3.0 hig rev leanout
04-09-2012, 01:29 PM
#1
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3.0 hig rev leanout
I have a stock rebuilt 3.0 that I put cams in. Only did a k&n dropin and stock muffler is still on for now. I just put an 02(Fast Airfuel reader) on it and noticed it runs fat but not to bad, gets leaner then I'd like in the top. Starts at 11 drops down to 10.5 around 2500 then around 3k its starts coming from 11 to 13.5 by 4k. I did pop the cover off the vafm thinking I was gonna need to lean it, I would like to lean the bottom end but the top is already lean. so I left it stock for now and am staying out of the upper rpms.
Any thoughts on what might be working wrong?This definetly explains how peaky the moter is at rpm so if I could get a consistent reading across the powerband it should wake it up.
I could take a video but it will have to wait untill i get a day off on the weekend and get a second person to watch the meter if it helps. Any thoughts appreiciated.
Casey
Any thoughts on what might be working wrong?This definetly explains how peaky the moter is at rpm so if I could get a consistent reading across the powerband it should wake it up.
I could take a video but it will have to wait untill i get a day off on the weekend and get a second person to watch the meter if it helps. Any thoughts appreiciated.
Casey
04-09-2012, 01:58 PM
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Could be a clogged fuel filter causing it to lean out on top.
BTW, how are ya liking the cams and which ones did you end up going with?
BTW, how are ya liking the cams and which ones did you end up going with?
Last edited by BMcEL; 04-09-2012 at 02:17 PM.
04-09-2012, 02:52 PM
#3
As a matter of fact I do...
First and foremost, your entire approach to tuning this engine. Which you've gone about in reverse order. Meaning, your nifty little A/F ratio meter is all but useless without a means to do anything about the way the ECU is programmed to deliver the fuel throughout the powerband. But there's no way to do that unfortunately. Aside from upgrading the ECU, as in having it rechipped. And even if you do, your still basically stuck with whatever the new chip is programmed to do. This is OBDI, not OBDII.
Listen, if you want to try messing with the VAFM setting go for it. You'll be able to change things quite a bit as far as the overall A/F ratio(richer/leaner at all rpm). But it's not going to fix whatever issue it is that you think you have with the "powerband". There's only so much you can do with the stock ECU on these things. And you're asking for too much from it.
First and foremost, your entire approach to tuning this engine. Which you've gone about in reverse order. Meaning, your nifty little A/F ratio meter is all but useless without a means to do anything about the way the ECU is programmed to deliver the fuel throughout the powerband. But there's no way to do that unfortunately. Aside from upgrading the ECU, as in having it rechipped. And even if you do, your still basically stuck with whatever the new chip is programmed to do. This is OBDI, not OBDII.
Listen, if you want to try messing with the VAFM setting go for it. You'll be able to change things quite a bit as far as the overall A/F ratio(richer/leaner at all rpm). But it's not going to fix whatever issue it is that you think you have with the "powerband". There's only so much you can do with the stock ECU on these things. And you're asking for too much from it.
04-10-2012, 10:35 AM
#5
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I changed the fuel filter when i rebuilt the engine about a yr ago, old one was clean when i cut it. Maybe it's time i get a remote fuel pressure gauge in the truck though. it's been a while since i checked the tps. I'll have to go over it again, as for the vafm, I wasnt expecting to find the fuel trim this far off in one area, the only reason i put the o2 on it was curiousity, now I know.
now on to the cams. if it was a stick truck i would love it, as it is my only wish is that it either pulled from lower rpm or I had a high stall converter so it would snap into the power. I'm tossing some thoughts into either a converter or moving the cam timing a little but either of those would have to wait and would'nt do anything about the leaness.
Normally I'm a support your local shop but in this case I would rec going with the original and give Colt Cams a call. no one seems to have problems and they were great on the phone.
was thinking if i can't find anything overtly wrong with the system when I get new cam gears i'll grab the factory set of cams to be a fall back.
now on to the cams. if it was a stick truck i would love it, as it is my only wish is that it either pulled from lower rpm or I had a high stall converter so it would snap into the power. I'm tossing some thoughts into either a converter or moving the cam timing a little but either of those would have to wait and would'nt do anything about the leaness.
Normally I'm a support your local shop but in this case I would rec going with the original and give Colt Cams a call. no one seems to have problems and they were great on the phone.
was thinking if i can't find anything overtly wrong with the system when I get new cam gears i'll grab the factory set of cams to be a fall back.
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