YJ 4.2 to 4.0 MFI Need help with finishing touches.
Hello all...... Bought a '92 y with a 4.2 in it last yr. The paperwork, title was obviously screwy as the 4.2's were 1990 and before and the Vin on this was for a 92 but had a 4.2 in it. Anyhow, the body and fratme were in great shape for western New York, so I bought it and went to work. I rebuilt the 4.2 bottom end (psitons, rings, pump.etc..). During this time I bought a 92 junk body and frame Renegade for the motor, tranny and such. I nuttered up the 4.2 and put the refurbished 4.0 head on it with a new distributor(hei).
It ran well with the new DGEV weber, so I took my time until this spring to install the 4.0 EFI. I just got it up and running two weeks ago but still have a few items to finish. I have searched quite a bit, and have lurked on this site in particular to figure out this conversion. Some of the things I have to finish, I can't find definitive answers to and hop that someone can help.
Jeep now: 1992 with a converted to 4.0 multi-port fuel injected engine.
I kept the v-belt driven steering, water pump and alternator which I upgraded to a 125A model. The Alt. upgrade has been great as the charging guage stays rock steady regardless of what lights and accessories are on.
I think the jeep was a combo of several years of jeeps 88-92 and I ended up with the Franken jeep. But alls pretty good now as I've straightened a bit of the mess out.
I need help on.....
1. As the jeep is an automatic with a tf999 auto transmission, the drive selection on the column used rods and linkage to shift, and a kickdown rod linkage also. When converted to a 4.0 throttle body, I do not have the right kickdown cable bracket or lever on the transmission. I do have the 4.2 kickdown bracket on the transmission that used a rod for kickdown purposes. The 4.0 throttle body uses a cable from throttle body to transmission kickdown lever. I need the lever for the transmission kickdown cable duties. I had the 92 transmission rebuilt for use with the still then, carb, operated sytem that used rods and linkage. Like a dumb #ss I cant locate the 92 lever that was on it originally. I've looked locally and online but can't locate one. Has anyone fabbed up this cable link to the kickdown?
2. The original wiring harness inside and out was from the earlier 4.2 yj version... haven't been able to figure out the tach set up. Does signal for the
originate from the computer to feed the original 4.2 tach, or are the two tachs different animals?
3. With the Map sensor plugged in, the engine is sometimes hard to start and sometimes cuts out when warmed up. Would this have something to do with the 4.0 efi being installed on the 4.2 block putting putting the Map sensor readings out of range for a complete 4.0. The engine runs pretty smooth without it, but probably not at its best efficiantcy. Im getting about 12-14 mpg's , the mpg's for a 1992 is listed at 14/15 city/country, that's without the map sensor plugged in. I did disconnect the 4WD vacuum system and installed a posi-lok cable for reliability- would not having a reserve canister no longer in the vacuum system cause a wild running efi system. I have replaced all of the system sensors with new except the VSS. I had installed a new VSS but it's drive stem broke so I re-installed the old one which seems to be working fine.
4. The distributor I installed from the 1992 has the cam sync sensor located at the bottom of the distributor cup whereas most other distributors for the 4.0 have a under the cap, top of the cup, disc shaped sensor. Would this newer style work in place of my older distributor type. The connectors appear the same, but there were differences in the 1991-1992 and other yrs of the YJ Fuel injection systems. The computer I have is for a 1991-1992 MFI system 4.0L system.
Thanks for any help or leads ...... I've learned tons from this site and wouldn't have gotten this far without it.....