Ignition timing control- sort of...

[mendelmax]

Hi guys.

There have been few discussions close to that, but lately I've got an idea I'd like to consult with you.

My situation is that I have everyday access to a high octane fuel (98-100 RON), but on the other hand, I'd like sometimes to travel to places that don't have such high octane gasoline.

Now the idea is- we can change the ignition timing by moving crankshaft position sensor. What if we drilled extra mounting holes on the tranny bell and put more sensors in- let's say one in the stock position, one 5* advanced, one 5* retarded. We could then make a dash mounted switch to choose which one do we want to use. In case of ping we could simply turn the jeep off, flip the switch and therefore retard the timing.

What do you guys think? Am I missing something at this point? Or is this a good idea?

[crustodd]

Hello,
If you're willing to invest the money, this is exactly what a UniChip will do. I have a '94 XJ with a 4.7 stroker. I have five positions on the UniChip I recently had installed. #1 is minus 3 degrees of timing with reduced fuel curve (it was to rich in open loop), #2 is plus 2 degrees timing, #3 is plus 4 degrees timing, # 4 is MINUS 5 degrees timing (is case I can only get 87 octane), # 5 is same as #1, but with 50% fuel added back in. It works well. Check for a local tuner that is installing these or call UniChip at their HQ's in the state of Oregon, USA.

[mendelmax]

The problem is that every pre-mapped chip is not too good to use in my region, since I have different fuels than you guys in US. For example AFAIK noone on this board uses propane, I can.

So, I believe I could make more power by remapping ECU on the dyno, but then I have to be able to somehow retard the spark, which stock ECU doesn't permit, and this is where my idea comes

[crustodd]

Hey Mendel,
I guess I didn't explain the UniChip. It is a custom install. The OBD II can be a plug-n-play, depending on the bolt-ons you might have, but my OBDI 4.7 was a custom tune. They use the dyno and road tuning from a laptop. I just ran about 3.5 gallons of 100 octane aviation fuel in my 20 gallon tank this weekend. I had the chip in the plus 4 degree setting. The torque was REALLY FAT! It'd stay in overdrive at less than 30 MPH, chuggin' right up hills, just easin' on the peddle. I think I got over 20 MPG, but I need to fill it back up to be sure. Off road in the sand, it JUST RIIIIPS! Climbs dunes easy, ran cool, very fun to drive.

[gradon]

I haven't gotten my unichip custom tuned yet, but the 2720021 that I have for the obd2 jeeps only has a two-position switch(thus only two maps to choose from). If all you're looking for is to retard timing and adjust fuel, get split second's ftc1.