hi guys.

i've got a funny circumstance here that i am dealing with; ecu is all stock, and i have a 2.5" downpipe, cat delete, and rear muff delete. i have tuned the car with a wideband LM-1 (road tune) and a HKS Super AFR.

here's the thing: when i do a WOT pull in 3rd gear on the highway, the A/F is between 11.7 and 12.0 (too lean for my tastes). when i shift into 4th and mash it, the A/F is 11.2 - 11.5 (about where i want it to be).

what is going on here? shouldn't the A/F ratio be gear independant? why is it different depending on what gear it is in?

thanx alot

todd

 

what kind of gas are you using? your A/F looks fine to me for your 3rd gear which is your stongest gear. all dyno pulls are done on 3rd gear also.

 

hello!

i am using Texaco 93 octane (here on the East Coast, 93 is all over the place).

i guess i should mention the settings on the Super AFR: they start at 3500 rpm (-1) and work up to 7000 rpm (-12).

i use the car for an everyday driver (20k miles per year) plus the occasional track event (i am an instructor for the PCA and BMW and Ferrari, etc). i want the car to be "safe"; therefore, i am a little concerned with the 3rd gear A/F.

i'm guess i'm still wondering why the A/F would vary to a richer number in 4th gear? i just did another couple of road runs, and it definitely goes down into the 11.1 - 11.2 range when doing a hard pull in 4th. its 11.7-12.0 in 3rd gear.... ?

again, the ecu is oem stock, no mbc, no flash, no electronic boost control....

thanx

todd

 

i would highly suggest a flash. if its running rich in 4th, your ECU could be detecting knock, therefore pulling timing. is 93 the highest pump gas you can get. i though they had 94 out there? i know they do in FL.

 

hello again.

i don't think it is knocking; it is pulling like a freight train in 4th, and isn't pulling boost (1.3 bar on the factory gauge) in 4th.

sometimes one can find 94 at a Sunoco, but mostly i use the 93 oct.

keep the theories coming, please!

todd

 

how much boost do you run?? maybe you need a little more to "lean it out" ...

 

its stock boost; no flash, no mbc, no ebc.

when i am driving it, especially on track, i want the ecu free to pull timing and boost if it detects any knock... i like the safety features built in to the oem computer; i think oem computer has pretty good "save your butt" features if knock occurs.

therefore, i don't run the commonly used mbc....

todd

 

Al's dynoflash retains all the stock ECU safety. he just gets rid of the other limitations like speed limiter, pushes rev limiter to 7800rpm from 7404, & adds timing. with a good flash on 93 octane, you can run about as much timing as i'm running on the '03. at least 9 degrees advance on the 1st 2 gears, & at least 16 degrees advance on 3rd & 4th this is how evos are tuned in FL on 93 octane @20 psi. my '03 on stock cams pulls all the way to 7800 in 3rd & 4th. with aggressive cams, i can add in another 3-4 degrees on all gears. Al even has a dynoflash now where you don't even need a boost controller i think. may have to search tho.