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#1
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Is this too Lean
I was doing 65-70 mph and I saw 14 to 14.3 for the AFR. Is this too lean? I think it is. Fast EZ EFI 2.0.
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#2
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Not during cruise, no. Depending on your engine combination it could be anywhere from spot on, to a little rich.
My engine likes to cruise up around 14.7-15:1. It doesn't start getting unhappy until the AFR gets up to around 16:1.
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-Jason 1969 Pontiac Firebird |
#3
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Watch the AFR as you go down the highway (maybe have another person drive, as you tune).
Watch the coolant temp, TPS, load, duty cycle, etc. Then adjust the cruise AFR up or down maybe .2 - see what changes. If you start feeling a lean-surge, then richen it up. I have the XFI Sportsman system on my 455, which uses the same throttle body you have. I've been able to put my highway cruise AFRs into the 15's, and the motor runs smoothly.
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'73 T/A (clone). Low budget stock headed 8.3:1 455, 222/242 116lsa .443/.435 cam. FAST Sportsman EFI, 315rwhp/385rwtq on 87 octane. 13.12 @103.2, 1.91 60'. '67 Firebird [sold], ; 11.27 @ 119.61, 7.167 @ 96.07, with UD 280/280 (108LSA/ 109 ICL)solid cam. [1.537, 7.233 @93.61, 11.46 @ 115.4 w/ old UD 288/296 108 hydraulic cam] Feb '05 HPP, home-ported "16" D-ports, dished pistons (pump gas only), 3.42 gears, 275/60 DR's, 750DP, T2, full exhaust My webpage http://lnlpd.com/home |
#4
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Every engine will want something different.
I've been all over the place with cruise AFR looking for a sweet spot and that's what it's going to take, some experimentation. I can tell you on my Chevelle it doesn't like being any leaner than 15:1 at cruise, in fact I'd say it's borderline happy there, and if I tried leaner the loss of power was noticeable and drivability suffered. However I've tried 15:1 on extended cruises and it doesn't pick up any more MPG. Because of that I've settled on low to mid 14's for cruise AFR on that particular car and the MPG's are the same. One thing worth mentioning that I've done is run an extra Innovative wide band along side the 02 for the Holley. Don't know of anyone else that has mentioned trying this. I've noticed the Innovative consistently reads about a 1/2 point leaner than the holley 02 does at all points. Keep in mind I've used that Innovative wideband for tuning for many years on the street and at the track long before the car went EFI so I trust what it says. Actually the same deal on the GTO too with an Innovative wide band along side the Holley 02 and it reports almost exactly the same way, with the Holley about a 1/2 point leaner. Makes me curious what alga rhythm Holley uses on that 02 or what might be different about it. Anyway, with that said, when I was experimenting with lean cruise on the Chevelle, it was the Innovative that was reading around 15:1 where the engine was borderline happy, while the Holley was reporting mid 15's for AFR. I eventually worked on the cruise areas in the fuel table to keep my AFR's around 14.3-14.5 on the Innovative which tickles the higher 14's on the Holley 02. This still gets me the same MPG on the highway and the engine is happier. Keep in mind stoich for 10% ethanol fuels is 14:1 and not 14.7:1 so there's that to consider. Trial and error till you find a happy spot. |
#5
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Some of the differences in readings could be that one uses a Bosch sensor and the other NTK. The NTKs are known for more accurate readings.
I too have noticed both my cars like the 14.3-14.5 range for cruise. .
__________________
. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
#6
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Both of mine are Bosch. The Holley Sniper uses it's own specific Bosch sensor. I think NTK is used on the Holley Terminator and Dominator systems and uses a different style connector.
I know guys have modified those Sniper connectors in an attempt to try and switch over to NTK but I don't know how successful they've been at doing it. I'd be curious to know if Fi-Tech and FAST are the same way. I've only had experience with FAST but I don't remember the sensor used on the last one I played with. |
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