cruiser54

Yup. Now is the perfect time to pull the CTS and flush the block.

That's what I was thinking. Good time to pull the CTS and flush water through the waterpump opening.

No. The CPS gernerates it's own signal to the ECU independent of all other systems. You can test it. A goos ground refreshing, connector refreshing, C101 cleaning if applicable, coil to ICU refreshing should all be done. Those are covered in the link in my signature with photos. Do the ground behind the taillight for sure.

The MAP sensor line doesn't have anything to do with the vac ball. It ONLY goes from sensor to throttle body. I'd look at the vac source line at the rear of the intake manifold. It could still pass emissions if the line was compromised and would still supply some vacuum to the HVAC system & cruise) The "double" ball (football) is usually only present with cruise...which I don't have. AFAIK it's not "double the capacity" it two separate chambers with a wall(septum) between them, and two separate in/out lines (that may or may not T together. In general, even a disconnected vac ball won't affect the engine performance much. How's the idle?? Correct. MAP hose compromised = no pass. Vac system to reservoir hose compromised = pass.

Absolutely!! NGK plugs, Belden wires, Premium cap and rotor. all at Napa. And, while you're under the hood, check your leak this way to be sure of it's origin: 　 I'd be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF. Everybody, who doesn't own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking. Many mechanics, friends, people on Jeep forums who can’t see your Jeep from where they’re at, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it? A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don't jump on the RMS/oil pan gasket bandwagon right off the bat. Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons. First off, the engine sits nose-up and any oil will run back to the RMS area. Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber's adage apply here. "$hit flows downhill". Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first. Revised 02-26-2013

I left the dealership in 1992, but that name sounds familiar. I dealt mostly with Lonnie and Big Al. Remember Darrell, the Renault Alliance guy?

got a link? Redwolf Can't find it now. I looked for it before I posted his name up. I think it's ftpiercecracker1. Search him.

It's not a poor design. Reducing the amount of braking force on the rear wheels when the weight shifts OFF the rear wheels is the best way to avoid spin-outs. It is, in fact, not just a good thing but a VERY good thing. A number of other small and midsize pickups also use similar proportioning valves. Chrysler killed the Comanche because the Comanche was a better truck that could do everything the Dakota could do, in a smaller package. Chrysler didn't want to have the Comanche competing against the Dakota and they weren't about to kill the Dakota ... so they killed the Comanche. True story. Chrysler's engineers thought they were better than the Jeep engineers. Originally said the 4.0 was gonna go away real quick and the 2.5 was going with it out the door. HaHa, the 2.5 ended up in the Dakota and the 4.0 went on to over 5 million produced. Ram got the XJ based front suspension, too.

ftpiercecracker did an excellent write-up on the fix.

York Motors Prescott, Arizona.

Where the CTS is, is the lowest point of coolant in the block.

Yes, it will!! It's where it can all settle around the cylinder walls. Believe me, I've had these engines apart. Pull the CTS and run some water through the block after it has draind to flush it out. You can use a hose into the thermostat housing with the stat removed.

Crusier, how the heck do you get that plug out?!?!? It is not a simple 3/8 drive extension. I found that the plug is actully a 5/16 square. I took a 3/8 extension and ground down the square end till it fit in the plug. I have never heard of any socket or anything that has a 5/16 square. Don't pull the plug. Pull the CTS. It's in the same coolant galley. That is the temperature sensor right next to the plug correct? just to the left of the plug on the exhaust manifold side of the engine? If that is what you are talking about I did pull that sensor out before and when I did there was solid metal behind the sensor. No fluid came out. Should it be an open hole?!? You pulled the knock sensor. The CTS sits higher up in the block and has an electrical pigtail on it.

Define "checked all grounds". Did you dislodge the throttle body to MAP sensor hose or the electrical connector at the MAP?

Crusier, how the heck do you get that plug out?!?!? It is not a simple 3/8 drive extension. I found that the plug is actully a 5/16 square. I took a 3/8 extension and ground down the square end till it fit in the plug. I have never heard of any socket or anything that has a 5/16 square. Don't pull the plug. Pull the CTS. It's in the same coolant galley.

Perhaps all the good coolant should be drained and saved. Then, remove the CTS from the side of the block and flush the block. I had a Renix with a ton of rust accumulated down there and only got it out by "pulling the plug". It didn't circulate during normal operation. It just sat there.

Do a fuel pressure test. The sound of a pump priming is no guarantee of proper fuel pressure or volume.

Look at it this way. The 90 Renix made 182 HP. The 91 and later HOs made 190 HP. So, the HO head ain't good for 25 HP. The biggest difference in HP was the 58mm throttle body on the HO versus 52MM for the Renix and the fact that the HO had a better designed exhaust manifold. 8HP, and only at higher RPMs, without a bit of extra torque.

Gonna have a headpipe built without the "crush"?

Click on the link in my signature and go to the post called "connector refreshing". There's a photo of a 10 pin connector that gets all corroded. Start with that. The Ground Refreshing is always a good idea. Click on that one. Are you aware of the lighting ground behind the driver's side taillamp?

Excellent plan. Don't be shy about adding extra grounds per my write-up.

Do this regardless: Renix Ground Refreshing The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, failed emission tests, and wasted money replacing components unnecessarily. The components grounding at the dipstick tube stud are: Distributor Sync Sensor, TCU main ground, TCU “Shift Point Logic”, Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff. The factory was aware of the issues with this ground point and addressed it by suggesting the following: Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint. Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely. While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely. Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end. First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely. Remove the other end of the cable from the rear of the head using a 3’4” socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely. A suggestion regarding the braided cable: I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18” long with a 3/8” lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116. A further improvement to the grounding system can be made using a #4 cable, about 10” long with 3/8” terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115. For those of us with Comanches, it’s very important to remove the driver’s side taillamp assembly to access the ground for the fuel pump. Remove the screw holding the black ground wire. Scrape the paint from the body and corrosion from the wire terminal. Reattach securely. If you want to upgrade your grounds and battery cables in general, contact Jon at www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price. Revised 03-04-2013

Renix Vacuum Harnesses The vacuum harness that attaches to the front of the valve cover and includes the grommet/fitting, and is called the front harness, is Napa part number BK 715-1367 The vacuum harness that is closest to the air cleaner, EGR etc, and is called the rear harness, is Napa part number BK-715-1366. The tube from the rear of the valve cover to the intake manifold is part number 715-1365. Revised 09-11-2012

Which dealership and where? I was Service Manager at a dealership form 1980 through 1992.

ALWAYS check the tightness of the track bar bracket to frame rail bolts. Put a wrench/socket on them and give a good pull on it. This was such an issue when the Jeeps were new that we took it upon ourselves at the dealership to do this in the pre-delivery inspection.