take a look at this log

[BadLSX]

i've been having a lean issue up to 1500 rpm or so ever since i had my car tuned by a very reputable tuner in April. i've done logging for him on several different occasions & apparently he can't figure it out. i'll post the log & the tune & let you guys check it out. the car is mechanically fine, good fuel pressure, no vacuum leaks, leakdown & compression tests performed. i'm sure there are no issues with the car & feel it has to be in the tune. let me know what you guys think.10.19.1.tun10.19.10 ColdStartWarmup.efi10.19.10 DriveAroundTown.efi

[WeathermanShawn]

Seems to be a major issue with your O2's not switching..or switching very erratic.

I take it your are attempting to run closed-loop, MAF enabled. Your Injectors are not stock?

I will defer on the injector tables (not my specialty), but your narrowbands stay rich, then stay very lean, occasionally switch.but very slow.

How many miles on the O2's? Whatever the answer, I might just try a new set. Until you get that straightened out, closed-loop will be very difficult to achieve..

[BadLSX]

i believe its is closed loop, MAF enabled. i'm running 30# Ford racing injectors. the 02s have about 2000 miles on them. i'll se if i can dig up the 02s i removed & see if that helps. i think the 02s in the car currently are either NGK or Bosch, i cant remember for sure. what is a good 02 to use?

[BadLSX]

would this affect how the car runs at WOT, such as at the dragstrip? i was at the track Saturday & the car was down 4-5 mph also, compared to normal.

[WeathermanShawn]

I use the rear Corvette O2 sensors for my front two sensors. So far 30K+ on them.

At highway speeds they switch about 3-4 times a second. Do you have headers? Some headers collect heat differently, so your location of the O2's may be the key. Mine are near the collectors..just 'ahead' of the high-flow cats.

As far as the drag-strip, down 4-5 mph is pretty significant. Now if there was a difference in weather (higher DA's) that will cut your mph. If you were shifting at a lower rpm, that might also affect your mph..but rule of thumb is every 1 mph = ~10 HP..so 4-5 mph is a lot.

What mods do you have?

If you feel your car is really down in power, then that can be addressed. If you were overly rich (AFR), that would cut you down some. Of course overly lean or significant KR would also be a concern. You would need to log WOT to really know. Technically the O2 sensors are not utilized during PE Mode or WOT, but if your overall fueling is off then it could be a problem...

[BadLSX]

ok, i put new Bosch 13111 02 sensors in tonight & it didn't help. where do i go from here? i'm going back to the track tomorrow, hopefully my MPH comes back. whats funny is that Doc did a mail order tune for me after i originally had the car tuned. the car seemed to run better & everything. so i had another very reputable guy tune it this past April, hoping to get it dialed in. i feel he didn't get it either. how is it possible that a guy who is over 1,000 mile away can make my car run better without seeing it & these so called "top name tuners" can't seem to make it better when they have the car in their posession? sorry for the rant, i'm better now.

[WeathermanShawn]

You never listed your mods. That might help when others look at your tune also.

One of the first things I do when I look over someone's tune is load up a stock OS and compare the differences. A lot of your Idle learning parameters have been disabled and obviously LTFT's have been disabled along with a number of DTC's codes. So, its never an easy read..especially when someone has changed from stock injectors.

So, I defer from addressing the tuner issue.

If you are saying you changed your front O2 sensors and they are switching as slow as your previous log and your car can not maintain stoich..then it is some problem I can't see in your tune. You might post up your new log. It might also help if you can log SAE.FUELSYS. That will tell us if you are indeed going to closed-loop and when.

We will give a bump to this thread and see if someone else has some ideas. You need your O2's functioning properly to utilize a closed-loop tune.

Do you do your own tuning? Also, again your mods please..

[BadLSX]

i'm sorry, i forgot about listing my engine mods. i have 1 7/8 headers, texas speed MS4 cam (239/242, .649/.609 111.5LSA) 30#ford racing injectors, 25% underdrive pulley, 160* thermostat. i believe that is everything i did to the engine. what all DTC are disabled that shouldnt be? what idle learning parameters are disabled? my biggest question though, i why do so many people disable LTFT. if it works how i think it does, wouldn't that be beneficial for the PCM to know how much fuel to add or trim? i'm not a tuner by any means, thats why i've paid 2 different guys on 2 different occasions to tune this car. i will definitely get a log today eithre on my way to or from the track.

[WeathermanShawn]

Thats definitely an aggressive cam!..

The major problem I see with your Tune is that the MAF Calibration Table B5001 has only been altered at the very top of the scale. The MAF Airflow amounts are being grossly underestimated. Thats probably the main reason you are lean. Your STFT's are adding a lot of fuel, but with LTFT's disabled you are not getting the additional fuel needed at WOT.

The best advice I can give you is to do what everyone on this forum has done. Take a stock tune and build it from there. Calibrate the MAF and VE Table either utilizing AUTOVE or CALC.VE Table. That is the only way to then decide what you want disabled or not.

Quite frankly it is asking too much for another member to rebuild your tune and you will never learn how to do it that way.

So in summary your lean AFR issue is because your MAF Table has not been calibrated. Your are lean because your airmass is being underestimated.

You have some tuning to do...

Good luck..

[Taz]

If this is a purely competition vehicle, you may want to consider running in SD. If this vehicle sees some time on the street as well as the track - switching from the 160 F thermostat to a 180 F thermostat will help the engine last longer, and may actually assist with tuning in some “street manners”.


Regards,
Taz