Im having a blm problem where they stay above 128 and eventualy max at 160 in most the cells. both sides are within 5 of each other. I have 30# motorsport injectors and have set the constant acording. I have raised the fuel presure to around 45 at idle and with no vac goes to around 50. this has no effect on the blms. Shouldnt this cause the pcm to start pulling fuel out instead of still adding fuel? I have checked for exhaust leaks to see if I am getting a false sig from the o2s.Any ideas or am i just tuning in the rong spot.I also have no codes. Thanks for the input.Im using lt1edit
C.T.

 

160 is as high as a stock tune will go, you are adding 25% more fuel that your sensors and injector constants are calculating. Something is drastically wrong.. Doubt both O2's would be bad within 5 of each other. You sig is 91 S10, what engine and ECM/PCM are you running. Are you SD mode and sure the cyl volume , injector lbs, and VE tables are set correctly.

 

Try setting the injector constant lower, this will help make global changes.

 

Im in mass air mode and its a L99 4.3l LT1. could my mass air be out of call ?

 

Do you have any header leaks or things like that (not even where the headers hook to the duals)?

Does the truck foul plugs quickly (is it rich or is the correction necessary)?

Are you sure you have a good seal from the maf to the throttle body with no vacuum leaks (you didn't descreen it did you)?

Are the o2 sensors oscillating back and forth properly in closed loop?

What kind of airflow does it report g/sec idling and then going down the road about 60mph steady?

You're sure there are no missfires?

 

Raising the fuel pressure from 43.5psi to 50psi increases injector flow by 7.2%. Perhaps your PCM is adding the 25% it can add by raising the BLM"s to 160 (as noted above - that's the upper limit), and then adding additional fuel by rasing the short-term fuel corrections (INT's). Your increased fuel pressure may be lowering the short-terms, but the required correction is still more than +25%.

But you are going about it the wrong way. Makes no sense at all to just start raising fuel pressure to try and correct elevated BLM's. Find out what is causing them to rise. What if you have a large vacuum leak? What if you have severe misfires? What if you have exhaust leaks before the O2 sensors? What if your O2 sensors are bad/contaminated? What if your MAF is screwed up? What if there is a leak between the MAF sensor and the throttle body?

 

I have checked the exhaust for leaks but have not checked for any vacuum leaks at intake or air inlet. How do I check for misfires? except for the obvious lightening storms under the hood at night, I know how to check for that and I have none. I havent noticed the plugs fouling and the o2s oscilate as normal. The mass was descreened when I got the setup. At idle it reads around 8 or 9 and at 40 mph it goes from 36 to 40 at 48 mph and then changes cells and drops to 36 gm/s at 50 and stays steady all through the 55mph drive time. Thanks for the replies.

 

Your airflow values are within range, certainly not 25% too low like your fuel trims suggest. If you send me a copy of your tune I will be glad to give it a look. A log would be good too, sometimes you can spot things that seem unrelated but are the cause.

You can usually pick out missfires because the engine will run or idle rough.

Did you do any sort of mods to the o2 sensor harness (extensions etc)?

You are absolutely sure they are 30# injectors? where did they come from? Have they sat a long time after being used?

Are you sure your fuel pressure isn't falling off, the adjustable fpr are known to have problems keeping pressure.

 

Check for a leaking injector at the o-ring. I just had this happen to me and I too got a lean condition.

 

I reviewed your tune and your log and unless the l99 uses a different maf sensor than the lt1 your maf tables are F***ed. Way off, almost as if somebody went and multiplied the entire set of maf lookup values by some percentage smaller. I suspect that is the source of most of your problems.

The tell tale thing in the log was when you started the motor and it was in open loop, the o2 values were stuck on 100 or less the entire time. Which is pretty much dead lean and also the reason it died when you first tried to start it.

I can post the correct tables and send it to you as a .bin file and you can find a converter to make it an lt1 file, or I guess I could email you what should be in the tables for a stock maf setup.

Your wot tables kinda look like a joke too at the moment, there is no way you will get a decent air fuel ratio when you step on it the way it is right now.

I haven't looked any closer than that at it yet, timing seems very very conservative in the log file at a glance. Let me know what you wanna do.

 

WS6T3RROR pm sent

 

You have email ct.

 

Thanks Josh. I got it uploaded and it has never idled so nice. Its raining so cant do much today but Im gona do some logging tomorrow, supposed to be clear.