Overheat and smog fail

No leaks at FPR

pulled an injector:

Tips of nozzles look clean. But there is black sludge build up below the manifold o rings and around the outside of the nozzles???
 
88trailcrawler said:
No leaks at FPR

pulled an injector:

Tips of nozzles look clean. But there is black sludge build up below the manifold o rings and around the outside of the nozzles???
Click to expand...

It is not the outside of the injector you are worried about. Once again:

Fuel injectors "pull the rail assembly, leave the injectors clipped to the fuel rail (make sure the clips are still on each one!!!!) turn on the ignition switch switch to run for a few seconds (getting fuel pressure and see if any leak"

The other option is to attach a fuel pressure gauge to the test port (they cost about $25-$30, or rent one for free), run the fuel pump (ign-swch on), a few seconds, then off, then watch the pressure gauge. If the pressure slowly drops it MAY be a leaking injector, in which case you need to see which one.

I have also tested fuel injectors with a 9 volt battery, and by just blowing into the injector inlet (mouth) to see if there is an obvious leak, if it is sealing, but a 30-40 psi fuel pressure test is a better test.

It may be possible for a partly clogged injector to not atomize the fuel properly causing a missfire and poor fuel burn, but that would cause an idle miss I think.

Any exhaust manifold cracks, especially near the O2 sensor?

Read up here on O2 sensor tests!!!

http://www.naxja.org/forum/showthread.php?t=1012701&highlight=oxygen+sensor+test

and here on Smog tests:

http://www.naxja.org/forum/showthread.php?t=966054&page=6
 
I guess I got sidetracked, but now my fuel rail, injectors and FPR are all nice and clean with new seals.

Confirmed no injector leaks. Double checked for intake manifold leaks, none found. No visable exhaust manifold cracks.

I re did the sea foam treatment to create the white cloud and found some white smoke was escaping at the exhaust manifold doughnut seal. It that close enough to mess with the 02 sensor?

Still don't have an analog tester

Is that fluctuation test just to save the cost of an O2 sensor?

Autozone has the Bosch O2 for under $50. It's going to be easier for me to just replace it than to get a reliable test on it.

If I am/will be successful at:
- cleaning injectors/confirming no leaks
- seal at doughnut
- new O2 sensor
- oil change (just for kicks)
- confirmed Vac to MAP.

Would it be reasonable to expect a better test result?
 
This jeep is kicking my butt.

I think it is time to drag it into a shop that can diagnose and repair.

After all I did today, I drove it around the block and out on the boulevard to get it up to temp, everything ran good.

I let it idle in the street while I hosed down the drive way, when I pulled it into the driveway it died, and now will fire up but quickly dies, like it's getting flooded..

Now I can't even run it.
 
OK, sorry I was starting to panic.

After taking 10 deep breaths, I went back out popped the hood and found one of the wires was dislodged at the inside of the front fender, driver side.

Jeep runs good, no fuel injector problems caused by me.

I guess I have concluded that I am not able to perform a reliable test of the O2 sensor, and current thought is to stick a new one in and retest.

After that, I may just need to drop it off at a diagnosis shop that can run reliable tests on the sensors.

Thoughts?? Chances of passing??
 
The donut leak can mess with the O2 sensor and the CAT performance and the emissions test. IT can also overheat the engine blowing on the block!!!

The test will tell you if the O2 sensor is reading the engine running rich, lean, and when it is running rich or lean, or normal stoich. It should cycle at idle, wide swings, it should narrow to tight value at 2000 rpm, it should go rich at fast acceleration, and lean on deceleration. So the meter allows you test the complete system, sensor, engine and computer as a system.

Did you run the injector leak test yet, or fuel pressure drop test yet that I asked for?

88trailcrawler said:
I re did the sea foam treatment to create the white cloud and found some white smoke was escaping at the exhaust manifold doughnut seal. It that close enough to mess with the 02 sensor?

Is that fluctuation test just to save the cost of an O2 sensor?


If I am/will be successful at:
- cleaning injectors/confirming no leaks
- seal at doughnut
- new O2 sensor
- oil change (just for kicks)
- confirmed Vac to MAP.

Would it be reasonable to expect a better test result?
Click to expand...
 
That wire sounds like the fuel pump power. Was it attached to a ceramic white part?

I doubt you will find a shop that knows how to service a Renix jeep anymore. They are too old, old tech, no OBD-II in them to tell techs what to do, LOL.

Read this:

http://www.naxja.org/forum/showpost.php?p=244916072&postcount=34

and
http://www.naxja.org/forum/showthread.php?t=1012701&highlight=oxygen+sensor+test&page=5

88trailcrawler said:
OK, sorry I was starting to panic.

After taking 10 deep breaths, I went back out popped the hood and found one of the wires was dislodged at the inside of the front fender, driver side.

Jeep runs good, no fuel injector problems caused by me.

I guess I have concluded that I am not able to perform a reliable test of the O2 sensor, and current thought is to stick a new one in and retest.

After that, I may just need to drop it off at a diagnosis shop that can run reliable tests on the sensors.

Thoughts?? Chances of passing??
Click to expand...
 
Yes, I had fuel rail pulled with injectors clipped in, confirmed pressure, no leaks.

BTW one of those injector clips flew off somewhere into the engine bay and gone forever. I guess a trip to the JY is in order.

I get it, the local shop will likely just charge me their rates to chase and guess, I might at well keep at it.

O2 sensor:
I'll read up and get a reliable test. Sounds like the test is not just to confirm the sensor is good, but to figure out if the sensor is reading and sending a signal indicative of another issue.

Can I test the O2 signal at the top of the engine (101 connector) seems it would be easier and more accurate.

Doughnut
The leak I found was during the Seafoam cycle when it was bellowing a white cloud out the tail pipe. When I crawled under the jeep, I saw some white smoke hovering out, volume was similar to a cigarette sitting in an ash tray.

Those bolts are NOT going to move. What about wrapping the connector with auto parts exhaust tape? Just to get buy.
 
I can't see the nuts on the bolts, but I have had good luck spray soaking them with PB Blaster several times for several hours. Messing with old ones is always risky, and can lead to having to pull the exhaust manifold if the studs are on their last legs, and need to be replaced!!!!

If you replace the nuts with new ones, use BRASS or Copper!!!

I installed an easy to reach set of insulated male-female blade connectors on mine for multipurpose testing, since the OEM connector is not convenient.

Kabelschuh_verschiedene_commons.jpg


Just for the hell of it, you should test the CTS and MAT temp sensors to make sure they are good, and not so far out of whack that they are keeping it open loop (running rich) in spite of a good O2 sensor. The ohms versus temp specs are in several old threads here on NAXJA, or PM me for them (need an email)
 
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DJ: thanks for those part numbers both Napa and Autozone near me were stumped, now I have a number for them to order.

Mike: there is a really good electronics/electrical supply near me, I'll go see if I can find a decent analog multimeter and set up some various test connectors.

I'll PM you my e-mail if you have list of items to test and parameters to test for, that would be great. I have a Chiltons around here somewhere, but not sure if it has that kind of data in it.

Anyway, looks like may be venturing into Renix diagnosis.

I'll try PB on those doughnut seal bolts, but they look pretty fused.

Thoughts on a wrap or copper RTV temp fix? I know it's a hack job, but It appeared to be a fairly low volume.
 
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You will want a high impedance analog volt meter!!! Try and get 20,000 ohms per volt or better.
 
Note from DJ
Tip that may help with the removal of your doughnut seal nuts, after soak time use only 6 point deep socket with long extension with a breaker bar (3/8” is best), try to tighten the nuts first to test for movement, be gentle don’t try to mussel them loose, the object is to remove the nuts not breaking the studs off.

If movement is felt when tightening you are on your way to success now spray with more penetrating fluid and back the nuts off till reasonable resistance is felt, stop and tighten the nuts again. More penetrating fluid, keep repeating this process until nuts are remove without breaking off the studs we hope.

If no movement was felt in the first attempt at tightening it’s time to get creative (you’re working on a Jeep). If you have a long handle flat blade screwdriver grab it and a hammer, place the shank of the screwdriver parallel to the threads on the stud with the flat blade part of the screwdriver across two of the long portion of the nut out a little bit from the threads on the stud and give the screwdriver handle a whack with the hammer, hopefully the vibration will break the nut loose enough that movement of the nut can be achieved which will led to successful removal of the nuts. If you don’t have a long handle screwdriver become creative, if you have an old bumper jack handle take a hacksaw and cut off the bent part and use it as a chisel or whatever you have available that might work, even something flat will transfer the vibrations to the nut. Good luck
 
Okay, I did some more reading up.

Since the smog test is done at 15mph and 25mph, we are diagnosing issues in the "Closed Loop" mode. From what I can tell the O2 sensor is the primary sensor relied upon for Fuel/Air ratio during cruising or "Closed Loop" operation. All others appear to be more relevant when the engine is NOT at operating temp.

QUESTION: At what temp. does the "Closed Loop" mode kick in? Wondering if I should now disconnect my e-fan bypass and let the engine run a little hotter during next test.

So I will focus on this O2 sensor/signal testing FIRST and move on to the others next.

I have determined the following:

Terminal A is 12v supply to the O2 sensor heater
Terminal B is the common ground
Terminal C is a 5v signal from ECU (somehow gets compared to a static signal vs. resistance in the O2 sensor)

Here is my testing plan:
Vehicle Connector (sensor disconnected):
- Test 1: Confirm 12v signal to O2 sensor heater (A-B on the vehicle plug)
- Test 2: Confirm 5v signal to O2 sensor resistor (B-C on the vehicle plug)
- Test 3: Check ground to O2 sensor < 1 ohm and ,.05v (B to ground at vehicle plug)

Sensor connector (Sensor disconnected):
- Test 4: Check sensor heating element max 5-7 ohms (A-B on sensor)
- Test 5: ??? No static/cold test for resistance of sensor (B-C on sensor) move to test 6 and 7

Back Probe B-C (Sensor connected):
- Test 6: At idle, sensor signal varies between 1-4 volts at 1 sec. intervals. (is this the ONLY test that requires an analog meter)
- Test 7: at 2000 rpm 2-3v constant (2.3-2.6v ideal)

QUESTION: If I am correct that the smog test is done in "Closed Loop" mode, would test 6 be relevant to my emissions results or Would test tests 1-4 and 7 be sufficient in determining if the O2 signal is causing the rich condition produced during the emissions test?

Today, I am going to perform the tests I can (1-4 and 7) with the digital MM I have, and will consider purchase of an analog if all these check out.
 
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The 1-4 volt swing test, confirms that it is in closed loop. A steady voltage at say around 1 or 4 volts (steady meaning 3-4 volts, or 1-2 volts, and never reaching 2.45 V and crossing to the other side) is a sign that SOMETHING IS WRONG!!!!

Many things can cause the ECU to default to open loop. Renix should go closed loop at temps above about 60 F so if the CTS is telling the ECU the temp is 120 F it should be already in closed loop.

Rapid acceleration and deceleration will swing to the 1 and 4 volts extremes for several seconds, if the O2 sensor is working!!!! It is the best test to see if the O2 sensor is working right!!!!

The 2.45 V tight range at 2000 rpm is a good test of everything. If it is at 1-2 or 3-4 volts (or worse) at 2000 rpm, the problem is in the O2 sensor-ECU-fuel system - weak spark, bad valves.....and so on, or worse. (that is where the diagnostics gets real interesting)

If it reads lean, you can spray carb cleaner into the throttle body and see if the analog meter jumps to rich. If it does the O2 sensor is good!!!!

An old O2 sensor will show a very slow moving needle on the analog meter, while a new sensor will show rapid swing times!!! A dead sensor will usually not move the meter needle at all.
 
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OK so I have NO 12v signal down to O2 sensor. (Ground and 5v tested good)

Was not able to run engine running test yet because I was able to pull the exhaust doughnut.

I am going to pick up the new O2 sensor because the one I did have in the jeep had very high resistance at the heating element side (A-B). So I figure better to have a fresh one for continued testing.

Question/Theroy:
- Is it possible that no 12v signal/No heated O2 sensor was sending a lean signal, causing the jeep to run rich and causing premature wear on the O2 sensor and CAT?

- Keep in mind this jeep mostly does short (3-5 mile) around town trips.

NEXT ACTIONS:
- I need to restore 12v signal to O2 sensor (and stick exhaust doughnut in) so that I can proceed with the engine running test of the O2 signal.

- I confirmed 12v at the relay plug (tab 5)
- Sent 12v signal down center (tab 3) to O2 sensor connector (worked)

- Is this now an ECU thing, a relay ground thing or ???

- Is it possible that this lack of O2 heating is the root of my problems?
 
88trailcrawler said:
OK so I have NO 12v signal down to O2 sensor. (Ground and 5v tested good)

Was not able to run engine running test yet because I was able to pull the exhaust doughnut.

I am going to pick up the new O2 sensor because the one I did have in the jeep had very high resistance at the heating element side (A-B). So I figure better to have a fresh one for continued testing.

Question/Theroy:
- Is it possible that no 12v signal/No heated O2 sensor was sending a lean signal, causing the jeep to run rich and causing premature wear on the O2 sensor and CAT?
Click to expand...

YES!!

- Keep in mind this jeep mostly does short (3-5 mile) around town trips.

NEXT ACTIONS:
- I need to restore 12v signal to O2 sensor (and stick exhaust doughnut in) so that I can proceed with the engine running test of the O2 signal.
Click to expand...

Use a new donut, don't reuse the old one, or it will leak again!!!

- I confirmed 12v at the relay plug (tab 5)
- Sent 12v signal down center (tab 3) to O2 sensor connector (worked)

- Is this now an ECU thing, a relay ground thing or ???
Click to expand...

Usually it is a bad relay, or dirty contacts!!! The renix ECU's almost never go bad. Renix is KNOWN for ground problems!

- Is it possible that this lack of O2 heating is the root of my problems?
Click to expand...

ABSOLUTELY!!!! The donut leak adds to the problem, and from what you said the heater in the O2 sensor was also bad!!!! It should have been 8 ohms IIRC.
 
- 12v to O2 restored (Engine needs to be running, maybe was never lost)

- Pulled O2 sensor had a bad heating element, I replaced it with a back up I had that tested good.

- fixed doughnut, I did smear a bit of copper RTV on so, I gotta let that cure before I run it.

- Contemplating re smog test prior to engine running O2 test.

- Going to new "more forgiving" test center that will put about 10 freeway miles on her before test, the other one may have been too close (2-3 miles, no freeway) for things to heat up, especially if the O2 sensor was not pre-heating.

- If it fails again, I have 30 days, to re test for free. (O2 sensor engine running test, other sensors, compression test, etc.)

- Problem is I guess I don't really know how to back probe reliably without damaging the sensor.
 
Back probe means mean probing the back side of the connector, with the sensor connected the wiring harness. I usually just probe through the wire insulation, until I have installed an easier access connector.

88trailcrawler said:
- 12v to O2 restored (Engine needs to be running, maybe was never lost)

- Pulled O2 sensor had a bad heating element, I replaced it with a back up I had that tested good.

- fixed doughnut, I did smear a bit of copper RTV on so, I gotta let that cure before I run it.

- Contemplating re smog test prior to engine running O2 test.

- Going to new "more forgiving" test center that will put about 10 freeway miles on her before test, the other one may have been too close (2-3 miles, no freeway) for things to heat up, especially if the O2 sensor was not pre-heating.

- If it fails again, I have 30 days, to re test for free. (O2 sensor engine running test, other sensors, compression test, etc.)

- Problem is I guess I don't really know how to back probe reliably without damaging the sensor.
Click to expand...
 
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