shwert

I've been trying to find the source of my lean code for months now and have come to think its within the tune. Bama tunes will send a tune to make up for the deleted EGR and LT's for $50 but I'm not sure of how well that'll work being a "canned tune." I've contacted B&R out of Moore, OK and they will charge $125. I'm wondering what you guys' opinion on this is.

cliffyk

What code is being thrown?

The EGR delete should not affect AFR, however it would throw a code if the EGR is not turned off in the tune. The LT's will throw a code if the the O2 Transport Delay table has not been modified.

shwert

1131, 1151, 1153, and 1171. Fuel pressure checks out fine at 29 at idle, no vacuum leaks that i'm aware of. Its been frustrating me for months now, and the tune seems to be the last thing I can think of. Plus I want to spray the car but I need this out of the way first.

cliffyk

P1131 and P1151 indicate the both front O2 sensors are "stuck" lean even though the PCM has been "cycling" the mix as it does in closed loop operation. This is most likely because the O2 Transport Delay table in the tune needs to be adjusted for the long tube headers.

The O2 Transport Delay values are the time in seconds, for various loads and rpms, that the PCM expects to see a change it has made to the AFR affect the front sensors. Here is the stock table for my '03 GT:



Because the LTs place the front sensors further back from the exhaust ports it takes longer for the newly correct exhaust gases to reach the sensors--here it is after having the values increased by 20%, typically they would be increased by 15% to 25%:



I think you mean P0153 (slow sensor response, bank 2 sensor 1) and P0171 (system too lean bank 1) for the other two codes (P1153 and P1171 are not part of our car's diagnostics).

P0153 is likely related to the O2 delay table being incorrect, however P0171 could be an exhaust leak at the manifold or somewhere near the sensor.

uberstang1

When you delete your EGR you'll get a lean code, I can't remmeber which one it was but I got it when I deleted my EGR. Tuner sent me an updated tune with egr delete and it never came back agian.

cliffyk

Usually all you get is P0401, EGR insufficient flow, and the electrical codes for the DFPE (P0405/P1400) and EVR (P0403/P1409) if they have been removed.

shwert

Thanks again cliff, I'm looking at my xcal now and it reads p0171, p1131, and p1151. I have a tiny exhaust leak right at the collector in the middle of the 4 pipes. What do toy think of bama tunes? I'm thinking it might be worth the extra $25 over the local shop price for lifetime tunes. Can they adjust the delay table percentages? Also I only have an xcal2, does anyone know if I can load tunes from bama with that or do I need to have an xcal3?

cliffyk

An exhaust leak could definitely trigger the P0171 code. The others are likely related to the LTs.

I have never had any relationship with BAMA, however they are well respected in the community and should be able to adjust the O2 delay table.

My only comment is regarding mail-order and canned tunes in general. By definition they cannot (unless you get very lucky) be optimal for a specific engine as all engines, configurations, and operating environments are different and ever-changing.

Optimal tunes can only be achieved in "hands on" mode, with so-called "dyno tuning" being 2nd best, and tweaked real-world optimisation (perhaps preceded by a dyno-tune) being the very best.

Though I have never had a dyno-tune performed, my car has been up on the rollers 5 or 6 times in the 4-1/2 years I have owned it--first to get a baseline, and then to gauge progress. I have, thanks to the people in Daytona that have the dyno, been able to tweak things between runs; but the real true optimisation has been accomplished via back-to-back runs on a deserted back road, using my trusty 15-year old GTech-Pro performance tool.

I have no idea, I suspect you can--ask them...

uberstang1

I got two codes, for bank 1 and bank 2 running to lean when I deleted mine.

cliffyk

Weird. I don't know why deleting the EGR would cause a lean code unless there were an air leak at the block-off plate or introduced somewhere else...