HO swapout...fuel ?'s

OK heres the deal. A little over a year ago I did a HO swapout in my 87 xj. I basically followed the wright up on Cherokee America on doing so. What I have now is a rich running XJ. I have a K&N cone, TB spacer, Borla header, 2 1/2" pipes with Hiflo cat and Flowmaster. The jeep is still running its 87 computer, fuel rail and fuel pump, and the instal was a 97 motor.
I have hooked the comp up to a Snapon Diag. computer and everything seems to be running in parameters, no codes. I dont have the #'s written down, if I need them I can hook back up on friday night to get them.
I have read a few blurbs on adjustable MAP and FPR's, what is the general thought on them.
Does anybody have any idea what kind of fuel pressure I should be running? What other problems can be going on to make me run so rich. Im getting about 10 mpg.
Any help.......thanks Kurt

Well... Where d'y'wanna start?

If you're running the HO (what year) intake and injectors with the Renix computer you're dealing with the issue that the RenixII's fuel mapping is not set-up for the flow rates from the HO's injectors -- the RenixII is set-up for injectors that flow 18.6lb/hr while the '91--95 HO injectors flow at 21 lb/hr, the 96-98 at 23.2 lb/hr and the 99-end flow 22.5lb/hr ----- the operating pressure for those rates is 39psi from '87 - '95 and changes to 49spi with the one-piece filter/pump from '96 - up

So - that'd make you a bit rich... (about 13% more flow than expected if you're running a '95 injector with a RenixII ECU and pump)

Also -- who's O2 sensor did you keep? hopefully the RenixII unit -- it's NOT a typical O2 sensor (resistive output, NOT a voltage generator like the HOs use)

Also - is it safe to assume that you're running the Renix's flywheel on the back of your HO? (they have different tone rings - the RenixII will reset each revolution if you ask it to, which could cause you to inject quite early leaving a fair amount of fuel hanging in your intake...not atomized but deposited for having sat there so long (injectors should start to fire about 76*BTDC exhaust for each cylinder)

??

OK, as I can remember the 4.0ho was out of a '97XJ, the fuel rail stayed on the motor. The flywheel was changed out to the '87 one. The fuel pump is from the '87 as are the sensors (O2, knock, water, cps, tps, all of them). The distributor is from the '87. Map sensor is origonal ('87)

I guess I should say Im not quite where I should be on my gearing (3.73's and 35's) and I know that is causing some of my fuel eco. loss, its the rich smell of the exhaust that I want to correct. I passed emmisions not too long ago, and I seem to be running pretty strong and the engine is responsive, it still gets up and goes, but I know its not right

I am getting the scanner back tonight so Ill post up my #'s after I get them.

Fuel pressure test results

Key on/relay on 37psi
Key on/relay off 32psi
Running 28.5psi

If I read your posts correctly, you dropped in the '97 engine and did not change the injectors. Which means they are probably too large for the Renix system.

However, if you run so rich that you can smell it at the tailpipe, I don't understand how you could have passed an emissions test. How are you calculating your fuel mileage? Have you accounted for the non-standard gearing and oversize tires? (i.e. is your odometer corrected?)

injectors are off of the '97 motor.

I just got the 29 tooth speedo gear to index tonight.

After the swap out there was no smell up to about 4 months ago, its getting progressively worse.

Ok I got the scanner hooked up
For the shop mechanics out there its a Snap-on Diagnostics MT2500

the fuel rail had been changed out to the 97's

Im going to go ahead and list off what it read, maybe someone can make sence out of the #'s and find a problem

RPM ~790
O2 (v) 1.23-4.98
INJ (mS) 4.7
Loop Status closed
Exhaust rich/lean (switching back and forth)
ST fuel trim 108-123
LT fuel trim 90
MAP sensor (v) 1.5
MAP ("Hg) 11.7
MAN VAC ("Hg) 18.3
Baro Pres ("Hg) 29.8
TPS (v) 0.51
Throttle (%) 10
Throttle SW clsd
Fuel sync --
Collant (*f) 195
Charge temp (*f) 121
Spark Adv (*BTC) 14
Knock 0
Battery (v) 13.9

In the amount of time that it took me to get the scanner to work and take down the #'s (about 15 min) the exhaust/ fuel smell from the jeep was starting to get to me, and yes I had both doors open.