1990 Toyota Corolla Intake

JACKOLSON

MEMBER
1990 TOYOTA COROLLA
4 CYL
FWD
MANUAL
85,000 MILES

I have a carbey.

What do you mean by "running the intake thru the A/C or to the A/C"?

And, how do I properly set the A/F ratio? Using the old school "tune by sound" and using the gas analyzer. Why should I set it to Lean Best Idle? What's Lean Best Torque? What are the downsides of running it rich? I realized that a rich mixture, say a rich best torque helps cold burning, mean the cylinders don't get that hot. I know it may foul up the spark plugs but I'd rather replace plugs than cylinders. Right?

The internet documents are just crap, they always talk about a certain ratio for their products and they always talk about EFI, I don't have EFI, and I don't want EFI. I like to stick with the old school carburetor.

Thanks.

3 Replies

MMPRINCE4000

MECHANIC
8,548 POSTS

Best way to set the A/F ratio is on a chassis dyno with a wideband O2 sensor.

Cruising generally runs an AF ratio of 14.7 to 1. When at WOT or power is needed, AF drops to 13.0 to 1 or sometimes lower. This is to prevent a lean engine which can burn a piston is seconds.

It has been several years since I used a chassis dyno to tune a car (nitrous), but it was $75 for the session.

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Friday, November 20th, 2009 AT 8:26 AM

JACKOLSON

MEMBER
67 POSTS

Hi,

It would take eternity to find a dyno here in my country, LOL, people are just so old school here that I don't even see anyone using that much tools, modern tools on their vehicles, but anyway, since I don't have access to a dyno, can I have my car checked for emissions and just take note of the O2 reading? Is that right? The O2 reading will give me an idea of my A/F ratio, right? What value am I after so that I will have a stoich A/F ratio of 14.7:1? I can set it up higher than that right, a little bit rich, just to induce a little cold burn, right? I am not considering fuel economy. I'd pay for fuel than pay for repairs. Am I making sense of what I'm doing?

Thanks and more power.

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Friday, November 20th, 2009 AT 10:45 PM

MMPRINCE4000

MECHANIC
8,548 POSTS

Wideband O2 sensors are much more sensitive to A/F ratio than standard ones.
They have come down it cost considerably from 10 years ago when they cost $2000.

The problem with a standard O2 sensor is that it is not "real time". Widebands are real time.

Start rich and work your way back, under WOT NEVER get above 13:1.

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Saturday, November 21st, 2009 AT 8:53 AM