Any Mechanics Out There

[BrianGSDTexoma]

I have a 1997 Jeep GC. I use it to pull the boat. While sitting there idling while I am doing what ever with boat it starts idling really rough and throws code P0171 Right bank lean. 4.0 so only one bank. Few months ago I replaced Map sensor and Flow Sensor. No problems since. I had to replace battery last week. While loading boat today it happened again. When get boat back in storage and restart it is fine. Not sure where to go from here other than maybe O2 sensors? I need to retire this thing but can't swing a newer one right now.

 

[TNJAKE]

Could be a vacuum leak

 

[TNJAKE]

Oxygen sensor for your model is 50-60 bucks and pretty easy to change. Would be a cheap route to rule it out

 

[TNJAKE]

Notice a sulphur like smell coming from the exhaust?

 

[Brokenhandle]

How's it run otherwise, ok while driving? I'm not a mechanic but have had many vehicles over the years that had bad o2 sensors...that check engine light never bothered me being on. I got tired of changing them and they don't last long.

Ryan

 

[chopsaw]

Lean condition , could be a vacuum leak or not enough fuel .
Bad vacuum hose can be detected by using carb cleaner LIGHTLY spray around hoses and control valves while the engine is idling . If the engine picks up , then it's sucking air in that area .

If that has an EGR valve that could also be suspect .

Low fuel at idle could be a dirty or sticking injector , or possible low fuel pressure .
There are other causes like the air fuel not being regulated correctly . Mass air flow sensor maybe .

 

[dls1]

I'm definately not a mechanic, but my daughter had the same code pop up a couple months ago on her car. In short, it's saying that the engine is running lean on bank 1, meaning the air to fuel ratio is biased towards air. In her case, it was an O2 sensor, but it could also mean several other things including a vacuum leak as TNJAKE mentioned. Best to have a mechanic check it out before driving it too much any more.

 

[6GRILLZNTN]

Did the code stay on after re-start? My car popped the same lean code last year. O2 sensor fixed it. I found one on Amazon for $20, with the factory plug. Like others have said, it could be dirty injectors, vacuum leaks, etc.

 

[BrianGSDTexoma]

This something that is intermittent. Only happens once in a while. Runs fine while driving. When it does it usually after cool off few minutes it is fine until who knows when it does it again. When it happens exhaust does smell and kind of black.

 

[BigW.]

I know very little about cars. Thankfully we now have youtube and google. Certainly helps, but I wish I had actual knowledge. Good luck.

 

[bigfurmn]

Grand Cherokee P0171 Code Defined:​

The P0171 code on a Jeep Grand Cherokee will often be thrown if the fuel injection system is not operating properly. Typically the code will be triggered by a lean condition in the engine.

There aren’t usually any drivability issues associated with P0171. For most people the first sign that anything is wrong at all is the service engine soon light coming on.

Here are the typical symptoms that something is wrong when you have code P0171.

• Mileage- may or may not suffer depending on how much the air fuel mixture has changed.
• Misfire– If the air fuel mixture has gotten too far from factory specs, this can cause the Grand Cherokee to misfire.
• Idle Issues– With the air/fuel mixture altered, the vehicle can idle erratically as the computer compensates to keep the engine running.

Hope this helps. I am not mechanic but used to be in auto body so if you get in a wreck I might be more help.

 

[TNJAKE]

This something that is intermittent. Only happens once in a while. Runs fine while driving. When it does it usually after cool off few minutes it is fine until who knows when it does it again. When it happens exhaust does smell and kind of black.

When an o2 sensor is failing the rough idle will come and go until eventually it will be constant

 

[chopsaw]

When it happens exhaust does smell and kind of black.

That would be a rich condition . I read that it said the conditions over lap . If it dumps fuel the PCM compensates into a lean condition .
It's been a few years , but I was an ASE certified Auto Mechanic before I got in the Carpenters . You can chase parts or have it checked out .
One problem could be causing another code to throw .

 

[TNJAKE]

Also if it is an o2 sensor it's likely the upstream o2 sensor and not the downstream sensor. Your symptoms point to upstream

 

[normanaj]

Sounds like exhaust leak to me.

 

[JIMSMOKES]

Old School. Clean all battery connections especially negative/ground. Not just the battery but where they connect to engine and body!

 

[BrianGSDTexoma]

Sounds like exhaust leak to me.

I think I do have a manifold leak but wouldn't it do it all the time?

 

[BC Buck]

Next time does that turn off then restart. see if the same or idles OK.

 

[pc farmer]

If it is upstream O2. Just unplug it, the computer will use a compensate value. A downstream isn't that big of a player.

 

[clifish]

I have a cheap OBD2 scanner from Amazon like $20. I t will read codes and reset the CEL. I have the same 4.0 in my Wrangler and reset it plenty. Sometimes they come back (then I replace the O2 sensor) some times they don't come back.