'02 S10 4.3L - Really lean up top

[jakebdb56]

I'm tuning a buddy's truck and for some reason up top at WOT the O2's are reading 80mv. I'm not sure why since my commanded a/f is around 12.5

Anyone else have this problem? I haven't seen this before.

Btw, here's the tune file I'm working with right now, and the log.

Another note: during the shift of 1-2 the exhaust pops and shows a knock. I'm positive it's not "real" knock coming from the motor but maybe false knock from him having ghetto chopped exhaust that pops? haha.

Thanks,

Jake

[Russ K]

I've seen a bad Maf cause your lean condition. Unplug the Maf, if the O2's are no longer lean, then replace the Maf.

Russ Kemp

[JerryH]

I was looking at the scan... could a defective O2 not give similar results?

[jakebdb56]

Thanks Russ, I'll check it out. I got rid of all the knock in the motor and we're now running some pretty good timing and noticing some good results. We're at about 22* @ WOT and commanded a/f is 12.26. It definitely feels a ton better than stock, especially with all the PE limiters taken out and TM deleted. Do yall happen to know what transmission is in the S10? I think it's a 4L60E but it might be the 700R4? I was just wondering why the shift pressures were incredibly low in the stock tune. I think it was commanding something like 30psi at 200lb-ft.

Anyways, thanks for the help and I'll post some updates. He's probably going to run it again at the track next weekend when I take my truck with the new cam out there. His best 1/4 was 15.8 so I'm hoping to get him to a lower 15.

ps. What kind of cam spec would be decent in the V6? I dunno how different these motors are compared to V8's with cam selection.

[casper]

It will have the 4l60E trans........

[jakebdb56]

alrighty, that's what I figured but his damn truck is dropped so much I couldn't get up under it to verify.

[jakebdb56]

worked on some more tweaks to the tune. Everything's going pretty quick since I'm using RTT. RTT just makes it nice for us lazy people haha. VE tuning has been a breeze with RTT. He's getting some pretty high IAT's but hopefully he'll fix that with some wrap on his intake tube.

[JerryH]

You are lucky that RTT is available for your V6. I do not think that the 3800 PCMs lend themselves to that at all. About the only way to get close to that is to have something like an ARC-II or or other aftermarket external fuel control units.

[UR50SLO]

Is real time tuning avalible for 98Ecm's? I'd heard it was coming out... how can I use that on my setup? or is that possible?
Thanks, Scott

1998 Turbo 4dr Jimmy.

[jakebdb56]

The RTT is convenient and faster honestly, but having a small screen on the laptop keeps me going back to my desktop with the 22" widescreen to do all my big edits after making several logs.

[JerryH]

I have a 17" for my tuning needs that sits on a laptop stand, it gives me a ton of screen real estate to play with. I was looking at a 21" Toshiba, but man, that would not fit on the laptop stan easily, nor even be easy to work with in the car, but man it was huge... lol.