I have a L99 A4 in a S10 with mild portwork on heads and intake,CAI,headers, and full exhaust. I have LT1edit and changed the program (just the size) for the injectors. While datalogging at idle and cruse speeds my O2 mv stay in the low end (teens to 400) and every once in a while jump up to 700. At full or hard accell they go up to around 800 or 900 for a while and fluctuate like they used to before the inj. change. I pulled a plug and sure enough it read lean. Do I need to do more tuning, and to what? Im new at injection and am trying to learn. Any info to where to go next would be appreciated.

 

I just checked my presure, its at 35# at idle, Is this low?

 

a little, bump it up to around 42 psi or so, see what happens

 

If the oxygen sensors are switching from low numbers to high numbers, and your long term fuel trims are between 108 and 160 (best around 128) then you are running just as you should be. The numbers you see for the O2 sensors are just sampled and may skip around a bit, but they need to go from below 450 to above 450 and not be too sluggish. Your fuel pressure will be around 37 or so at idle unless you pull off the vacuum line, then it will go up to 42 or 43 if it's working right. From your description, it sounds like you are OK, not lean - but check the stuff I said.

 

The reg works checked that today also. I forgot to say this morning I got a left bank 02 lean fault and this afternoon a right bank O2 lean fault. Could I be running lean because my injector flow rate is for a higher PSI than Im running? Wouldnt that make them flow less than programed ?

 

What are the BLMs (long term fuel trims) at?

 

Ill look them up they are on my laptop and post back.

 

At idle both are 160. From 650rpm to 1300rpm they go to 150 to 153, at 1350rpm back to 157 to 160 while Im driving.While decellarating they do the opposite. These seem to be the readings for the RPM ranges given while I was datalogging. At one point they dropped to 120 going 38MPH at 1025 RPM and the O2s were reading 36mv lft and 27mv rt.I think that was when it threw a code.What could have caused this

 

You have a definite long term lean condition, so the PCM is adding all the fuel it can within it's adjustment range. You could have a vacuum leak, or a leak in the intake tract after the MAF sensor. The O2 sensors need to be switching - if they are not, it might cause that. Since your plugs look lean, I don't suspect a leak in the exhaust, because that would create a false lean condition which would then make you run rich. IF none of the above and the engine is healthy, you can try reducing the injector size if the BLMs are high across most of the log, or if they are just high around idle and slow speeds (short pulsewidths) you can increase the turn-on time by 10% and see what happens. Also make sure all your injectors are firing and squirting.

 

Tomorrow is my friday so I will have the next two days to mess with it. Ill try those changes and do some more datalogging. Thanks for the help.

 

Sure - just make sure it's healthy before you go adjusting everything - if there's a real mechanical problem, you don't want to try to make up for it by changing your fuel or something.

 

We knew that from the first post.

Sure. If you ignore the part where the problem started after he changed the injectors.

 

Yes. Change the constant or up the pressure.

 

What injectors did you get, and where from? Sounds like you may have been scammed.

Can you email me the datalog?

Mdenz@hotmail.com

 

Your BLM's are adding about 25% extra fuel. You just increased your flow constant by 25%. Certainly makes the actual injector size suspect.

If the injectors are really what they claim to be, check each one to make sure the O-ring is still there on the end that sticks into the manifold.