Renix in Closed Loop at 120*

[Ecomike]

OMG, do you people read posts before you reply? LOL. He soldered them all, NO C-101 left!!!

 

[cruiser54]

I misread it. I thought he said he dreaded cleaning the C101!

 

[Ecomike]

I misread it. I thought he said he dreaded cleaning the C101!

Yep, his last post said "I removed the C101 plug, soldered the wiring, all grounds and sensor wiring have been tested back to the ECU." updating the older C-101 info.

This is going to be an interesting one. 5-90's comment has me thinking I let my 87 run rich a little too long, and thus need to replace the O2 sensor again, if I want to get the last of my missing fuel economy back.

 

[kcjeep6]

Yes now it is just running rich now, with an occasional backfire which could be the fluffy plugs. I found the Sync Sensor in the distributor signal was weak. I installed a new O2 sensor and it operates the same as my other two O2 sensors, yes I am getting 14 volts to the heater. I have checked all the grounds; I plan on rechecking the grounds tomorrow and the sensor wiring back to the ECU plug just in case I missed something.

I believe I have been running rich for the last 5k miles (hence low compression), my wide band quit working about 18 months ago and I was commuting to Palo Alto when I noticed an increase in fuel consumption. This year while at KOH the MAP vacuum line came off, I was able to make it home after replacing the line but I have had issue ever since.

I just got my 2500 a couple of months ago plus I fixed the wide band today so I could verify the F/A mixture it is 10 to 10.5 in open loop. I think I’m going to get a printer for the 2500 so I can save and compare information; I'll take some screen shoots tomorrow. It’s been interesting learning how the 2500 displays information I ended up not trusting the information and found myself double checking with my DMM.

I’ll ship the ECU when I get a chance with a note!

AVR Adjustable Voltage Regulator. If it was still installed I could see if changing the MAP voltage had an effect.

Would an exhaust leak upstream make both the O2 and wide band read rich?

 

[Ecomike]

This year while at KOH the MAP vacuum line came off, I was able to make it home after replacing the line but I have had issue ever since.

Would an exhaust leak upstream make both the O2 and wide band read rich?

I would try a new vacuum line to the MAP sensor. I had a brand new vacuum line recently that was defective internally, it was not round, leading to a small leak, or could be collapsing some under strong vacuum.

All it takes is an exhaust leak, to fool the Renix O2 CONTROL feed back sensor into running the engine rich (thinking it is very lean) long enough to give up. The second O2 sensor is just reading the results. And EGR stuck open can do this too, I think!!!! The O2 sensor compares internal O2 density to external O2 density! Exhaust leaks are a known source of problems, and the jeep headers are known for cracking, and for loose manifold bolts.

 

[old_man]

I appologize if I am bringing up a question about something already answered, but I didn't see it. You say you changed all the sensors. Did that include the air charge sensor on the manifold just aft of the throttle body?

You never hear about it and most people don't even know it is there. You can check it with a simple ohmeter. It will royally screw with your mixture if it is bad.

 

[xjtrailrider]

I appologize if I am bringing up a question about something already answered, but I didn't see it. You say you changed all the sensors. Did that include the air charge sensor on the manifold just aft of the throttle body?

You never hear about it and most people don't even know it is there. You can check it with a simple ohmeter. It will royally screw with your mixture if it is bad.

I had that same issue a few years ago and what a difference that one sensor made.

OP, you have all of the best RENIX gurus that exist helping you right now, learn all you can from them. I know I did! My 90 is running like a champ and gets an easy 19mpg mixed driving. My 4.0 is not a stroker but it has been worked on. Bored .040, decked and milled with a 3 angle valve job. I chased one issue after another until I found each small issue which all made huge changes. The vac line to the MAP is a biggie! The MAT/CTS sensors will cause rich conditions. And like all of these good men have said, if it has been running rich for a while you may have other issues to deal with like your O2 and cat.

 

[cruiser54]

Just another random thought and I know an ECU has been swapped in as a test unit.

How about taking the plug off the ECU and tweaking the receptacles so they grab the pins tighter. Spray it all out with a good electronics cleaner.

 

[djgrayxj]

Note from DJ to OP kcjeep6

In your post #24 you stated Quote: “This year while at KOH the MAP vacuum line came off, I was able to make it home after replacing the line but I have had issue ever since.

My questions to you is when you replaced the MAP vacuum line, #1 did you replace it with the original vacuum line? #2 if your Throttle Body on your ‘88 is the same as my ‘88 there are two ports vertically that the MAP vacuum line can be inserted into. The MAP vacuum line must be inserted into the lower port and must be sealed tight so that MAP will receive correct intake manifold vacuum below the throttle plate. And question #3 do you have an aftermarket exhauster header installed on your stroker.

Please keep us posted as to progress. We are all looking for your success at solving this long ongoing problem.

 

[djgrayxj]

Note from DJ to OPkcjeep6

In your post #24 you stated Quote: “This year while at KOH the MAP vacuum line came off, I was able to make it home after replacing the line but I have had issue ever since.

My questions to you is when you replaced the MAP vacuum line, #1 did you replace it with the original vacuum line? #2 if your Throttle Body on your ‘88 is the same as my ‘88 there are two ports vertically that the MAP vacuum line can be inserted into. The MAP vacuum line must be inserted into the lower port and must be sealed tight so that MAP will receive correct intake manifold vacuum below the throttle plate. And question #3 do you have an aftermarket exhauster header installed on your stroker.

Please keep us posted as to progress. We are all looking for your success at solving this long ongoing problem.

 

[djgrayxj]

Note from DJ to OP kcjeep6

Another question regarding KOH outing did you go splashing around in any water while you were there?
TPS hate getting wet!

 

[kcjeep6]

O2 voltage has been verified back to the ECU and it is reading rich, less than 1 volt.

Just a note on the 2500, it receives information from the ECU thru a serial bus for most of the inputs and outputs. What it reads is what the ECU is reading. There are a few inputs that are direct, mostly relay state.

I replaced the MAP vacuum line yesterday because it broke, I installed a “T” at the MAP so I could plug in a vacuum gauge, the gauge is reading the same as the 2500. Yes the vacuum line is in the lower hole, I’ll put a little silicone on it today.

Now the MAT/CTS are something I am going to look at today, I have been so busy with O2, Sync, Map and TPS that I only did a quick check. The CTS reading on the 2500 is good and closely follows a thermometer in the radiator. The MAT was reading ambient with the motor off and follows the CTS only lower but I can see it warming up. I think I should take a very close look at these 2 inputs.

Water at KOH? Not this year! I did develop an exhaust manifold gasket leak while at KOH and that was my first repair in this mess. All test have been done after this repair.

I am running a Borla header, Bored TB with spacer, XJ Armor air filter adapter and 24# Ford Racing Injectors. This set worked well for several years.

I appreciate the help of the best Guru’s on the planet and will keep everyone posted.

What I am seeing is the Short Term Trim trying to lean out the exhaust but it can’t so the ECU defaults to open loop.

 

[Ecomike]

O2 voltage has been verified back to the ECU and it is reading rich, less than 1 volt.

Just a note on the 2500, it receives information from the ECU thru a serial bus for most of the inputs and outputs. What it reads is what the ECU is reading. There are a few inputs that are direct, mostly relay state.

I replaced the MAP vacuum line yesterday because it broke, I installed a “T” at the MAP so I could plug in a vacuum gauge, the gauge is reading the same as the 2500. Yes the vacuum line is in the lower hole, I’ll put a little silicone on it today.

Now the MAT/CTS are something I am going to look at today, I have been so busy with O2, Sync, Map and TPS that I only did a quick check. The CTS reading on the 2500 is good and closely follows a thermometer in the radiator. The MAT was reading ambient with the motor off and follows the CTS only lower but I can see it warming up. I think I should take a very close look at these 2 inputs.

Water at KOH? Not this year! I did develop an exhaust manifold gasket leak while at KOH and that was my first repair in this mess. All test have been done after this repair.

I am running a Borla header, Bored TB with spacer, XJ Armor air filter adapter and 24# Ford Racing Injectors. This set worked well for several years.

I appreciate the help of the best Guru’s on the planet and will keep everyone posted.

What I am seeing is the Short Term Trim trying to lean out the exhaust but it can’t so the ECU defaults to open loop.

Bingo, I think I figured out part of your problem Please read post 70 and older on this thread, hell, read the entire thread:

http://www.naxja.org/forum/showthread.php?t=1012701

A low voltage is lean, NOT RICH!!!!

There maybe a typo, or confusing info in the FSM on this?

My comment in post 69:

Read it again, the patent says that Wiki is right and the FSM is wrong (if in fact the FSM is reversed?).

One thing you missed, to add to the confusion, is that if the engine is running rich due to a leaking fuel injector (say on one cylinder) or FPR, the ECU may be fighting the leak by trying to run the rest of the engine lean, and if there is an exhaust manifold leak near the O2 sensor, all bets are off as to what the O2 sensor reading really means!!!

I am pretty sure (IIRC) that a high voltage O2 sensor reading on renix, is a rich, excess fuel reading. I will try and dig up my old notes later when I get time, but reread the bottom text of your patent post, it says high voltage is rich, excess fuel.

If the computer is reading a lean out of control condition it will switch to open loop!

 

[GSequoia]

Jon:

Brick via VT-100

As an added bonus I can hook it up to any 4.0 equipped XJ ever produced. Handy since I have a '96 as well as my '89.

 

[Ecomike]

The rest of the story!

http://www.naxja.org/forum/showpost.php?p=245636429&postcount=68

 

[GSequoia]

KC -

I'd personally take a long hard look at wiring. Look for any issues there, correct it, then see if you have to put a new O2 in. I was battling an open loop issue for awhile, it would also hit closed loop briefly after start up then go to open. My symptoms weren't as bad as you (I wasn't running quite so rich), in fact above is a readout while I was having my issues.

My problem ended up being an issue that went clear back to 2004 when I had a shorted O2 loom. It burned off the insulation on the O2 heater wire coming out of the relay center. Because that wire was in the middle of the loom it didn't give me a problem for a further six years. Ultimately it ended up grounding out and causing the O2 heater never to fire, that caused the Jeep not to hit closed loop. Interestingly from the brick end and even from the meter things appeared to be in good order, it wasn't until I started digging that I found the issue.

Once I corrected that wire I hit clean closed loop and passed a smog check with no problem.

 

[GSequoia]

Bingo, I think I figured out part of your problem Please read post 70 and older on this thread, hell, read the entire thread:

http://www.naxja.org/forum/showthread.php?t=1012701

A low voltage is lean, NOT RICH!!!!

There maybe a typo, or confusing info in the FSM on this?

My comment in post 69:

If the computer is reading a lean out of control condition it will switch to open loop!

Negative Mike. The Renix O2 sensor works in the opposite direction of most O2 sensors. Low is rich, high is lean.

 

[Ecomike]

Negative Mike. The Renix O2 sensor works in the opposite direction of most O2 sensors. Low is rich, high is lean.

Yes, I just rechecked all my notes, low signal voltage below 2.5 V is rich. Thanks for the catch.

 

[cruiser54]

What are the actual fuel pressure readings?

What if the fuel pressure is actually higher than is read? Faulty gauge?

 

[Ecomike]

OK, so pretty much ignore this posted idea. I had it backwards this time, LOL.

Bingo, I think I figured out part of your problem Please read post 70 and older on this thread, hell, read the entire thread:

http://www.naxja.org/forum/showthread.php?t=1012701

A low voltage is lean, NOT RICH!!!!

There maybe a typo, or confusing info in the FSM on this?

My comment in post 69:

If the computer is reading a lean out of control condition it will switch to open loop!