Mixture adj. help
Thread Starter
Racer
Joined: Apr 2002
Posts: 305
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From: Hammond In.
Mixture adj. help
Hi all
Had to take my car in for its emissions test today and the only way I could pass is to retard the timing and lean out the mixture. Got everthing back but I think Im off on the mixture. Can anyone help with a easy fix, or get me started in the right direction.
Thanks in advance
Ernie 81 SC
Had to take my car in for its emissions test today and the only way I could pass is to retard the timing and lean out the mixture. Got everthing back but I think Im off on the mixture. Can anyone help with a easy fix, or get me started in the right direction.
Thanks in advance
Ernie 81 SC
Thread Starter
Racer
Joined: Apr 2002
Posts: 305
Likes: 0
From: Hammond In.
Pete
Thanks for the quick reply, I thought I marked and remembered everything I did before I took it to get checked, got the timing but Im just a little off on the mixture. Good news is I passed the test
Thanks for the quick reply, I thought I marked and remembered everything I did before I took it to get checked, got the timing but Im just a little off on the mixture. Good news is I passed the test
Rennlist Member
Joined: Oct 2004
Posts: 20,607
Likes: 16
From: Bakersfield, CA, for now...
Emissions tests are a royal pain! During my last test I had to show the smog shop the under-lid decal that explains how to set the timing (remove hoses, slow idle speed with adj. screw, etc.). Fortunately the guy was interested, we worked through it, and what do you know? The timing was right on the money. The reason that I'm worried about your car is because it should have passed without mixture tinkering. If the 02 sensor is connected and the cat is working it should have passed easily. CA has the toughest rules in the country, and my '82 runs so clean it could pass if the requirements were twice as tough. Make sure the car is at operating temp, the 02 sensor is disconnected, and the exhaust sample is taken pre-cat. Good luck with it...
Pete
Pete
Thread Starter
Racer
Joined: Apr 2002
Posts: 305
Likes: 0
From: Hammond In.
Pete
I did not disconnect the 02 sensor, and what kills me is the fact that my car was running like a top. Im a little confused about the exhaust sample being taken pre-cat. In Indiana they just stick a hose to the tail pipe and go from there. I was tempeted to run it through without touching anything but if you fail you have to take it to a shop and prove that you had work done to be able to run it through again.
I have a new 02 sensor but I really dont know how old the cat is. What are the signs of a bad cat? And without me knowing the age do you think I should change it out? Anyway timing is right on and I know I very very close with the mixture. I just one of those guys that want it right.
Again thanks for the time
Ernie
I did not disconnect the 02 sensor, and what kills me is the fact that my car was running like a top. Im a little confused about the exhaust sample being taken pre-cat. In Indiana they just stick a hose to the tail pipe and go from there. I was tempeted to run it through without touching anything but if you fail you have to take it to a shop and prove that you had work done to be able to run it through again.
I have a new 02 sensor but I really dont know how old the cat is. What are the signs of a bad cat? And without me knowing the age do you think I should change it out? Anyway timing is right on and I know I very very close with the mixture. I just one of those guys that want it right.
Again thanks for the time
Ernie
Technical Specialist
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Rennlist
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Joined: May 2001
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From: TX
On 80 and later SC's, you can also hook up a duty meter to the FI test connector on the left frame member under the black relay box in the engine compartment, to determine lean/rich performance.
Rennlist Member
Joined: Oct 2004
Posts: 20,607
Likes: 16
From: Bakersfield, CA, for now...
Ernie: To determine if the cat is OK, an exhaust sample is taken before the cat (there is a nipple welded to the pipe just in front of the working part of the cat), and a second sample is taken at the tailpipe. Of course, the tailpipe sample should be considerably cleaner. I think that I might have confused you. When the car is "smog tested" the exhaust is measured at the tailpipe with all systems hooked up. When the car is "tuned" the mixture is set hot, pre-cat, with the 02 sensor disconnected. After the car is set to factory spec, and everything is back together, the car will run nice and clean out the pipe. Hope this helps.
Pete
Pete
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