97 Cherokee sputtering, "popping" issue
 

1997 Cherokee Sport. 4.0HO. Automatic trans.

Long time lurker, and have searched this issue thoroughly and still can't figure it out, figured I'd get your guys' opinion on it before I proceed.

When I bought this Jeep, I was told that it had a sputtering issue and was running kind of rich, and the codes he pulled were related to an injector. Took it to my mechanic, we replaced the injector and the problem seemed to have gone away (it may or may not be related at this point, I'm really not sure). It's not my daily driver at the moment, so I don't drive it a whole hell of a lot to be able to gauge it too well.

When I start it, sometimes I have to crank it, or turn the key back and let it sit on 'ON' for a few seconds before starting it up. Sometimes it's easy to start up, sometimes it's not.

The other day, I decided to take it to Advance to get the batt tested, because sometimes issues can turn out to be the simplest solution. I wanted to rule the battery out. Battery test came out great. I hop in the Jeep to start it, the fuel gauge goes wonky on me and reads empty - fuel light comes on. I KNOW I had a plenty of gas when I left.

I pull out of Advance and onto the main road and it just acts like it doesn't want to go. Sputtering and whenever I lay on the gas, it makes a "popping" noise. Not sure if it's backfiring or coming from the front. You can clearly hear it in the cab.

It's fairly intermittent, and it's the same thing I had in the beginning, only worse. Some of the symptoms seem to point to CPS, but I pulled one of the plug wires off, put a nail in it and held it against one of the bolts on the valve cover, and had spark. I just couldn't tell real well what color it was, not sure if that matters.

I do have a video of the sound/issue.


It starts at about 32-33 seconds. You can see the tach where I lay on the gas to get it going because it started sputtering, and you can hear the popping noise. I apologize for the quality of the video, I was really just trying to catch the issue the best I could while not wrecking lol.

I'm aware that it could be anything - but I wanted go get a few of you guys in on it, since you know what you're doing more than I do.

Some things of note:

It does have an exhaust leak, and I've ordered the new manifold
The downstream o2 sensor wire has been cut

Any help on this, I would really appreciate and I'm excited to be part of this community.

Edit: I should also note that it doesn't really sputter while it's stopped, only while accelerating. It does have a cam in it (not sure if that matters). The idle that I get is definitely a bit rougher than normal. I definitely can tell a real difference between the lope of the cam, and the rough idle. I also smell a slight fuel smell when this is happening.

What are the codes? When it sputters and pops do you notice the charging gauge going nuts? When you crank it up and let it idle does it start the popping and sputtering?

I had the same problem to start with and as it turned out my cam sensor was bad, then I had to adjust the timing more as well...

Here's a few things you might want to check...

This is what I've found so far online on another forum...

"any alternator that has leaking diode allowing AC out will definitely effect the PCM"Saw this quote on another forum so I started searching. I found several mentions of leaking diodes effecting the PCM and causing anomalies in the*electrical*system. I also found several mentions that with one failing diode the alternator could still charge enough or be intermittent and may test as good. I stated the other day that most of my engine codes were gone but the alternator wasn't charging. Well when I excited the alternator the misfires and engine codes came back. I charged the battery fully last night to make sure I could get to work today. I had zero voltage all the way to work. At lunch I removed the battery so I could test the Battery*Temp*sensor. Sensor checked out fine. Put battery back in and hooked it up to the charger. On the trip home I had zero volts. I noticed that the check engine light was not illuminated. Disconnecting the battery earlier had cleared all the codes. I had no misfires on the way home and no check engine light. Checked codes when I got home anyway. Had a P1682- - (Charging system doesn't seem to be working well. Check alternator, etc.) The misfires and CPK and CMP and other codes that I have been experiencing were gone. Went back out and started the Jeep and excited the alternator. It ran on 13.5 volts for about 2 minutes before it went to zero. Pulled codes. P1682, P1391, P0320, P0340, P0351, P0300 etc. Called O'reilly's and asked if they could do an extended time alternator test and they said yes. I'll do that tomorrow. I also learned that a bad diode will drain the battery after a few days of no use. The previous owner only drove this car a couple of times a month since it was an extra vehicle and he had this problem. As a matter of fact the battery was dead the night I bought it. I drive it every day and have not experienced battery drainage. It was also suggested on one site to test for AC voltage at the output. This would point to a "leaky" diode. I'll update after I've finished running down this rabbit hole too...

This is also from the same person on the same thread...

Took the alternator to O'reilly's and they did 3 extended test and they all came back as passing. After what would be a long story about unsuccessfully trying to find an alternator shop I decided to just buy a new one. I went home and put it in and started her up. Alternator was charging 14v. I let it run for about 10 minutes and it was still charging. Took it for about a 30 minute drive so I could get up to highway speeds.*It's still charging, I have no engine codes and my cruise control is working like it should.So, as of now I'm going to say that a bad diode in an alternator may still charge and may check as a good alternator but it can also leak AC voltage that will reek havoc on the ignition system and throw engine codes and screw with*electronics.

He went on to say that he had been driving his jeep for about a week with no issues and no codes... So you may give that a try as well...

Hopes this helps you...

As far as codes, I haven't had my buddy run a scantool yet. Might take it over to Advance soon and have them do it and get the codes from them. I'd prefer to leave it in my driveway while this going on, because I don't want to get stuck at a stoplight or something.

I did do the key trick a few days ago and got the following codes:

12 - Battery disconnected in last 50 key cycles

25 - IAC circuit/wiring fault (this was caused from when we were cleaning the IAC and had started it up, since it was unplugged)

22 - Coolant Sensor out of range or disconnected (plug is cracked and it comes disconnected sometimes. I have it temporarily fixed for now - coolant temp readings are fine)

45 - Didn't really understand this code, but upon searching it seemed to be related to the Neutral Safety Switch. Talked to a Jeep mechanic friend of mine and he looked it up and said it had to do with the o2 sensor. The plug to the downstream o2 sensor has the wiring cut.

21 - o2 sensor wiring faulty (the wire is cut to the downstream sensor)

27 - Fuel Injector control circuit (we replaced a faulty injector, could still have not reset)

55 - End of Code Read

I do have a bad NSS - but that's a whole different issue. The Jeep does have a new alternator, distributor and battery. So I'm not sure if that would be the issue or not. The wonky gauge only happened when I pulled out of the parking lot, and hasn't happened again yet.

I wonder if perhaps the catalytic converter hasn't partially collapsed. Tap on the converter with a small hammer or screwdriver hammer and see if it makes a rattling sound.

That's an interesting point. I'll knock on it tomorrow and see if there's anyone home.

I would say possibly a bad o2 sensor. I know you said its cut so that could be the problem. Mine use to stall out for a few seconds buck forward pop ect... Replace the upstream o2 sensor and it all stopped. So I would check both sensors. Doesnt hurt to replace both. Pretty cheap on amazon to, about 30 each instead of $80 for one at oreilys.

Yeah, that's a good idea too. I think I'll get the codes read on it, start from there, and go ahead and replace those o2 sensors anyway. I'll post any updates to this thread so people searching in the future would have some sort of resolution.

Knocked on the cat, no rattle. Also noticed that when the sputtering happens, the temp gauge goes a bit wonky. On the drive up the road, the temp gauge went back to normal temp (between 195/210) and it drove fine. I'm going to test this theory some more, but I know I do have a faulty coolant sensor.

The question is - is it the sensor itself or the wiring harness? The plug that goes into the coolant sensor is messed up, so I'm not sure if replacing the sensor will even fix it if the plug is bad.

Got the following codes:

P0118 - Engine coolant temperature sensor
P0705 - Transmission range sensor (neutral safety switch?)
P0138 - o2 sensor, bank 1 sensor 2 (I knew about that one)
P0320 - Crank sensor condition

On a 1997 OBD2 vehicle? no way.

Well of course not, you said it's been gutted which FYI is illegal and is subject to a large fine.

I have no idea why it was doing the 2 digit codes. Threw me for bit of a loop once I started researching it more. But that's what it did.

I didn't do it. Previous owner did. I plan on replacing the cat.

Not really sure I understand...

Rule #5 - Illegal Activity
5. Do not talk about illegal activity on this forum. This includes illegal drugs, parties, wheeling, internet use, etc. Violators of this rule will be dealt with on a case by case basis. This rule includes the discussion of removing catalytic convertors, this is illegal and not allowed to be discussed on this site.

Fixed. I had looked over the rules, but I overlooked that one part. I guess I didn't comprehend them as well as I had thought. I apologize. I'll read over the rules again to make sure I didn't miss anything else.