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.

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.

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.

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.

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.


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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.

The early Innovative wideband tools used the NTK sensor, that's why they were so expensive.

The bosch don't read very well outside of a narrow range, but for most purposes, they do fine in general automotive use. They have issues, just to say. (would have to lookup what that range is, but it's something like 10-22, and the NTK is like 5-35 or something)

Any of the Holley ecu aside from the 'entry level' ones accept NTKs. Connectors are diff because there's more wires I believe, depending, and the ecu has a controller built in for each type.

If you're doing race gas or E85, you want the NTK sensor. They recover from extreme conditions (like a flood) and live longer too.


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We do nothing but straight pump gas engine builds anymore. Got away from race gas decades ago due to cost and lack of availability. Doubt I'll ever consider E85 for anything either since it's still not widely available everywhere.

I do have an early Innovative LM-1 wideband that is a portable unit I bought maybe 25+ years ago to tune multiple cars with. That thing still works flawless. I don't even remember which sensor it has, it's never been a concern. I do know the Holley Sniper Stealth EFI's used on both cars, and the Innovative 2 1/16 wide band gauges used in both of those cars are all Bosch. In fact I had to replace one of the Innovative sensors last year, and just put another Bosch in it.

There is a way to re-pin the Holley to accept the NTK, there have been some extensive posts on it. I've just never been interested in revamping the system like that since it works fine as is. Plus I've never found anyone with a success story they've shared doing it, lol.

Pretty sure the Stealths use an HP ecu as base, which supports NTKs. The earlier Terminator throttle body setups used the HP ecu too (like on my 442).

Pretty sure the NTKs draw more amps, but I'm a little grey on that right now, would have to check.

Sensors come in like 5, 6, 7, and 8 wire, so it would depend on which is being used. Holley uses a specific type of the bosch and the NTK, one type of each, the HP-up ECUs have an 8 pin connector for the O2, so pinout would tell you which is which. (on the sensor side).

I know the controllers are different for the 2 types, so if you don't have a drop down in the software for each, I doubt it would work right. I don't think it could initialize right.

Maybe I'll go look at it again and try to figure that out, but for the basic 'street' user, the bosch should be fine. If you're doing any type of alt gas, or boost/N2O, it's 'recommended' to use the NTK.


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