Automatic - Manual Conversion = Running Lean?

[ciscobird]

The A4LD gave up its ghost so I decided it was time to do the M5OD conversion. Before the conversion, I would warm up and run the 3.0 engine once in every while during 3-4 months between the time it broke down and when I was ready to pull the tranny off with no apparent negative effects.

However, once everything was hooked up and ready after 3 months, the engine would start up fine but after 5-10 minutes of idling steam/smoke (not exhaust gases) would start emitting off both sides of the y-pipe causing me to become alarmed and shut the engine.

I checked and adjusted the timing (it was firing at 20 deg BTDC after the conversion, it's back at 10 deg) but it still is giving off light smoke off the surface of the y-pipe. It makes me think that it's running lean because if it was too rich, the catalytic converter would turn cherry red like it once did many years ago before I had injectors cleared and cleaned.

I have yet to drive it around in fear of destroying the engine.

I thought about swapping out the ignition coil but found that it's the same for both automatic and manual models so that leaves the ECM/PCM.

Would swapping out the automatic ECM/PCM to the manual model help or am I just overreacting/over analyzing?

I thought about the old fuel, maybe it was causing to run lean but it was running ok when I warmed up the engine occasionally before the conversion. Also, I added a bottle of fuel cleaner along with a couple gallons of premium fuel (the tank was holding 85-octane when it broke down on me in the middle of Arizona desert last summer).

(Haven't filled out my signature yet but it's '91 3.0 Reg Cab, 7' Bed, everything stock.)

Looking forward to any inputs, thank you.

 

[stmitch]

The manual trans PCM is probably going to be necessary for the truck to run properly. By using the auto PCM without an auto trans, the PCM is still trying to control shift points of a trans that isn't there, and that causes issues. Atleast that's the way it works in my OBD2 truck.
I don't know that it would cause the smoke from the y-pipe that you mentioned though. Is there something like grease or oil on the outside of the y-pipe from when it was removed and installed? Is there anything touching the y-pipe like wiring?

 

[ciscobird]

The manual trans PCM is probably going to be necessary for the truck to run properly. By using the auto PCM without an auto trans, the PCM is still trying to control shift points of a trans that isn't there, and that causes issues. Atleast that's the way it works in my OBD2 truck.

So far, I've not driven it around so it's been stationary and idling. I thought about the 3rd/4th gear switch but the truck hasn't been up to that speed (typically around 45-50 mph for the gear to shift) yet. I was prepared to build and splice in a jump switch, either temporary where I could switch it on/off manually or leave it on permanently to bypass the PCM control.

I don't know that it would cause the smoke from the y-pipe that you mentioned though. Is there something like grease or oil on the outside of the y-pipe from when it was removed and installed? Is there anything touching the y-pipe like wiring?

I thought the same, especially after remembering that I spilled some crutch fluid on one side when inserting the line to the slave but it's smoking off equally on both sides, right under where the y-pipe bolts to the headers. Also, the smell isn't like what I'm accustomed to (fresh & clean oil burning smells like popcorn popping, old leaking/seeping oil smells different, & tranny fluid burning is entirely different).

Bottom line, I'm not concerned about the transmission shifting point programmed in the PCM (at least, not yet) but the firing parameters programmed. I'm assuming that since the weight of the flywheel is different from the torque converter it may be a factor affecting the firing parameters.

The Y-pipe is all clear of wiring and accessories.

I've done research on numerous Ranger forums and found that there are equal numbers of people driving with original PCM as opposed to those who went ahead and swapped to the manual PCM.

I love my '91 Ranger (I'm the second owner since '93) so you can understand why I'm very cautious. The last thing I want to is to burn the engine just because I overlooked something.

Thanks!

 

[stmitch]

I haven't seen many OBD1 trans swaps, so I'm no expert, but on all of the OBD2 swaps I've seen that used the auto PCM, the trans functions had to be deleted by a tuner. Not sure if there's a way to get around that on OBD1 without burning a chip.