It seems to me that the air/fuel mixture reading is just about as important as it gets when tuning correct? I assume regardless of car/motor there must be some kind of rule of thumb. I know that during my Dynoflash last week AL had to tune back a bit because of a lean condition caused by my fuel pump. What is a good number/bad number? Thanks for helping out-

 

Hope that, this will help you lighting up thinks..

http://toyotaperformance.com/af_metering.htm

 

well, what is a good number depends on a lot of factors. if you want all the gas to burn, you will need to be at 14.7:1. This will not produce a lot of power but you will definitely pass an emissions test. For maximum power, you should be at about 12.1:1, you might not pass emissions, but you will sure have lots of fun. You can go anywhere between those two "extremes" to balance out your desires for power and clean air.

but wait, why do people have air/fuel ratios like 10.5:1? well, sometimes you need extra gas in the cylinder to keep the air and fuel mixture from exploding rather than burning. a lot of gas will be unburnt and you will see black smoke coming from your tailpipe, but, your engine will not be damaged.

as you can see, your question has no simple answer. i have barely even touched the base of the subject here. you can use a search engine to find out more information.

strike

 

you could say there was a general range, but ...

timing, design, octane, dot dot dot, have an impact on the right afr.

I think I have seen ranges expressed from 10.5 to 12 on evo's at wot.
I would throw out the extremes and be happy, but some well known tuners live on the ends.

 

That was a good link...thanks.I think I have a "general" idea. I was close to 14 last weekend at WOT. Thanks to all the replied-

 

Put in a new pump the tune again and shoot for 11.4 af at wot.

 

Thanks ixcwlr8...that is exactly what I will do.... question...Is it a simple matter of the stock pump not flowing enough AL said the stock pump was "bad"...i would think it either would be bad or good...that same night evo's that were "modded" more than mine with stock pumps were just fine...any explaination? should I be concerned about a fuel restriction somewhere else? fuel filter etc...

 

Stock pumps have been known to fail to keep up with demand once you start modding. Get a Walbro 255 and you can once again sleep soundly.

As far as your AFR is concerned, it will be directly related to what type of gas you run. If you are running 93 octane, then an AFR of 11.4 should be ok. If you are running racegas, you'll be able to push up to 12.0, if you're running 91, then you might want to stop at 10.5-11.0. The optimum AFR of your setup will also be determined by how much timing your running ... go too agressive on your timing and AFR at the same time and the grenade fairy may decide it's time for a visit.

When you are researching optimum AFR, make sure you read up on AFR for turbo charged cars. Generally speaking an NA car can get away with running leaner than a turbo car.

l8r)

 

10-4 got it. Walbro is in hand-

 

Here are some great threads.

http://www.honda-tech.com/zerothread?id=1060267
http://www.honda-tech.com/zerothread?id=979788
http://www.honda-tech.com/zerothread?id=846069

 

Watch what you read on H-T, like any other forum, it's full of BS.

Mase knows his stuff though.

 

Agreed. You have to be able to differentiate between the bull**** and facts. Common sense, knowing who or of the user, etc.