Howdy and Help!

I have a 2003 MCS with 42K miles. I have a Service Engine Soon indication and the fault code is P0171 (according the CarChip). It trips at 3,005 RPM at 39 MPH with the same temp, engine load, and other readings. And help to what this may be? I have checked the PCV valve and looked for a vaccum leak (I have not removed the intercooler). The car runs fine. Thanks in advance for your help.

Ciao for now,
Frodo

 

0171 = system too lean ( bank1 )
Does the light go out then return? Could be the new tank of gas. Just a guess would be the up stream o2 sensor.

 

Well I do have to fill up today. I can try some 98 this time but the light stays on. When I download the CarChip (I know it does not tell you everything) it always trips under the same conditions. It did happen after a "quick" trip up the mountain and back. I ran it hard and I thought it might be the hose I replaced on the PCV valve it had a sharp bend and now I used a proper 90* hose. Not too worried about it but I don't want to go to the dealer unless I have to. I am stationed in Italy and they only have a 2 year warrentee. Thanks for the help so far...

 

This CEL has happened to me, 1 time after a change of gas to a different brand. Note, after a softwaer update done by the dealer. 5 monthes later the light came on, went off, came on, then went off not to come on again. However in your case I suspect that a sensor might be a problem, key is might.
If the light stays off & the car runs fine, it could just be that tank of gas. If there is a sensor for the PCV, I have no idea where it is located.

 

Are you running the MTH maps?

Theo

 

No maps, only a BMP intake which has been on it for 2 years.

 

Just wondering, because I get the same error code when highway driving and the cruise control is used. But I have the MTH standard maps loaded.

Theo

 

Okay, just got back from my vacation and the SES light went out. I noticed it going up another mountain at a steady speed/RPM. The problem started after a "quick" trip up the mountain and a slow idle down. I have heard someone else having this code and driving up/down mountains. Any thoughts?

 

I got this code on two occasions, both right after driving down mountains. However, I was also using different fuel at the time as I was road tripping in the US, and I live in Canada. (Oddly, the fuel was nominally higher octane, 92 as opposed to my usual 91.) The mountain-driving factor sounds like too much of a coincidence to ignore though. If anyone has any theories I would appreciate hearing them.

BTW my mods are: 15% pulley, Alta CAI, Milltek cat-back, Detroit Tuned bypass valve, and VGS.

 

is the dreaded "flat spot". At very light throttle, the car isn't getting enough gas. Don't know why, but it's a software issue. It rears it's ugly head during the freeway driving with cruise control because the computer is working at very light throttle....

Matt

 

Yeah, Matt...that's exactly when I have gotten the light. Peake tool always says P0171 with only one code stored. Also, I have the JCW 210 software loaded with the (circa 2004) "regular" MTH A/F maps loaded.

I now carry my Peake in the car when traveling on highways. I hate that yellow light staring at me!

Theo

 

Matt has a good point, the flat spot, where there is a lean condition, however with this car, there is not realy any driver feel from the lean condition. Since the last BMW software upgrade, 2K+, the light has not come on (in this car ). This is a known software problem.
Is 10% eth mandated in NH? It is here in MA, not that this is relative to your light ( but maybe ).

 

Hey Matt! I'm about 3 miles from you in Easthampton!

Theo

 

Matt lives in CA, I wish I lived 3 miles from him...........

Theo, you live in Easthampton MA? If so I've got some stuff for you to try

 

Ooops! I named Matt but I meant Steve. Yeah, Steve I'm just next door. I'll PM you.

Theo

 

I've gotten this code on the highway too. No problem, just cleared it with my peak tool and kept going. The code that I get nearly every startup however (P0456) is driving me mad. Gotta get that looked at... The gas cap doesn't get any tigher....

 

get to a dealer, it's probably the emissions pump that pressurizes the system to test it. I've heard of several of those going out.

Matt

 

Yeh, I will. At the moment, I'm trying to finish my dissertation, so when that ugliness is over I will deal with it.

 

I had the same problem when I had the GIAC 15% software running on my car. I would get it going up a hill coming home from my parents every time.

I talked to Eric at Helix, he recommended doing the VGS mod which helped the flat spot feeling some but didn't do anything about the CEC.

I switched to the MTH tuner file with my 15% pulley and never got the light or code again. Recently went to 19% and an new MTH flash still no probs.