Any stock OBD II ECM's that will drop into an obd l yj

[tequila mike]

Adjustable injector pulse width on OBD ll
My mechanic says he can do this.
I have an OBD I yj 4.5 manual tranny running lean/Aem afr gauge.
running 12.9 to 13.2 uphill wot
and 14.6 to 15.7 freeway wot
with map adjuster set at 5.4 v into map.
I think i read a late 1995 computer is OBDII but could not confirm this info.
What do you think?
Any help would be much appriciated.
M

[jsawduste]

OBD1 ran till 95 on YJ`s. Then the 96 up ran OBD 2 which is now a TJ.

Two different animals and not interchangeable.



Well you technically you could but it would`nt be worth it the hassle.

[tequila mike]

Thanks jsawduste
This is off a cherokee form i just found also.
2) 1996 was the "official" first year for OBD-II, but it was also a "changeover" year - I've run across some /very/ late 1995s that had OBD-II, and some /very/ early 1996 vehicles that had OBD-I (not specificially Jeeps, either.) 3) To switch to OBD-II would require a compatible control unit (4.0L/242ci w/manual transmission, sounds like) from 1996 and a wiring harness. Lookup to see what sensors, if any, changed between OBD-I and OBD-II as well - I don't recall offhand, and that notebook isnt' handy for me at the moment. You'd be in for a fair amount of work, and you'd really be better off if you had the entire donor vehicle to hand while you were working (and FSMs - Factory Service Manuals - for 1995 and 1996 model years.)

"Upgrading" your current PCM isn't really an option - not only is the PROM different (Programmable Read-Only Memory chip, the bit that stores all of your vehicle's information) in its programming, but the PCM logic and control bus are also different, making it rather different internally. The CAN Bus (Controller Area Network - how OBD-II runs information back and forth) is also not present in OBD-I, which means wiring changes as well. And, the instrument cluster is (I think) different - as OBD-II IPs (Instrument Panels) are driven by the CAN Bus instead of discrete individual sensor signals.

Yeah - it's going to be a fair amount of work. Not impossible, merely difficult.
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[jsawduste]

Mike, a quickie answer.

Before I went to OBD 2 for engine management I would choose one of the aftermarket systems that replaces the entire engine control system. Accel DFI comes to mind but there are others.

OBD 2 will require a different sensor arrangement. Also the IP harness as well.

The communications is (CAN BUS) is totally different. Another thing is that the ECM will always try to move any sensor settings back to factory parameter.

Like you said, it is doable but a lot of work and IMHO not worth it when you have other systems to work with.