Rough Idle/CELs?

[bmrrwolfe]

The CEL came on the Jeep this morning driving to work, but seemed fine when driving. On the way home it seemed to start running a little rough at idle, but ran fine under any load. Also if you shift the ****** into park, the idle seemed to improve, and not have the shake it had in gear.

When I got home I ran the CEL, and it showed 5 codes.
P0174
P0157
P0420
P0174 (yes a duplicate?)
P0430

About a month and a half ago I had 2 codes for the bank 2 sensor 2, which I replaced with a Bosch 02, cleared the code and it hasn't had any issues since now.

After clearing the codes, I let it run for 5 minutes, and scanned the system again, and two codes were back:
P0171
P0174

Generally I have an idea of where to look, but this one stumps me as its both banks of the exhaust, and lean conditions?

Any ideas where to start??

Looked for any vacuum leaks or cracked plastic vacuum lines, didn't see or hear any obvious ones. Also gave the cats a light tap with a rubber mallet, and did not hear any rattling or signs of them coming apart.

 

[streetglideok]

The CEL came on the Jeep this morning driving to work, but seemed fine when driving. On the way home it seemed to start running a little rough at idle, but ran fine under any load. Also if you shift the ****** into park, the idle seemed to improve, and not have the shake it had in gear.

When I got home I ran the CEL, and it showed 5 codes.
P0174
P0157
P0420
P0174 (yes a duplicate?)
P0430

About a month and a half ago I had 2 codes for the bank 2 sensor 2, which I replaced with a Bosch 02, cleared the code and it hasn't had any issues since now.

After clearing the codes, I let it run for 5 minutes, and scanned the system again, and two codes were back:
P0171
P0174

Generally I have an idea of where to look, but this one stumps me as its both banks of the exhaust, and lean conditions?

Any ideas where to start??

First mistake, Bosch. You should never use Bosch sensors unless they were OE, to which they aren't. NGK/NTK, Denso, or Mopar sensors are what you should be running. Bosch sensors are of a different design, and perform slower, causing both codes, and in some cases running issues.

P0171/P0174, says Bank1 and Bank2 are running lean, even with the engine control module doing max corrections. P0157, that's an O2 sensor code for Bank2 sensor 2. P0420 and P0430 are codes signaling poor catalytic converter performance, and in most cases means replacement is needed for both banks.

You haven't put in E85 fuel right? You have under 30k miles on your NGK copper plugs, correct? If over 30k on the plugs, or they are not copper core plugs, then your first step is to replace them with the correct plug. NGK is the OE plug, gap has to be manually set at .040". Champions are often used, though they are a tad longer on the insulator, pointing to them being a little hotter heat range.

 

[bmrrwolfe]

First mistake, Bosch. You should never use Bosch sensors unless they were OE, to which they aren't. NGK/NTK, Denso, or Mopar sensors are what you should be running. Bosch sensors are of a different design, and perform slower, causing both codes, and in some cases running issues.

P0171/P0174, says Bank1 and Bank2 are running lean, even with the engine control module doing max corrections. P0157, that's an O2 sensor code for Bank2 sensor 2. P0420 and P0430 are codes signaling poor catalytic converter performance, and in most cases means replacement is needed for both banks.

You haven't put in E85 fuel right? You have under 30k miles on your NGK copper plugs, correct? If over 30k on the plugs, or they are not copper core plugs, then your first step is to replace them with the correct plug. NGK is the OE plug, gap has to be manually set at .040". Champions are often used, though they are a tad longer on the insulator, pointing to them being a little hotter heat range.

NGK Plugs are copper and have about 18k on them, and will be done again in the summer. Gas is not E85. Few stations around here have it, and this is one of 3 three stations that I go to regularly, but just incase it is a gas problem, I got some gumout gas treatment and added gas. Put a few more miles and its showing the two codes P0171 and P0174 twice...

I can try to swap in a different brand 02 sensor, but I don't see that being a cause for both banks to run lean.
Also looked for any vacuum leaks under the hood, but did not hear any hissing, and did not see any obvious cracks. I pulled the battery cables to reset the computer and with the new gas and treatment, will see if that did anything. I wish it wasn't 20 degrees out with an expected 6-8" of snow tomorrow..

 

[Snail Farmer]

x2 on the O2 sensors. I would replace them with NTK first, then see what codes you're left with. I'd be willing to bet most of your codes will disappear with the proper O2 sensors. I had a P0420 code also a couple of months ago. I ran some CataClean through it, and it went away and hasn't returned.

 

[bmrrwolfe]

x2 on the O2 sensors. I would replace them with NTK first, then see what codes you're left with. I'd be willing to bet most of your codes will disappear with the proper O2 sensors. I had a P0420 code also a couple of months ago. I ran some CataClean through it, and it went away and hasn't returned.

Well after adding the gas treatment and 8 gallons of 89, let it run for a few mins to work into the fuel system and I did about 15 minutes of suburb driving (most of driving is suburb driving about 4 miles each way to work) it did not have the rough idle it had before at stops. The CEL did not come back on, but I read the computer anyways and the P0171 & P0174 were there..

Ordered one new NTK sensor, should be here Friday to replace the Bosch sensor.

 

[Snail Farmer]

I always replace all my o2 sensors at the same time but if you're just concerned whether replacing them will fix it then replacing just the downstream should be fine.

Sent from my HTC One using the power of Mary's purse

 

[bmrrwolfe]

Attached a couple numbers from the scan tool doing a live scan while it was idling in the driveway.

Not sure if that helps with anything, as they seem to fluctuate a lot.. A good half hour of driving around, it feels normal, the idle sits at about 600 (normal) does not shake or have a rough idle at a light like it did, and the CEL did not ever come back on, but even after clearing the codes they show up on the scanner within 10 minutes of driving.


Also the ESP/BAS and traction light came on while letting it idle in the driveway, I then restarting it and it was off, but came back on a few minutes into my drive. Don't think this could be related in anyway..

Edit: A little research points the ESP/BAS and traction light to the steering angle sensor, needing an alignment. If the ABS light was on (which is not) it would be a speed sensor or ABS sensor.

 

[streetglideok]

Attached a couple numbers from the scan tool doing a live scan while it was idling in the driveway.

Not sure if that helps with anything, as they seem to fluctuate a lot.. A good half hour of driving around, it feels normal, the idle sits at about 600 (normal) does not shake or have a rough idle at a light like it did, and the CEL did not ever come back on, but even after clearing the codes they show up on the scanner within 10 minutes of driving.
Not a lot of scan data shown, but interesting to see B2S2 readings.

Also the ESP/BAS and traction light came on while letting it idle in the driveway, I then restarting it and it was off, but came back on a few minutes into my drive. Don't think this could be related in anyway..

Edit: A little research points the ESP/BAS and traction light to the steering angle sensor, needing an alignment. If the ABS light was on (which is not) it would be a speed sensor or ABS sensor. I think your research is flawed. Unless it is related to you incorrectly using the battery disconnect to reset things, the SAS doesn't suddenly need an alignment to correct itself. Without codes and scan data, you're guessing, but at least it's with your money.

The reason for telling you to remove the junk O2 sensor has less to do with the lean codes, but more to do with the B2S2 code you had set. When looking at the scan tool data, you need to look at long term and short term fuel trims for both banks. Have someone help you by driving it for you. Monitor the trim data, and see when it goes 20+%. If it is under load, then you may have a fuel issue or air calculation issue. If it is at idle, then that points to a vacuum leak issue. You won't hear a vacuum leak that will cause your issues. If it points to a vacuum leak, then you'll need to use brake cleaner, propane, or a smoke machine to find the source.

 

[bmrrwolfe]

The reason for telling you to remove the junk O2 sensor has less to do with the lean codes, but more to do with the B2S2 code you had set. When looking at the scan tool data, you need to look at long term and short term fuel trims for both banks. Have someone help you by driving it for you. Monitor the trim data, and see when it goes 20+%. If it is under load, then you may have a fuel issue or air calculation issue. If it is at idle, then that points to a vacuum leak issue. You won't hear a vacuum leak that will cause your issues. If it points to a vacuum leak, then you'll need to use brake cleaner, propane, or a smoke machine to find the source.

Thanks for the information. Also on the traction control issue, I was just pointing out what I have seen from people with similar issues, I will not be doing anything with the suspension unless the problem persists, and even then, I would just get an alignment when I decide to put on new tires this summer/fall.

After work today, I will have the girlfriend drive it around while I monitor the scan tool.

On a note the traction controls lights went off and did not come back on the 10 minute drive to work today, neither did the CEL. After I got to work I ran the scanner and it was only showing a P0157 (B2S2 the one that will be replaced)

 

[streetglideok]

The ESP/traction control lights can come on due to an engine code, depending on what code is set. Every carmaker is different in that regard. One thing you never want to do, is pattern diagnose a problem. A lot of guys in repair shops do this, and have themselves fooled into believing they are diagnosing problems. These are frequently the same tools found on the news when they do an expose' on repair shops. You can use pattern problems as a guide, to help rule out issues, but never rely solely on it. You must follow thru and test/confirm.

 

[bmrrwolfe]

The traction control is not of any concern at this point.


Drove home and for an 5 mins around the neighborhood and no stumbles at all and normal power. Ran the scanner again, and again no CEL but it showed:

P0420
P0430
P0171
P0174

and the 02 sensor code disappeared..

I used brake cleaner to try to find any vacuum leaks, with no luck..

I'm at a loss with this one..

Also when you said "Monitor the trim data, and see when it goes 20+%. If it is under load, then you may have a fuel issue or air calculation issue"

Which names/abbreviations am I looking for on the scanner to try to find this 20+%?

 

[streetglideok]

Your O2 code will likely return later on, its a bosch,lol.
You're looking for LTFT 1, LTFT 2, or long term 1, long term 2. It'll be something along those lines. P0171 and P0174 set when the fuel trim reaches 20% typically but some say 25%. Positive numbers reflect the module is adding fuel (means it thinks the engine is running lean), and negative numbers mean its taking away fuel(running rich). +/- 5% is normal. You should also see short term fuel trim data. You add that to the long term to come up with your actual fuel trim. If long term b1 is 15% and short term b1 is 6%, you have 21%.

 

[bmrrwolfe]

Your O2 code will likely return later on, its a bosch,lol.
You're looking for LTFT 1, LTFT 2, or long term 1, long term 2. It'll be something along those lines. P0171 and P0174 set when the fuel trim reaches 20% typically but some say 25%. Positive numbers reflect the module is adding fuel (means it thinks the engine is running lean), and negative numbers mean its taking away fuel(running rich). +/- 5% is normal. You should also see short term fuel trim data. You add that to the long term to come up with your actual fuel trim. If long term b1 is 15% and short term b1 is 6%, you have 21%.

02 Sensor will be done on Friday, and I will be doing new NGK V-power plugs at the same time.

Scanning after work today, I found a "fuel system 2 CL-Fault"

any ideas??

 

[streetglideok]

Where did you come across that?
Here is a screen shot off a scan tool I have, with my KJ

You must be registered for see images attach

You may have to save it, and blow it up to clearly see what it says

 

[bmrrwolfe]

Where did you come across that?
Here is a screen shot off a scan tool I have, with my KJ

You must be registered for see images attach

You may have to save it, and blow it up to clearly see what it says

On my scan tool, (craftsman) it does not show any charts like yours.. After scanning it show the errors a and freeze frame of about 28 abbreviations and numbers. (I have two pics from the first page of this thread) The first two abbreviations:
"FUEL SYS 1- CL"
"FUEL SYS 2- CL-FAULT"

So its sensing an issue with the fuel for bank 2? (passenger side)

Also the tool gives you other options for live data, but not in chart form.

 

[streetglideok]

Your cheaper scan tools won't do what mine does, with the graphing and flight recorder mode. With what you have, it may not display fuel trim data correctly, if at all. Fuel trims should have a number next to them that changes. Long term is a longer average or trend, short term is basically real time adjustments.

 

[bmrrwolfe]

Your O2 code will likely return later on, its a bosch,lol.
You're looking for LTFT 1, LTFT 2, or long term 1, long term 2. It'll be something along those lines. P0171 and P0174 set when the fuel trim reaches 20% typically but some say 25%. Positive numbers reflect the module is adding fuel (means it thinks the engine is running lean), and negative numbers mean its taking away fuel(running rich). +/- 5% is normal. You should also see short term fuel trim data. You add that to the long term to come up with your actual fuel trim. If long term b1 is 15% and short term b1 is 6%, you have 21%.

I finally got a chance to pull the reading for the fuel trims.

At an idle they were:
STFT B1 -.08%
LTFT B1 5.5%
STFT B2 -2.3%
LTFT B2 7.0%

Obviously they flucuated, but thats a general representation as how they were at an idle. Under acceleration they changed to higher numbers but only for a second then would return to similar numbers.

Another item I was watching was the O2 sensor voltage.

02S B1 S1(V) .095
02S B1 S2(V) .760
02S B1 S1(%) -.6
02S B1 S2(%) 99.2

Again this was just a pic I took of the screen, but the voltage for S1 was all over the board, and the % for S1 was always low and S2 was always high.

For Bank 2 the %'s were similar but the voltage for S1 were more consistent around .625 and S2 were around .505.

The actual CEL light appeared last night and it was reading just:
P0420
P0430
P0174

This morning the same codes were there with an added
P0158 (B2S2 High Voltage)

Of course it was -2 out this morning, so I am hoping it will warm up this afternoon to get the plugs and 02 sensor done..

 

[streetglideok]

How high do the fuel trims spike to, when taking off? Also, if you can view freeze frame data, see if you can review the freeze frame for the P0174. Look at the RPMs when the code set.

The front O2 sensors, B1S1, and B2S1 should switch, once they warm up, which is within 90 seconds of startup on a cold engine. Look at the screenshot I put up on post #15. Look at the second row of graphs. The first two graphs are O2 sensor readings. The trace line reflects what the voltage is doing, its going up, and down, switching as they call it. That is normal. The downstream sensors, B1S2 and B2S2, should not switch once warmed up. They should have a fairly steady voltage. Yours likely wont though, because you have a P0420 and P0430 code set. Those codes set when the cats don't work right, and those downstream sensors switch too many times in relation to the front sensors.

Since it seems your fuel trims are ok at idle, pay attention to how high they go when taking off. Is it just an initial spike and it goes back to normal, or does it spike up and stay up until letting off the gas? When it does this, do both short term and long term go up? You're running a little lean at idle, but no worse than mine. If you click on my pic I posted, so that it blows up a little, that second row of graphs, from left to right is
B1S1 O2, B2S1 O2, then STFT-1 and STFT-2. The third row is LTFT-1 and LTFT-2. If you look at each graph, there is a vertical line just right of center. That's not by accident, that's a tag, and is in the exact same spot on each graph. It helps compare events from all the graphs at once. Top row of graphs shows my TPS, reflecting my throttle. If you look, you'll see a trend, where my LTFT numbers are elevated, 8-12% at idle, and they drop to about 0 when I'm taking off. That's pointing towards a different issue than yours from the sounds of it. Reason I'm pointing this out, is so that a visual of what goes on may help you understand what you're seeing, and what we are looking for, and for anyone else needing a cure for insomnia, lol. Your scanner won't do all what mine can as far as saving and uploading files, but as long as you know what you're looking for, and understand what you see, then it isn't important.

 

[profdlp]

This is so far out of my league it isn't even funny, but I wanted to wish you well!

 

[streetglideok]

This is so far out of my league it isn't even funny, but I wanted to wish you well!

Lol its not all that bad. If you lived in the area, I could teach a class on this stuff