Anyone else throwing a code for PO 171 "System Too Lean" Bank 1? It happend to me about once every week or so. I have done a lot of data logging and it only happens at low RPM and low load sites. It never happened before I changed injectors from stock to 580cc. Anyone else have this problem?

 

I used to get that too. Do you have cams? My idle was everywhere.
Then in openloop fuel, I added 30% fuel in the 0% col from 500rpm to 1750 then added 20 deg advance in the same col. Smooth idle, no ses.

 

If I remember correctly you also had an injector problem. Do you think it may have been related to this code?

I do have cams.

 

I get it when boost ramps faster than the tip-in throttle.. happens when the car is cold, if I don't get on it until the car completely warms up, it doesn't get that code.. but I haven't yet had the time to tweak it out..

 

My injectors were ok. I had the cleaned and balanced at RC, now thet are primo. I don't think they casued the code. Once I added fuel and timing at idle, I haven't seen the code.

 

I'll have to do some experimenting when I start having more time again..

 

It concerns me because I never had this problem until I switched injectors and it has happened a few times after the car is warm, but always at low RPM and Load.

 

Yeah, very low duty cycles.. Keep in mind with larger than stock injectors, the response at low load and low RPM is going to be "Lazy" therefore at times it will run lean.. All I can suggest is data logging for several days and watching conditions, you'll probably see its a tip-in condition at a particular speed or transition point that you can adjust for.. you can likely adjust your scaling on the injectors a bit to make them run "Fatter" (Setting the injector size a bit smaller in the UTEC) should help. Trust me, I even have this problem with stock injectors because of my blowthrough MAF when I tip-in, I tip-in lean and have to compensate accordingly or I get the same CEL.


I'm hoping that the UTEC gets some of the firmware upgrades we need such as Idle speed, idle quality adjustments (Fuel/Timing) and tip-in and deceleration offset among other features. (I still think having a built in analog MAF to Karmann converter is a better idea than speed density)

 

This code is usually due to Long and Short term fuel trims being maxed out in the + correction.

If you have a scantool log them to see what they are doing. The best way to set these is to make sure your fuel trims are within +/- 10 percent. This will fix the CEL.

 

Sounds good. I will give that I shot

 

Yeah that actually makes sense, I recall seeing my fuel trims "out of range" and constantly resetting and then going out of range again..