Backfire using Speed Pro

[Jeff Rand]

Just converted from a sequential DFI to a speed pro. I also went from 72# to 83# injectors on my stage 1. I installed the Speed Pro and retained the jumper wire from the MAS to the Map. I received a 83# program from Jack Cotton via e-mail and had problems reading what he sent me (series of numbers and symbols). I installed the program anyway and checked the setup parameters which showed the crank ref. angle at 10 degrees and the firing order set at 165432. When I was online the spark advance showed 30 degrees with the key on. Tried to start the engine and it cranked for a few seconds then a loud backfire. I checked the spark plug wires (they were removed when I replaced the injectors) and the connections on the speed pro.
Any suggestions?
Thanks,
Jeff Rand

 

[TurboJim]

Cam sensor out of time?

Cranking PW might be a little low, low enough to cause a lean backfire?

I dont know what harness you used, but I got mine from PTE and I grab the MAP signal from under the dash, NOT from the MAF wire. You might verify yours is connected correctly. Also make sure you have the proper MAP selected (2 or 3 bar)

 

[vtec4gs]

on some of the honda 4 bangers, backfires is when the ign wires are switched for couple of the cylinders, when using programmable engine management, its sometimes due to wrong firing order.

not sure if this helps with your 6 cyl, but might throw some hints.

also, if ign timing at idle is too high she will also backfire... out the intake.

Greg

 

[Jeff Rand]

Found my problem to be the MSD DID-4 was in the off position. The DIS has a feature where you can place a switch on the gray wire with the other side to ground and this disables the sysyem. I am not sure why the engine would backfire with the gray wire grounded but it does.
Jeff