GEMS - General Engine Management Systems Ltd - Forum

Good Morning All

We run a Group A Evo IX, the car has a Gems diff controller, engine ECU and CD35 display. Last year the car started to miss fire in the tarmac map, It sounds like it's dropped a cylinder, but was fine in all the other maps. Last week it started doing the same in the locked map.

Our tuner has looked at it with no success. We have changed the ACD switch, unplugged the Mitsu dash as well as the CD35, we have also unplugged the cable that links the diff controller to the engine ECU. None of these things make a difference. We also installed a new diff controller and had the same problem.

Any help or advise would be greatly appreciated.

Also the Tarmac light is on permanently no matter which map is selected.

Well, as the only thing you've not replaced is the ECU, it looks as if it may be causing or trying to rectify a problem. I am assuming no changes took place prior to this misfire manifesting itself..? Is it a regular misfire, gets worse with heat, any other notable factors..?

I would like to have a look at the calibrations for both the ECU and ACD if at all possible as it is nigh-on impossible to diagnose intermittent faults without them. Also, if you could arrange for a run and log pertinent data (coil charging, fuel PWs, sync data etc.) that is the usual material needed for a decent diagnosis. If you could send them to the Tech.Support (at) gems.co.uk email address, I will endeavour to take a look as soon as I am able.

Regards, Rick

Thank you for the quick reply Rick.

The miss is consistent, we have not driven it with the miss but engaging the map when the car is hot or cold gives the same symptoms.

No changes were made just before the symptoms appearing, it ran fine for one tarmac event and then started missing at stage start the following weekend. The miss on lock just started after an event.

I will try to get the information and will send it.

Thanks again.