Bakerunc

Hey guys, so my 97 XJ which I have had for awhile has recently been going through some pains. Recently did a tune up on her, including: the Distrib. cap, new NGK plugs because store didn't have enough champions, and new wires. Had to change out the solenoids for the transmission wasn't shifting into overdrive..ok check all running good. Decided since I some muck in the radiator (was on it when I bought it) I decided to buy a manual radiator and put an external cooler on it for the transmission..ok check all running good!


NOW...yesterday I get the wonderful p0301...misfire on cylinder one. Immediately when I get it home from work, checked the resistance on all injectors and reading 13.0 Ohms. So then pulled spark plug on #1 cylinder and it wasn't fouled nor was #5 cylinder ( though they did have like a ash color to them no build up though??) but switch the two just in case annnnd still getting the p0301 code within 5 minutes of it idling. Now it did idle slightly rough I noticed before I got the CEL, stayed around 750 but was like a sputter every couple second with very minor vibration. Now and then I'll crank it up and I will smell what seems to be like its running rich at time but have never gotten any codes for 02 sensor or anything and the rich smell goes away almost immediately after smelling it. I do feel like from the sound of the jeep when outside of it, that it sounds like there might be a exhaust leak mid way around the bell housing. But have not confirmed.


I have read that Cam sensor has given folks problems? So maybe just get a new one of those? The 97 has coil packs correct not the rail like the 00+?

Current compression results as of tonight, erased code and hasn't came back yet but it has just sat and idled:

1st-115
2nd-120
3rd-115
4th-120
5th-110
6th-115

Bustedback

The the 97 has a distributor and plug wires, not individual coils or a rail, the cam sensor is right under the rotor, very simple to replace.

tjwalker

Question. Did you ever have the cylinder 1 misfire BEFORE you performed the tuneup? If the answer is no, then it is very possible that your misfire is being caused by something to do with your new tuneup hardware.......you'd be surprised how often new things fail, especially early in their life. So plug wire, distributor cap are in play here. If you have your old ones, I'd swap them back in one at a time as an exercise in ruling them in or out. I'm not saying that is your problem, but it is something that you have to consider.

As for injectors, you checked them electrically with an ohmeter and they were in spec, but that doesn't mean that they couldn't fail functionally.

If this were my XJ, I'd proceed in this order. Swap plug wire and run it and see if code keeps popping, then swap the distributor cap, then swap the #1 fuel injector with another cylinder and see if the misfire follows. Your compression is fine.

A very methodical strategy is your best bet here. Good luck and keep us updated!

Bakerunc

Yea, CPS is a super easy fix especially compared to dropping the oil pan but I learned some tricks there for next time.

Thanks TJ for your insights!, I did over the look the potential for some of the parts I replaced like the cap and wires. Im ball parking cause I can't remember specifically but it was Fall sometime last year when I did my tune up because I had CEL and rough running issue. So up till now no problems. I let it idle for about 10 minutes last night and never got a code. I have to run some errands close to home today so I plan to drive it and see if it comes back. And I can check for pending codes. If it does I will swap out the plug wire first, then cap, move injector, and if that doesn't work well then I'm going after the sensor under the distrib. I'm guessing.

I'm just glad that the compression was good

Firestorm500

Actually the compression looks low to me, although they are all within a few points of each other.

Do you have any unexplained coolant loss?

cruiser54

Good possibility there is a bit of carbon under a valve.

There are ways to treat that, but check out the stuff Mr. Walker highlighted first.

Bakerunc

There were some coolant lose issues before I replaced the radiator, the over flow tank would not stay full. But since I replaced that and added an external cooler, my coolant stays full now.

I haven't compared my numbers directly to others but I think I remember seeing one xj with 140's? on compression. What would you recommend to treat carbon build up? The newest update I have is that I drove today for a total of probably 75-80 miles and still no CEL regarding a misfire so I have not tried to swap anything since for a full day I have no CEL and no pending codes. XJ has ran great as far as I can tell. I am pretty sure I still have an exhaust leak but other than that?

cruiser54

Let's see if it returns.

It wouldn't hurt to grab some BG44K and add it to a full tank of gas. Run the tank down to half and fuel up again. Run that tank as close to Empty as you dare before filling up again.

Bakerunc

So still no more misfire code! drove it all day today. Tomm I think I am going to use some seafoam in the vac line since I can't find the BG44k around me. At least see if the seafoam and maybe check the compression again after.

tjwalker

Your compression numbers really are okay; it's more important that the compression results of all the cylinders be close to each other. And yours are.

While your numbers are just a smidgen low, (120-150 is spec) your results are not at all unusual. I've sometimes found that slightly high or low numbers can be related to the compression gauge itself. Try a different gauge and it might read slightly differently.

But even if a different gauge reads the same, compression is really not a problem with this engine. I would not get hung up on chasing this.

cruiser54

Seafoam sucks. amazon has 44K.

Bakerunc

Thats what I have gathered from reading...Have you tried anything else other than seafoam and 44k?

cruiser54

Water.