OHV to SOHC wiring swap

[Jay-Rad]

Hey guys,

Well I'm trying to swap my 95 4.0 OHV explorer engine with a 98 4.0 SOHC explorer engine. I'm hoping to use my 95 wiring and sensors on the new motor to avoid dealing with the ECU. So far I beleive I can make most of the old electrical system fit on the new engine. The only problem I'm having is finding a way to make my cam sensor work. My old OHV engine has a three wire hall effect sensor with: (+12v line, -/ground, and a signal wire)the sensor sends a +5v pulse to the ECU when at TDC if I understand it correctly. The sensor on the 98 SOHC engine is a prox/electromegnetic pickup sensor with two wires. I have concluded that I will not be able to use the old sensor for this so I most find a way to make the new sensor work or find another alternative. I know very little about the new sensor, I have the wiring diagram for both motors but do not know the specs (voltage input/output, pulse width, on/off time) for the new sensor. If I can just get a +5v pulse at TDC with this sensor it will solve my problem. I've been thinking about soldering a resistor on one leg to drive a transistor out to another resistor for +5v but I think I'm taking it to far. Any info please help I'm losing my mind, I need any help I can get.


Thanks,

Jay-Rad

[rwenzing]

You should use the correct PCM for the engine that you install. Anything else can and will be a can of worms. Even if all the sensors could somehow be be made to work, the spark and A/F ratio calibration will be wrong between the OHV and the SOHC engines.

HOWEVER, if you have an automatic transmission, it is controlled by the same PCM. You would still be in trouble if there are incompatibilities between the transmission and PCM. A 95 might have had a 4-speed auto but the 98 SOHC Explorer PCM is probably for a 5-speed. Not good. Even if the transmissions have the same gear count, there could possibly be transmission calibration differences between the years/engines.

I hate to say it but there's a good chance that there will be a few more problems waiting to bite you. Engine swaps on late model EFI vehicles can be a nightmare.