Megajolt backfire

benno1275 · Post by **benno1275** » Mon Jul 11, 2011 8:03 pm

So I have been running a megajolt v4 for a couple of months now and to start with it was great.
but just recently I have been getting all sorts of bother anyway to start with I had the car rolling roaded and it all set up perfect couple of weeks went by and I had a hesitation at about 2700rpm and the engine wouldnt rev any higher than that, so after a bit of playing with some maps I ended up having to increase the degrees by 10 which made the engine run perfect. Now here's the weird part intermittently it goes into a mode where the engine backfires through the exhaust when rpm's are around the 3100 mark and the load just dies I have tried different edis units and cranks sensors. Can anyone else shed some light to what else it could be? Thanks

Post by **brentp** » Tue Jul 12, 2011 12:52 am

You might want to check the design of your crank sensor mounting bracket. it has to be extremely rigid or the EDIS module will lose sync with the trigger wheel and cause misfiring.

Also, check the gap and runout between trigger wheel and sensor. Sould be 1mm nominal.

benno1275 · Post by **benno1275** » Tue Jul 12, 2011 6:32 am

I have checked for any play In the crank sensor and can confirm that it is all rigid and that the gap is 1mm away from the trigger wheel. I also did a data log last night when I put my foot down and got to high ish revs 3500-4000rpm the car holds back and I see on the data log that kpa drops to around 15kpa causing it to backfire.

Post by **brentp** » Tue Jul 12, 2011 3:39 pm

Thanks for the update. So when you put the foot down the measured manifold pressure drops (more vacuum)? Where do you have your MAP sensor attached?