Hello all,

First post here. Recently purchase an '89 Convertible as my latest toy. Have several questions for you. First some background in case it is useful:

Car has 131,000 miles. automatic. Had a seriously leaky brake booster when purchased, replaced that this morning. It has headers and no cats. Other than the things I am asking about, it runs and drives great. Now, for the questions:

1) Below is a picture or what looks like a hose barb coming out of the throttle body with no hose attached. Right in the center of the pic in between the intake tube and the coolant hose, it angles slightly down. What is this and what should be attached there?


2) The car smells like it is running rich, and an emissions probe verifies that the CO is high at 3.05% seemingly indicating unburned fuel. Is there a manual mixture adjustment or is it all handled electronically?

3) The car runs cool, 170-180 degrees on the highway without A/C on. I assume this indicates a stuck-open thermostat. Could the car running this cool be causing the rich mixture?

4) Most of the time the car idles beautifully. But once in a while the idle will jump up to 12-1400 and stay there for a while. Eventually it will settle back. I have played with as many different variables I can think of to try and establish a pattern, but I find none. Ideas?

Thanks in advance

Scott

 

1) Below is a picture or what looks like a hose barb coming out of the throttle body with no hose attached. Right in the center of the pic in between the intake tube and the coolant hose, it angles slightly down. What is this and what should be attached there?
Looks like someone by-passed the t-body coolent line for lower t-body temps.
The car smells like it is running rich, and an emissions probe verifies that the CO is high at 3.05% seemingly indicating unburned fuel. Is there a manual mixture adjustment or is it all handled electronically?
Having no cats will cause a rich smell even though it isn't running rich. A better indicator would be to look at your o2 voltage.
The car runs cool, 170-180 degrees on the highway without A/C on. I assume this indicates a stuck-open thermostat. Could the car running this cool be causing the rich mixture.
This could cause a slightly rich condition as the ecm looks at engine temp to adjust the air/fuel ratio. Might be an open t-stat, might be a 160 deg t-stat, and seeing that the t-body coolent lines have been bypassed this would be my guess.
Most of the time the car idles beautifully. But once in a while the idle will jump up to 12-1400 and stay there for a while. Eventually it will settle back. I have played with as many different variables I can think of to try and establish a pattern, but I find none. Ideas?
No idea, put a vacuum guage up to it and tell us what you see.

 

Follow up questions in Blue

1) Below is a picture or what looks like a hose barb coming out of the throttle body with no hose attached. Right in the center of the pic in between the intake tube and the coolant hose, it angles slightly down. What is this and what should be attached there?
Looks like someone by-passed the t-body coolent line for lower t-body temps. Should I care?
The car smells like it is running rich, and an emissions probe verifies that the CO is high at 3.05% seemingly indicating unburned fuel. Is there a manual mixture adjustment or is it all handled electronically?
Having no cats will cause a rich smell even though it isn't running rich. A better indicator would be to look at your o2 voltage.OK
The car runs cool, 170-180 degrees on the highway without A/C on. I assume this indicates a stuck-open thermostat. Could the car running this cool be causing the rich mixture.
This could cause a slightly rich condition as the ecm looks at engine temp to adjust the air/fuel ratio. Might be an open t-stat, might be a 160 deg t-stat, and seeing that the t-body coolent lines have been bypassed this would be my guess. You mean your guess is 160deg thermostat? Any reason I shouldn't change?
Most of the time the car idles beautifully. But once in a while the idle will jump up to 12-1400 and stay there for a while. Eventually it will settle back. I have played with as many different variables I can think of to try and establish a pattern, but I find none. Ideas?
No idea, put a vacuum guage up to it and tell us what you see. Hooked up where?

 

Should I care? - Only if you drive in cold weather conditions, even then I doubt it would be much of an issue.

You mean your guess is 160deg thermostat? Any reason I shouldn't change? - Up to you, I'm sure some people would disagree with me but I prefer my engine temp to always stay over 180, below 215. Anything under and it isn't running as efficiently as it could. Also all the clearences are speced to run around 200degs, when it's cooler you have a greater chance of ring blow by, causing hydrocarbins to get into the oil, causing the oil to thin and become acidic eating away at the soft bearing materials in the engine. Take this part with a grain of salt because I'm sure you'll find many on this forum that don't agree.

Hooked up where? - Some place after the throttle blade. Fuel pressure reg port would be a good spot.