Fried_guy

Hello everyone.

I recently purchased a 2000 Cherokee Classic. The PO informed me it has a 4.6 stroker from titan engines with 10k miles. He also said it overheats when idling— which I know is a common problem. Overall the jeep was in excellent condition so i bought it.

I drove it home 100 miles at night with a buddy following. No issues other than loose steering.

The next day I started looking it over and found the following:
1. The aftermarket aluminum radiator with triple electric fan setup was leaking. I removed it and the aftermarket system with the stock setup.
2. Clogged heater core and lots of debris in system. I flushed the system multiple times, added clr, flushed a few more times. Heater core unclogged. Used plain water until system was complete.
3. water pump was oozing. I replaced it with a flowkooler model.
4. I checked for hydrocarbons in coolant and they were present. I ripped off the head, cleaned up the head and block REAL good, visually checked for damage and checked for warping. Blown head gasket. Replaced with new gel pro head and I take/exhaust gasket. No more hydrocarbons.
5. Rough idle. Had a rough idle and slight misfire. I was able to increase vacuum from 16s to 18s by fixing 2 vacuum leaks. Rough idle still existed. Replaced all o2 sensors. Replaced all other sensors except for cps (still waiting for it). I’m keeping all sensors and they stay in the jeep for backups. No change in idle.
6. So AFTER I did all the work it started stumbling REAL bad on acceleration and stalling when coming to a stop. Starts right back up, stumbles, and then stabilizes (with a rough idle).

So yesterday I was cleaning and inspecting all electrical connections and adding dielectric grease. On a side note I added the grease to 2x of my o2 sensors and ruined them— avoid that. Anyway, I got to the 3 large connectors by the oil dipstick and found that almost all of the wires in the 7-wire connector had broken insulation around every wire and are exposed.



Could that be contributing to the problem? What’s the best way to fix this? What else should I check for?

tech

The only way that could be a problem is that it gets wet or shorting I would clean it and use liquid tape to core all those wires have you done a compression test ? and maybe the fuel injectors .

Fried_guy

Okay. I’ll blast them white some electronics cleaner and seal them up then.

I’ll be running a compression and leak down test today or tomorrow. I checked resistance and continuity on injectors and they all check out okay. And they all make it to the pcm with no resistance. How do I test them further?

The last engines I worked on were carbureted small block Chevys. So the mechanical part I’m very familiar with. Not too savvy with the fuel injection portion of it all.

Thanks

bluejeep2001

You should be able to get a part number off your injectors...if you stroke you need larger injectors. They might not have done that. What color are the spark plugs...tan,very white or black. Also picture or describe injectors...might be stock jeep. Pull off a o2 sensor connector, preferably a front one...goes into preprogram mode..see if it clears up. You did a lot of work for an engine with only 10k on it. When you put head back on, did you seal up front left headbolt? Goes through the water jacket.Also run a compression test. More questions after you get back on results of above questions

Fried_guy

So I cleaned up and sealed the connections real well and the idle greatly improved. There was still a slight stumble, but it seemed much better. Then I got a CEL, which it hadn’t had in a while.

P0202. So I unplugged it while it was running and the idle seemed to improve. It was a little shaky, which I expect, but the idle “pattern” was consistent. I connected my fuel pressure gauge and with the injector disconnected, the pressure fluctuated between 49 and 50ish.

When I plugged it back in, the idle would get a little — not rougher I guess, but had no repeatable pattern. It would stay at the same rpm and then idle up for just a bit or two and then idle back down. The fuel pressure was pretty much right at 49psi, with very little fluctuation.

So I just removed the #1 and #2 injectors and found the oring that goes into the manifold on #2 was pretty badly torn.




I also broke most of the ev6 connectors, they were very brittle. So I’ll be replacing those.

I’m hoping this is the source of the problem and will be inspecting and replacing the orings by this weekend.

And I this really hasn’t been much work. I want this to run a looooong time and don’t feel comfortable with most other peoples’ work. I love the simple pushrod engine and it’s somewhat nostalgic for me.

Fried_guy

Update.

I pulled all the injectors and the orings were very hard on most of them. A few of them were slightly torn. So I found some 24# 4-hole injectors and replaced all 6.

I then adjusted the valvetrain to 20 foot-pounds at TDC of each cylinders compression stroke and installed new rocker arm bridges (without bending them this time).

Then I removed the spark plugs and did a compression check and all cylinders came out to 150 psi +- 5psi.

I lightly cleaned up the spark plugs and replaced the original coil rail and cleaned up some more connections I missed.

I took of my TB and cleaned it up real good again and while I was inspecting it I found a small tear in the vacuum tube for the MAP sensor. I sealed it with a dab of super glue and then covered it with a few layers of heat shrink tubing then reassembled with a new TB gasket. I adjusted the kick down cable.

Then I smoked the system to check for vacuum leaks and found none.

I reset the PCM and I fired it up in the garage and there was a VERY faint misfire, which seemed to get better the more it idled. The engine ran significantly cooler and with much less ticking from the engine. The idle RPMs dropped a little from before as well. Overall, the engine sounded MUCH MUCH better and I was pretty happy with the result.

I let it completely warm up and get the oil pressure get down to 45psi and backed it out of the driveway. Immediately I noticed it was lacking power. I decided to test drive it anyway.

This is what I found when test driving:

* The engine felt like it had very little power
* The transmission didn't shift right
* There seemed to be a popping sound when I gave it gas from a stop (sometimes)
* My turn signals were acting funny-- they were getting stuck on after they blinked a dozen times or so
* My OBD2 scanner kept losing connection with the engine running (worked fine with the engine off in the run position)
* About 1/2 way through the test drive the idle RPMs went from 600ish to 1200ish and wouldn't go back down
* When I parked it, the RPMs shot up to 2500ish
* There were no CELs during the test drive
* I shut down the engine and visually checked for vacuum leaks-- none that I could see
* After I restarted it I got 2 CELs-- P0122 and P0123 (TPS sensor stuck low AND high), and the idle RPM in park and drive was 800ish
* I couldn't clear the CELs

At this point it was beer o'clock and I was done for the day.

I don't think it's the TPS as this is a brand new one and in my garage it all seemed perfect (but what do I know?).

I read something about a clocking spring that could be the cause of this, but don't want to dig into the steering wheel until I've exhausted most other possible problems. Any thoughts?

I also will be installing a new crank position sensor this evening as I read the OBD2 connection can act funny if it's failing.

I'm going to continue to research diligently, but ANY direction would be great.

Thanks for your help.

Fried_guy

Work and life in general have been keeping me too busy to work on the XJ over the last few days.

I'll be testing the TPS tonight using the instructions found here:
TPS high voltage - Jeep Cherokee Forum in post #3
I've picked up an analog voltmeter and will do a sweep test too.

I'll also recheck my grounds and wires in general to make sure nothing is shorted/broken/loose, and all have a strong connection and possibly recalibrate my camshaft position sensor if there's time.

I'm planning on replacing the crankshaft sensor this weekend. I don't think that will resolve my TPS issue, but it could help with my OBD2 problems. And if it doesn't, then I have a backup sensor... which I want of each sensor while I can still find them.

My clock spring was delivered today and will be installing that this weekend if the above actions done resolve it.

ttt

Fried_guy

Update.

Other than a small vacuum leak, which was corrected with a new O-ring, the TPS tested fine.

I removed my horn relay and tested again and the problem persisted, so I'm ruling out the clock spring (for now).

I cleaned my grounds again and they all seem good with almost 0 resistance.

I replaced all the EV6 connectors and there are no other broken wires that I could see.

Over the last few days, I've developed a whistling sound and noticed my headers were glowing. I can't precisely locate the sound and it gets louder as the engine warms up, so I can only assume it's the manifold gasket that's leaking. I made a mistake when I ordered it and got some off brand gasket instead of the felpro. In my haste I decided to install it anyway. I hope this is the problem as the only cost is a new gasket and some time. Unfortunately my old man hands have been killing me lately, and I can only do so much wrenching before calling it quits. I hope to have it replaced this weekend.

I can't see any other problems with the engine.

Any other suggestions?

I'll update when I get more info.

Fried_guy

Update (and Merry Christmas).

I know it's been awhile, but here's what I've done so far.

I replaced the manifold gasket. It was definitely leaking. But the whistle persisted.

I found the MAP vacuum hose I "repaired" was still leaking, so I replaced that too.

I vacuum tested all the lines with a hand held vacuum pump and found the HVAC/CC line wasn't holding vacuum. After tracing the lines I found that one of the POs had tried to repair the line that goes to the CC servo with JB weld. Obviously that wasn't working. So I removed that line for now and capped it off. I can live without cruise control for now.

I replaced my IAC and the whistle went away.

I repaired my leaky rear main seal while I was as it. I examined the bottom end and everything looked good. No metal shavings and the cam looked good.

I fired her up and brought her to 2500 RPM for a few minutes. I let her idle and she idled good right away. I got her warmed up and pulled out the driveway and "POP!". Intake backfire as soon as it was under load. RPMs increased a little. I immediately turned around and put her back into the garage. 2 vacuum lines popped off (presumably from the backfire), so I reconnected those and the idle went back down to normal.

I received 2 mopar O2 sensors (pre-cat) and will be replacing those when I get home today. If that doesn't help I'll be replacing (and indexing) the camshaft sensor as well.

I hope this works as I'm out of ideas at this point.

Thanks!

Fried_guy

Update (and Happy New Year).

I replaced both upstream O2 sensors with mopar OEM ones... no change.

So I changed out my cam position sensor and made sure it was indexed properly (and it was)... no change.

I noticed that in the garage, in park, when I revved it up for a bit and then let off it would die (this was new). So I suspect it may be my IAC. I've ordered a new OEM mopar IAC (and TPS and MAP) just in case.
Can a failing IAC cause it to backfire through the intake?

I'll be checking my valvetrain tonight to make sure there isn't a ben pushrod or broken spring.

I checked all my wires again and made sure nothing was pinched or touching.

I notice my front pre-cat (this is a CA emissions 4.0) was glowing red.

Anything else to look for?

ttt

bluejeep2001

Glowing red means its blocked or your cam timing is way off...dumping unburned fuel into the cat because the injectors are firing too late

Fried_guy

I found a vacuum leak which seems to have been coming from the IAT and at the TB gasket. So I'll replace the IAT and the TB gasket and seal it up.

I've ordered an all new mopar OEM crankshaft position sensor, mopar OEM tps, mopar OEM iac, mopar OEM map, mopar OEM iat. I'll replace those one at a time and test.

I've also ordered a new fuel filter which I will be installing by itself and testing.

If none of those solve the problem I'll check my cats to make sure they aren't clogged/destroyed. I'll check my fuel pressure again, but last time it checked out good. If it's bad I can plan on replacing my fuel pump as well.

After that, all that's left is the PCM, right?

bluejeep2001

The filter is in the pump module in the tank...if you have good pressure, the filter is a waste of time. Disconnect the front O2 sensors...takes them out of the picture and sets the fuel flow to a preprogram mode that works very well, just not good enough for cali emissions...see if your misses and red pipes clear up. Since you seem more than adequately handy you might want to try the coil rail eliminator mod. I did mine a couple of years ago with a screamin demon coil and have been extremely happy ..starts on a 1/4 crank every time . I don't like glowing headers, but i doubt they're blocked. If they were so blocked that they glow at idle, you couldn't get any higher rpm out of them. Is your code reader also a scanner what is ign advance at idle, whats map reading

Fried_guy

The filter on my 2000 XJ is external to the fuel tank. It looks easy to replace, so I'll be doing it anyway.

I'll try and drive it with the O2 sensors removed and see how it responds.

I ordered the components for the viper coil mod as well.

My code reader does display ignition advance. I remember I saw it bouncing around but don't remember the actual values. I'll post the results when I have a chance to check it.

My TPS was delivered today as well... I'm hoping to get that on tonight and test.

Thanks for all the help. I'll post back results when I get them.

Fried_guy

So I've been busy af. I haven't had any time to work on the jeep until the past week.

I've replaced ALL sensors (including O2) with mopar OEM sensors. I bench tested them before install.

No change.

I converted from a coil pack to the dodge viper coil.

No change.

I changed out my spark plugs.

No change.

I unplugged the O2 sensors.

No change.

I smoked the engine again. No leaks.

So I started to think this is fuel delivery related.

I found a small leak in fuel line at the manifold, so I replaced that.

No Change.

So I put my fuel pressure gauge back on and started monitoring the pressure under various conditions.

At idle, my fuel pressure fluctuates (flutters) between 41 and 56 psi. I notice that when the car "stumbles" (might not be a stumble) the fuel pressure stabilizes right at 49 psi... just for a second. Then goes back to fluttering.

When I bring up the RPMs I don't see any fluttering, but there is still a slight miss.

Sometimes, after the RPMs are up for a while, when it goes back to idle the gauge reads right at 49 psi with no fluttering and it idles great (for that moment).

I stopped the engine and bypassed the fuel pump relay to turn on the pump. The pressure was fluctuating and sounded like rattling from the pump. I was rather low on gas from all the testing so I put in a gallon of premium. The rattling stopped and the pressure went back to 49 psi. I thought solved it! Low gas! NOPE! No change.

When I turn off the fuel pump the pressure immediately drops to 45 psi and slowly drops down to 0 (over the course of 2 hours or so).

I checked my optima red top battery thinking it wasn't providing enough power at idle and found that it was low. So I got a battery charger, charged it up and tested again. No change. And it looks like the battery is in poor condition. So I purchased a yellow top that I will be putting in tonight.

I tested all my grounds. I tested resistance/voltage to and from my fuel injectors. All seems perfect.

I'll check the electrical connection to the pump and I have a new pump/regulator I'll start to put in tonight if the connections are good. I'm hoping that's the problem. Everything else has been thoroughly checked.

And I was wrong about the external fuel filter... what I was looking at was the charcoal filter. My fuel filter is part of the regulator.

Sorry for the long posts.

Any words of wisdom?