Hello all. A mate and I have a problem with plugs on our A-Series engines.
I run a 998 which is supercharged and friend has a 1275 on a 45. You will be driving along and it will cut out the rev counter will drop to 0 on the screen the MJ programme will freeze, the engine looses all power its like hitting a brick wall. This also happens when you have the mj unplugged so on limp home. you can rev it on the drive but under load you get this problem.
If you change the plugs the car returns to normal. You can get away with closing the gap on the plug. so far we have tried 6 and 7 NGK's, NGK Iridium (Lasted about 400 miles) and I have just put i some Bosh super 4's. This exact same thing is happening on my mates NA engine so its not a supercharger thing. We are using different types of brackets, Vr sensors and both have v high quality shielded twisted wiring, plus it stops if you change the plugs....
Anyone had issues with plugs?
Thanks for any help
MJ A series Spark plugs
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Spockie-Tech
- Posts: 152
- Joined: Wed Jan 02, 2008 12:52 pm
- Location: Melbourne, Australia
You might be chasing a red herring with the plugs.
While there is a "reflected impedance" characteristic that will affect the coil primaries according to the plug gap, I cant offhand think of any reason why that would cause the EDIS to shut down.
What coil packs are you using ?
Have you monitored the 12v power feed to the EDIS module and made sure its voltage isnt sagging under load ? Try turning all the accessories on, headlights, wipers, fans etc and see if that affects when the problem occurs.
Watch the VR sensor signal (with a scope if possible, a multimeter if thats all you have available) to ensure you are getting a good trigger signal.
What are the common factors between your mates install and yours ?
Same trigger wheels, power and ground attachment points, coil packs ?
When/How does it "recover" and start firing again ? When the revs drop ? Back off the accelerator ?
As the load on the engine increases, the cylinder pressure increases, meaning the coils have to reach a higher voltage before the plug fires.. Is there anywhere that the High Volltage could be leaking back into the primary side ? Plug wires arent too close to the coilpack wires or anything like that ?
Thats all I can think of to start with. EDIS in limp home is pretty simple...
While there is a "reflected impedance" characteristic that will affect the coil primaries according to the plug gap, I cant offhand think of any reason why that would cause the EDIS to shut down.
What coil packs are you using ?
Have you monitored the 12v power feed to the EDIS module and made sure its voltage isnt sagging under load ? Try turning all the accessories on, headlights, wipers, fans etc and see if that affects when the problem occurs.
Watch the VR sensor signal (with a scope if possible, a multimeter if thats all you have available) to ensure you are getting a good trigger signal.
What are the common factors between your mates install and yours ?
Same trigger wheels, power and ground attachment points, coil packs ?
When/How does it "recover" and start firing again ? When the revs drop ? Back off the accelerator ?
As the load on the engine increases, the cylinder pressure increases, meaning the coils have to reach a higher voltage before the plug fires.. Is there anywhere that the High Volltage could be leaking back into the primary side ? Plug wires arent too close to the coilpack wires or anything like that ?
Thats all I can think of to start with. EDIS in limp home is pretty simple...
Thanks for the reply.
The two cars both run the following the same:
MJ 4 fully built units we didn't make them
Wiring harness (Both made by me) We used shielded cable from the Rolling Road place very high quality he uses it on all of the management installs he does.
The fault appears at about 3500-4000 when you demand full throttle on both cars. I has appeared twice on my car once during the rolling road setup where the car was switched to iridium plugs which seem to solve it. We have both tried different sensors EDIS units and coil packs. We have different types of Ford sensors, Ford coil packs, mounting brackets, and trigger wheels. We got replacement coil packs, sensors and EDIS units, all swapped to no avail.
When we have had the issue I have driven my car slowly to halfords swapped the plugs in the car park and then nailed it out and its been fine to 5700 rpm where it hits the limiter, my mates revs to 6800 where it hits the limiter, so its not like we have never had it working.
The cars are a 68/69 mini's with no extra electrics up until MJ we have been running Dynamo's 22Amp. We both upgraded to 45A alternators with no extra load expect the MJ to ensure we don't get any dips in power. as it happens both faults occurred in day light hours so no lights, heaters etc.
On the tests you mention what should the voltages be?
The only other thing I can think of is the RR operator when he had mine on the rollers and was trying to sort the issue connected the shield to the neg wire on the sensor end, which wasn't on the diag when I made the harness. at the EDIS end its to the ground (All grounds are mounted to the same place). But as I say i did 400 miles on the irdium plugs a lot of which were on open roads with some full throttle action.
I will check the Firmware versions tonight.
I have just checked I'm running 4.0.2
Config Software 4.0.1
Thanks for any help
Graham
The two cars both run the following the same:
MJ 4 fully built units we didn't make them
Wiring harness (Both made by me) We used shielded cable from the Rolling Road place very high quality he uses it on all of the management installs he does.
The fault appears at about 3500-4000 when you demand full throttle on both cars. I has appeared twice on my car once during the rolling road setup where the car was switched to iridium plugs which seem to solve it. We have both tried different sensors EDIS units and coil packs. We have different types of Ford sensors, Ford coil packs, mounting brackets, and trigger wheels. We got replacement coil packs, sensors and EDIS units, all swapped to no avail.
When we have had the issue I have driven my car slowly to halfords swapped the plugs in the car park and then nailed it out and its been fine to 5700 rpm where it hits the limiter, my mates revs to 6800 where it hits the limiter, so its not like we have never had it working.
The cars are a 68/69 mini's with no extra electrics up until MJ we have been running Dynamo's 22Amp. We both upgraded to 45A alternators with no extra load expect the MJ to ensure we don't get any dips in power. as it happens both faults occurred in day light hours so no lights, heaters etc.
On the tests you mention what should the voltages be?
The only other thing I can think of is the RR operator when he had mine on the rollers and was trying to sort the issue connected the shield to the neg wire on the sensor end, which wasn't on the diag when I made the harness. at the EDIS end its to the ground (All grounds are mounted to the same place). But as I say i did 400 miles on the irdium plugs a lot of which were on open roads with some full throttle action.
I will check the Firmware versions tonight.
I have just checked I'm running 4.0.2
Config Software 4.0.1
Thanks for any help
Graham
Been researching installing a Meagjolt and came across some plug info:
http://www.alfabb.com/bb/forums/engine- ... -2l-2.html
post #23 says,,,,,,,"I use BP6ES with 52 thou gaps. I'm told that I should be running the BPR's because the resistance helps prevent
back spikes from resetting the ECU but I haven't had any problems so far."
http://www.alfabb.com/bb/forums/engine- ... -2l-2.html
post #23 says,,,,,,,"I use BP6ES with 52 thou gaps. I'm told that I should be running the BPR's because the resistance helps prevent
back spikes from resetting the ECU but I haven't had any problems so far."
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Spockie-Tech
- Posts: 152
- Joined: Wed Jan 02, 2008 12:52 pm
- Location: Melbourne, Australia
The voltage to watch is the 12v supply voltage to the EDIS and the coil pack.
I dont know what the EDIS's lower operating limit is, but if it dips below 12v while the engine is running, that would be a potential problem.
If lowering the plug gap or installing new plugs fixes it for a while, that sounds like its a high-tension interference problem.
As the plugs age, or the gap increases, the voltage reached by the coils to fire the plugs will go up - perhaps at some point with the increasing voltage, you are getting an insulation breakdown somewhere and its getting noise into the low tension EDIS side, which would no doubt upset the Edis and probably cause it reset.
The firing voltage goes up with increasing cylinder pressure as well, which is probably why the symptoms only occur at full-throttle.
Have you tried different plug leads, and routing them a different way ?
Keep them well away from all other wiring.
I put a "Trick" Jacobs ignition system on my Charger once (CDI computer, fancy "variable reluctance" coil and silicon leads) and was having all sorts of strange ignition woes. Went around in circles for a while, until I happened to pop the hood late at night and saw this funky blue glow (corona discharge ?) along the plug leads in the dark. Changed the leads and the glow and the problems went away - the leads were only a few weeks old !
I dont know what the EDIS's lower operating limit is, but if it dips below 12v while the engine is running, that would be a potential problem.
If lowering the plug gap or installing new plugs fixes it for a while, that sounds like its a high-tension interference problem.
As the plugs age, or the gap increases, the voltage reached by the coils to fire the plugs will go up - perhaps at some point with the increasing voltage, you are getting an insulation breakdown somewhere and its getting noise into the low tension EDIS side, which would no doubt upset the Edis and probably cause it reset.
The firing voltage goes up with increasing cylinder pressure as well, which is probably why the symptoms only occur at full-throttle.
Have you tried different plug leads, and routing them a different way ?
Keep them well away from all other wiring.
I put a "Trick" Jacobs ignition system on my Charger once (CDI computer, fancy "variable reluctance" coil and silicon leads) and was having all sorts of strange ignition woes. Went around in circles for a while, until I happened to pop the hood late at night and saw this funky blue glow (corona discharge ?) along the plug leads in the dark. Changed the leads and the glow and the problems went away - the leads were only a few weeks old !
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Spockie-Tech
- Posts: 152
- Joined: Wed Jan 02, 2008 12:52 pm
- Location: Melbourne, Australia
well I have been looking at all sort. I started with the plugs and checked the resistance, which according to NGK should be 5 ohms, we got higher reading from newer plugs, 4.2 - 4.9 the new bosh plugs are 5.0 - 6.1 so I tried pairing them but again I think this was just leading us down the wrong way.
I looked at the common factors again and then re-looked at the wiring as I had made both looms..
The VR sensor wire that I connected had the shield connected to the ground wire at the EDIS end but the RR had connected the shield to the neg sensor wire at the sensor end. I have disconnected the shield at the sensor end and run a wire from the shield back to the earth of the car.
I have put the plugs back in in matched pairs, not to stop the problem but to try and show it up. I have the car on about 20-30miles of driving yesterday night. on full boost, light driving etc and it never missed a beat... so it needs more testing. I made the change to the other car which shows the problem more than mine and we will have to see.
The thing that's puzzling me is if we were getting noise on the line but we have had the cars running fine why wouldn't it do it all of the time? or why when we switch the car off and kill the power to the mj wouldn't it re-set? not that I care if it all works ok from now
I looked at the common factors again and then re-looked at the wiring as I had made both looms..
The VR sensor wire that I connected had the shield connected to the ground wire at the EDIS end but the RR had connected the shield to the neg sensor wire at the sensor end. I have disconnected the shield at the sensor end and run a wire from the shield back to the earth of the car.
I have put the plugs back in in matched pairs, not to stop the problem but to try and show it up. I have the car on about 20-30miles of driving yesterday night. on full boost, light driving etc and it never missed a beat... so it needs more testing. I made the change to the other car which shows the problem more than mine and we will have to see.
The thing that's puzzling me is if we were getting noise on the line but we have had the cars running fine why wouldn't it do it all of the time? or why when we switch the car off and kill the power to the mj wouldn't it re-set? not that I care if it all works ok from now
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Spockie-Tech
- Posts: 152
- Joined: Wed Jan 02, 2008 12:52 pm
- Location: Melbourne, Australia
It would depend on what the source of the noise was.
As i mentioned, *if* the noise source was the high tension from the coil/lead/plugs, then the noise will vary according to the engine load. As the cylinder compression pressure goes up - when you reach peak torque and full throttle - then the plug hits a higher voltage before it sparks.. which would likely increase the radiated noise level from the HT circuit.
So it would make sense that the symptoms only occur at times of maximum stress on the ignition
How the EDIS copes with noise and how it resets or shuts down I dont know.. I would assume that Ford would have designed a fair level of high voltage protection into the unit given its application, but exactly what that protection would do and how quickly it would clear after copping a zap is unknown. Overvoltage can throw electronics into all sorts of weird states ("latch-up", "avalanche breakdown" and other semiconductor arcanery..
Anyway I'm glad it seems fixed..
As i mentioned, *if* the noise source was the high tension from the coil/lead/plugs, then the noise will vary according to the engine load. As the cylinder compression pressure goes up - when you reach peak torque and full throttle - then the plug hits a higher voltage before it sparks.. which would likely increase the radiated noise level from the HT circuit.
So it would make sense that the symptoms only occur at times of maximum stress on the ignition
How the EDIS copes with noise and how it resets or shuts down I dont know.. I would assume that Ford would have designed a fair level of high voltage protection into the unit given its application, but exactly what that protection would do and how quickly it would clear after copping a zap is unknown. Overvoltage can throw electronics into all sorts of weird states ("latch-up", "avalanche breakdown" and other semiconductor arcanery..
Anyway I'm glad it seems fixed..
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Rich in Vancouver
- Posts: 13
- Joined: Fri Mar 06, 2009 9:04 pm
- Location: West Coast of Canada
Anything new? Have you sorted out your problem?
I am running MJ on a blown B-series engine so am very keen to see how similar engines perform
What did you finally settle on for a points gap? I have been running BP7RE3 at .025 with no problems but want to try a larger gap for the fatter spark.
I am thinking .035 for a starting point.
Cheers,
Rch
I am running MJ on a blown B-series engine so am very keen to see how similar engines perform
What did you finally settle on for a points gap? I have been running BP7RE3 at .025 with no problems but want to try a larger gap for the fatter spark.
I am thinking .035 for a starting point.
Cheers,
Rch