Megajolt loosing spark!
Turbo Mini Forums

I have just put my engine back together and had it driving fine last week. It was running rich but i seem to have sorted this by redoing my choke seals and resetting the fuel pressure.

The problem i have now is that i seem to be loosing my spark just as i come onto boost. The car revs ok when no boost is created.

I have checked to make sure i have power to the megajolt unit, edis and coil pack when it misfires which it has. I can see this as the timing light stops working. I have removed my Vr sensor and cleaned the plug out as well as checking the gap to the trigger wheel.

Ive cleaned and gapped all the plugs.

When the misfire occurs the megajolt software goes to 0 and the rev counter drops to zero. The car starts to run when the revs drop back down and will misfire again just as it comes back upto boost.

Does anybody have any ideas as im abit lost? Also is there any way of checking the coil pack, edis and Vr sensor with a multimeter?

Cheers Ron

if the rpm in the megajolt sotware is going to 0 that points to the VR sensor.

does the MAP drop or just the rpm? if so the jolt is probably loosing power from the batery.

have you checked all of your power connections and earth's

You havent accidentally changed the rev limit setting in the software have you?

I have checked the powers and earths and they seem to be ok and holding when i have the missfire. If you look at the table where you edit the map it drops to the lowest value. However i didnt look at the rev counter on the megajolt software.

I dont understand why it will run fine until the point the engine starts to make boost.

I have removed the hardcut unit and set the rev limit at 10000rpm.

Edited by Star Mag on 19th Apr, 2009.

I had the same issue it dropping to 0. the consensus was:

loosing connection with the sensor:

-So the gap is too big to the trigger wheel

-or in my case there was noise on the line. I had used the very very expensive shielded wire but. I had wired the shield at the edis end to the earth (All earthed star'd so back to the same point) at the sensor end the RR had connected the shield to the neg side of the sensor, I removed this and connected the shield to the body so back to earth. Never had a problem since.

Edited by gr4h4m on 19th Apr, 2009.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

The sensor position hasn't moved and it's been working for about two years. Although I did check it. Where did you get your sheilded cable from?

sent you a PM but it was from my local RR.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I have sorted my Megajolt problem after a lot of head scratching!

I started by getting some new shielded cable from Maplin and routed the cable so it was no where near my battery cable. I also changed the vr sensor for a new one. This did seem to smooth the running but it didnt cure the problem.

I then tried swapping the coil pack but this also had no effect, i knew that the plugs and leads were good as these were replaced when the engine was rebuilt.

I then moved onto the edis checking the plug and earthing points. I swapped the edis and this cured my problem.

The car has now done its run in period and i have now started to wind the boost up. A big thank you goes to Paul S who kindly let me borrow a edis and coil pack at very short notice and gave me a tour of his many projects!

I cant wait to see the miglia go down the strip