Help on AFM adjustment for stage 2 ported intake manifold and bored throttle body.

1012 Views 7 Replies 4 Participants Last post by 88 LE, Dec 15, 2005

illusive562

Discussion Starter · Dec 13, 2005 (Edited)

Hey guys...ive searched throught the entire forum and found a thread about leaning the AFM by 2-3 clicks clockwise...but question is, i am getting my intake manifold ported and radiused, and also my thottle body bored...instead of leaning it, am i suppose to go the other way around and richen the mixture? or can i still lean it?..i want the most optimum peformance...thanks

car info:

1991 camry 4 cyl 3sfe
23 k miles automatic

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JetspeedCamry

· #2 · Dec 14, 2005

Hmm...logic would suggest that you'd need to richen it......or even leave it.
Think of this....normally you lean it for a stock setup....
But after increased flow, you need more fuel, so leaning would then go TOO lean...but leaving it would for optimum, depending on how much you port....going RICH may make it too RICH...
if that makes any sense

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90 Gen2

· #3 · Dec 14, 2005

no advice.

uh, a wide-band o2 sensor is inexpensive compared to dyno tests and all of this work.
I'd say get one so that you'll know why you're doing whatever you do and when you've done it enough, instead of just guessing. If performance is the point, you have to measure performance to know what you've done.

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illusive562

Discussion Starter · #4 · Dec 14, 2005

JetspeedCamry said:
Hmm...logic would suggest that you'd need to richen it......or even leave it.
Think of this....normally you lean it for a stock setup....
But after increased flow, you need more fuel, so leaning would then go TOO lean...but leaving it would for optimum, depending on how much you port....going RICH may make it too RICH...
if that makes any sense

That was actually what I was thinking also...but im so tempted to richen it even more...well for right now its about 3 clicks lean and I feel a a big difference in throtle response...well since the intake manifold is being ported and radiused and the throttle body bored...wouldnt the afm restrict airflow? is there such thing as porting the afm also? lol

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90 Gen2

· #5 · Dec 14, 2005

illusive562 said:
.well since the intake manifold is being ported and radiused and the throttle body bored...wouldnt the afm restrict airflow? is there such thing as porting the afm also? lol

yeah, s'called port injection!
you could test that though too with pressure sensors up and downstream of it.
I know that for other cars with AFMs they have been found not to be flow restricitons.
maybe there's a toyota motor with a more up to date intake system you could adapt,
but then that would make your expensive manifold work for nought....

wideband o2 it, I'd say, or if seat of pants is good enough, seat of pants test it back n forth.

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illusive562

Discussion Starter · #6 · Dec 14, 2005

90 Gen2 said:
yeah, s'called port injection!
you could test that though too with pressure sensors up and downstream of it.
I know that for other cars with AFMs they have been found not to be flow restricitons.
maybe there's a toyota motor with a more up to date intake system you could adapt,
but then that would make your expensive manifold work for nought....

wideband o2 it, I'd say, or if seat of pants is good enough, seat of pants test it back n forth.

can i just buy a autometer a/f gauge and connect it to the stock o2 sensor which connects to the ehaust manifold instead? i have two o2 sensors...one is connected to the exhaust mani and the other is just right below the manifold...

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90 Gen2

· #7 · Dec 15, 2005

that would probably help convince you that spending the money for the wideband was useful at least, and maybe even be useful if it's way off.
give it a try!

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88 LE

· #8 · Dec 15, 2005

illusive562 said:
can i just buy a autometer a/f gauge and connect it to the stock o2 sensor which connects to the ehaust manifold instead?

If you want to waste your money and have a useless gauge, go for it.

Your O2 sensor(s) are narrow band, not wideband.

Narrow band only senses 14.7:1. It can't sense the actual A/F ratio, unlike a wideband O2.

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