This is a tough one. Code 172

[Muslhound]

Ok..... 92 ranger 4.0. 305000 miles,on the old engine figured it was time for a up grade. I bought a 2000 4.0 with 96000 on it with confirmed service records. I regasketed the entire. (minus the head gaskets) engine and was very happy with the overall condition of the engine.

I used the intake off my 92 with my old injectors.

After getting it going it started idling rough, babble at low RPMs and higher than it should. I replaced the wires, plugs, 02 sensor, ECT, TPS. I ran a fuel pressure test and it pasted.

I should mention that the truck was an automatic and is now a 5 speed. I got codes 629 and 566 on the KOEO test pasted the CM test. I got the 536 and the 172 during the KOER test. I checked every hose and fitting 10 times and sprayed a whole can of starting fluid around looking for a vaccume leak. I finally tore it back down to the lower intake to make sure I didn't slip a gasket to no avail. I started the truck without bolting the air box together and noticed it was running better. Run a KOER test and didn't get the 172 code. Put the new air cleaner back in and it kicked the 172 code again and didn't seem to run as smooth.

I ohm tested the injectors and put a new fuel filter in as well. I'm sure I missed a bunch of stuff that I did things like I put a ECM from our other 92 4.0 just to have it do the same.

What do ya think???

 

[Muslhound]

Do ya think I should be using the crank positioning sensor off my 92? Should I be using plugs for the 92 or 00?

 

[RonD]

536 is the BOO test, brake switch test, ignore it
566 and 629 are because computer is not hooked up to an automatic trans.
Automatic computer have different software inside than manual trans computers so varying idle could happen but not misfiring or stumbling

Plugs will be the same and engine wouldn't start if CKP(crank position) sensor was wrong.

leak in exhaust manifold gasket at the head will cause O2 sensor to see extra air in exhaust(lean) so computer would add more fuel than it needs too causing rough running.
Just mentioning because it is often over looked and you did just install them.

To have a single bank lean code(172) on a V6 engine means it could be lower intake vacuum leak on that side, exhaust leak(above), O2 sensor or wiring.
Also a misfiring cylinder on that bank pushes the unburned oxygen into exhaust so O2 sees that as lean exhaust, but you could tell there was a misfire.

MAF sensor or upper intake air leaks, or low fuel pressure should cause BOTH banks of a V6 to show lean codes, so with only one bank showing the code I would look at just that bank

Adding air filter should not effect any thing, check near by wiring, or any vacuum hoses on the air filter housing.

And just confirm the coil packs wiring to spark plugs
3 4
2 6
1 5
Front

I mix that right side up at the coil or at the spark plugs all the time.