Was hoping~ engine trouble too soon!

[Infidel Edition]

OK. '89 RENIX... 185,000 mi.
Within the last year:
new plugs
new cap and rotor
new TPS and CPS
new O2 sensor
new battery
regular oil / air filter... etc.

I just picked up a head from a friend that I'm going to rebuild and was going to do the rings and everything (like a middle up engine rebuild) when it gets warmer.
There is a "perspiration line" from the head gasket down. Not a solid leak. But a sign that it's gonna go in the next 5,000 / 10,000 miles for sure.

Also, I ditched the AC compressor and most recently, change the nurf ball vacuum can for a softball sized ~ relocated by firewall. * ditched the vac.disco on the front axle so the can is now only running the climate controls.
* could that be the issue?

I don't burn much (if any) oil. No really. I've gone on road 600+ mile road trips with less than a 1/2 qt. loss.
Though once or twice, I've burnt off a full qt. in a 300 mi. stretch.
* oddly, the oil loss is on the same mountain stretch as the non-loss. So temp related?

I don't know if it's related, but I just posted the brake issues. = peddle goes to the floor like there's no back pressure. gotta pump the peddle a few times...
Vacuum loss = maybe the issue running into the engine?

I've always had a random "high idle" sometimes it's 1200 rpms - other times 700... And I've been hunting for a vacuum leak that would be related...

OK. Now to my issue.
Back in Sept, I had the issues where after the long drive (900+ mi. at 85mph speeds) it sputtered and died at the main gate. A few hours later, it ran fine.
The assumed issue was the TPS ~ I adjusted per instructions and all was well.
Over the last weekend, I had a similar issue. However, it was at 45 / 50 MPH on the highway. 300+ miles into the drive. I thought I had water in the gas.
The engine just crapped out for a moment = pumped the gas peddel and nothing ~ stalled... popped the clutch and started back up + back fire?
Ran like crap for the rest of the sub-zero drive to KFalls.
Put a red bottle of Heat in the tank. All was fine.
.........not the brakes, but the engine..........

Then, on the way home, going over the pass (ice and cold) it sputtered a few times when I was stuck behind a slower moving vehicle and had to downshift.
But after I passed them (yes, it was a passing lane) and got back up to 50 mph, all was well for the rest of the trip home.

I'm gonna do a compression check this weekend (after I find my gauge). But it doesn't act like bad compression.
-no oil loss issues / starts fine and idles fine / AWESOME fuel economy (highway better than 25 mpg on average)...
I'll also look at the plugs for discrepancies when I check the compression.

It's running ok again. But I don't want to get stranded in the middle of ?? next month.

What other info is needed?

Ideas?

[Brasscatz]

Hmm... I have an interesting issue somewhat similar that I suspect is my engine grounds. Mine hasn't gotten bad enough where I have gone in to fix it. Has happened a grand total of 4 times in 2+ years of owning it. Especially check that braided ground wire going from the back of the valve cover to the firewall. Clean up the connections real good, maybe even replace it with some upgraded wiring.

Now the other fuel related possiblities: Fuel pressure regulator, pump/filter, injectors

[Infidel Edition]

Hmm... I have an interesting issue somewhat similar that I suspect is my engine grounds. Mine hasn't gotten bad enough where I have gone in to fix it. Has happened a grand total of 4 times in 2+ years of owning it. Especially check that braided ground wire going from the back of the valve cover to the firewall. Clean up the connections real good, maybe even replace it with some upgraded wiring.

Now the other fuel related possiblities: Fuel pressure regulator, pump/filter, injectors

Did the big 3 upgrade too~ upgraded generator and lines. But the ground line is off the side of the block.
Is there another braided line on the firewall side? didn't notice anything. Might be MIA from the PO?

replaced the fuel injectors with the neon injectors way back as well. But still the same regulator.
I need to do Comanche91's fuel gauge mod!
Guess now is as good of a time as any.

[Brasscatz]

Yep, there are 2... a ground strap drivers side attached to head and runs to firewall, looks like a wide braided strap.. The other passangers side on the block to fender I think.

I'm trying to find pictures of it

[Brasscatz]

Ok, looks like this guy replaced his with a better gauge wire, but this is the one I'm talking about (red one)

[Brasscatz]

Well gee... I should've continued looking at the pictures before I posted that last one lol. here's a better pic, and the link to the page I'm looking at.
http://www.jeepforum.com/forum/f11/replaced-engine-ground-strap-writeup-lots-picks-444082/

[Brasscatz]

Of course, I don't know if RENIX Jeeps have them, I just realized that. I need to stop skimming posts and actually read them lol. It may have them, but I've never had first hand experience with renix, so I'm not sure.

[Infidel Edition]

Of course, I don't know if RENIX Jeeps have them, I just realized that. I need to stop skimming posts and actually read them lol. It may have them, but I've never had first hand experience with renix, so I'm not sure.

I don't know either...
Wasn't 1 when I got it.
But if there was, I'd think there'd be some sign of it missing ~ I'll have to dig around.

[xj-jake]

Here you go guys this link should help. Renix Jeep help

http://www.jeepforum.com/forum/f140/cruisers-mostly-renix-tips-1304879/

[Infidel Edition]

so the old jeep guy at work said... computers going bad / got a short.
anyone know a good check for that?

[Brasscatz]

Just for grins, give this a shot. There's a jeep issue I learned about where there are two little screws in the PCM that can cause it to short and in turn make the Jeep sputter and die. I'm interested to see if this fixes it. http://www.xjtalk.com/showpost.php?p=169553&postcount=55

[Infidel Edition]

Just for grins, give this a shot. There's a jeep issue I learned about where there are two little screws in the PCM that can cause it to short and in turn make the Jeep sputter and die. I'm interested to see if this fixes it. http://www.xjtalk.com/showpost.php?p=169553&postcount=55

so this plug is under the overflow on the engine side of fire wall?
or something under the dash?
the computer is steering column side, center dash...
not sure if there is any connection on engine side:confused:

[Brasscatz]

I haven't seen it on an 89, but yeah the computer is under the dash on yours.

[Brasscatz]

Ok, so I found a diagram of it, not sure how much it will help ya but you could possibly test it by following the instructions on this link: http://www.justanswer.com/car/2dnvt-intermittent-start-1989-jeep-cherokee-engine-will-start.html

The guy's problem differs from yours, but there is a diagram and testing process in there

[jimmixj]

The computer in the 80s XJ is A JTEC board usually located on the fender or firewall. It is easily identified by 3 rectangular plugs going into a box about the size of a CD player. While your jeep is running give the plugs a shake by hand, usually in my experience the plug closest to the wire loom that carries the 3 plugs, and see if you can duplicate the symptom. Also, check your Crank Position Sensor and/or connector; the CPS is mounted in the top of the bellhousing on driver's side and the connector is usually right on top of the Intake in that same area. Dirt and time combined with vibration can cause all sorts of gremllins in the ECM cicuits. AS for your lo pedal/ hi idle; sounds like your brake master/ booster has reached the end of the road. The master causes the fall-away pedal, you will be able to fool it by stomping the pedal but soft feel will return on next apply. Vacuum leak in booster is easy to identify; with engine idling and vacuum gauge attached to intake, depress and hold pedal. You will see a drop in vac corresponding to an increase in idle. Hope this helps and Good Luck!

[jimmixj]

Oops! Guess I didn't read far enough into your post either! (See Jim? You're not alone!) Just reread your original post and saw that you have already done the CPS, so it's a safe bet that's not the problem. The ECM connector is most likely the culprit; I've had a noid light hooked inline while shaking those connectors and actually seen the light flicker in time with the shake. Gonna take a pic of mine when it gets light out to post; should be the same setup...

[xj4life2]

first let me start by saying the Renix system is a whole different beast in itself, The ecm is under the dash on that one and can only be read using a "drible scanner" Jeep / Chrysler is the only ones to ever have them and they are just about gone at the dealerships also. Even my new snap on scanner wont read one. That being said its real tough to diagnose a bad ecm on the renix. I would suggest if you feel that the ECM is bad grab one from the JY and swap it in. However I don't think that's your issue. Check fuel pressure and the regulator. Sound like the pump is going bad. As for the brakes do you have the renix brake system? If so you do not have a booster. Pressure is controlled by the ABS pump and the small reservoir that looks like a grenade just above the master.DO NOT MESS WITH THIS UNLESS YOU HAVE RELIEVED THE PRESSURE < IT CONTAINS OVER 2500 PONDS OF PRESSURE!!!! Does the ABS light come on when you have a brake issue? If so the pump may be bad ,They are lifetime warrantied from Chrysler(federally mandated ). The Grenade looking thing is not but cheap enough, only available from Jeep. Master cylinder is near impossible to find and very expensive if you do. However again this is only realted to the Renix brake system. I will try to send you a complete renix repair manual if you can verify this is the system you have.

[jimmixj]

Dang!
Sorry Dave, disregard ALL that I said re your Renix. Not only did I miss the "Renix" bit, after I went to take photos of my own ECM yesterday am I found out that I didn't even know what my system is. Bein a mad scientist ain't all it's cracked up to be! My apologies, hope you get it sorted out!

[Infidel Edition]

I don't know either...
Wasn't 1 when I got it.
But if there was, I'd think there'd be some sign of it missing ~ I'll have to dig around.

wow brainfart~
it was camouflaged behind a clump of wire and vacuum hose.
will upgrade that tonight
+ upgrade the under dash point as per the notes in that link.

[Infidel Edition]

The computer in the 80s XJ is A JTEC board usually located on the fender or firewall. It is easily identified by 3 rectangular plugs going into a box about the size of a CD player. While your jeep is running give the plugs a shake by hand, usually in my experience the plug closest to the wire loom that carries the 3 plugs, and see if you can duplicate the symptom. Also, check your Crank Position Sensor and/or connector; the CPS is mounted in the top of the bellhousing on driver's side and the connector is usually right on top of the Intake in that same area. Dirt and time combined with vibration can cause all sorts of gremllins in the ECM cicuits. AS for your lo pedal/ hi idle; sounds like your brake master/ booster has reached the end of the road. The master causes the fall-away pedal, you will be able to fool it by stomping the pedal but soft feel will return on next apply. Vacuum leak in booster is easy to identify; with engine idling and vacuum gauge attached to intake, depress and hold pedal. You will see a drop in vac corresponding to an increase in idle. Hope this helps and Good Luck!

there isn't any noticeable diff in the idle... :bang: but I swear I can occasionally hear a hiss! and there has always been a strange hi idle at odd times = but not other times. initial start up is correct idle (usually) and at temp sometimes high idle (1200+) but not always.
so booster pry not the issue..... gonna swap out the MC this weekend if I get time. will just drive the wife's car


first let me start by saying the Renix system is a whole different beast in itself, The ecm is under the dash on that one and can only be read using a "drible scanner" Jeep / Chrysler is the only ones to ever have them and they are just about gone at the dealerships also. Even my new snap on scanner wont read one. That being said its real tough to diagnose a bad ecm on the renix. I would suggest if you feel that the ECM is bad grab one from the JY and swap it in. However I don't think that's your issue. Check fuel pressure and the regulator. Sound like the pump is going bad. As for the brakes do you have the renix brake system? If so you do not have a booster. Pressure is controlled by the ABS pump and the small reservoir that looks like a grenade just above the master.DO NOT MESS WITH THIS UNLESS YOU HAVE RELIEVED THE PRESSURE < IT CONTAINS OVER 2500 PONDS OF PRESSURE!!!! Does the ABS light come on when you have a brake issue? If so the pump may be bad ,They are lifetime warrantied from Chrysler(federally mandated ). The Grenade looking thing is not but cheap enough, only available from Jeep. Master cylinder is near impossible to find and very expensive if you do. However again this is only realted to the Renix brake system. I will try to send you a complete renix repair manual if you can verify this is the system you have.

non ABS ~ stock without it I think. but after this many years its hard to tell what's stock and what's my parts.

I can get a reverb computer for $100 +/- for direct swap.
is the JY a direct swap? or would that require some other tweaks?
...and would that give me a computer plug read out access?

[Infidel Edition]

hey
if it is the pump or the fuel regulator...
is there a good upgrade for either or both?
I believe the renix has the lowest fuel pressure of all the injected systems jeep made...
but the regulator is different than the 91+ and on the opposite end of the rail

[Brasscatz]

Unfortunately, not that I know of. Others may have heard of an upgrade

Sent from my Samsung Galaxy S4 because my microwave couldn't do it

[Infidel Edition]

had two services yesterday (1 was a WWII vet that had 6 beach landings & took shratenal every time) ~ and 1 on Friday + crappy cold and rain
so I haven't gotten to do
:mad:

today my family is getting together at my dad's for football and gumbo and beer...
so not gonna get work done today either.

[XJ Wheeler]

had two services yesterday (1 was a WWII vet that had 6 beach landings & took shratenal every time) ~ and 1 on Friday + crappy cold and rain
so I haven't gotten to do
:mad:

today my family is getting together at my dad's for football and gumbo and beer...
so not gonna get work done today either.

Must be a humbling experience doing those services.

Send some of that gumbo down my way, haven't had any in a while.

Sent via messenger pigeon - i talk, he types.

[Infidel Edition]

i try to stay mentally ad emotionally unattached at services. like "toy soldiers" is what they say in training.
but at the old guy services (older ladies too, but not as much) its really interesting to listen to their stories.
and the one yesterday, another old guy was trying to explain to us how to properly fold a flag... and kept telling us he could help out if we were nervous...

old guys like that make me smile

[XJ Wheeler]

i try to stay mentally ad emotionally unattached at services. like "toy soldiers" is what they say in training.
but at the old guy services (older ladies too, but not as much) its really interesting to listen to their stories.
and the one yesterday, another old guy was trying to explain to us how to properly fold a flag... and kept telling us he could help out if we were nervous...

old guys like that make me smile

I can see that. I would be the one getting to attached i'm sure.

Old guy stories are great. I'm riveted when i can hear some, especially the more "mechanical" one. :D

Sent via messenger pigeon - i talk, he types.

[jimmixj]

had two services yesterday (1 was a WWII vet that had 6 beach landings & took shratenal every time) ~ and 1 on Friday + crappy cold and rain
so I haven't gotten to do
:mad:

today my family is getting together at my dad's for football and gumbo and beer...
so not gonna get work done today either.

Thanks for your service Dave! The older I get the clearer I see that those "old Guys" (and gals) built the world I live in!:patriot:

[Infidel Edition]

It's the young ones that mess with my head.
Had a 20'ish looking mom with a 3 or 4 month old in her lap that I presented the flag to.
Messed me up for weeks.
Drank a lot of tequila after that.