Help! Getting Code P0171 (Fuel System Lean)

[Richard Koch]

I need some help to get my Viper running correctly again. I am planning to drive it some 3,000 miles to VOI 12 in Charlotte and I need to get the engine issue figured out.

A little backgound on the car: It is a 1999 RT-10 with 88,500 miles, smooth tubes, Belanger cat back exhaust, and high flow cats. It has a mild SCT Tune, but I restored the stock tune and it did the same thing. I have been running it on track and driving it a bunch this summer and everything has been going well.

A few days ago I ran it completely out of gas. This is the first time in my 68 years that I have ever run out of gas with one of my cars. I was able to get enough gas to get to a decent gas station to fill the tank. On my way home I got a check engine light and the code was P0171( 1/1 fuel system lean- a lean air fuel mixture has been indicated by an abnormally rich correction factor). I cleared it and after driving 30 miles got the code agan. I figured some junk may have come loose and perhaps the injectors may be dirty, even though it has a fuel filter. I got some injector cleaner (Sea Foam) poured it in and ran a complete tank of fuel through the car. It brought up the P0171 code again. I got a new fuel filter and replaced the old one which was partially clogged. I figured this was the solution and today it went 16 miles and I got the code again. After some running (in 85 degree weather) it started to burble a little, but would run well with more throttle. I also noticed sooty black in the exhaust tips.

I am curious whether anyone has had something like this happen to them. I have fairly new plugs and wires and the engine has been fine up till I ran out of fuel. I haven't gotten and other codes that address injectors or any other subject. Some forums I have visited talked about O2 sensor faults or bad injectors. I am fortunate to have another good set of injectors in case they may be the problem. I haven't been able to detect any vacuum leaks or other problems with the engine. The only odd thing I noticed when I shut off the motor was a muffled "****"' from under the right side hood on 2 different occasions. I also wonder whether I may have damaged the fuel pump during the short time it was pumping only air.

I would appreciate any help I can get to help solve this. The closest dealer with a Viper tech I know of is in Portland , Oregon, 3 hours away. Perhaps some of my other Viper mechanics in the area may be able to trouble shoot the problem or someone on the forum can point me in the right direction..

 

[Jack B]

Before the code is set how is the LTFT on both sides. In addition, are both o2's switching at the same rate.

 

[SNKEBIT]

Is it possible you hurt the fuel pump running out of gas? That's alot of miles and age...............................

 

[Richard Koch]

I thought of that. I am checking a couple of other things, but a check to see how much output it has would be a good idea. It is a huge pain to replace it and expensive, so I will eliminate simpler things first. Thanks for the input.

 

[Jack B]

Before the code is set how is the LTFT on both sides. In addition, are both o2's switching at the same rate.

That code is often associated with a a bad O2 sensor or the ground in the O2 sensor circuit, if you look at your LTFT and O2 switching rate, those two items can lead you to a the problem, any OBD scan tool will give you that info. Another simple test is to look at the fuel pressure, you don't want it below 50 psi. The schrader valve is on the rear passenger side intake, again any fuel pressure gauge can be attached . The odds are, one of the above will be at issue.

 

[Richard Koch]

Thank you Jack B. I have been making slow progress. I don't have much in ther line of diagnostics, but I have eliminated a few items and tomorrow I will try to get to a local tuner to get hooked up to diagnostics. Here is what I accomplished: I changed out the fuel filter which was partially clogged. I also found that the Make Up Air Tube on the front of the engine was damaged and I had to put new hose on it to complete it. I put injector cleaner in the fuel tank and put 110 miles on the car today without throwing any codes. Unfortunately it ran poorly towards the end of the driive and I had sooty black stuff all over the exhaust tips. I changed the sparklplugs today as another item to check and the 1,3,5,7,9, bank plugs wwere sooty black and nearly fouled. The right side , 2,4,6,8,10 are burning nearly perfect with a nice tan color. I thiink your suspicion of the O2 sensor sounds very likely. I will have them check that as well as the other items you suggert. I would imagine if it is bad that I should change out both , having nearly 89,000 miles. The only other question I would have is whether a bad MAP sensor could do the same thing? With what I have read the O2s sensors seem to fail more often, so hopefully that will fix my problem.

Is there a resonably priced device which would allow me to check for the LTFT etc? I was wondering how much it would cost as I plan to play with Vipers for quite a while and it would be nice to have in my shop.

I am planning to leave for Charlotte on September 21st, so I have to get the Viper fixed up so I don't have any surprises on the drive. Thanks again for the technical advice. I am old school on cars, but I am reading and trying to learn all the cool new stuff. I will let the foirum know what the final fix is.

 

[Richard Koch]

Good News! We have found the cause of the engine problems that caused the code to throw. My local tuner, MAX RPM in Bremerton, worked on the car today and found that the rear driver side O2 sensor was bad. He cleaned it and put it on the other side and it showed the right side as bad. That confirmed that the sensor was faulty. I had them replace all 4 of O2 sensors because I am at 89,000 miles and the others are reaching their life expectancy. I made the decision based on the age of the car and what I have read about longevity of O2 sensors.

I will pick up the car tomorrow after they get the repairs done and run diagnostics again. You were correct in suspecting the O2 sensors and now I can be more confident my road trip to Charlotte should be a good one.

The shop was very thorough and noticed that my serpentine belt was damaged. Part of the belt was chewed up and we found a small pebble lodged in one idler pulley. They will check all the pulleys before installing a new belt. It wasn't something I would normally look for, but I was glad they found it. In the future I will do that inspection when I change oil or do other under the hood maintenance.

This was a neat place where they allowed me to hang out with the mechanic doing the checks. I was able to see everything he did as he was doing it and examine all the parts and conditons he found. I actually learned a lot from the him during this work. If I had taken it to a local Dodge dealer I would have been very suspicious of anything they found as well as their solutions. They are famous of "selling you up" on parts and getting you to buy things you don't need.

Again, thanks to the people on the forum who sent me the right direction. I did the basic "boiler plate" checks and then turned it over the the diagnostician and things are looking up.

 

[Jack B]

As far as OBD scanners there are numerous hand held devices. Probably a better choice would be an OBD interface software package. Two of the most popular packages are EASE and Palmer Engineering.

 

[Richard Koch]

Thanks for the information on the OBD scanners. I will check into them.