Lean code but running rich - JeepForum.com
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post #1 of 113 Old 10-07-2019, 07:25 PM Thread Starter
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Lean code but running rich

Alright normally I'd talk to que89yj but he has some family stuff going on.

So I am getting a lean code but the engine is running rich you can smell the gas in the exhaust. I have replaced the exhaust manifold thinking it was cracked it wasn't. Fuel pressure is dead on when checking it at idle. It runs worse cold when it warms up it runs better but still rich. It runs like absolute **** cold constantly stumbling. I replaced the O2 sensor again. The first one wouldn't move from .13 volts on the meter even if I sprayed carbon cleaner in the intake till it almost stalled. I have a new map on its way but I am not so sure that's gonna fix it. I am open to ideas suggestions or troubleshooting that I don't know about. This issue is kicking my ***.


1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

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Originally Posted by Magnum View Post
I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim
Quote:
Originally Posted by ldso View Post
. It started with a $200 axle, and a few thousand dollars later I was done :)
Quote:
Originally Posted by Luuca View Post
diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...
Quote:
Originally Posted by Overhead View Post
this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.
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post #2 of 113 Old 10-07-2019, 09:16 PM
1project2many
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I'll take a stab although I believe it takes a special kind of person to work with Chrysler electrons.

Think about this from the computer's point of view. If the computer thinks the engine is lean then it will add fuel. You were seeing .13 V with the previous O2 sensor, far below the stoich point, and the engine was running rich. So it makes sense to expect the problem is the ecm's response to a lean sensor reading. But changing the sensor didn't work. So now what? Ler's cover some basics.

When the ecm is in closed loop it relies on O2 feedback to decide whether the engine is rich or lean, then it adjusts fuel based on the feedback. Closed loop generally occurs after the engine is running for a certain amount of time, after coolant temp reaches a minimum point, and after the O2 signal begins to switch from rich to lean and back. When the ecm is not in closed loop it relies on pre-programmed values to keep the engine running. These pre-programmed values are entered at the factory based on testing with original parts and they are usually close enough that the engine runs well. Open loop operation typically occurs at wide open throttle, during rapid deceleration, and after startup while the engine is warming up.

If the O2 sensor was causing the problem you should see the engine run well from startup until closed loop begins. You should be able to disconnect the O2 sensor to prevent the ecm from entering closed loop and find the engine runs well when warm and cold. But this doesn't happen.

I'd be wondering about issues that cause the pre-programmed values in the ecm to be incorrect. The ecm believes the injectors deliver a certain amount of fuel based on a specific fuel pressure. Have you changed any injectors recently? Have you confirmed fuel pressure is at the factory level? The ecm calculates fuel delivery based on coolant and air temperature. Have you been able to confirm the coolant temperature sensor provides the correct reading for engine temperature? The ecm calculates fuel delivery based on air density which it gets from the MAP sensor. Do you have a way to match MAP sensor readings to engine vacuum? Have you checked MAP sensor voltage at idle? And finally, the ecm watches O2 values to determine the O2 sensor is active. If the ecm is seeing O2 activity when it should not then it may assume it's time to go into CL. Unfortunately it is possible for the ecm to influence the O2 readings. So I would consult with the factory manual to confirm, then look for a .45 volt reading on the O2 sensor line with the sensor disconnected. This is called a bias voltage and it works against O2 signal voltage. If this value is not correct it may indicate a faulty ecm.

Sorry I don't have more specific advice. But this is the strategy I would take in the shop.
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post #3 of 113 Old 10-08-2019, 07:02 AM
jtec
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some thoughts -
How many wires on o2 sensor HARNESS?

As this is a RENIX system and there are some differences with o2 return signal... The colleague we need to contact is ................Wait his name will come to me .... BRAIN ISSUE will add it ASAP

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #4 of 113 Old 10-08-2019, 07:07 AM Thread Starter
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Quote:
Originally Posted by jtec View Post
some thoughts -
How many wires on o2 sensor HARNESS?

As this is a RENIX system and there are some differences with o2 return signal... The colleague we need to contact is ................Wait his name will come to me .... BRAIN ISSUE will add it ASAP

Negative Ghostrider. This is not the Renix system. Mine is a 93 its the Mopar system.

1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

Quote:
Originally Posted by Magnum View Post
I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim
Quote:
Originally Posted by ldso View Post
. It started with a $200 axle, and a few thousand dollars later I was done :)
Quote:
Originally Posted by Luuca View Post
diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...
Quote:
Originally Posted by Overhead View Post
this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.
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post #5 of 113 Old 10-08-2019, 07:10 AM
jtec
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IIRC cruiser54 * was a renix go to guy

You do have a RENIX system? before bugging him...

Spelling might be wrong still thinking

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #6 of 113 Old 10-08-2019, 07:20 AM
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OK just saw the confirmation NOT renix.......

How many wires on o2 sensor - still thinking, ex leak, ECT, and o2 heater issue...

I am regrouping
You say reading is FIXED at @.12v even when spraying carb cleaner to richen it... ?

SORRY confused .... was thinking a 89/90... this is a 1993 . regrouping, am at work and multitasking...

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #7 of 113 Old 10-08-2019, 07:23 AM Thread Starter
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Quote:
Originally Posted by 1project2many View Post
I'll take a stab although I believe it takes a special kind of person to work with Chrysler electrons.

Think about this from the computer's point of view. If the computer thinks the engine is lean then it will add fuel. You were seeing .13 V with the previous O2 sensor, far below the stoich point, and the engine was running rich. So it makes sense to expect the problem is the ecm's response to a lean sensor reading. But changing the sensor didn't work. So now what? Ler's cover some basics.

When the ecm is in closed loop it relies on O2 feedback to decide whether the engine is rich or lean, then it adjusts fuel based on the feedback. Closed loop generally occurs after the engine is running for a certain amount of time, after coolant temp reaches a minimum point, and after the O2 signal begins to switch from rich to lean and back. When the ecm is not in closed loop it relies on pre-programmed values to keep the engine running. These pre-programmed values are entered at the factory based on testing with original parts and they are usually close enough that the engine runs well. Open loop operation typically occurs at wide open throttle, during rapid deceleration, and after startup while the engine is warming up.

If the O2 sensor was causing the problem you should see the engine run well from startup until closed loop begins. You should be able to disconnect the O2 sensor to prevent the ecm from entering closed loop and find the engine runs well when warm and cold. But this doesn't happen.

I'd be wondering about issues that cause the pre-programmed values in the ecm to be incorrect. The ecm believes the injectors deliver a certain amount of fuel based on a specific fuel pressure. Have you changed any injectors recently? Have you confirmed fuel pressure is at the factory level? The ecm calculates fuel delivery based on coolant and air temperature. Have you been able to confirm the coolant temperature sensor provides the correct reading for engine temperature? The ecm calculates fuel delivery based on air density which it gets from the MAP sensor. Do you have a way to match MAP sensor readings to engine vacuum? Have you checked MAP sensor voltage at idle? And finally, the ecm watches O2 values to determine the O2 sensor is active. If the ecm is seeing O2 activity when it should not then it may assume it's time to go into CL. Unfortunately it is possible for the ecm to influence the O2 readings. So I would consult with the factory manual to confirm, then look for a .45 volt reading on the O2 sensor line with the sensor disconnected. This is called a bias voltage and it works against O2 signal voltage. If this value is not correct it may indicate a faulty ecm.

Sorry I don't have more specific advice. But this is the strategy I would take in the shop.
OK I am gonna try to hit all your questions in order. First from Talking to Que before we have determined that even in open loop Que thinks the fuel maps have changed to be rich because of long term fuel trims being maxed. He thinks this will also effect open loop operation as well since it has been going on awhile but I didnt know it until the drivability issues that made me check for codes.

Fuel pressure at idle is exactly where it should be. 31psi with vacuum and 40psi if I pull the vacuum. The injectores have been changed to the the mustang 5.0 4 hole injectors but that was months ago and it ran great for months with no codes. I have not verified other sensors yet but in a fit of frustration I ordered a new MAP sensor coolant temp and Intake air temp sensor while will arrive in the next few days. I have had to repair the wire harness several times because of the PO hacking it up and I am thinking I am gonna just get a new engine harness but its gonna be a few weeks for that since they arent cheap. I am gonna give the sensors as shot as I heard they can cause this as well but I have no personal experience with it.

Added info. It seems the colder it is the ****tier it runs. It was so bad this morning the Jeep had to stay home. It was running so rich I couldnt get it to warm up enough to hit closed loop.

Now a question about bias voltage. I only recently hear about this. Should that voltage be on the signal wire or on the power wire for the O2. Atleast I call it the power wire that may not be correct. Its got the power and ground for the heater and then what I call the signal and power for the sensor. SO which wire should I be reading that bias voltage on?

1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

Quote:
Originally Posted by Magnum View Post
I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim
Quote:
Originally Posted by ldso View Post
. It started with a $200 axle, and a few thousand dollars later I was done :)
Quote:
Originally Posted by Luuca View Post
diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...
Quote:
Originally Posted by Overhead View Post
this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.
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post #8 of 113 Old 10-08-2019, 07:48 AM
jtec
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what are ALL the codes?

.13 suggests RICH what will new o2 sensor report ?
Spraying carb cleaner to a rich engine will not check sweep- you need to add air ..

LETS TRY To Add air- remove FPR* vacuum line is there any fuel in hose?
Line had good vacuum?
Did vac leak from removing hose change o2 voltage?

Is there good vac at MAP?
Is engine reaching correct ECT ?

*FPR fuel Pressure Regulator?

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #9 of 113 Old 10-08-2019, 07:59 AM Thread Starter
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Quote:
Originally Posted by jtec View Post
what are ALL the codes?

.13 suggests RICH what will new o2 sensor report ?
Spraying carb cleaner to a rich engine will not check sweep- you need to add air ..

LETS TRY To Add air- remove FPR* vacuum line is there any fuel in hose?
Line had good vacuum?
Did vac leak from removing hose change o2 voltage?

Is there good vac at MAP?
Is engine reaching correct ECT ?

*FPR fuel Pressure Regulator?

I havent probed the new O2 yet I wont get a chance to until tomorrow evening. I replaced the exhaust manifold as part of troubleshooting this. I have a good idle RPM so I dont believe its vacuum and a few weeks before this I went through the entire vacuum system.

.13v is lean .9 volts would be rich. The entire fuel system was replaced a month before this started. New FPR new pump. Fuel pressure however is accurate at idle. I have not figured out a way to test it while driving as my gauge has a short hose and I would have to run it through the wheel well to be able to close the hood. I have a brand new bosch pump to replace the cheap chinese pump in there. I may go ahead and throw that in this weekend. Also has a new fuel filter. New lines New injectors. All 1-3 months old.

I am not sure what you mean by ECT?

I do have good vac at the MAP but its original so I have a new one coming along with coolant and air temp sensors.

Yes good vac on FPR and it reacts as expected. No fuel in the hose. I dont really see a way to ad more air except to pull vacuum lines which then raises idle.

1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

Quote:
Originally Posted by Magnum View Post
I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim
Quote:
Originally Posted by ldso View Post
. It started with a $200 axle, and a few thousand dollars later I was done :)
Quote:
Originally Posted by Luuca View Post
diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...
Quote:
Originally Posted by Overhead View Post
this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.
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post #10 of 113 Old 10-08-2019, 08:01 AM Thread Starter
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Oh I forgot the codes. 12,33,51,55. So all the normal ones except 51 which is o2 reporting lean condition. No exhaust leaks either that would also give it a false reading.

Its a 4 wire o2

1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

Quote:
Originally Posted by Magnum View Post
I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim
Quote:
Originally Posted by ldso View Post
. It started with a $200 axle, and a few thousand dollars later I was done :)
Quote:
Originally Posted by Luuca View Post
diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...
Quote:
Originally Posted by Overhead View Post
this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.
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post #11 of 113 Old 10-08-2019, 08:33 AM
jtec
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ECT is engine coolant temp -- is it reaching the 195 deg expected temp AND is sensor reporting correctly - new sensor is on order I think?

When doing fuel pressure, I like to attach gauge DUH -- turn key ON record higest reading before pump goes off (@3seconds) then keeping key on record pressure in 5 min - this allows checking - injectors, FPR, and tank check valve. Does it drop?

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #12 of 113 Old 10-08-2019, 08:34 AM
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closed - wrong chart/info

issue is o2 sensor heating up... cold temp and open or closed loop... GTG

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #13 of 113 Old 10-08-2019, 08:54 AM Thread Starter
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Quote:
Originally Posted by jtec View Post
ECT is engine coolant temp -- is it reaching the 195 deg expected temp AND is sensor reporting correctly - new sensor is on order I think?

When doing fuel pressure, I like to attach gauge DUH -- turn key ON record higest reading before pump goes off (@3seconds) then keeping key on record pressure in 5 min - this allows checking - injectors, FPR, and tank check valve. Does it drop?
Fuel pressurizes to 31 at key on without starting. It holds pressure for atleast 10 minutes with no drop at that point I called it good.

Coolant temp sensor is on order. Going by my temp gauge It will sit at about 180ish sometimes itll get to 200 driving country roads. If i am on the highway itll run at 200 if I run it hard I can get it to 210 where it used to be before I put in a new rad hoses thermostat and radiator. Come to think of it after doing that it started running cooler than it used to which seemed normal since the cooling system was just replaced. I also replaced the water pump.

Now I am thinking I am wondering if the jarring or maybe I hit the sensor or got some silicon on it. I mean it ran fine for 3 months after doing that just cooler but I am wondering if that may have been the start of that coolant sensor failing. Though when that sensor goes it always thought it caused a no start or hard start condition. She starts up fine and idles fine. Once I start driving it is when it starts acting up. But it always seems to idle pretty good.

1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

Quote:
Originally Posted by Magnum View Post
I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim
Quote:
Originally Posted by ldso View Post
. It started with a $200 axle, and a few thousand dollars later I was done :)
Quote:
Originally Posted by Luuca View Post
diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...
Quote:
Originally Posted by Overhead View Post
this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.
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post #14 of 113 Old 10-08-2019, 08:58 AM Thread Starter
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Quote:
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closed - wrong chart/info

issue is o2 sensor heating up... cold temp and open or closed loop... GTG
I have no idea if the sensor is heating up. I would assume so since I just put a new sensor in last night and same issue. I am gonna probe the sensor tomorrow evening after work and see if this one is doing the same thing. If it is especially if its the same reading I think I am gonna assume a wiring problem

1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

Quote:
Originally Posted by Magnum View Post
I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim
Quote:
Originally Posted by ldso View Post
. It started with a $200 axle, and a few thousand dollars later I was done :)
Quote:
Originally Posted by Luuca View Post
diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...
Quote:
Originally Posted by Overhead View Post
this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.
Siva283 is offline  
post #15 of 113 Old 10-08-2019, 07:56 PM
Luuca
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IMO, Air temp sensor. Its gotten colder in the mornings and if it malfunctions, it would explain the extra fuel at all times.


you have one on the way IIRC.
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