Intermittent miss

jeepjoe43

jeepjoe43

YJ Enthusiast
Lifetime Supporting Member
Joined
Dec 4, 2020
Messages
926
Location
Black Canyon City, AZ 85324
Hi guys,
Took Fluffy for a walk this morning and now I have an intermittent miss.
Drivable, No-codes, just irritating and it has an occasional miss while idling.
She was running smoothly some weeks before I brought her home.
I've Not done a thorough inspection yet, as of this post she's still hot, it's hotter than Satan's sack outside and it's only getting hotter.
After finding Packratticus Bastardicus tail-light damage, I didn't see any other evidence under the hood, but something isn't right.
I suspect I may have further Pack-Rat damage elsewhere.
Going to check plugs, wires, cap, Sensor wiring, etc when it cools off.
Any thoughts?
 
Ooohhh...when I brought home my 91 from down your way it sat and was invaded by them bastages. Chewed up tail light wiring and what I believe to be the wires to the fuel pump. Drivers side just above the rear cross member and up on the tank. Hotter than Satans sack ;) perfect description. Sheesh, here south of Quemado now and its rained every day just about for almost 3 months. Not lots but enough to keep it cool and the weeds happy. Were also 7500 elevation thankfully so its stays cooler. Course I'll be screaming bloody haities come winter when i freezin my nuggets off.
 
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Having just changed the the tank, sender and pump, i am aware of where that harness is.
Giving it's location, it is in prime Pack rat realestate.
That being said, it seems to be running rich when it misses and I'm wondering if might not be a sticking injector.
I'm going pick up some injector cleaner tomorrow after work when I'm closer to Wally-World and see what happens.
I've also wondered it I haven't fouled the O2 sensor by moving it out of the head-pipe to the exhaust manifold.
If I don't warm it up before driving it, it throws code 52, O2 sensor rich.
Pack-rat damage does remain my prime suspect. Cork sucking, Ice hole Bastages...Sons of Magicians!
 
jeepjoe43 said:
Bosch
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I've heard bosch is no good for O2 sensors, at least on the TJs, but I find that shocking. I personally have used NGK and Mopar and both ran the same. NGK came with some super long wiring though, which I didn't really have the tools to nicely shorten the wire (without using butt crimps or solder) way back when, so I eventually got a Mopar. I believe those are all gone but I think the long wiring on the NGK is so that it fits the long length for the 2.5 so they can market the part to fit both engines. 4.0s need the wiring to be shorter which is why it was too long.

It's just a standard 4-pin weatherpack so in this day and age, if I needed a sensor, I would buy the NGK and shorten the wiring myself by recrimping WP pins to the proper length.

Maybe try the NGK, worst case it does nothing and you just return it or keep as a spare.
 
Curious on the 02 sensor relocate. Is it now where by the pipe flange it can still get a mix of the cylinders gasses or picking up a single cylinder mostly? Ive also read numerous posts saying Bosch is not good for these things. No to drag out a story but I worked at a German car parts importer warehouse long ago. The New Bosch platinum plugs can on the market. The owner, a devout and proud German individual, had a new Cherokee and was heading to Tahoe to ski and asked me to install a set of the new super plugs. Upon his return he had me put the factory Champions back in. He said it ran like chit,got terrible mileage and had lost power. I had the same experience installing them in a 78 Suburban with a 350. After years working there and seeing more than my share of failed Bosch products I pledged to never use Bosch anything again. Sorry for the long story...
 
jeepjoe43 said:
I've also wondered it I haven't fouled the O2 sensor by moving it out of the head-pipe to the exhaust manifold.
If I don't warm it up before driving it, it throws code 52, O2 sensor rich.
Click to expand...
I missed this part. I'm curious, why did you move it? I would think the stock location would be better than anywhere else since it's collectively evaluating an average of all the cylinders at the pipe rather than further upstream where it may be feeling one cylinder more than the others.
 
Gilaguy23 said:
Curious on the 02 sensor relocate. Is it now where by the pipe flange it can still get a mix of the cylinders gasses or picking up a single cylinder mostly? Ive also read numerous posts saying Bosch is not good for these things. No to drag out a story but I worked at a German car parts importer warehouse long ago. The New Bosch platinum plugs can on the market. The owner, a devout and proud German individual, had a new Cherokee and was heading to Tahoe to ski and asked me to install a set of the new super plugs. Upon his return he had me put the factory Champions back in. He said it ran like chit,got terrible mileage and had lost power. I had the same experience installing them in a 78 Suburban with a 350. After years working there and seeing more than my share of failed Bosch products I pledged to never use Bosch anything again. Sorry for the long story...
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I've mostly heard stay away from their O2s and plugs, but I've never heard really any factual info or personal experience stories so I've always taken that recommendation with a grain of salt. There are also plenty of good reviews on the YJ Bosch O2 sensor, so it's not always bad I guess.

I've also heard that Bosch is great for other things, especially fuel pumps and injectors. And many of the YJs actually used a Bosch fuel pump from the factory (not sure if mine was Bosch or Walbro but it was still perfectly working when I removed it).

For plugs, after trying the fancy Iridium plugs, I'm back to stock champion coppers. I used to run the fancy ones with the hope of running them longer but really that is a waste of time and not helpful. Better to just change the coppers at their intervals since it gives you a reason to see their condition and the operation of the engine at each cyl. Not like changing spark plugs every 50K is really that big of a deal, it takes maybe 45 min to an hour working really slow.
 
Bosch always had a great reputation until... they split into Bosch Germany and Bosch USA. For some reason the US side doesn't have the same quality control and the parts often fail whether it's their injectors, alternators, ignition coils or whatever else they make. This is coming from many BMW and VW owners and repair shops.

It could be the injector and cleaning it can only help but maybe not solve the problem. How long or what's the duration of the miss? If it's a quick bump that made be ignition related, if it's a one or two second stumble that may be fuel from you single point injector but again it could go either way. Can you tell if the misfire is possibly one cylinder or the entire engine? All four cylinders will give a stronger buck feeling as opposed to a light bump.

I've had good luck using Sea Foam in the tank or slowly pouring it into the intake to decarbonize and clean the intake and valves.
 
machoheadgames said:
I've mostly heard stay away from their O2s and plugs, but I've never heard really any factual info or personal experience stories so I've always taken that recommendation with a grain of salt. There are also plenty of good reviews on the YJ Bosch O2 sensor, so it's not always bad I guess.

I've also heard that Bosch is great for other things, especially fuel pumps and injectors. And many of the YJs actually used a Bosch fuel pump from the factory (not sure if mine was Bosch or Walbro but it was still perfectly working when I removed it).

For plugs, after trying the fancy Iridium plugs, I'm back to stock champion coppers. I used to run the fancy ones with the hope of running them longer but really that is a waste of time and not helpful. Better to just change the coppers at their intervals since it gives you a reason to see their condition and the operation of the engine at each cyl. Not like changing spark plugs every 50K is really that big of a deal, it takes maybe 45 min to an hour working really slow.
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I suppose its a mixed bag on things they make. Its simply a personal preference for me. If it dont give me a warm fuzzy feeling I veer away from some things. Take Mobil 1 oil for instance. Just didnt make me happy the few times I used it. Consumption went way up with M1 compared to other brands "full synthetic" Im just weird I suppose with some things. Obviously Bosch can make quality stuff. After all every Cumming engine uses a Bosch Injector pump still I believe. Cant be all bad even is the one on my 93 literally grenaded the case and all. Recon that's what ya get for cranking up the fueling to far. ;)
 
machoheadgames said:
I missed this part. I'm curious, why did you move it? I would think the stock location would be better than anywhere else since it's collectively evaluating an average of all the cylinders at the pipe rather than further upstream where it may be feeling one cylinder more than the others.
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I moved it because I didn't see that the pipe wasn't drilled at it's bung until after I had it installed.
Didn't drill it out insitu because I didn't want metal shavings in the cat possibly becoming a fire starter from the tailpipe.

At the beginning of my bug hunt, I was investigating the O2 local, Chilton told me it was in the exhaust manifold, but it wasn't.
There was a plug instead, so I assumed I had 2 sensors at the cat, and bought 2, so I now have a spare.

Knowing it would fit there, and having a million other things to while I had access to a lift, I moved it.
What difference would 4" make? Even asked my mechanic buddy and said None.

Ignition misfiring will also cause the rich condition, she used to smell stinking rich ALL the time with the old O2 and exhaust.

I'll be starting my investigation sometime this week looking for rat damage, looking at the plugs, wires, cap.
A cracked cap can absolutely drive you bat-shit.
Suppose it could be the CAM sensor, but there aren't any codes for it.
It doesn't matter, replacing the distributor was already on my to-do list, just haven't got there yet.
 
Update:
Rat inspection, nothing, but it wasn't very thorough still looking.
Poured a bottle of injector cleaner in last night, but I didn't run it.

just finished running running it for about 45 minutes and these were the results.
Same miss at idle after start.
Let it warm-up turned into a dead miss.
Popped the hood to do some tap testing and it smoothed out before I could get a screwdriver.
Revved it some and went back to missing at higher speeds and intermittent miss at idle with a New smell, Sulfur.
Let it idle a little longer and it smoothed out at idle and revs, and it quit stinking.
Haven't taken her around the block yet because my car was blocking and I just didn't feel like moving my 200 degree oven.
Maybe later this evening when I run the freakin' cows out of my yard.

Probably ought to add injectors to the to-do list too, if for no other reason than just because.

Test drive, Crumby at first but then it got hot and ran great, it got hot because the fan relay wasn't kicking on.
Not terribly hot 220-230, this is starting to smell like an O2 sensor.
Who'd a thunk 4" would have made a difference?
She idled without a hiccup for another 30 minutes without a blip.
 
Sulfur stink sure sounds like a loaded up cat or failing one. Probably sounds funny but I must be super sensitive to smells. I took out my Champion uber super tip plugs,whatever they were and installed plain old copper plus cheapo plugs. The exhaust smells different now,seems to run the same but..... Sounds like your on the right track.
 
The sulfur smell threw me, one would think it's the cat, except it's brand new along with the rest of the exhaust.
It only did it briefly and went away.
I think maybe it got a heavy snort of injector cleaner that hadn't quite mixed yet.
 
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