99 Wrangler has p0171 error code

[DaveB]

My brothers 99 wrangler with a 4.0 has a check engine light on after coming back from southern Utah. It was running like it wasn't getting enough gas, it would idle but couldn't go very far at high speed before it died. He took it to Autozone where they hooked it up to a scanner and it showed a p0171 error code. P0171 means that the engine is running too lean in bank1 (the bank of the engine with cylinder one) as indicated by a computer correction to the mixture that is abnormally rich. When he drove it yesterday it ran ok but still had the check engine light on. After doing some checking on the web the possible causes of this code are: poor fuel pressure, injector(s) plugged, mat, ect or map sensors, vacuum leaks, exhaust leaks, and exhaust sensors. So has anyone had this error code show up ? and what did you find was the problem ?
Thanks for any ideas,
Dave

 

[sukaB]

My brothers 99 wrangler with a 4.0 has a check engine light on after coming back from southern Utah. It was running like it wasn't getting enough gas, it would idle but couldn't go very far at high speed before it died. He took it to Autozone where they hooked it up to a scanner and it showed a p0171 error code. P0171 means that the engine is running too lean in bank1 (the bank of the engine with cylinder one) as indicated by a computer correction to the mixture that is abnormally rich. When he drove it yesterday it ran ok but still had the check engine light on. After doing some checking on the web the possible causes of this code are: poor fuel pressure, injector(s) plugged, mat, ect or map sensors, vacuum leaks, exhaust leaks, and exhaust sensors. So has anyone had this error code show up ? and what did you find was the problem ?
Thanks for any ideas,
Dave

If you did as many as we have and had troubles finding this prob, hunting it down and putting in new sensors???????
Everytime, Sending unit....start there!
Everytime I get them with symptoms their all different with different codes and stumbling issue's, Like I say Sending unit should be your prob there...

 

[DaveB]

Well I think I found the problem. I found that the wires to the first oxygen sensor were rubbing on a metal heat shield for the tranny shifter cable and two of the wires insulation were worn through and the wires were exposed and shorting to the shield. I swapped my spare in and now it runs fine. The check engine light is still on so I guess my brother will have to take it somewhere to get it reset.
Dave

 

[sukaB]

Well I think I found the problem. I found that the wires to the first oxygen sensor were rubbing on a metal heat shield for the tranny shifter cable and two of the wires insulation were worn through and the wires were exposed and shorting to the shield. I swapped my spare in and now it runs fine. The check engine light is still on so I guess my brother will have to take it somewhere to get it reset.
Dave

It will reset if no other problems are current...
3 starts and runs it should go out...
Good job for finding the prob..

I always start with the easy crap,fuel press and then check sensors, they seem to slow TJ's down the most and quickest.

 

[tagaustatoppen]

I have a similar problem with my 97 wrangler. The exaust manafold has a leak. I have not gotten the code for the engine light but it only comes on for a day and then goes off for weeks at a time. It acts like its not getting either fuel or spark. would the leak in the exhaust make it ack like this? or would there posable be more? I also wounder if anyone had run aftermarket headers on there wrangers and if there have been successful. I dont know if i should get a stock manifold or get headers.

 

[DaveB]

I have a similar problem with my 97 wrangler. The exaust manafold has a leak. I have not gotten the code for the engine light but it only comes on for a day and then goes off for weeks at a time. It acts like its not getting either fuel or spark. would the leak in the exhaust make it ack like this? or would there posable be more? I also wounder if anyone had run aftermarket headers on there wrangers and if there have been successful. I dont know if i should get a stock manifold or get headers.

This problem on my brothers Jeep came back a while after I changed the sensor. What I found was that the fuel mixture was too lean. His problem ended up being the fuel filter or fuel pump. Can't tell you for sure which since I swapped both at the same time. His jeep has been running fine since. Another brother had the cracked manifold problem on his TJ. It would run rough and occasionally die when we were wheeling. I'm not sure if he got any error codes but the jeep ran badly because the oxygen sensor wasn't getting a good reading because of the many manifold cracks. He found a new manifold on the net for about $75 and it fixed his problems. The new manifold has been redesigned and is supposed to not be so prone to cracking.
Dave

 

[Cory]

He found a new manifold on the net for about $75 and it fixed his problems. The new manifold has been redesigned and is supposed to not be so prone to cracking.
Dave

Any ideas where he obtained the manifold from?

 

[DaveB]

Any ideas where he obtained the manifold from?

No, but I can ask.

 

[Samuraiman]

No, but I can ask.

It's a JEEP thing I wouldn't Understand.

 

[tagaustatoppen]

I kind of think that the fuel pump is having problems too. (ill find out after i chagne the manifold.) the problem seams to get worse as it gets below half a tank so i wonder if there are other problems? I'll find out tomorrow!

 

[Cory]

No, but I can ask.

That would be appreciated.

 

[DaveB]

That would be appreciated.

Here is the place he got it from:
http://www.1aauto.com/1A/ExhaustManifolds/Jeep/Wrangler

Dave

 

[tagaustatoppen]

I've replaced the manifold and it runs. I hope this will fix the proplem. I run a tank of gas through it and find out if i still get same problem.

 

[Cory]

I've replaced the manifold and it runs. I hope this will fix the proplem. I run a tank of gas through it and find out if i still get same problem.

Did you replace the exhaust manifold yourself? How big of a job is it? Does it require any specialized tools or equipment. Is this something the average person can do without expert knowledge?

Thanks

 

[tagaustatoppen]

Did you replace the exhaust manifold yourself? How big of a job is it? Does it require any specialized tools or equipment. Is this something the average person can do without expert knowledge?

Thanks

It is a really simple job if you have a set of wrenchs and socks you'll be ok. I have worked as a mechanic for several years so that may be way I say its simple. You need to disconnect the manifold from the exhaust pipe before you get it all the way apart though (mine was broke all the way on both of them). If you have one that needs to be changed I can give you more help. If you really want some help PM me or email me.

Tyler

Edited to add the quote.