Cruiser's RENIX diagnostics thread

[cruiser54]

Is there a diagram somewhere of all the possible spray points?

No. All around the intake manifold and where it meets the head. All the fittings on the intake manifold.

 

[JoshInReno]

No. All around the intake manifold and where it meets the head. All the fittings on the intake manifold.

Rear-most intake manifold bolt loose. Damn near killed the engine when hit with brake clean. Looks like it's going to be a fun spot to try to get to.

 

[JoshInReno]

All of the bolts on the top of the manifold have been tightened. Solved about 95% of the problem (so far, still need to drive it home and see what happens on that trip).

I will get to the bottom ones this weekend at home. What's weird is there was NO NOISE whatsoever for a leak that size.

 

[djgrayxj]

Note from DJ
One of these will help.
Sears
GearWrench 1/4'' Drive Impact Universal Joint
http://www.sears.com/gearwrench-1-4inch-drive-impact-universal-joint/p-00991669000P?prdNo=5&blockNo=5&blockType=G5

 

[cruiser54]

All of the bolts on the top of the manifold have been tightened. Solved about 95% of the problem (so far, still need to drive it home and see what happens on that trip).

I will get to the bottom ones this weekend at home. What's weird is there was NO NOISE whatsoever for a leak that size.

Actually, that's normal and why we use throttle body cleaner to find vacuum leaks.

With the engine cold, tighten the intake/exhaust bolts from the center out to each end.

 

[djgrayxj]

Note from DJ
Torque Values for 1990 XJ & MJ Manifold
Information from Kelley’s Works in Progress

Combination Manifold Inner Screws/Nuts, 3/8"-16 x 1¼" @ 30 pound-feet
Combination Manifold Outer Nuts, 3/8"-16 @ 23 pound-feet

 

[cruiser54]

Note from DJ
Torque Values for 1990 XJ & MJ Manifold
Information from Kelley’s Works in Progress

Combination Manifold Inner Screws/Nuts, 3/8"-16 x 1¼" @ 30 pound-feet
Combination Manifold Outer Nuts, 3/8"-16 @ 23 pound-feet

Thanks. I was too lazy to go out to the garage and get my manual.

That said, have fun torqueing those bolts using wobblies and extensions.

"Forearm tight" is my non politically correct technical term for how tight to make them.

 

[Ecomike]

If one could reach them with PB Blaster first, it might do a better job if the threads are rusted and dirty.

 

[cruiser54]

If one could reach them with PB Blaster first, it might do a better job if the threads are rusted and dirty.

I live in Arizona and never consider the rust factor.

 

[88cherokeexj]

i just want to throw a shout out to cruiser for making this thread. i had the famous crank but no start on my 88 xj and did a few of the tips posted here and now the jeep starts faster and easier than it has since ive owned it. thanks

 

[JoshInReno]

If one could reach them with PB Blaster first, it might do a better job if the threads are rusted and dirty.

LOL - no rust in Nevada either.

 

[gaucho919]

Hi Cruiser, I have been reading all your Renix troubleshooting tips all day. I recently acquired a 1990 XJ that had been sitting since '99. It started fairly quickly, I bled the clutch and it was a good running jeep(with lots of sludge). The timing chain was rather loud so I replaced it the day before yesterday, the new timing chain was quiet then got loud. I suspect the sludge isn't letting oil to it. Now the real problem; the day after doing the timing chain(yesterday) I took the Jeep up in the forest service roads in the mountains 6-8" of snow jeep drove great plenty of power, I hit a bump pretty hard, so hard the power steering sucked air in the lines. Once I was back on the pavement, the jeep would stutter under acceleration then accelerate normal once the RPM went up. After messing with it all day it's gotten worse. I have cleaned the grounds at the dipstick, adjusted the TPS it was at .52 volts now at .83, tested the map sensor it is good, tested the MAT sensor seemed fine too. Now the crank sensor only goes to .3 VAC while cranking. Jeep takes a long time to fire up. I haven't checked fuel pressure yet, I will tomorrow I need a gauge. I am stumped, could you point me in the right direction please?

 

[cruiser54]

CPS is at a weak point. .35 and lower can cause long crank times or no-starts. Unplug the connector to the CPS, clean it out, and plug it back in and see what happens.

You may end up replacing the CPS.

A more complete listing of my write-ups can be found here.
http://www.cherokeeforum.com/f51/cruiser54s-mostly-renix-tips-153657/

 

[gaucho919]

Could the low voltage on the cps cause loss of power and instant gain of power again?

 

[Ecomike]

Could the low voltage on the cps cause loss of power and instant gain of power again?

No, if you test the CPS while running you wil see the voltage is way higher. It is only a starting problem.

Check the MAP sensor vacuum line at the throttle body. Sounds like it came loose from part of your story regarding acceleration issues.

OR:

The O2 sensor wiring got damaged (drive shaft or exh-manifold damaged it?)

Or the TPS signal is unstable. Did it get wet? Check the sweep for a noisy jumpy signal from idle to WOT, best done with an analog meter.

In my experience a smooth idle but unstable acceleration is either of the three above, or variable fuel pressure, so look for a crushed fuel line too!

Good luck

 

[gaucho919]

I checked the TPS from idle to WOT and it went thru the curve smoothly no dead spots. O2 sensor wiring looks undamaged. Map sensor vacuum line has no leaks. Yesterday my idle jumped to like 2500 rpm, I was finally able to bring the idle back down by unplugging the MAP sensor and plugging it back in. One thing I noticed today is that it gets worse as the engine warms. This morning it took long to start but once it started it idled smooth and the loss of power under acceleration wasn't as much. I left it idling while inside carquest, when I came out the engine had died. Took a while to start again and had a huge loss of power it was hard to even get it going and the idle wasn't stable. I am trying to track down a fuel pressure tester.

 

[Ecomike]

Temp sensitivity leans toward the temp sensors, air and coolant, MAT and CTS.

Also check for 12-14 volts for the heater in the orange wire going to the O2 sensor!!! If it is missing, that will cause the problem too.

 

[gaucho919]

I want to thank y'all so very much, even though it wasn't electrical, now I am a lot more familiar with the Renix electronics. Low and behold it was the little 4" piece of rubber hose in the fuel sending unit, it was loose. The jeep runs great now, and I am no longer frustrated haha

 

[cruiser54]

Simple stuff.

 

[Ecomike]

"4" piece of rubber hose in the fuel sending unit"

??????? Can you be more specific, Vacuum line, fuel line??? Fuel pressure Regulator????