cruiser54

Some people, like the PO of your Jeep most likely, can screw up an anvil with a rubber mallet.

I doubt the DRB will pick it up. Howzabout doing a "wiggle test" on all parts of the engine harness with it idling?

4 cylinder then?

Actually, Renix goes into closed loop real quickly also. I believe it's more related to O2 signal than temp. I've observed this more than once with my DRB hooked up.

Engine vacuum? I have a photo of a diagram but don't know how to post photos, or I would.

Don't believe those people any more.

Ditch the Fram.

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, and wasted money replacing unnecessary components. 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 12-04-2012 I added to this so it would include a ground connection specific to the Comanche.

I agree. and, Eagle thanks for posting that link. The big issue, besides general quality, is whether the oil filter has an excellent anti-drainback valve. Since our oil filters are mounted upside down, this is super critical. Wix, Napa Gold, Mopar have good valves.

Free and easy, too.

Pump may be prining but at a low pressure.

That's what I always thought, too. But some people have said that's wrong.

I agree with the cleaning of the CCV tubes first. But, the hacking of the tubes was an unpublished and recommended procedure from Jeep Tech when the Renix Jeeps were new.

Make sure the CCV lines are good, too. Enjoy your Jeep. Stumble on this: http://www.cherokeeforum.com/f51/cruiser54s-mostly-renix-tips-153657/

Ever seen one? Like your screen door. Not worth much as a filter...

No kidding. I'm confused...........

I'll post an image of the valve cover flutes before and after if someone shows me how.......

Cruiser’s Valve Cover Mod Most early and even later Renix 4.0s could be bothered by excessive oil in the air cleaner box. A fix from my old days as Service Manager at a Jeep dealership follows. Information was provided to me from a buddy at JeepTech during those days. I don’t believe it ever came out in a Technical Service Bulletin. 　 Remove the valve cover and turn it over. Next, remove the fluted tubes that are now facing you by removing three screws on each. Chop 1 inch off each of them. Then, about a half inch up from the area where you just sawed them off, drill a half inch hole in the tubes so the holes will face the rear of the valve cover. Clean and de-burr/sand all rough edges nicely, clean with solvent, and reinstall. Don’t be concerned about the chintzy gaskets that will probably crumble into oblivion when you remove the fluted tubes. They can go back together without gaskets.

Replace the harnesses anyway. YOu know the grommets no longer seal and there's probably plenty of cracks and loose vacuum lines. Be sure to clear out the vacuum fitting on the intake manifold. It can get quite coked up. 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 http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=BK_7151367_0269070623 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. http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=BK_7151366_0269070622 The tube from the rear of the valve cover to the intake manifold is part number 715-1365. http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=BK_7151365_0066877355 Revised 09-11-2012

Here's a thought, too. In this write-up the connector for the lighting is described. Worth looking at. I suggest unplugging EVERY electrical connection in the engine bay you can find, whether engine related or not, and spraying it out with a good electronics cleaner, visually inspecting the terminals making sure they haven’t retracted into the plastic holder, and then plugging it back together. There’s a critical 10-pin connector for the front lighting system located in front of the air cleaner and behind the left headlight assembly. Don’t miss that one. Also be sure that the connectors to the ballast resistor mounted near the air cleaner housing are clean and tight. ALL of the relays should be removed, the terminals wire-brushed until shiny, and the receptacles sprayed out with contact cleaner. Then plug them back in. I do this on every Renix Jeep I purchase or work on for someone else. Revised 07/23/2012

Possibly. But, the TPS can be diagnosed quite easily and is a high failure rate item. And, if you have a 2.5 like in your profile, you have an ISC not an IAC. Works completely different than a 4.0..

A good TPS for either manual or auto can be had at Napa for under $50. No need to pay big money for a Manual TPS. Use the Auto one and just don't use the plug for the trans.

Jeep Engine Oil Viscosity This was taken from pages 82 and 83 of the 1989 Chrysler/Jeep owners manual. Selecting Engine Oil Viscosity When changing or adding engine oil select the proper grade by using the chart on the following page. Select the grade that corresponds to the ambient temperature range you expect to encounter before your next oil change. 30*F to 100*F+ 20W-40 or 20W-50 0*F to 100*F+ 10W-30 or 10W-40 -20*F to 60*F 5W-30 Rotella 15-40 and Wix or Napa Gold for me.

Rust-Mort.

Yep. Either they're dirty or disconnected.