What does the '87 computer do at ~ 63 mph?
Thread Starter
Race Director
Joined: Oct 2000
Posts: 16,477
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From: Enter Post Count Here
What does the '87 computer do at ~ 63 mph?
I have a pretty decent cam-shaft in my 1987 auto. It currently has factory programming, I am working on getting a Diacom run for it.
Around town, and at less than about 63 mph, it does just fine. Fuel to Air Ratio runs right about 14:1.
But, as soon as I cross that threshold, and the car goes into a severe lean condition. This is only at constant throttle, with any throttle applied, and the car stays stoich/rich.
So, what is going on? TCCM lock-up occurs at 47 mph.
Thanks.
[Modified by NoWorries, 12:40 PM 4/19/2002]
Around town, and at less than about 63 mph, it does just fine. Fuel to Air Ratio runs right about 14:1.
But, as soon as I cross that threshold, and the car goes into a severe lean condition. This is only at constant throttle, with any throttle applied, and the car stays stoich/rich.
So, what is going on? TCCM lock-up occurs at 47 mph.
Thanks.
[Modified by NoWorries, 12:40 PM 4/19/2002]
Melting Slicks
Joined: Apr 2001
Posts: 2,122
Likes: 224
From: Ca.
Re: What does the '87 computer do at ~ 63 mph? (BobMachus)
Is it an original program from an 87? The 87 is tdf 32B, which doesn't have a hwy mode in it. What's your cam specs? And what are you basing the F/A ratio on? Wide band? Where's the blms? Sorry for all the questions, but we really need more info.
Thread Starter
Race Director
Joined: Oct 2000
Posts: 16,477
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From: Enter Post Count Here
Re: What does the '87 computer do at ~ 63 mph? (drive it)
Yes, it is the factory programming. The cam is a Powermax 2032, duration 214/218 .455/.465 112*. The F/A is based on a standard AC Delco O2 sensor, which is completely seperate from the computer sensor, I know its not the most accurate. A thought that I had today is that possibly on the highway its cooling off enough that the O2 sensor is reading falsly.
What is a blms?
What is a blms?
Melting Slicks
Joined: Apr 2001
Posts: 2,122
Likes: 224
From: Ca.
Re: What does the '87 computer do at ~ 63 mph? (NoWorries)
Yes, it is the factory programming. The cam is a Powermax 2032, duration 214/218 .455/.465 112*. The F/A is based on a standard AC Delco O2 sensor, which is completely seperate from the computer sensor, I know its not the most accurate. A thought that I had today is that possibly on the highway its cooling off enough that the O2 sensor is reading falsly.
What is a blms?
What is a blms?
Whats you're vac. reading? If you do have a vac. leak that'll show it up pretty easily.
Yes with your mods you could use some tuning on your prom program....Hmmmm......just noticed you said the TC locks at 47mph-that's higher than the stock program-maybe it's a hypertech in there? Or already been mod. for fans and TC?
Be sure to give us your diacom run-that'll be invaluable.
Melting Slicks
Joined: Apr 2001
Posts: 2,122
Likes: 224
From: Ca.
Re: (scorp508)
Around town, and at less than about 63 mph, it does just fine. Fuel to Air Ratio runs right about 14:1.
I thought that 14:1 itself was pretty lean. No? :confused:
I thought that 14:1 itself was pretty lean. No? :confused:
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Drifting
Joined: Mar 2001
Posts: 1,636
Likes: 3
From: Lafayette IN
Re: (scorp508)
I thought that 14:1 itself was pretty lean. No? :confused:
12:1 would be richer. 15.5:1 would be leaner. Kinda all based on the load and RPM range though, because 15.5:1 is not necessarily lean if that is what your engine is running correct at under light loading and highway speeds. But yeah, for idle and stuff, 14.1:1 would generally be considered slightly rich for that load/RPM.
