cmp on 4.0l?

[mo24valve]

I bought a 4.0l to put in the place of a 2.9l i had go bad, the 4.0l i bought has a cmp sensor but i have searched numerous salvage yards for the correct wireing harness but non of the 4.0l rangers or explores i have searched have a cmp sensor. So my question is if i use a computer and wiring harness from a non cmp 4.0l will the engine run correct? Thanks in advance im new to this group and you guys are great and very informative.

 

[adsm08]

Yes. If the computer isn't looking for that sensor it won't miss the signal and the engine will run just fine.

Even if you have a computer that is looking for the sensor it can run ok. It will shut down or stall soon after starting about every other time, but it still runs.

 

[mo24valve]

Thanks for the quick response!

 

[adsm08]

Yeah, the CMP sensor was actually not that common. It shouldn't be there at all up to 1992, 93 would have had it only for Cali emissions, and 94 was hit or miss as well. From what I have seen of 94, all the Explorers had it, but only the Cali Rangers.

 

[mo24valve]

Thats great to know, I have a computer from a 1992 4.0l and wireing harness from a 1994 4.0l, neither had a cmp so it sounds like it should work for me,

 

[adsm08]

Have fun. In 93 the computer changed places and the wiring harness changed from a U to a J shape.

You can use a later harness, but it will require some "modifications".

 

[mo24valve]

What do you mean by from a u to a j shape? And i already swaped the computer, it plugged right together

 

[Andy D]

Please post your progress. Thanks In Advance.

 

[mo24valve]

I definitely will, I plan on doing a complete write up after im done with this project lol

 

[adsm08]

On the early trucks the computer is on the passenger side and the bulkhead connector fro the dash to engine connector is on the driver's side. This gives the harness a U shape when it is laid out in the truck.

In 93 they moved the computer over to the driver's side, right under the big white plug, and not much of it goes back towards the firewall on the passenger side of the engine, giving it more of a J shape when laid out. Unless you take the harness from an Explorer, but there are issues using that harness.

If you are swapping from a 2.9 to a 4.0 you will need the engine wiring harness.

 

[mo24valve]

Yeah I noticed what you were talking about last night, I guess this weekend I need to try snd find the correct wireing,

 

[mo24valve]

I originally bought just the 4.0l engine wireing harness but the conections were completely different and wouldn't hook to the existing 2.9l harness, so I bought a complete 4.0l harness just happens to be the wrong one so i guess the 3rd time will be the charm