Unknown XJ running issue

[kingfisher23]

Hi everyone! First time poster, and first time XJ owner!

I have a 98 Cherokee with a strange issue. When I'm driving, the Jeep occasionally feels like it "drags", almost as if a strong gust of hit were hitting it from the front. I can feel the vehicle pull. The effect is brief but it can happen several times in a row. The rpms do not dip or change when it happens.

The engine threw two codes, 0700 and 0705. I've already diagnosed a gummed up NSS by testing the plug with a multi meter. I'm going to fix that tomorrow. The NSS is causing a no-crank condition right now due to the cold weather. No other symptoms (backup lights work, engine won't start in R/D, etc.).

What I am wondering is, what's the likelihood that the NSS is causing the drag/pause? I've never owned an XJ before (CJs and a WJ) so I don't know their quirks.

I can pretty much work on anything in the engine, but I'm not great at diagnosing problems. Jeep has 217k miles on the original transmission but had a new engine dropped in 20k ago, if that matters.

Thanks in advance! I've already learned a ton reading through the forum.

Evan

[4.3LXJ]

One thing that comes to mind is the crank position sensor. It probably has never been changed and is a part people neglect as long as it works OK. When they start to go, they can cause a variety of symptoms such as you list all the way to it just quits and can't restart. They should be changed every 100K

The other thing that probably hasn't been changed is the O2 sensors. Also a neglected part, they can cause the air/fuel mixture to be marginal and loose power. They should be changed every 50K

A marginal condition from either of those sensors will not cause a code to generate

[kingfisher23]

So I pulled and cleaned the NSS today. It was pretty well gummed up. Reinstalled it, reverse lights work. I cleared the codes and they stayed gone through two starts.

I realized I'd forgotten the rubber gasket in the NSS so I pulled it again and resembled it correctly.

BUT!!!!!

I'm still in a no-crank condition. Battery tests out fine. I turn the key and all I hear is a click in the fuse box on the passenger side. All fuses are good, both inside the cab and in the engine compartment.

I can bridge the connections on the starter and jump the starter to crank the Jeep, so I think the starter and solenoid are ok. Jeep has been running fine after I get it started.

I pulled the CPS plug and tested the resistance between B and C. It showed up at about 500 ohms.


This last time I started it up, the CEL came back on. I pulled the codes: p0700, p0743, p0753.

I'm at a loss now. Can anybody suggest tests, diagnostics, etc I can do at this point? I don't think my transmission is suddenly shutting down (knock on wood!) but I'm not sure where to go from here.

[kingfisher23]

UPDATE #2:

I cleared the transmission codes before driving the Jeep home from my shop (13 miles, full speed range, etc).

It looks like the NSS cleaning did its job. I have overdrive back (didn't realize it was missing) and the dragging problem seems to have disappeared.

The other codes did not reappear at all during the drive or when I jumped the starter in the driveway.

Still no crank!

A little bit more background: this no-crank issue started as an intermittent thing week before last. It presented for the first time when it got really cold one night while I was working at the local ski mountain. 11:30pm, 12° outside, the Jeep wouldn't crank when I first turned the key. I had to rock the key a couple of times to get it to turn over. Same thing happened the next morning when I went to start it. I think it happened one more time that week. Every other time I'd go to start it, no issues. Then on Thursday night, the temp plunged into single digits and it snowed about an inch. I went out Friday morning and the Jeep wouldn't crank at all, no matter how many times I tried it. That brings us to today and the partially successful NSS repair.

Relevant info:

I have good fuel pressure and good spark. The starter cranks the engine just fine if I bridge the leads on the solenoid. The battery is putting out about 14v. The cables and posts are clean and in good condition. The jeep runs fine once it's been cranked. No codes in the computer.

My next step (and really the only one left I know) is to check the ignition signal at the starter. That'll take an assistant, so I have to wait until later to try it out.

Any and all suggestions would be greatly appreciated.

Evan

[nickyg]

I have hears of the ASD relay causing problems. but I don't have too much experience in that field. couldn't hurt to swap it out

[4.3LXJ]

Check the fuse for that starter relay? Verify current into and out of it?

[kingfisher23]

Check the fuse for that starter relay? Verify current into and out of it?

None of the fuses I could find that directly relate to the ignition system seem to be burned out. I checked #s 9, 10, 11, 19, and 25 in the cabin, plus all the ones in the engine compartment. Any others I should look at?

I haven't checked for current through the relay. Where and how should I test it?

Sorry for all the basic-sounding questions. I'm fairly new to vehicle maintenance, despite a lot of time spent working on other machinery.

van

[4.3LXJ]

You should have current at the number 30 terminal (numbered on the bottom) spade. It should pass current to the #87 spade. An easy way to check this is pull the fan relay and substitute it. If it works, replace the relay. If there is no current there, you likely have a blown fuse

[kingfisher23]

I didn't take my multimeter out to test the current, but I switched the fan relay and no dice.

I don't think my ignition switch is the problem, because I hear a noise in the interior fuse panel when I turn the key to the start position and the lights on my window switch panels go out. That tells me (I think) that the switch is engaging.

But a voltage test at the starter confirmed that the 12v ignition signal is not reaching the solenoid. The battery-to-solenoid wiring is good, as evidenced by the ability to jump the solenoid and start the engine.

So what is there on the ignition signal side of the circuit to break continuity?

I rechecked all the interior fuses and none of them are blown. Same with all the larger fuses in the PDC under the hood.

:banghead::confused:

Evan

[4.3LXJ]

The starter relay. That is why you need to verify current to it

[kingfisher23]

The starter relay. That is why you need to verify current to it

http://www.jeepforum.com/forum/attachments/f11/172774d1292805820-power-distribution-center-1998-xj-limited-clipboard02.jpg

So based on this diagram, I should run the leads of the multimeter to the negative battery terminal and the slot labeled 10 on the Starter Motor Relay, correct? Do I need to have someone turn the key for me while I check the voltage or is this circuit live at all times?


Once again, thanks for all the suggestions and instructions.

Evan

[4.3LXJ]

#10 should be hot with key on. Either #11 or 13 should be hot with key in start

[Pastorjosh]

I was going to say your "dragging" was probably torque converter related, but seems like you have that figured out. I have a friend that is having an extreme cold no start. Ended up being the starter.


Sent from my iPhone using Tapatalk

[kingfisher23]

The Jeep lives!

I followed the advice above and pulled voltage on the starter solenoid. Nothing. Crud.

Pulled voltage on the ignition switch. Juice there. That's a good start.

As I pulled out the wiring diagram to try and track down the break in the system, I figured it'd be would be worth my while to to pull all the fuses again.

DOH!

Turns out I managed to miss a blown MAX-30 fuse in the PDC. Replaced the fuse, now it cranks right up. :mock: I feel like a goober, but the Jeep is up and running again. And now I know a bunch more about the ignition system than I did going in. :xj-red:

Moral of the story: make sure you check your fuses with a light.

I'm left with the question though, how would a fuse cause an intermittent no-crank condition? Is it possible that the mucked-up NSS is what caused the first problem and the blown fuse?

[4.3LXJ]

Glad you got it fixed. Yes, some bad contacts somewhere could cause intermittent failure. Those are the hardest to find. However, if it happens again, try starting it in N instead of P. If it does, you found it. The NSS