Hello,

Lifetime lurker but on the move to restore an inherited 1988 Jeep Cherokee 4L Renix. I have read most of the O2 posts.

One of my parts I wanted to replace was the Oxygen Sensor. Running down a rough, backfire idle at start. Calms down after like 30 seconds.

One part of this question I could have solved if I had the issue 3 years ago. But, it has come to my attention that the O2 sensors of that particular year are not really made anymore. Well, they are but not in the Ceramic body style. Most articles/posts here describe the old type sensors that when people order, they get some metal type of design thats "supposed" to work but fail quite often.

(not listing all but some example)
NTK23553
BOSCH12009
WALKER PRODUCTS25023501

All show ceramic stock photos but are shipped metal designs.

Now, I have read about Titania sensors, I have read that NTK/NGK are some of the best sensors, BUT reading RECENT reviews suggest the conversion from the Ceramic style body to the metal style body have made these sensors less reliable for the Renix engines. All this info makes my head split.

So, does anyone have a Renix that you recently had to replace the O2 sensor, had luck with a new style brand, or know of a brand that still has the old design and is somewhat reliable and not give me issues in two months. I don't want to throw money at a wall with the O2. I live in an area that has one parts store so, I cant exactly go to 40 stores looking for old stock.

Also, I know of all the tips to do. And I am working on it. This jeep is at 120k. Other posts have asked something similar but didnt really have an answer.

Any help would be appreciated. Thank you.

 

O2 sensor really shouldn't be doing anything for the first 30-seconds after start. Possible that something else is throwing the mixture off, and the O2 sensor is actually correcting it? How's it run at wide open throttle when it doesn't use the O2 to correct the mixture. I'd wonder if you have an injector leaking fuel into the cylinder or letting fuel run back to the tank. Does it improve if you cycle the key on-off a few times first? The fuel pump only runs for a few seconds at key-on, and stops until the computer sees the crank turning. The on-off trick gives it some extra priming.

 

If you do decide it needs injectors, there's a few guys on here that test and sell refubished Bosch 4-hole injectors that work well. For an 1988, the Bosch 746 are a straight drop-in. I've been running them since my 89 started weeping gas out of side of an injectors.

 

I put an NTK on my '88 just over 2 years ago just before smog check then and was able to still pass CA smog with no problems last May. Another brand I use is Standard.

Check your TPS adjustment.

Also check out http://cruiser54.com/

 

On an 88 I would complete Tips 1 through 5 at www.cruiser54.com before doing ANYTHING else.

I agree totally with you on the O2 sensor situation.
What happens is the heater section of the sensor fails. Or, it has low voltage or bad ground.
You guys need to take an ohmmeter with you to the junkyard and test the O2 circuit resistance. If it's 8 to 13 ohms, grab that sensor. Orange to black wire for your probes.

 

I'm right at a year and 5400 miles on an NTK 23553. It has the metal body, but I have not had any issues with it. Have you considered purchasing a REM II (RENIX Engine Monitor) from nickintimedesign? The O2 sensor slams data really fast once it gets going, but lawson is correct, it doesn't do much until the engine goes into closed loop after start up, which is about 30 seconds.

 

Sorry for the late reply, been under the weather. I am going to go ahead and get the NTK O2 dmoe69. I don't believe I have much of a choice as I have one pickapart type junkyard in all of Maine, Kennyupull. And as you can imagine, Im not the only Cherokee owner to go looking for an older O2 sensor...

Also went ahead and ordered a new tank, pump, filter. I did a fuel pressure test and it holds no pressure. From what I gather this is common when these old pumps sit for a long time.

I also am planning on the injectors lawsoncl, I think they have been replaced before. One injector I noticed looks like 1/4 inch higher than the rest. Having done injectors before on other cars, I can bet money, whoever left a seal in the hole and just installed it on top. It doesn't leak, but I'm smart enough to know, that doesn't look right.

Ordered new cap, rotor, wires and coil (coil is in case, I think mine is still ok wasn't very expensive). Reason is I noticed two plug wires were different than the rest. I don't know why I didn't notice it before, but I did now. Did the coil clean,refresh on this already.

Working on steps 1-5 of Cruisers path to makin Cherokees run ok... Did the neutral safety switch clean as I had no reverse lights. Converted to an open radiator system. From what I was told, it had an overheating issue. So instead of trying to chase down a gremlin, I replaced it all and started from scratch. Waterpump, OE thermostat. Hoses, radiator, etc.. new temp sensor back to original location, they had moved it to the thermostat housing. Pff... new shroud old one was missing. Now I can FEEL the pull of air from the front. Throttle body clean, gaskets, IAC clean... both rear brakes were non functional, so, they are all rebuilt.

Also looked into Nicks Rem II for awhile now, but as he stated Covid has reduced his available parts and a backlog and high demand have made an endless out of stock option.. So, still monitoring.

The backfire is weird, for like the first 30 seconds, maybe minute or two, time flies when frustrated, it runs horrible, If I throttle it it will stumble and backfire through the intake. Like I put a firecracker in the throttle body. pop pop pppop. If I let it sit rough idle, It will clear up and run great. Throttle response is great. It was odd. I am wondering if I did something to cause this. It didnt use to backfire when starting. Sometimes cleaning things creates a problem. After reading some more after Saudade mentioned the TPS. I didn't mess with it, but, maybe it got some cleaner in it through the side of the intake.

I do live in Northern Maine, vehicle is from Houston, Texas. So, old, no rust at all. I do appreciate all the help and suggestions. Just wondering if its worth putting all this work into. I know its a "Jeep" thing. But I'd only use it on our loggin roads to go fishing, I dont plan on rock climbing.

One more thing to Cruiser54 if he happens to read this, I read your write up on TPS adjustment. I do have a question, since my renix jeep is auto. So engine issues is the 3 prong. Transmission issues is 4 prong. I get that, but in theory say your engine is running fine but trans is acting up and you need to adjust the reference,output etc... But wouldn't that also throw out the values for the 3 prong plug, engine side? Or vice versa? If my transmission is shifting fine, (as it is) and the tps needs to be adjusted on the 3 prong engine part, couldn't or wouldn't it mess up the values for the transmission part? I just dont get how the TPS can separate the two settings with one adjustment..

 

You're doing great.
As for TPS, I always rely on the Engine side adjustment.
What people don't realize is the auto trans TPS has 2 different TPSs inside. One for the engine and one for the trans. They work backwards from one another.
Adjust with the engine side. That side is more tempermental than the trans side. When you're on the trans side, it's for diagnosis, not adjustment. It is very forgiving.
Don't go adjusting anything until grounds are verified in Tip 5 and fixed in Tip 6.

 

Ok so, Im one of "those" people who forget to followup a post. A little late for sure, but I did fix my stumbling issue.

Of all places, it was my distributor. The camshaft position sensor was broken inside and flopping around. I never thought to look at it and I think I read a post by Cruiser54 about another topic saying that the distributor/ecu/distributor indexing is a dumb system in that if the distributor was broken, the ecu would figure out the timing and keep the jeep running even out of time. Then I checked, with a flash light inside and sure enough it was flopping around under the pulse ring. Here is the weird part, the pulse ring edge was bent down for some reason, maybe prior owner, who knows, but that bend down must have contacted the cam sensor plastic and broke it.

I did get an Carquest Distributor as there doesn't seem to be any decent ones around, I did check to make sure the drive gear was not out of sync (the 180 degrees off thing with the pin) and that thing fired up and ran so smooth. I did run into another issue of the crank sensor needed to be replaced as prior owner did not route the wires away from the header and it melted. So... fun times. But, it popped in my head to come here and finish out my post. Late. But, finished. I appreciate everyone here helping.

 

Ps. I did the grounds.

 

Hey, better late than never. Thanks for posting back.

Had a similar thing on my '88. Failed smog, did a full "tune-up". When I went to replace the cap and rotor and found the inside filled with a fine silvery dust. Sensor tip broke off and the ring slap chopped it into dust.

Did you do the distributor indexing Tip 13?

Cylinders #1 and 6 reach TDC at the same time. The ECU gets this from the CPS. But which one in on compression? ECU gets this from the camshaft sensor. So it takes a few revs (until it reaches 300 rpm) to sync the fuel injectors with the spark plugs (that why the cam sensor is really the sync sensor). Then the ecu starts the sequence. If there's no sync signal, it basically takes a guess as to which one is at TDC. Initiates the sequence and if no start, tries the other one.