99 Jeep 6 banger.

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99 Jeep 6 banger.

Best Answer I Can Give
 Any and all help would be thankfully accepted.

 You guessed it HI NOx.

 New 02's front and rear. New Cat's front and rear. This was before the best shop's in the hood got it.
Reset the computer. Was good. Not enough Monitors to pass. Now it has the monitors, back to it's old tricks.

 It first started out as Fail 15 pass 25. Now LEAN on both. HC next to nothing. CO Zero Point Zero. As I run it I can blip the throttle\more fuel\NOx go down.
Fuel pressure at specs.
The shop looking at it now has the books and the knowledge. One of the best guys in town. It's just beating him. Not normal for that guy.

                   ANY IDEAS Thanks in advance.

 This is the second one of these this town has seen. The first one I think they gave up on and junked it

 Jeep Cherokee 6 cyl Auto. 2 wheel drive. Cal.
 Life will give you rope. It will give you enough to make a ladder to pull yourself up, or an noose to hang yourself with.
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Re: 99 Jeep 6 banger.

D Rochells 150861
Cooling system ok?
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Re: 99 Jeep 6 banger.

Best Answer I Can Give
 Checked and good. In fact it's kind of COOL here. Got a coat on.

 It acts like it just wants to run LEAN.
 Life will give you rope. It will give you enough to make a ladder to pull yourself up, or an noose to hang yourself with.
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Re: 99 Jeep 6 banger.

D Rochells 150861
I've got an 87 Volvo with the same problem. NoX is 3000, after a new cat. When I unplug the O2 I can get the NOX to around 900. O2 signal is stuck around .04-.15. After consulting with the Oracle at the Volvo shop were gonna throw a MAF at it.
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Re: 99 Jeep 6 banger.

Karupt
In reply to this post by Best Answer I Can Give
Mass airflow sensor ?
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Re: 99 Jeep 6 banger.

scanner
In reply to this post by Best Answer I Can Give
Best Answer I Can Give wrote
                   ANY IDEAS 

 Jeep Cherokee 6 cyl Auto. 2 wheel drive. Cal.
Does this have the header type exhaust manifold?   If it does, have the shop pressurize the exhaust system with shop air, and try to detect a leak with a soapy water solution.   Cracks at the welds introduce air in the system, rendering the reduction bed useless.    
Why make it simple, when it will work equally as well complicated.
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Re: 99 Jeep 6 banger.

Best Answer I Can Give
 Thanks, It's good. already done.
 Life will give you rope. It will give you enough to make a ladder to pull yourself up, or an noose to hang yourself with.
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Re: 99 Jeep 6 banger.

none
In reply to this post by Best Answer I Can Give
Best Answer I Can Give wrote
...It first started out as Fail 15 pass 25. Now LEAN on both. HC next to nothing. CO Zero Point Zero. As I run it I can blip the throttle\more fuel\NOx go down...
Are you sure it is lean? I would check closer but I suspect you may be heading the wrong direction there. Anytime you "blip the throttle" it should go slightly rich which will cool the combustion and lower NOx.
I've hit rock bottom but I brought a pick and a shovel and I'm ready to dig!
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Re: 99 Jeep 6 banger.

Best Answer I Can Give
 Yes that's what it does.
if I shoot a ton of Propane down it the CO goes high and the NOx goes down. Then it corrects itself and goes lean again.

 Something is telling the computer, HEY we are rich. lean it out. It just wants to run on the lean side.
 Life will give you rope. It will give you enough to make a ladder to pull yourself up, or an noose to hang yourself with.
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Re: 99 Jeep 6 banger.

D Rochells 150861
Fuel Trims? MAP? ECT?
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Re: 99 Jeep 6 banger.

Best Answer I Can Give
 You drive it down the road with a scanner on it. Perfect numbers?
 I talked to the guy, I think they are going ti throw a MAP or MAF here shortly. I have seen it fix a couple GM's
 Life will give you rope. It will give you enough to make a ladder to pull yourself up, or an noose to hang yourself with.
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Re: 99 Jeep 6 banger.

D Rochells 150861
This post was updated on .
That's what our Volvo needed, 3000 to 300.

Correction, NOX is 86 at 15 and ZERO at 25. We cleaned some fucking air today boys.
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Re: 99 Jeep 6 banger.

none
The VOLVO has a MAF (L type injection) the JEEP doesn't have one (D type injection). The Jeep 4.0L has a speed/density system with a MAP sensor but if that was out of range I would think it would show when you look at the fuel trim numbers.
I've hit rock bottom but I brought a pick and a shovel and I'm ready to dig!
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Re: 99 Jeep 6 banger.

barrym95838
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I had a speed-density Celica here a few years back with a slightly skewed MAP.  Not quite skewed enough to code, but enough to cause a slight lean condition most of the time.  I think it was OBD1 though.

Same problem with a speed-density Concorde, but it was skewed far enough to run like straight shit.

barrym95838
EO/EI/LA/BA144107
“Never attribute to malice that which can be adequately explained by stupidity.”
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Re: 99 Jeep 6 banger.

none
In reply to this post by D Rochells 150861
D, regarding your 1987 Volvo, Back when those dinosaurs roamed the earth it was rumored that a stuck TAC would cook the air flow meter on those and cause it to fail. You can pull the wax pellet in the air filter housing making it stay to cold air if it is an issue.  
I've hit rock bottom but I brought a pick and a shovel and I'm ready to dig!
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Re: 99 Jeep 6 banger.

Best Answer I Can Give
 Rumor MY ASS. It was the truth.
The wax pellet would cause the door to take in HOT air.
Most shop's just wired the door to the fresh air position.

 Burned me on one. Not the second time.
 Life will give you rope. It will give you enough to make a ladder to pull yourself up, or an noose to hang yourself with.
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Re: 99 Jeep 6 banger.

D Rochells 150861
In reply to this post by none
Wouldn't that be a modification of an emissions controls system? Oh, I forgot the book doesn't show TAC for Volvos.
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Re: 99 Jeep 6 banger.

Best Answer I Can Give
 If you look it was so far under the car, you would never see it.
 Life will give you rope. It will give you enough to make a ladder to pull yourself up, or an noose to hang yourself with.
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Re: 99 Jeep 6 banger.

none
In reply to this post by Best Answer I Can Give
As for the 1999 JEEP 4.0L, I would check out more before throwing parts at it and hoping something sticks.

I would enter your current 5 gas readings into a Lambda calculator to determine if it is even lean.

The computer uses manifold absolute pressure(vacuum), throttle position, and engine RPM to determine how much air is entering the engine and with coolant temp input it will decide how much fuel to add. It will fine tune it with O2 readings. I would check these first if it shows lean.

I would double check the O2 sensor rise time with a lab scope and I personally would use a smoke machine in the tail pipe after the vehicle has cooled off to recheck for exhaust leaks before either cat.
I've hit rock bottom but I brought a pick and a shovel and I'm ready to dig!
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Re: 99 Jeep 6 banger.

Best Answer I Can Give
 Thanks. I will pass that along.
 Life will give you rope. It will give you enough to make a ladder to pull yourself up, or an noose to hang yourself with.
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