Not firing on all cylinders. Motec M48

Hey Guys, this could be along one. a shortened version of events (back story)
-Replaced manifold with Speedster 8 stack injection
-installed self learning ecu (turnkey efi)
-installed MSD 8579 and Digital 6AL

when i tried to run the car it was only firing on around 4 cylinders (checked with heat gun on exhausts)
then after many different trial and errors decided to go back to the motec that was originally on the engine.
Now I've put it back to the scorpion distributor (HEI) and the motel back in it.
Figured that it should run (rough) with the existing tune but its doing the same thing. Although it seems to run on Cylinders 1,2,3,5,6 with cylinder 5 getting extremely hot compared to 4. cylinders 1, 2 and 3 are within a decent range but 4 is no where near running.

It has spark. it seems to have fuel (running really rich out of the exhaust) but I'm thinking it may be something to do with the butterfly adjustment. although even when opened they seem to stay the same temp.

Any ideas or direction would be appreciated or even someone has a 302 base map for the MOTEC m48 with a 302 windsor and 8 stack injection i would much appreciate it. I'm really at my wits end.

i also have some pics of the diagnostics that i will try to upload soon.

Thanks so much for your time
 
I had a similar problem . I put the firing order in for a 302 as what the engine i have ........ People told me to put the 351 firing order in and she ran sweet .. If you have a tuned cam this can happen ...worth a try ....
 

Bill Kearley

Supporter
Check your firing order. Old 302 is 15426378 and windsor is 13726548 looking from above the rotor turns anti clock wise. in both cases make sure NO 1 is on comp stroke to TDC
 

Randy V

Admin
Lifetime Supporter
Most sequential fuel injection systems index off of #1 cylinder. I know Ford’s is that way. If you wire #1 plug to the wrong tower, the efi system is all screwed up. It will run, but it will run very badly. Not sure how your system is set up, but take this information with you as you debug the system...
 

Cliff Beer

Supporter
Ditto checking the correct firing order.

Where are you getting your base timing signal from? The distributor, or a crank trigger?
 

Bill Kearley

Supporter
I think with that dist and box you have you have to set No1 at tdc on compression and with rotor at the number one terminal ( of your choice ) wire the cap in an anti clock direction wise using the proper firing order for your eng.
 
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Hey gents, the firing order is set to the 351 firing order being the 5.0. That’s all set correctly and checked multiple times. The base signal is coming from the distributor, it’s got 4 wires coming from it. I was going to use the msd8579 but it can’t do sequential with a crank signal. The distributor I have in there currently has the sync and ref signal in it. Do pardon my lack of knowledge. I’m still tying to learn about this efi stuff.
And a quick side note, the car is running Smokey from the I burnt fuel so we know it’s not running right, however when running and we open throttle bodies for 7 + 8 the car sounds a lot better but the pipes some seem to heat up enough either. Any ideas on the gap for the butterflies?
 
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Bill Kearley

Supporter
If you have a dual sync, mmmmmmmm. I am putting mine together as well and know nothing about it. Can you plug yours into a laptop, get on wifi and find a geek 14 year old to go on team view to look at the issue. ( Holly Hp, home made distributor and Borla 8 stack )
 

Randy V

Admin
Lifetime Supporter
Hey gents, the firing order is set to the 351 firing order being the 5.0. That’s all set correctly and checked multiple times. The base signal is coming from the distributor, it’s got 4 wires coming from it. I was going to use the msd8579 but it can’t do sequential with a crank signal. The distributor I have in there currently has the sync and ref signal in it. Do pardon my lack of knowledge. I’m still tying to learn about this efi stuff.
And a quick side note, the car is running Smokey from the I burnt fuel so we know it’s not running right, however when running and we open throttle bodies for 7 + 8 the car sounds a lot better but the pipes some seem to heat up enough either. Any ideas on the gap for the butterflies?
As long as #1 spark plug wire is in the position indicated by the distributor manufacturer, you should be okay from that perspective. If you are even 1 tower position off to the left or right, it will run like absolute crap (as you have described)..
The rest is in the grounding of the injector harness along with the ECU and that it is aware of the precise firing order..
Run a jumper wire from your injector harness ground to the ECU’s ground as a double-check..
If I had not already been bitten by these bugaboos, I would hold my tongue...
 

Bill Kearley

Supporter
I was just working on mine and had a thought. Check the red and blue wire loops that come out of your 6AL box and make sure they are not cut.
 

Ian Anderson

Lifetime Supporter
Supporter
Long shot but I remember about 10 years back and Paul Thompson was battling a Motec system.

The crank position sensor had been bumped and was now too far away from the toothed wheel resulting in it producing random TDC readings.

https://www.gt40s.com/members/p-thompson.10974/
https://www.gt40s.com/threads/help-engine-malfunction-need-advice.26446/
https://www.gt40s.com/threads/motec-engine-management.14471/#post-124560


Ok so 16 years ago ...... I need to get out more!

Ian
Haha that’s half my life ago, it doesn’t run a crank sensor. It’s all controlled by the dizzy i believe.
 
As long as #1 spark plug wire is in the position indicated by the distributor manufacturer, you should be okay from that perspective. If you are even 1 tower position off to the left or right, it will run like absolute crap (as you have described)..
The rest is in the grounding of the injector harness along with the ECU and that it is aware of the precise firing order..
Run a jumper wire from your injector harness ground to the ECU’s ground as a double-check..
If I had not already been bitten by these bugaboos, I would hold my tongue...
It is possible that the engine wasn’t exactly on tdc. There isn’t a good mark on the engine but I’ve found something I believe to be the correct markings. The dizzy was put in around 5 BTDC. The tower position is definitely correct though and the motel knows the correct firing order,

It could be the earth so will check that but I’d assume if the ea th wasn’t right I wouldn’t be getting the spark and fuel in it that I am getting. Will do this anyway as a precaution. I’m leaning to it being a tuning issue with the ITB’s. Maybe not getting the right air/fuel into the cylinders.
 

Cliff Beer

Supporter
Hey gents, the firing order is set to the 351 firing order being the 5.0. That’s all set correctly and checked multiple times. The base signal is coming from the distributor, it’s got 4 wires coming from it. I was going to use the msd8579 but it can’t do sequential with a crank signal. The distributor I have in there currently has the sync and ref signal in it. Do pardon my lack of knowledge. I’m still tying to learn about this efi stuff.
And a quick side note, the car is running Smokey from the I burnt fuel so we know it’s not running right, however when running and we open throttle bodies for 7 + 8 the car sounds a lot better but the pipes some seem to heat up enough either. Any ideas on the gap for the butterflies?
To ensure you have even air flow through the ITBs don't bother with gap....use a flow meter like a carb synchronizing air flow tool. Sync the ITBs at idle, and at part throttle.

Is your EFI self learning with an O2 sensor feedback loop? If yes, is your 02 sensor in a common chamber downstream or on just one individual cylinder pipe?
 
To ensure you have even air flow through the ITBs don't bother with gap....use a flow meter like a carb synchronizing air flow tool. Sync the ITBs at idle, and at part throttle.

Is your EFI self learning with an O2 sensor feedback loop? If yes, is your 02 sensor in a common chamber downstream or on just one individual cylinder pipe?
I will look into seeing if I can get the flow meter to test the itb's.

It was a self learning ECU and was batch injection. I thought that may have been causing the Initial problem and now I went back to the motec m48 that was running just a single throttle body. So in that respect nothing has changed apart from moving to the 8 itb's.
Also the 02 sensor reads cylinders 1 to 4 just after the collector. It shouldn't be a problem though as the car ran with it like that before as well.
 
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The ECU needs to be synchronised to the trigger angle of the dissy. I think M48 calls it CRIP angle or something. You really need to get a laptop on it to get the trigger synchronoising right.
You might get lucky and be able to rotate the dissy a little while the engine is running to find a sweet spot where it runs cleaner.
No good looking at throttle balance or AFR's until it runs properly.
 
The ECU needs to be synchronised to the trigger angle of the dissy. I think M48 calls it CRIP angle or something. You really need to get a laptop on it to get the trigger synchronoising right.
You might get lucky and be able to rotate the dissy a little while the engine is running to find a sweet spot where it runs cleaner.
No good looking at throttle balance or AFR's until it runs properly.
Thanks, I will get into it this week and see what I can come up with. Sounds like it could be a promising path to take.

But if this was the issue how come it was the same with the msd8579 and msd 6AL box? That's a different setup and was having the same symptoms.
 
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So If I have this correct, you initially started with Motec on a single TB setup (assume a 4bbl type) We are assuming it all ran sweetly in this configuration. You then changed to a self learning ECU and a different dissy with an MSD box on an ITB setup and have issues. Now you are reverting to the original motec and dissy on an ITB set up.

Has all the original motec wiring been reinstalled / connected correctly (per original) inclusive of grounds and power?

Has the TPS (throttle position sensor) on the ITB setup been calibrated in the Motec? A small change compared to where the single TB setting is will effect what the Motec sees as the actual throttle position and hence fueling, be it idle or any other position.

You said the the dissy is a dual sync (Ref / Sync) type. Is this what was in the original setup or was this changed as well? if it was changed, Is it hall effect or inductive? Motec will need to know. Also, if it was changed it is entirely probable the CRIP angle will now be different.

As noted earlier, has the CRIP angle (base timing angle) been set in the Motec or at least the original dissy positioned EXACTLY as it was in the original single TB arrangement.

It is assumed the dissy is a non advancing type? The Motec will do the ignition advance not the dissy. Very important that the dissy and motec are seeing the same timing.

Are the injectors connected in the correct firing order sequence?

Have the throttle blades been set so they are all fully closed in all TB's at a full closed position. Then, are they opening evenly via the cable linkage? (disregarding actual airflow at this stage until running reasonably well) Then, set idle stop screws so the blades are slightly open to help with just getting running / idling. Some of the cheaper ITB systems have very dodgy linkages that flex and / or are not consistent in the closed to open motion.

The ITB's will require different fueling and probably timing maps compared to the single TB. You should be ok with existing mapping to get it running reasonably at least but, it will require re tuning to suit the ITBs.

Just some thoughts for you.
 
So If I have this correct, you initially started with Motec on a single TB setup (assume a 4bbl type) We are assuming it all ran sweetly in this configuration. You then changed to a self learning ECU and a different dissy with an MSD box on an ITB setup and have issues. Now you are reverting to the original motec and dissy on an ITB set up.

This is correct.

Has all the original motec wiring been reinstalled / connected correctly (per original) inclusive of grounds and power?

As correct

Has the TPS (throttle position sensor) on the ITB setup been calibrated in the Motec? A small change compared to where the single TB setting is will effect what the Motec sees as the actual throttle position and hence fueling, be it idle or any other position.

Yes I've modified the old tps to fit the new setup and calibrated using the min and max on the software.

You said the the dissy is a dual sync (Ref / Sync) type. Is this what was in the original setup or was this changed as well? if it was changed, Is it hall effect or inductive? Motec will need to know. Also, if it was changed it is entirely probable the CRIP angle will now be different.

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? 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?

As noted earlier, has the CRIP angle (base timing angle) been set in the Motec or at least the original dissy positioned EXACTLY as it was in the original single TB arrangement.

This is most likely off but as per answer above not sure if it's the main problem.

It is assumed the dissy is a non advancing type? The Motec will do the ignition advance not the dissy. Very important that the dissy and motec are seeing the same timing.

However It is setup is how it ran on the car before.


Are the injectors connected in the correct firing order sequence?

All the Injector harness connections are labelled so should all be back in the same configuration.


Have the throttle blades been set so they are all fully closed in all TB's at a full closed position. Then, are they opening evenly via the cable linkage? (disregarding actual airflow at this stage until running reasonably well) Then, set idle stop screws so the blades are slightly open to help with just getting running / idling. Some of the cheaper ITB systems have very dodgy linkages that flex and / or are not consistent in the closed to open motion.

I've got a small gap currently (about the width as a piece of paper) will look at opening a bit more.

The ITB's will require different fueling and probably timing maps compared to the single TB. You should be ok with existing mapping to get it running reasonably at least but, it will require re tuning to suit the ITBs.

Yeah I was told by someone who does motec stuff it should still run ok on current setup and just to get it tuned later.

Just some thoughts for you.
 
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