About to give up

[Gasman1979]

The long term adjusts to keep the short term happy and in the center of it's range so it can make quick adjustments in either direction. If short term goes all the way negative long term will adjust itself to make short term get back to near zero so short term can do it's job, short term needs to be able to quickly respond in either direction constantly , so it's long term's job to keep short term in the middle of it's range so it can do that. The fact that your long term stays negative means there is a rich condition, or a perceived rich condition. It's not going to move positive until short term starts demanding more fuel by moving positive itself, which it's not going to do if it's getting info that there is a rich condition.

This is the best video I know of on fuel trims, it's 46 minutes long but well worth it for anyone interested in understanding fuel trims.

I agree. I don’t think it’s a positive read. I think it’s a false read causing the rich condition. The cherry red exhaust and worsening performance issues with rising temps leads me to believe it’s actually lean but signaling rich thus making the lean condition worse. What the hell is causing it tho ??? My O2 reads are good bouncing between .08 and .68 steady. The MAP is reading right. 1.5 at full throttle. The intake air reads about 165 degrees today which seems legit. The coolant sensor is reading 210-215 until the lean AF mix causes the motor to heat up. There’s prolly some damn simple explanation but I just can’t see it. It’s driving me crazy.

 

[Gasman1979]

I'm not real informed on the 2.5 so I'm just throwing some data out there for consideration, but glowing exhaust manifolds can also come from a rich condition, or retarded timing. Are there other indicators you are using to determine it's running lean besides the glowing manifold?

Could you have one or more injectors leaking or stuck open? Excess fuel would explain your deeply negative LTFT. Or maybe the idiot PO put higher flow injectors in there thinking it was gonna make more power without realizing they needed a tune to correct the pulse width.

For the 2.5 experts ...Would the 2.5 PCM run without tripping a code if the distributor is a tooth off?

The guy PO did a timing chain and cover replace just before I bought it and the distributor cap and wires look new. I think I need to get the #1 TDC on compression and pull the cap to see if I’m in time. Also isn’t there old school marks on the 2.5 I can reference as well ? The computer is running positive 15 timing at idle. Not sure if that’s norm or not tho. I’m leaning hard toward a mechanical issue like retarded timing too brother !!! I’m gonna verify tomorrow.

 

[Gasman1979]

Yeah, well, the other people have the advantage of not having a jeep that is in need of forum assistance, so I guess they have the luxury of acting however they like. When you're the guy in need of help, the tone of their responses will mirror yours. ¯\_(ツ)_/¯

And for context, in another thread you insisted you had the right speedo gear when it turned out you read the chart wrong, so maybe less about how much you know. You'll find that everyone here wants to help you get your jeep running, I promise.

Somebody famous once said something about how a gentle answer turns away wrath, but a harsh word stirs up anger. They went on to say that the tongue of the wise adorns knowledge, but the mouth of the fool gushes folly. So do whatever you want with that advice.


ps. Where at in Arkansas?

lol. Shit. I thought you said where IS Arkansas. Being funny. My bad. I’m just south of Pine Bluff.

 

[NashvilleTJ]

It sounds like for multiple reasons there is still no clear answer as to whether the mill is actually running rich or lean, or how much so. Gasman, have you considered dropping in a wideband O2 with an AFR guage? Or do you have access to a tailpipe sniffer which shows AFR?

 

[bluescapegoat]

I'm not real informed on the 2.5 so I'm just throwing some data out there for consideration, but glowing exhaust manifolds can also come from a rich condition, or retarded timing.

Can you elaborate on this? Curious how an overly rich condition can cause the exhaust to glow red, aside from maybe a combination of overly rich and retarded timing igniting the fuel in the exhaust.

My understanding has always been rich mix runs cooler. Unburned fuel carries away heat, not to mention it occupies space where air could have been and utilized for burn, further driving down temperatures.

 

[Gasman1979]

It sounds like for multiple reasons there is still no clear answer as to whether the mill is actually running rich or lean, or how much so. Gasman, have you considered dropping in a wideband O2 with an AFR guage? Or do you have access to a tailpipe sniffer which shows AFR?

I have not but I’ll look into that today.

 

[Gasman1979]

Can you elaborate on this? Curious how an overly rich condition can cause the exhaust to glow red, aside from maybe a combination of overly rich and retarded timing igniting the fuel in the exhaust.

My understanding has always been rich mix runs cooler. Unburned fuel carries away heat, not to mention it occupies space where air could have been and utilized for burn, further driving down temperatures.

That’s always been what I was taught too. Rich = flood = cooler. Lean = more air = hotter. Like taking an air nozzle and blowing into a fire. It flames up and gets hotter. So I’m curious how it could cause the stuff I have going on. I know it can push basically raw fuel into the CAT and it burn there making the cat hot Af but I don’t have a cat.

 

[freedom_in_4low]

Can you elaborate on this? Curious how an overly rich condition can cause the exhaust to glow red, aside from maybe a combination of overly rich and retarded timing igniting the fuel in the exhaust.

My understanding has always been rich mix runs cooler. Unburned fuel carries away heat, not to mention it occupies space where air could have been and utilized for burn, further driving down temperatures.

Rich mix burns slower and may still be burning when it leaves the port. There may also be a secondary combustion when hot unburnt fuel comes into contact with new oxygen during intake/exhaust overlap.

I think it needs to be pretty rich to do it though. I still believe it holds true that a slightly rich mixture "runs" cooler than a lean one, but at a point the timing of the combustion comes into play, and his problem seems to come out at high rpm blasting down the highway when the mixture doesn't get as much time inside the cylinder.

 

[Gasman1979]

Rich mix burns slower and may still be burning when it leaves the port. There may also be a secondary combustion when hot unburnt fuel comes into contact with new oxygen during intake/exhaust overlap.

I think it needs to be pretty rich to do it though. I still believe it holds true that a slightly rich mixture "runs" cooler than a lean one, but at a point the timing of the combustion comes into play, and his problem seems to come out at high rpm blasting down the highway when the mixture doesn't get as much time inside the cylinder.

Makes sense.

 

[ColoJeep]

Have you been able to verify the timing , and also the cats are not plugged ?
Both of these could cause your symptoms.

 

[freedom_in_4low]

Have you been able to verify the timing , and also the cats are not plugged ?
Both of these could cause your symptoms.

I think in his other thread he said the cats have been removed.

I'm pretty curious about the timing though.

 

[ColoJeep]

I think in his other thread he said the cats have been removed.

I'm pretty curious about the timing though.

I should have been more specific , cats and mufflers , any exhaust restriction . If the timing is retarded enough you will get " afterburn " which will make the manifolds glow and engine performance suck. I don't have direct experience on ECM controlled engine's being out of time , however it appears the ECM is trying to correct a condition that may be caused by the PO physically setting the mechanical timing incorrectly. On my Mark IV big block afterburn will cause the
square body gas tank vents to hiss like letting air out of a tire !

 

[Gasman1979]

Have you been able to verify the timing , and also the cats are not plugged ?
Both of these could cause your symptoms.

No cats. Cut off. Gonna verify timing today.

 

[Gasman1979]

I should have been more specific , cats and mufflers , any exhaust restriction . If the timing is retarded enough you will get " afterburn " which will make the manifolds glow and engine performance suck. I don't have direct experience on ECM controlled engine's being out of time , however it appears the ECM is trying to correct a condition that may be caused by the PO physically setting the mechanical timing incorrectly. On my Mark IV big block afterburn will cause the
square body gas tank vents to hiss like letting air out of a tire !

No cats and new flow master 40 muffler. I wanted certainty I wasn’t dealing with exhaust restrictions. My next step tonight is to get the engine at TDC #1 compression stroke and verify timing isn’t mechanically miffed.

 

[bluescapegoat]

Rich mix burns slower and may still be burning when it leaves the port. There may also be a secondary combustion when hot unburnt fuel comes into contact with new oxygen during intake/exhaust overlap.

I think it needs to be pretty rich to do it though. I still believe it holds true that a slightly rich mixture "runs" cooler than a lean one, but at a point the timing of the combustion comes into play, and his problem seems to come out at high rpm blasting down the highway when the mixture doesn't get as much time inside the cylinder.

I can see what you're saying but I don't know that it's very likely unless the timing is also off, which is a distinct possibility here and kind of what it seems like we're all gravitating towards.

I say I don't think it's likely just based on my experience with tuning my own 4.0, I can run it as rich as 9.5:1 at WOT before I start noticing a huge lack of power and at no point does it get hot enough to make the exhaust glow red. I'm not an experienced tuner though, so just entirely anecdotal.

I can also say that if you retard the timing enough that the spark itself is igniting unburned fuel in the exhaust stream it makes a hell of a racket.

 

[Gasman1979]

I can see what you're saying but I don't know that it's very likely unless the timing is also off, which is a distinct possibility here and kind of what it seems like we're all gravitating towards.

I say I don't think it's likely just based on my experience with tuning my own 4.0, I can run it as rich as 9.5:1 at WOT before I start noticing a huge lack of power and at no point does it get hot enough to make the exhaust glow red. I'm not an experienced tuner though, so just entirely anecdotal.

I can also say that if you retard the timing enough that the spark itself is igniting unburned fuel in the exhaust stream it makes a hell of a racket.

I really think at this point I’m dealing with a timing issue. Be it mechanical or ECU driven by bad intel from the sensors. My next step is to verify accurate mechanical timing. If that ain’t right I’ll fight this until I finally get mad enough to fill it with Tannerite and shoot it

Ps. I’m highly redneck, don’t think I’m not capable and at times willing to do dumb shot like that

 

[freedom_in_4low]

I can see what you're saying but I don't know that it's very likely

I think you're probably right that it's less likely, but I'm not sure it's unlikely enough to completely ignore.

unless the timing is also off, which is a distinct possibility here and kind of what it seems like we're all gravitating towards.

I haven't figured out how timing would affect the LTFT in this way. Seems like the only way it would show in the AFR and LTFT is if it was burning so late that it was still combusting at the O2 sensor...seems like a longshot but if that was the case, there would still be excess oxygen which would make it look lean and the LTFT would go positive trying (probably unsuccessfully) to reach a point where the oxygen was all burned up at the O2 sensor, wouldn't it?

I say I don't think it's likely just based on my experience with tuning my own 4.0, I can run it as rich as 9.5:1 at WOT before I start noticing a huge lack of power and at no point does it get hot enough to make the exhaust glow red. I'm not an experienced tuner though, so just entirely anecdotal.

Just looking at the numbers - if LTFT is -22% and that's getting AFR to 14.7, then without the correction it would want to be around 11.5 AFR. Doesn't seem rich enough to experience secondary combustion in the manifold, based on your experience.

Question for @Gasman1979 - the LTFT is a table made up of "cells" that cover different ranges of rpm, map, TPS. Is the LTFT consistently in the -20s or is that within a specific RPM such as idle? Most importantly, when you're doing these highway runs when it's losing power, what is the LTFT at that operating point?

I can also say that if you retard the timing enough that the spark itself is igniting unburned fuel in the exhaust stream it makes a hell of a racket.

Wouldn't you have to be close to 90° to do that? i wasn't thinking spark, I was just thinking of the residual heat of combustion and the hot metal surfaces igniting a mixture supplied with fresh oxygen.

 

[Gasman1979]

I think you're probably right that it's less likely, but I'm not sure it's unlikely enough to completely ignore.



I haven't figured out how timing would affect the LTFT in this way. Seems like the only way it would show in the AFR and LTFT is if it was burning so late that it was still combusting at the O2 sensor...seems like a longshot but if that was the case, there would still be excess oxygen which would make it look lean and the LTFT would go positive trying (probably unsuccessfully) to reach a point where the oxygen was all burned up at the O2 sensor, wouldn't it?



Just looking at the numbers - if LTFT is -22% and that's getting AFR to 14.7, then without the correction it would want to be around 11.5 AFR. Doesn't seem rich enough to experience secondary combustion in the manifold, based on your experience.

Question for @Gasman1979 - the LTFT is a table made up of "cells" that cover different ranges of rpm, map, TPS. Is the LTFT consistently in the -20s or is that within a specific RPM such as idle? Most importantly, when you're doing these highway runs when it's losing power, what is the LTFT at that operating point?



Wouldn't you have to be close to 90° to do that? i wasn't thinking spark, I was just thinking of the residual heat of combustion and the hot metal surfaces igniting a mixture supplied with fresh oxygen.

It’s mostly at idle. It does come positive some (say roughly -17) at highway speeds. The power loss begins to really happen after 4-6 miles and the engine gets to temp. Then (I assume due to the lean condition) it starts to run warm to hot and really loses power then. The LT is consistently low -20’s. I had hoped clearing the memory and driving would reset the fuel trims but it doesn’t. It starts out ok (all info at idle btw) but over the course of 3-5 minutes the ST lags into the -10 to -12 range and the LT quickly heads south to the -20’s trying to make the ST happy. It does have a slight rough idle. Not enough to call it a “miss fire” just a slight tremble and not smooth.

 

[Gasman1979]

I think you're probably right that it's less likely, but I'm not sure it's unlikely enough to completely ignore.



I haven't figured out how timing would affect the LTFT in this way. Seems like the only way it would show in the AFR and LTFT is if it was burning so late that it was still combusting at the O2 sensor...seems like a longshot but if that was the case, there would still be excess oxygen which would make it look lean and the LTFT would go positive trying (probably unsuccessfully) to reach a point where the oxygen was all burned up at the O2 sensor, wouldn't it?



Just looking at the numbers - if LTFT is -22% and that's getting AFR to 14.7, then without the correction it would want to be around 11.5 AFR. Doesn't seem rich enough to experience secondary combustion in the manifold, based on your experience.

Question for @Gasman1979 - the LTFT is a table made up of "cells" that cover different ranges of rpm, map, TPS. Is the LTFT consistently in the -20s or is that within a specific RPM such as idle? Most importantly, when you're doing these highway runs when it's losing power, what is the LTFT at that operating point?



Wouldn't you have to be close to 90° to do that? i wasn't thinking spark, I was just thinking of the residual heat of combustion and the hot metal surfaces igniting a mixture supplied with fresh oxygen.

When the power loss starts you can apply more or full throttle and it almost feels like you are riding the brakes.