are no failures in sensors or wiring broken, etc during the removal / refitment.

yeah it seems the next step is to check the timing out and to see if there are any air leaks. Will keep you updated with the next symptoms/successes!
 
#30
Something else while I think of it, (unrelated to the cylinders not firing) but, when you changed to the new IR manifold, are you re-using the injectors used in the single TB injection system?

If not, are they the same flow capacity and the same electrical resistance? If different, the resistance value will need to be changed in the Motec software and you could also do a global fuel % trim to suit the injectors if there is a difference as well.
 
#31
Something else while I think of it, (unrelated to the cylinders not firing) but, when you changed to the new IR manifold, are you re-using the injectors used in the single TB injection system?

If not, are they the same flow capacity and the same electrical resistance? If different, the resistance value will need to be changed in the Motec software and you could also do a global fuel % trim to suit the injectors if there is a difference as well.
Hey mate, yeah all the same Injectors so that shouldn't be the problem.
 
#32
So looks like I'm caving and going back to the original single throttle body setup for now. Tried running again today with a fair few adjustments on tune. The dizzy was out and we put it back in at TDC. This time cylinders were:
1 warm/hot
2 hot
3 hot
4 warm/hot
5 hot
6 cold
7cold
8 cold

Whether this has something to do with the dizzy placement or not I'm not sure. Increasing the fuel pressure helped a bit by making the first 6 hot and warm but 7 and 8 remained cold.
 

Terry Oxandale

Skinny Man
GT40s Supporter
#37
I may be having a similar problem, maybe. Running 8 stack, and have checked ignition and injection (Noid lights and moving the injectors around), and all are working properly, in time, and in proper sequence, and valving is all proper and to specs. Yet have two cylinders that run cool (header tubes cool or just slightly warm). Further review indicates that the butterflies on those ITBs are closed more than the other 6 (barely perceptible), and appears to be verified by the observation that once I get off idle, into part throttle, those cool tubes get as hot as the other tubes. I've thought about drilling pin-holes in the butterflies, and then allow them to close completely, but am concerned that they may get sticky if I do that (plates wedging into the bores of the ITBs).

One other issue I also had on my self-learning system was a lot of backfiring at one time, which was progressively getting worse. Just out of curiosity I went to open loop to see what would happen (I felt I had the AFR pretty close to right by that time), and the backfiring disappeared. From that point on I manually adjusted the AFR, based on the wide-band readings.
 
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#40
Mitchel, what's the status?
I'm curious what the problem was.
I have a similar problem, which I am planning to make it my winter project.
 
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