Switching 4.0L's

[onlyinacomanche]

I've been having some problems with the 4.0L in my 1990 Eliminator which is to be expected with an engine with hige mileage and i'm thinking about switching engines soon but I really like the 4.0L so I wanted to put a newer H.O. 4.0L from a '92 or newer vehicle in my truck. I have no idea as to what kind of work this would call for so I thought I'd ask you guys about all that I'd need to change over. My dad has a '92 Wrangler and the H.O. 4.0L in it is so much simpler and more powerful than mine. An suggestions or info would be greatly appreciated! Thanks and Merry Christmas!

 

-Will

[Pete M]

There's only a very small difference in power between the H.O. and non-H.O. as they left the factory. Changing to the 91+ system requires just about EVERYTHING electrical that has anything to do with the engine to be swapped over (including the harness in the dash). In my opinion, it's really not worth the effort. If your truck feels anemic, there may be a problem. Does it have the original catalytic converter? When was the last time you changed the air filter? Fuel filter? How many miles are on it? What condition is the tranny in? What size tires do you have?

Jeep on!

--Pete

[87manche]

I think the difference in power was what 13 HP? If you can feel the difference of 13 HP then your @$$ dyno is more tuned than mine. His wrangler probably feels peppier due to lower gears or lighter weight.

I agree with Peter that the electronics part of changing the motor is not worth it. In the short time that I've had my Renix system I've grown to like it. The system is dirt simple, with only a few sensors that will cause an engine to not run. It has a very low count of singple point failures.

 

A poorly running engine is either due to worn out mechanicals or something sending the ECU bad information.

I'd start out by checking the compression in the cylinders. If the top end of the motor seems to be ok then I'd move on to Fuel pressure, Injectors and spark/timing in that order. Find yourself a copy of the renix service manual. It's most helpful. I learned all about the Renix system when my MJ wouldn't start a few months back.

[onlyinacomanche]

Does it have the original catalytic converter? When was the last time you changed the air filter? Fuel filter? How many miles are on it? What condition is the tranny in? What size tires do you have?

 

 

 

New Catalytic Converter Old filters minus the oil filter a few days old. The Tranny is questionable, usually great around town does really bad with hills. She probably has around 140,000 miles on her. The odometer quit working right after I got her at about 131,000 and I'm running 31 x 10.5's. Should I start with putting all new filters in? Thanks for the help, Merry Christmas.

 

-Will Dement