Replaced Crank Position Sensor

[Teapott]

I'm gonna say this now; I'm 18 years old, new to this forum, and still learning more about Jeeps and mechanics overall, so please forgive me if I'm off about anything. The other day I was doing some extra part replacements. Replaced my ground cable that goes from the block to the battery. The next day I went to AutoZone, I replaced the Crankshaft Position Sensor in hopes to fix the notorious hard starting. I went to start it, it started better but runs horribly; super rich and misfires constantly. To put it in perspective, it sounds like I put in a really aggressive camshaft, asides from the whole running rich and misfiring part. I thought it was a faulty sensor and went to get the same part from NAPA. Installed that one, same result. Put the original one back in, same thing. I'm now running the one from NAPA while I'm trying to figure this whole thing out. This is my daily driver and run about 20 miles a day. Any input on what I should do would be greatly appreciated.

[eaglescout526]

Cruisers tips. Check those out. It will also help us greatly if you tell us the year and engine you have so the proper folks can help you.

 

Welcome to the addiction.

[Teapott]

3 minutes ago, eaglescout526 said:

Cruisers tips. Check those out. It will also help us greatly if you tell us the year and engine you have so the proper folks can help you.

 

Welcome to the addiction.

I drive a 1990 Mj with the 4.0 renix engine. Also, what do you mean by cruisers tips?

[eaglescout526]

 

Right here. Take a look at his tips. Chances are your truck probably has not had any of the fixes performed to it yet.

[MJCARENA]

Sounds like the vacuum line came off the MAP sensor.

[Teapott]

2 hours ago, MJCARENA said:

Sounds like the vacuum line came off the MAP sensor.

I went to check this out and it turns out that the line had snapped. I guess that at some point in the process of installing the new part or removing the old one, I pulled on it or something and snapped it. For the time being it's been Jerry rigged with heat shrinks and old rubber hosing. It's running rich, but no where near what it was like. Ill update more when I get more done. Thanks for all the help so far!

[coolwind57]

5 hours ago, Teapott said:

I went to check this out and it turns out that the line had snapped. I guess that at some point in the process of installing the new part or removing the old one, I pulled on it or something and snapped it. For the time being it's been Jerry rigged with heat shrinks and old rubber hosing. It's running rich, but no where near what it was like. Ill update more when I get more done. Thanks for all the help so far!

 

I'd had this same condition TWICE since I've owned my truck.  As soon as I read your symptoms, I immediately suspected the same  culprit as MJCARENA did.    Next time you have your throttle body off, do this:  http://cruiser54.com/?p=280.  It makes for a much better fix.  

 

Welcome to the addiction, my friend.

 

[cruiser54]

www.cruiser54.com is the best place to go for the most current Tips.

 

I'll attach 2 of them that apply to this thread. Tips 1 through 5 should be completed ASAP!

 

CRUISER'S MOSTLY RENIX TIPS

RENIX GROUND REFRESHING

OCTOBER 30, 2015 SALAD 45 COMMENTS

 

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.

All the components listed below ground at the dipstick tube stud:

Distributor Sync Sensor, TCU main ground, TCU “Shift Point Logic”, Ignition Control Module, Fuel Injectors, ECU main ground (which other engine sensors ground through, including the 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. If the whole stud turns, you can use a 7/32″ six point socket or wrench to hold it so the nut can be removed. Worst case, cut the wires and remove the stud and nut. Install new terminal eyelets on the wires when going back together.  Scrape any and all paint from the stud’s mounting surface where the wires will attach. Surfaces 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. Apply a liberal coating of OxGard, which is available at Lowe’s and other stores. 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, apply OxGard, 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 its intended use and subject to corrosion and poor connections at each end.

• 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. Apply OxGard. 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 with a liberal coating of OxGard.

2 STRONG suggestions regarding the ground system:

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 tail lamp 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.  Add a 10 gauge wire, with an eyelet on each end, from that grounding point to a bolt on the frame. Better yet, on both Cherokees and Comanches, complete Tip 29 for the best fuel pump grounding. Be sure to scrape all mounting points to bare metal and apply OxGard also.

If you want to upgrade your ground and battery cables with custom made parts, contact Neal at www.meanlemons.com 

 

 

CRUISER'S MOSTLY RENIX TIPS

THROTTLE BODY TO MAP SENSOR HOSE FIX

JANUARY 23, 2016 CRUISER54 29 COMMENTS

The Renix throttle bodies have a strange and failure prone connector on the side where the MAP supply originates and then runs up to the MAP sensor located on the firewall. This hose/pipe assembly is no longer available for purchase.

The real kicker here is how critical this line is in supplying the correct vacuum signal to the MAP, the most relied upon sensor for the ECU to read regarding air/fuel ratio. Any cracks, melted spots, or loose rubber connectors can cause major starting and driveability issues.

There’s a simple fix though. All that’s required is a 1/8” NPT tap, a new throttle body gasket ( Napa FPG 60742 ), a vacuum fitting (Napa 05703-B102), two vacuum elbows (Napa CRB2670), and a length of new plastic piping (Napa CRB2672).

Remove the throttle body and take it to the workbench.

Using an oiled tap along with a driver, carefully thread the lower of the 2 holes of the throttle body where the old fitting was plugged in. Don’t go too deep. These are pipe threads.

Flush the hole with carb cleaner and inspect for any left over cuttings.
This is an excellent time to do a complete throttle body and IAC cleaning.  See Tip 11.
Take the vacuum fitting (05703-B102 ) and apply a LITTLE bit of thread sealer on the threads only. I prefer Permatex #2 but almost anything is fine.

.

Carefully screw the fitting in until snug.

Install one of the vacuum elbows on the MAP sensor so it points toward the throttle body, and the other vacuum elbow on your new throttle body fitting so it points up to the MAP sensor.
Cut a length of the new plastic tubing (approximately 13 inches) to fit between the vacuum elbows and install it making sure there is enough slack for some engine movement. Route it according to the photo. We don’t want any rubbing or chafing with engine movement.  Not a bad idea to use some contact cement or Gasga-Cinch sparingly on the tubing to elbow connectors.