Nerys

Hello critters. Long time jeep owner. my 88 Cherokee is my baby. In fact its my first car purchased in 1996. It currently has about 453,000 on the clock (no thats not a typo) I changed engines at 452,000 miles.

I just put a new engine in her 1000 miles ago. bought a $900 rust bucket off ebay but with a virgin engine 120k on the clock.

I was driving the new one for over a year fixed things a bit before diving in for the swap the engines perfect. No flaws that I could find.

I did the swap. SO far so good had a lot to replace. 100% new exhaust cooling system etc.. everything.

I replaced every seal on the engine except the head gasket while it was out.

I am running into a wee problem. First its eating fuel like a pig. I used to net 22-24 mpg on my work commute with this (54 miles each way thats how I got half a million miles on it :-) hehe

I know some of that is the fraking ethanol there shoving down out throats but not all of it. I am also getting black powdery SOOT on the tail pipe and inside the pipe. its a fine powder I can wipe it off with my finger once its cold.

My googling says its either rings/valves or running rich. I am leaning toward running rich since there was ZERO soot issues prior to the engine swap and I am not loosing any power it feels fine. In fact it feels really good (I guess that engine with 452k on it really was pretty tired out :-)

I am wondering if during the extraction and installation maybe I damaged one of the sensors or something.

Suggestions on what I can test what to track down and fix to resolve this? while the soot does not directly concern me (though I did put $250 in a brand new exhaust from the headers back so I do not want to wreck it) I am more concerned about fuel economy.

I am loosing 100 miles of distance per tank full at this rate Thats costing me $22 extra per fill up :-( NOT happy!

Suggestions?

BlueXJ

Check the oxygen sensor. Sounds like it is in open loop and the 'puter tends to richen the mixture until the exhaust is up to par. The wire may have come off or the wire may have gotten pinched in the engine swap. Check that and get back to us.

BTW it is customary to go to the introduction section to let us know a little about you and where you are from.

tupton

x2 on the O2 sensors

Welcome to the forum!

TrueBlueXJ

Yeah, my thoughts are O2 sensors as well. There should be one in your exhaust down-pipe, and one at the end of the catalytic converter. Check the wiring, or just replace them altogether.

drakan1908

Welcome from Va.