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post #1 of (permalink) Old 12-19-2005, 07:48 AM Thread Starter
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cold weather = richer exhaust?

Is it typical that during colder weather for your exhaust to show signs at the tail pipe of a richer mix?
Have black buiild up after just one day..
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post #2 of (permalink) Old 12-19-2005, 08:43 AM
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Re: cold weather = richer exhaust?

I'm assuming you're still running the BBD carb. In cold weather the engine will take longer to warm up. That means the Feedback Carb's in open loop longer. The longer it takes for the carb to go to closed loop, the longer it takes for the engine to lean out.

So, the question is... does your carb ever go into closed loop and lean the fuel mixture?
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post #3 of (permalink) Old 12-19-2005, 09:24 AM Thread Starter
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Re: cold weather = richer exhaust?

No actually Iím running the Howell TBI set up..
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post #4 of (permalink) Old 12-19-2005, 10:41 AM
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Re: cold weather = richer exhaust?

By "richer mix" -- you mean the pipe color is blacker? You cannot go by color any longer - not since 1980!

You have a cat converter, it burns the rest of the HC that the engine missed - it changes the color to blacker - soot.
And, in winter, especially in the colder areas, the addatives in the gas change - those winter addatives burn with more soot too - blacker.

There's only one way to know if it's richer or leaner - use a modern exhaust gas analyzer like they use for smog testing. And, you must probe ahead of the cat to see the real thing.
A smog shop will probably charge you about $10-20 for a reading - and they'll explain it to you.

The toys like JC Whitney sell won't tell you anything.
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post #5 of (permalink) Old 12-19-2005, 11:09 AM
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Re: cold weather = richer exhaust?

[ QUOTE ]
By "richer mix" -- you mean the pipe color is blacker? You cannot go by color any longer - not since 1980!

[/ QUOTE ]

I'll be danged. Didn't know that... no clue, in fact. No one I am always looking at my tailpipe(s) and thinking I need a tune-up, etc...

Thanks for that tidbit. Now I can focus on other things - like using my E-brake once in awhile! [img]/ubbthreads/images/graemlins/grin.gif[/img]
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post #6 of (permalink) Old 12-19-2005, 01:39 PM Thread Starter
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Re: cold weather = richer exhaust?

Thanks Rich..
That's what i was hoping. I'll get the inspection guy to check it out for me. Hopefully its just a gold weather thing..
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post #7 of (permalink) Old 12-20-2005, 09:25 AM
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Re: cold weather = richer exhaust?

[ QUOTE ]
No actually Iím running the Howell TBI set up..

[/ QUOTE ]

If you're running the Howell TBI, the the easiest way to tell what's really happening is to put the system into Road Test Mode. This will tell you how often the engine is going in and out of Closed Loop. At idle, as example the engine drops out of Closed Loop to Open Loop. This causes a richer condition.

It's the first diagnostic that I'd run (and do, on my Howell TBI) to see if there was a reason for the build up in the tailpipe.
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post #8 of (permalink) Old 12-21-2005, 07:10 PM
 
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Re: cold weather = richer exhaust?



Anyone think of asking what the ambient temp was?
Maybe it's just a cold rich start or two...
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post #9 of (permalink) Old 12-23-2005, 11:13 PM
 
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Re: cold weather = richer exhaust?

I have an 04 Wrangler, 4.0 with 5 speed. I have occasional issues where the engine doesn't want to idle back when I lift off gas - like coming up to a stop sign, or shifting gears. It happens only below 33 mph (weird, but true). It's not throwing any fault codes. Could be it's dropping in and out of open loop? You mentioned "Road Test" mode - how can I do that with my 04, and how can I use that to tell me what's wrong?
Thanks!
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post #10 of (permalink) Old 12-24-2005, 12:34 AM
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Re: cold weather = richer exhaust?

Is the linkage and throttle body clean? Mine was doing some funny idling, I pulled the tb, cleaned it throughly and ended up replacing the throttle position sensor and cleaning the air filter problem went away.
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