| Air Fuel Ratio [message #107806] |
Tue, 07 December 2010 11:00  |
Oldngray
Messages: 544
Registered: August 2009
Location: Punta Gorda Florida
Karma: 0
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Senior Member |
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Finished the LC-1 installation yesterday and went for a ride this morning to see how it all works.
At idle, normal operating temp A/F range 13.5 - 14.0
Cruise Control @55 mph 13.8 - 14.0
in City driving @ 35 mph 13.5-14.0
Never had the gauge read above 14.0
From what I have read here and elsewhere, my Q Jet is running rich, however I do not know if it is enough to make a difference.
Richard MacDonald
Punta Gorda, Florida
Sold our TZE April 2015
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| Re: Air Fuel Ratio [message #107946 is a reply to message #107806] |
Wed, 08 December 2010 18:26  |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
Karma: 0
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Let me tell you mine is all over the place. While driving down the hiway it will run 14.5 but down hill it will go to 15.5 to 16. But in the mornings when its cool it reads richer than in the afternoon. The odd part it is will swing a little with steady throttle and no change in grade. like 1/2 a point or so. Still have a problem with a lean surge right before the secondarys open. Now,,,, Cliff Ruggles states in his book you should tune the Q.jet for runnin good not AFR.,,,,PL
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| Re: Air Fuel Ratio [message #107953 is a reply to message #107806] |
Wed, 08 December 2010 20:20 |
John Sharpe
Messages: 489
Registered: February 2006
Location: Texas
Karma: 1
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| Quote: |
Finished the LC-1 installation yesterday and went for a ride this morning to see how it all works.
At idle, normal operating temp A/F range 13.5 - 14.0
Cruise Control @55 mph 13.8 - 14.0
in City driving @ 35 mph 13.5-14.0
Never had the gauge read above 14.0
From what I have read here and elsewhere, my Q Jet is running rich, however I do not know if it is enough to make a difference.
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Richard,
You should be tickled to death with those numbers on a Q Jet. If that's the only criteria, I would leave well enough alone.
John Sharpe
Humble,TX
'78 Eleganza TBI
'89 Spectrum 2000 MPI V-10
'40 Ford Panel Delivery TPI
johnasharpe@gmail.com
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| Re: Air Fuel Ratio [message #107971 is a reply to message #107946] |
Thu, 09 December 2010 00:56 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Senior Member |
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| g.winger wrote on Wed, 08 December 2010 16:26 |
Let me tell you mine is all over the place. While driving down the hiway it will run 14.5 but down hill it will go to 15.5 to 16. But in the mornings when its cool it reads richer than in the afternoon. The odd part it is will swing a little with steady throttle and no change in grade. like 1/2 a point or so. Still have a problem with a lean surge right before the secondarys open. Now,,,, Cliff Ruggles states in his book you should tune the Q.jet for runnin good not AFR.,,,,PL
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The numbers are not bad. Randy Van Winkle and I did a fair bit of testing with TBI (easy to change A/F settings) and found that 16.3 or 4 to be about the best mpg we could do in lean cruise. The Q-Jet is not going to know about lean cruise, but the 16 when feathering it is good.
One of the tendencies is to play with the power valve (Power Enrichment... PE) and the secondaries opening. Both Randy and I have tried keeping the TBI out of PE and were shocked at how fast exhaust temperatures rise. You can start pulling a hill and have the PE not kick in and see the ET rise from 1150 to almost 13 in about 10 seconds. I am talking 50-60% throttle, here. It is a sad comment in engine engineering, but all but a very few vehicles use gasoline ( at $3.09 here ) to cool the cylinders when under a pull. It is an expensive way to cool cylinders but replacing burnt valves and pistons is way more expensive.
As far as the wide band numbers jumping around, that happens. Don't worry. Apparently cylinders do not all have a perfect explosion each time because even with the computer trying to hold the mixture at exactly 14.7 to 1, the Wide Band is constantly in flux by .5 or so. I was surprised, but have not heard of anyone getting a steady 14.7, which is the goal of all modern engines. I am guessing that is why most autos use a narrow band (14.7) which only tells the computer rich or lean... because it is never 14.7 for long. The oxygen left after combustion is just twitchy.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
[Updated on: Thu, 09 December 2010 00:57] Report message to a moderator |
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| Re: Air Fuel Ratio [message #107978 is a reply to message #107953] |
Thu, 09 December 2010 07:39 |
Oldngray
Messages: 544
Registered: August 2009
Location: Punta Gorda Florida
Karma: 0
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Senior Member |
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Thanks John, perhaps next year I will get the Howell system installed. Have been reading as much about TBI as possible. Not sure that I will go with EBL but sure want the ESC.
| John Sharpe wrote on Wed, 08 December 2010 21:20 |
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Richard,
You should be tickled to death with those numbers on a Q Jet. If that's the only criteria, I would leave well enough alone.[/quote]
Richard MacDonald
Punta Gorda, Florida
Sold our TZE April 2015
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