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Renix woes


zjrog
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So the story of the 90 XJ from hell has already been told. But as a reminder, it started running like crap during the a simple drive to college, and ended with overheating and making it home behind my ZJ. The XJ is a 1990 with 199,000 miles on it and probably needs a bunch of stuff swapped anyway. Also, someone used to like this rig and took care of it. Evidenced by past work in front and rear diffs with non-original sealant and a newer rad and waterpump and other parts.

 

After a friend of mine stopped by and we are comfortable that the headgasket isn't trash, we decided not to run compression test. Also, it was decided that I need to run some Seafoam through the tank and the motor. Admittedly, I was awefully frustrated and didn't really touch the rig much. I did talk with another friend (who used to work for Year One) about EFI and I did try a couple things. I unplugged the O2 sensor and all I really got was some backfiring that I didn't have before. I also repalced the plugs and distributor cap and rotor. I didn't replace the wires (yet) but had spark at all 6 wires anyway

 

So I went about trying to find the coolant leak and decided the radiator had sprung a leak somewhere. Couldn't repeat the issue, but didn't trust the rad. Considered a three row all metal unit, but this rig won't be a hardcore offroader nor will it tow. It will see some minor trails and in the future a 2" lift on 235/75-15s. Back to the task at hand, the rad was replaced with a single row stock replacement. Again, some stuff looks newer, so I reused the upper and lower hoses (they both still have tags on them!) and feel pretty solid. However we went and replaced all the heater hoses. Again, the waterpump appears newer, and the thermostat appears to have been replaced, so I left them alone. For now. Along the way, everything has been flushed, tons of chunks came out of the heater core and now we have heat in the cabin (my daughter will appreciate that in a couple months).

 

I also checked grounds and it seems they are all in place, but after some more thought, I'm not going to trust them, and redo every @#$%ing ground, even adding some for redundancy. When I did the grounds on the Ranger, I probably overdid it. But I don't ever want grounding issues to sideline the Warthog. Likewise, the XJ is for my daughter so I don't want it stranding her due to grounding issues. Kind of the same reason I gave a friend of hers a spare tire and wheel. My daughter will be riding in the friends XJ and a real spare instead of a doughnut will help them both.

 

So, the O2 sensor was replaced, Seafoam sits in the tank, hoses and rad replaced, new fuel filter installed. I will say that the thing is starting a little easier, but still runs rough above idle until about 3000 or more RPM. Seems the Throttle Position Sensor had been replaced before, I felt it might be bad, so, the replacement came in today and I swapped it over. Previously, the lower mounting screw had been cross threaded or such and is really munged up. It has been slightly modified now to fit a standard 8-32 screw. I followed the TPS adjustment, setting the proper 4.2 volts at throttle fully closed. Finished putting all the vacuum lines back and started it. Damnit, no real change. WTFO?

 

Twice today, I had the XJ running for better than 45 minutes at a time. No overheat sitting. I do not have the front header panel in place, so I'm not driving it around town to see if it overheats while running it badly.... I did run Seafoam and let it sit a while and restarted it. Neighbors were outside and thought I'd lost my mind and finally decided to burn it to the ground. Smoke cleared but the thing still doesn't run right. I did spray just about everywhere there was a vacuum line with some brake cleaner. The thought process being it would either rev or want to die, but no, no change.

 

So what I'm considering next, whether it makes sense or not, move the distributor back and forth in case the timing is screwy. Maybe the MAP sensor is whacked, or maybe replace the intake/exhaust manifold gasket. I'm just not sure what to try next. I'm at the point now of not wanting to spend any more money without a better direction to aim for. The sooner I get this done, the sooner I can decide if I'm fixing the Ranger front axle or going solid. Ideally, I want both rigs done before snow flies. Because I want my ZJ back so I can do the lift and throw on the 31s. Ideas and thoughts are more than welcome here. I'm frustrated and at my wits end.

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The timing is not adjustable. You can't rotate the distributor because it is locked in place with locating ears. Timing is taken care of by the crank position sensor (CPS) and cam position sensor.

 

There was a very old tech bulletin about cutting off the ears to "index" the distributor, but if it made it to 199,000 miles, it doesn't need it now. The indexing issue usually arises when installing an aftermarket camshaft that doesn't have the drive gear correctly indexed to the cam profile.

 

You might think about the cam position sensor in the distributor.

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I was wondering if the cam sensor/synch signal could be my culprit. If it were the crank position sensor, it would stay running at idle for nearly an hour and would be very difficult to start (unless I'm missing something...).

 

Thanks for a different direction to look for.

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Easy enough to check. The timing isn't adjustable, but there's still a timing index on the front cover and a timing mark on the vibration damper. Clean 'em up, hook up ye olde timing light, and see what it shows.

 

Excellent idea. I still have ye olde timing light, and the marks are there on my HO too. So are the marks supossed to line up if correct, or will I be able to see the advance, as in ye olde engines? :cheers:

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Gee, do I even have ye olde timing light? I'll have to check... WOW! I still have it! Haven't used it in at least 10 years!!!! So, tomorrow after I get home from work, I'll warm up the sick beast and run the timing light. So, am I looking for the timing to hold steady at idle, or will it bounce around some? Or bounce a round a lot? I'm REAL rusty on ye olde style mech troubleshooting. Damn computers...

 

Let me backtrack and fill in some details, since my original post was also posted on my local club board.

 

Ever since I bought this back in December, it has had a bit of a stumble at throttle tip in. doesn't matter what throttle position, vehicle speed or just idling. My daughter drove this rig over the many months, often for hours on end on dirt trails (nothing difficult). I've driven 100 miles roundtrip a couple times with no problems. So it was a surprise when the XJ started skipping and missing and losing power. We limped it the rest of the way to the nearest town as it could be revved to keep it at speed when floored. In the last mile before entering town the temp light came on and I drove the last mile anyway. Once parked it was apparent it wasn't going anywhere on its own, so we rented a Uhaul dolly and dragged it behind my ZJ the rest of the way to school (the XJ was loaded with my daughter's stuff since we were moving her into her apartment at school). By the time I got the XJ home, my ZJ had been abused for over 200 miles and I ignored the XJ for a week.

 

With everyting I've done now, i haven't even tried to drive it because it still skips badly when I run the throttle up. But it still idles smooth and can be revved above about 3000 RPM.

 

I'm frustrated but the rig is well worth saving especially since I just had it painted a month ago... John Deere Yellow...

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I believe there should be some advance at idle, but I don't recall how much. In the case of the sick beast, if there's suspicion of a slipped tooth on the timing chain I'd be looking for the timing to be right off the scale. Since I have 277,000+ miles on the original chain, I doubt very much that's the problem. I'm more suspicious of the cam position sensor in the distributor, and for that I'd be looking for erratic timing.

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SO I stayed up too late last night, and sitting at work this morning got a call from a friend of mine with more EFI knowhow than I have. Adn he agrees that the chain isn't the most likely cuplrit. But he was asking about the cam sensor/synch generator. Does the pulse ring in the distributor have just 6 windows in it? Or like other systems, does it have a high resolution and low resolution sensor? Seeing there are just three wires I'm guessing just the 6 windows for the pulse ring. Can't seem to find a picture of the pulse ring other than straight over the top.

 

Sucks to be at work when I want to work on the sick beast.

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Have no Idea other than double check the fireing order to make sure plug wires are all on correct plugs, Do the compression test, and hook up a vacume gage. Check fan clutch. Fuel pump,filter.I have a problem with fuel in my Dodge Ram not wanting to burn properly below 1/4 tank,try adding octane boost 104+ or just more gas maybe 89oct.

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went through the same thing with my 89 comanche 4.0 Ended up bein my fuel pump. check the pressure on the fuel rail. also i had to replace my injectors, seems like the commonly go out about 150k. mine had about 160k on it. it would start and run but no power and would stumble unless revved over 3 grand. it just gradually got worse.

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Well then, last night I went out to check on the following, fuel pressure is nice and squirts quite well, across the RPM range. And I changed the fuel filter last weekend. So unless I have bad injectors, or so I thought last night, it must be somethieng else. Next I tried to backprobe the cam sensor connector, but my little cheap digital meter doesn't have long enough probes, However when I disconnected the connector, I had a good ground, a 5 volt line and a 8 volt line (not sure what the 8 volt is for though...). I also pulled the dizzy cap and the pulse ring was tight (I had already replace dthe cap and rotor and all looked great...), removed the pulse ring and didn't see any damage and the cam sensor looked to be in good shape visually. I broke out the ancient tech timing light, and while I didn't spend much time cleaning the harmonic balancer or the markings, across the RPM range, the spot I fixed on stayed pretty much in one spot. It was starting to rain at that point last night so I buttoned everything up and called it a night.

 

This evening, my buddy brought over his compression tester. We originally ruled this out a couple weeks ago because we THOUGHT the idle was OK and it wouldn't idle if the headgasket were bad... Well, we were idiots. So, if I recall this correctly, we had 150 in cyl 1, 142 in 2, 135 in 3. See a trend? 120 in 4, 90 in 5 and 126 in 6. So, we/I wasted 2 weeks and more than a few bucks. But then again, now I kow certain things are just fine. But it looks like I will be doing the headgasket this weekend. No great mystery, as I did the headgasket on my ZJ last year. And while we have the head off, I'll do a quick look at the pistons and see if maybe the rings are OK or not. Easy to check with the head off.

 

Though, it kind of makes me wish I had done some things a little different. Last year when I bought the XJ, I ALMOST picked up one for parts. The idea was to tear the motor down and rebuild it just in case. Now, I wish I had. Can't go backwards.

 

So at least I know what I'm doing this weekend... :mad:

 

Thanks for all the ideas though!!! :cheers:

 

Edit: My friend actually wrote the numbers down, I went off memory... I guess I shouldn't do that... 155 145 130 120 100 140 Either way, 5th cylinder is dead and took a couple with it.

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Easy enough to check. The timing isn't adjustable, but there's still a timing index on the front cover and a timing mark on the vibration damper. Clean 'em up, hook up ye olde timing light, and see what it shows.

 

I guess that's a Renix thing; no marks except for one on the damper and nothing on the front cover. I stuck ye olde timing light on anyhow, and it was rock solid at idle, the reved it up to about 2K RPM and beyond and it advanced about an inch on the damper, still solid all through the RPM range. No marks so it told me nothing except the timing was solid and I had advance. Good reference maybe for later though I guess.........

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Well, picked up the headgasket set and an O-ring set for the injectors, so here is today's update...

 

So, after I cleaned the garage a bit so I could back the XJ into the garage, my buddy Scott swung by and we tore into the beastie. Disassembly was only a little challenging with the last couple manifold bolts are really tough to get to for bigger guys like Scott and I. I had to go get some new sockets as I didn't have any deep well 1/2 drive 16mm. Scott is a monster and tried really hard to break some of my tools, but then, they are cheapie stuff. One 3/8" drive ratchet has a misshaped square and one short extension is twisted, and one 1/2-3/8 adapter. But I will say that it was easier with two than when I did this myself on the ZJ last year...

 

So, what did we find? Nothing earth shattering. No blown through sections on the headgasket. No cracked pistons, nice clean cylinder walls. Though the ridge at the top of the cylinders is pronounced, it does have 199,000 miles on it. There has been some leaking between 3 and 4 and between 5 and 6.

 

 

Looks like some exhaust leaked into the oil galleries, but there was never any excess pressure in the PCV. And some carbon on the rear stud...

 

So the plan for tomorrow, is to do some cleanup on the block, the passenger side is pretty greasy. Try to get some head oil and coolant passages cleaned up and put the thing back together. What is obvious is that I will need to run a coolant system flush/cleaner to break up some of the mess in there, and of course a oil flush or a run some ATF or Marvel Mystery Oil to clean the oil system out.

 

So what is next to go wrong with the XJ? I mean, you'd think it would be happy to be a nice fresh color... And new rear axle bearings, and new hoses and TPS and O2 sensor and...

Considering what it looked like when I bought it.

 

Really want to get this thing out of the way once and for all so I can rehab the front axle or swap it for a D30 on that Ranger...

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I'm undecided on the spare parts I might be collecting. I can get a well robbed 87 XJ 2 door with an unknown condition non-running motor, to trans or tcase. Origianlly had a pukegoat 5 speed. So the D30 probably has 3.07 gearing so if I were to use it for the Ranger, I'd need a different carrier for 4.10s or maybe 4.56s... But might just use the XJ as a trail trailer. Make it simple and easy to pull for my ZJ.

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  • 1 month later...

Been over a month since I pulled the head off the XJ and since my last post. I've been sick and have had surgery since and 10 days ago a friend helped me put the head back on. Took my time cleaning parts as I went, and got it all back together. I was hoping for a nice running machine. But...

 

Started up once I had fuel pressure. Idled OK (but it did before too). Had a fuel leak shut it down. Fixed the leak... And, it still runs poorly, but at least it isn't backfiring.

 

Quick rehash of previous stuff looked at or replaced. Radiator and all hoses. Distributor cap and rotor, plugs and wires. Checked all vacuum lines. Replaced O2 sensor. Replaced TPS and adjusted (and adjusted again after headgasket swap). Headgasket and all other associated gaskets. Replaced injectors because one was missing the nozzle, replacemetns were from my parts XJ. Again checked that everything was plugged in and in the right places. I also replaced the 1990 gauge cluster/idiot lights over to 1987 full gauge cluster and changed the coolant temp sensor and oil pressure sender, so I can see what is going on (and everything works!!).

 

So here is what it does. It is a little hard to start, but will start. Settles into a smooth idle, but then will either surge to about 2000 RPM, or drop down to almost nothing and try to die. If I add throttle, sometimes it revs at that point sometimes it dies. At the nice smooth idle, if I add throttle, sometimes it revs at that point sometimes it dies. The exhaust smells a little of gas, but not excessively.

 

Last night a friend suggested MAP sensor (which in my first post I suggested, but had since forgotten about), and in another forum last night it was suggested the IAC motor and the EGR... So I have three things to look at when I get home. My friend that suggested the MAP sensor is pretty sure the Crank Position Sensor is OK since it starts and stays running.

 

Ideas, thoughts?

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So I got the CPS the other day, put it in today. Man what a pain in the butt that is!!!! But there was no change. :mad:

 

And so I pulled the Ignition Module from the parts rigs. No change... :no:

 

Back to the parts rig. Pulled the distributor, I mean, it COULD be the cam sensor... Umm, no. By this point, I'm very frustrated. EXTREMELY... :headpop:

 

So I go back and look at everything I've done to this point. Touch everything and check every connector. Again. Check all the vacuum lines again. Decided to take a break.

 

Since I thought the CPS had to be the deal, I didn't check the fuel pump, but there was fuel at the rail, and I don't have a pressure gauge. Wish I did!!! Fuel pump pulled and HELLO!!!! The little 3" length of hose INSIDE the tank is ROTTEN!!! I pulled it off the fittings, clamps and all, by HAND!!!!

And the clamp wasn't even fully on the fitting... :huh???:

 

Started it up, and it settled into a REAL nice idle. REALLY nice. Blipped the throttle, no stumble and it kept running when I let the throttle go. Decide to take it for a spin... Hey, this thing has BALLS! Well, compared to the best it ran before. Spun the tires around a couple corners. :brows: Pretty happy, this things run really good now. Now I can finish the cosmetics and install the console from the parts rig.

 

I think I earned a couple brews... :cheers: :cheers: :cheers: :cheers: :cheers:

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Congrats.

 

And yes, I was surprised also by how much power these engines have after I got mine to run right. In my case it was a broken plug wire causing me to run on only 5 cylinders. Gas mileage stunk also, but now I get 24 mpg on the highway if I stick to 65mph. Not bad for 21 year old truck with a 4 liter engine and auto transmission.

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Well, buttoned up the front of the XJ, replaced the bent bumper with a nice chrome one, dropped in the center console from the parts rig, and generally got it ready to give back to my daughter. I took it for another spin this evening, and am very happy with the performance. Its fun to drive right now too. It could snow a little this week so I might even get to do some MINOR snow wheeling...

 

If I can get the longer U bolts before my daughter gets home, I'll do the 2" coil spacers and rear lift blocks. Otherwise, that can wait till XMas break when it also gets a different set of wheels and tires.

 

Now, i can get busy stripping the parts XJ. The front axle is getting new gears and will go under my 90 Ranger. I do have to fab some long arms and mounting brackets. But should be pretty straight forward to swap in... Just maybe, this will be doen so my son can take that with him for next semester at school...

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