Ok had megajolt running for a while now and recently the pip / saw wire melted underneath my manifold so i re soldered the wires and connected the shielding together and then heat shrink on top. Not sure if this has got anyhting to do with the problem but now at about 2k under load in 4th gear i get a slight misfire and i lose all revs for a sec or 2, alot longer than a normal misifre.
THis could also be linked to the problem but not sure. I have low compression on cylinder 1 and have a sound just before 2.5k which sounds like pinking which i cant get rid of but this could be a cracked / worn piston ring.
any help would be greatly appreciated.
thx
alex
misfire loss of revs prob!
Moderators: JeffC, rdoherty, stieg, brentp
Well it could be many things, but nothing strikes me that there is a MJLJ problem (famous last words!)...
You should never "lose all revs" as the EDIS should keep everything going even if the MJLJ stops working completely
You could still have a wiring problem - are you sure you checked everything at least four times after the repair? - but that's unlikely to show itself just under load at a certain rpm
TPS or MAP?
Does it rev well past 2000rpm otherwise?
Back to basic fault-finding I suggest:
- check the re-worked wiring for a fifth time, then check all the other wires
- in the garage, does the advance change with rpm (use a timing light to observe) - if so the MJLJ is probably OK
- go for a drive without the MJLJ connected - will be very flat but under light throttle you should be able to get a decent amount of revs. Does it misfire then?
- check the map is still OK via the computer - and make sure the rev limiter isn't at 2000rpm as well....
I'm afraid you need to do more things and tell us what you find...
I doubt the mechanical problems you describe would lead to losing all revs for a few seconds...
You should never "lose all revs" as the EDIS should keep everything going even if the MJLJ stops working completely
You could still have a wiring problem - are you sure you checked everything at least four times after the repair? - but that's unlikely to show itself just under load at a certain rpm
TPS or MAP?
Does it rev well past 2000rpm otherwise?
Back to basic fault-finding I suggest:
- check the re-worked wiring for a fifth time, then check all the other wires
- in the garage, does the advance change with rpm (use a timing light to observe) - if so the MJLJ is probably OK
- go for a drive without the MJLJ connected - will be very flat but under light throttle you should be able to get a decent amount of revs. Does it misfire then?
- check the map is still OK via the computer - and make sure the rev limiter isn't at 2000rpm as well....
I'm afraid you need to do more things and tell us what you find...
I doubt the mechanical problems you describe would lead to losing all revs for a few seconds...
More ideas:
- try doing a 'datalogging' session with the Configuration Software and re-create the situation where you mis-fire and lose revs. Do you see interruptions in RPM readings? RPM 'spikes' or unevenness?
So the noteworthy recent event is the shorted SAW/PIP wires. For the SAW signal, which is emitted from the MJLJ unit, this output is protected by a current limiting resistor, so shorting it should not cause any problems.
For the PIP line- if you are able to observe runtime activity using the software, then you can feel confident the PIP signal is working as should.
Did your engine problems occur precisely after you repaired the melted cable?
You mention 4th gear around 2000 RPM- I'm inferring that this happens when the engine is under a certain amount of load, more so than if you did the same, say, in 2nd gear. Is this correct?
Is your VR sensor bracket loose or has it shifted?
- try doing a 'datalogging' session with the Configuration Software and re-create the situation where you mis-fire and lose revs. Do you see interruptions in RPM readings? RPM 'spikes' or unevenness?
So the noteworthy recent event is the shorted SAW/PIP wires. For the SAW signal, which is emitted from the MJLJ unit, this output is protected by a current limiting resistor, so shorting it should not cause any problems.
For the PIP line- if you are able to observe runtime activity using the software, then you can feel confident the PIP signal is working as should.
Did your engine problems occur precisely after you repaired the melted cable?
You mention 4th gear around 2000 RPM- I'm inferring that this happens when the engine is under a certain amount of load, more so than if you did the same, say, in 2nd gear. Is this correct?
Is your VR sensor bracket loose or has it shifted?
the car does not seem to be running properly between 2-3k, the accelleration slows down and i can feel the car struggle a little bit. im pretty sure the sensor bracket hasnt moved, ill check again but it is a kad part not home made and is pretty tight. i checked trigger wheel and thats fine, but will check again. problems started a while back. car ran great for a few weeks then the trigger wheel managed to move itself 90 degrees one nite and the car died. i fixed that all and the car ran pretty good again for a few days and then i started to develop a misfire at around 3k. but i think this was because of the pip line which was flexing where it had melted and so the car was running on and off mjlj and edis. when i run edis the car misifres at around 3k all the time. i ran on dizzy today and there was no loss of revs at 2k, but am now 80% i have a cracked piston ring on number 1 cylinder and so from 2-3k the car struggles and as a result of the ring i am losing performance. i am having problem sussing the problem as mechanical faults seem to be happening at the same time. will check over everything again tomorrow
alex
alex