Frankenstein engine

I've been living with a rod knock on two rod bearings for a year now. A lifter has now locked up and is hitting hard so it's time for a swap.

I need the Guru's to check my research and make sure I have this dialed in right.

88 XJ, 4.0, AW4, 231.
Still running renix computer.
A few years back I swapped in the HO head adn 19lb mustang injectors. It's always run rich. Also have a pacesetter header on it.

I scored a 98 engine, AW4, and 231 for $300 the other day. I opened the engine top and bottom and it's clean. No sign of sludge or wear. Looks great.

So, 98 engine, 98 intake, pacesetter header, renix computer and sensors,

Thinking about fuel pressure. I don't want to use the 19lb 5.0 injectors and I have a choice of the 98 injectors and fuel rail or a full set of 92 injectors on a spare intake.

The fuel pressure changed at a certain point but I can't seem to find when and whether they'll work with my renix setup....

Any guidance? Thanks.

lord this is a ticking tmebomb :doh:

Overdriven said:

So, 98 engine, 98 intake, pacesetter header, renix computer and sensors,

Click to expand...

Go back and get the 98 wiring harness and computer, and all the sensors....

Or just use the bottom end from the 98 and keep your renix head and everything else, just like mine. The HO is only rated at 13 more horse.

you could also build an adjustible MAP sensor and lean out the engine so you can re-use your injectors.

http://www.angelfire.com/my/fan/MAP_adjuster.html
http://www.go.jeep-xj.info/HowtoMAPsensor.htm

96 is the year they went from the 39psi rail w/ return to the 49psi rail w/o return. I would use the 98 block w/ head and intake and convert/splice whatever sensors(MAP, TPS, IAC, etc) to work with the renix ecu. If you search around, you'll find what you have to modify to use the newer engine with the renix.

ktwalker01 said:

lord this is a ticking tmebomb :doh:

Click to expand...

What makes you say that? I've done plenty of research and I've been running a HO motor in my XJ for a while. It would still be running if I didn't spend so much time in water crossings and overheating my engine. :gee:

The renix intake, throttle body, fuel injectors, and vacuum system have been gone for a while not. That's not an option to go back to. I wouldn't want to anyway.

JNickel101 said:

Go back and get the 98 wiring harness and computer, and all the sensors....

Click to expand...

Can't do this either for two reasons. First, the Jeep was Tboned and the engine, trans and xfer case were pulled and put on a pallet in my buddies Jeep shop. 2nd, I've got an internal cage that keeps me from pulling my dash out. Can't get behind it anymore.

Mainly my question is about the fuel injectors. Can I use the 98 grey top, or the 92 orange top, or....

I do plan on building an adjustable map if I'm still running rich.

gradon said:

96 is the year they went from the 39psi rail w/ return to the 49psi rail w/o return. I would use the 98 block w/ head and intake and convert/splice whatever sensors(MAP, TPS, IAC, etc) to work with the renix ecu. If you search around, you'll find what you have to modify to use the newer engine with the renix.

Click to expand...

I've already done the splicing and adapters to run the HO intake with my renix computer. Thanks for your answer, that was what I was looking for. I'll run the 92 fuel rail, injectors, and throttle body on the 98 intake... or maybe run the 92 intake on the 98 head if i can clean it up enough.... Thanks for the answer to my question.

The '98 AW4 isn't going to work for you without some significant mods since the output speed sensor is electronic instead of mechanical.

ehall said:

The '98 AW4 isn't going to work for you without some significant mods since the output speed sensor is electronic instead of mechanical.

Click to expand...

Not going to use the AW4. Mine is in great shape. Thanks for the input though.

Found this from Dino Savva on JU:
4.0 I6:
'87-'90 #53003956 18.6lb/hr @ 39psi
'91-'93 #33007127 21.0lb/hr @ 39psi
'94-'95 #53030343 21.0lb/hr @ 39psi
'96-'98 #53030778 23.2lb/hr @ 49psi
'99-'01 #04854181 22.5lb/hr @ 49psi

I will have to build the adjustable map no matter which injectors I use. I reading a thread on Mallcrawlin.com right now about a 99+ intake where he swapped in different injectors at different fuel pressures to get a dyno and feel for how they run.

I just learnd that the '98 head doesn't have a port for my coolant temp sensor. I'm using the port in the thermostat housing for my electric fan. I also need to create a boss for my knock sensor. Glad I took some time off this week to accomplish everything.