So their are many little issues with the MPI kit.

Some of the fixes are heavier or second throttle return spring to cut down on low speed surges with the sensative throttle.

Upping the fuel pressure
and having the dealership retard the timing through the copmputer. To stop the pinging.

Is it possible to do this timing adjustment yourself with one of those 150 to 300 dollar OBD II scanner thingies.

I figure for I might be able to get alot of use out of one of them scanner things.
I could get even more use out of it if I can retard the timing myself on my moms 89 YJ.

SO whats the deal?

the dealer "scanner thingies" are more like $2k, or about $500 on ebay, when they pop up. don't even think about buying one without the correct module for your Jeep. buying or even borrowing a module is like trying to find a cheesburger at a vegen convention. the OTC commercially available scanners (taht I know of) won't let you write to the ECU.
the pinging USUALLY happens on the 83-84 4.2L heads. really, for $300, a 4.0L head swap is the best soloution.

I have not found a tool that would write to the ECM but you can just mess with the way the computer perceives what is going on.

You could monkey the signal from the knock sensor to the ECM or you can physically reposition the crank position sensor on the bellhousing by a couple of degrees. I think there is actualy a high altitude semi adjustable crank position sensor that can be used for this purpose.

Now I forgot about that option.

Thanks

'Normal' OBDII scanners will not adjust anything, but they will read the data coming in real-time. Some also have a data-capture feature and PC link. I have the Auto Xray with the OBDII, Ford, and Chrysler cables & software. Pretty useful, but does not do what you'd need it to.

BTW, OBDII became a standard in 96, so your mom's 89 won't be able to interface with an OBDII only scanner. Some 1995 vehicles had it, but did not have to be fully compliant until 96.

Bryan