Another ? for Mike
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Senior Member
Joined: Apr 2000
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From: NC
Another ? for Mike
Hi Mike, I ran a 13.358@105.6 60' 2.1**. Also had the truck dyno'd 381.3 RWHP & 451.4 RWTQ. It was running lean 3200 to 4900 14.0 to 14.6 then started to drop into the 13's. It was 68 degrees. Is this normal for the air force one and the micro tuner? Also If I buy the upgraded tuner and 4# pulley will I have to change my thermostat and plugs? Also what other upgrades can the new tuner handle? If I install all this and I'm running too lean what recourse do I have? Thanks, Peter Maybe we should talk on the phone.
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Joined: Mar 1998
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From: Virginia
Hi Peter,
I will have to actually see all that data hardcopy Peter, and I'll also have to know the exact method that was used to attain those A/F ratios - if it was tailpipe sniffing, that always reads leaner as compared to dropping in the wideband 02 prior to the cats.
What normally happens when you nail the throttle to begin the dyno pull (which cannot even begin until you are at 80 mph in 3rd gear in the supercharged 5.4's so it doesn't downshift into 2nd), is it takes the PCM a second or two to switch from closed loop over to open loop so it can deliver the commanded A/F ratios. So seeing 14.64:1 (light-load stoich) is normal until the PCM responds, and then the A/F's get down to a reasonable range -
Now just to give you some basic FYI...................
In vehicles that are heavier than about 3600 lbs., the A/F's on the dyno will be leaner than what they actually are when the vehicle is being driven on the road, due to the load being much higher on the road - this is why the "best" tune on the dyno is generally not the tune that makes these vehicles run the quickest at the track. This is a factor in *any* vehicle that is significantly above about 3600 lbs., as the combined weight of the rollers on most chassis dynos is 3600 lbs., as opposed to a Lightning that actually weighs upwards of 5000 lbs. *and* the significant additional load that comes from aerodynamics as speed increases, and in this case we're not even starting until about 80 mph, so the aero load is already significant - this difference in load makes a significant difference in the A/F's, making the A/F's richer on the road than on the dyno. That's just some basic FYI stuff in general..........
At any rate, we do need to talk about this over the phone, but *before* calling me please FAX *all* that info over to us at (540) 862-9485 - the power plots, the A/F ratio graphs, whether the A/F's were measured by them making a hole in your exhaust before the catalytic converters and welding in a bung thru which to drop in the wideband O2 probe and then install a "cap" to close the exhaust back up when they finished, or did they just use the more common tailpipe sniffer - along with a complete list of *every* change from stock, every modifications, every aftermarket part, etc. - I'll review all that info carefully & then we need to go over it all in proper detail, which I'm more than happy to do for you, of course.
Thanks for your post, please shoot me all that data & then let's talk in detail, OK? Thanks!
I will have to actually see all that data hardcopy Peter, and I'll also have to know the exact method that was used to attain those A/F ratios - if it was tailpipe sniffing, that always reads leaner as compared to dropping in the wideband 02 prior to the cats.
What normally happens when you nail the throttle to begin the dyno pull (which cannot even begin until you are at 80 mph in 3rd gear in the supercharged 5.4's so it doesn't downshift into 2nd), is it takes the PCM a second or two to switch from closed loop over to open loop so it can deliver the commanded A/F ratios. So seeing 14.64:1 (light-load stoich) is normal until the PCM responds, and then the A/F's get down to a reasonable range -
Now just to give you some basic FYI...................
In vehicles that are heavier than about 3600 lbs., the A/F's on the dyno will be leaner than what they actually are when the vehicle is being driven on the road, due to the load being much higher on the road - this is why the "best" tune on the dyno is generally not the tune that makes these vehicles run the quickest at the track. This is a factor in *any* vehicle that is significantly above about 3600 lbs., as the combined weight of the rollers on most chassis dynos is 3600 lbs., as opposed to a Lightning that actually weighs upwards of 5000 lbs. *and* the significant additional load that comes from aerodynamics as speed increases, and in this case we're not even starting until about 80 mph, so the aero load is already significant - this difference in load makes a significant difference in the A/F's, making the A/F's richer on the road than on the dyno. That's just some basic FYI stuff in general..........
At any rate, we do need to talk about this over the phone, but *before* calling me please FAX *all* that info over to us at (540) 862-9485 - the power plots, the A/F ratio graphs, whether the A/F's were measured by them making a hole in your exhaust before the catalytic converters and welding in a bung thru which to drop in the wideband O2 probe and then install a "cap" to close the exhaust back up when they finished, or did they just use the more common tailpipe sniffer - along with a complete list of *every* change from stock, every modifications, every aftermarket part, etc. - I'll review all that info carefully & then we need to go over it all in proper detail, which I'm more than happy to do for you, of course.
Thanks for your post, please shoot me all that data & then let's talk in detail, OK? Thanks!