How would you tune for 3rd gear WOT KR?

This is for the 3800 W-body. Everytime I do a WOT run to the edge of the speedo, I see no KR in 1st, minimum KR in 2nd, and a butt load of KR in 3rd gear. :banghead: How do you tune out this KR for just 3rd gear? The majority of the PCM tables are multi-used for all gears, like the timing and fuel tables so if I reduce timing or change fueling it will effect all of the gears which can be undesirable. It's as if there's not enough fuel in third gear WOT (I have a Racetronix fuel pump with the rewire). To to keep the O2s somewhat steady I'm reducing the command AFR over time but the O2s still take a dive. The other question I have is the electronic boost controler on these 3800s, I have it plugged in and enabled but the PCM doesn't seem to opening the BBV to dump boost, if I could get the PCM to bleed boost in 3rd gear that would help. Thoughts, opinions? I don't have a wideband :(

MODS: L32 GenV M90; 3.4; XP CAM; TOGs; N* TB; Dynotech Stage 2 Trans

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Hi,

You should definitely get a wideband! Just commanding an AFR of X doesn't mean you really get an AFR of X. But your O2 values show that there must be something wrong with the fuel delivery. This could be either a problem with your fuel pump or some wrong parameters in the tune.

Please post your tune and a log.

- Mat

I appreciate your time to look at my bin. I have a Ractronix fuel pump with the re-wire from PRJs performance. A wideband will be a soon purchase. Thanks.

Hey Dave, you should try to hook up a fuel pressure gauge for some test runs. It looks like you are commanding plenty of fuel but not delivering. It almost looks like your injectors are going static because the output is completely flat.

Quote:

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Originally Posted by BlackGS

It looks like you are commanding plenty of fuel but not delivering. It almost looks like your injectors are going static because the output is completely flat.

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I absolutely agree. Your Injectors are static >5500rpm and above ~4500rpm they are already over 80%.

time for some bigger injectors, try 42s

Also while in 3rd gear the engine will be loaded more so you may actually be in a different part of your timing map. In the lower gears the engine has a better mechanical advantage due to transmission gears so as you shift into higher gears you will also put higher loads on the engine.
But it sounds like if your fuel injetors are going static then the lack of fuel at the higher loads is probably the major cause for the knock retard. You should log your injector duty cycle to help see this.

Looks like you stepped up from the PwrTuner. Like mentioned, time for bigger injectors and more importantly a wideband.

looking at the graphs you posted why is your boost so increased in 3rd gear ? more boost will require more fuel without it you will get kr

your kr at the speeds you would be making the 1-2 and 2-3 shifts is substantial also

Thank you. I upsized to a 3.6 pulley and I'm still seeing +3* of KR in 3rd gear at WOT around 110-120 so I think you're right about the stock injectors being maxed out. I'll probably get 65# so I have the option of going E85 if I choose. Thanks.

edit: I increased timing 2* with the 3.6. I don't think there is a fueling issue, I just replaced the filter, and I have a Racetronix fuel pump with the rewire from PRJ.

your injectors are max out at 99% get them 65 lbs injectors and put E5 in it. u wont be sorry u r where i was maxing them out i get the 65lbs and put E85 in it and it runs great

I'm running a Gen3, XP, 3.0, IC car on pump gas with my highest duty cycle being a 78%. That's on 42# injectors and commanding 11.8:1 AFR. I have it tuned perfectly with the wideband. So you can use that number and figure out how close you are to maxing out your injectors (assuming yours isn't tuned perfect and the 99% DC means nothing).

Your timing should INCREASE as the rpm's go up. For example, running 20* at 6400 rpm would mean you should be running 17* at 4800 rpm, with a nice smooth slope connecting the two. Before 4800, it shouldn't increase as fast as it does from 4800-6400. You know what I mean?

Also, do not for any reason look at your narrowband o2 voltage at wot. It means absolutely and literally nothing. My properly tuned car read 15mV at WOT on the narrowband, for example lol. It doesn't matter if you see a trend in the graph. Those things are so unpredictable at those ranges it's useless.

Command a constant 11.8:1 throughout the run and figure out when you enter 3rd gear (how man seconds into a run I mean). At this point and a little before, start making the fueling richer on your AFR vs Time table. Give her a total of, say, -0.5, slowly. So at 4200 rpm and 13 seconds in (or whatever) give -.2 then -.4 then -.5 or something.

If you can't run 11.8:1 AFR and about 18* of timing WITH a properly tuned maf table using a WIDEBAND, you have too small of a pulley or some other issue.

Spark plugs should be AL104's gapped no smaller than .050 with your mods.