new cams, first impressions
12-24-2011, 04:45 PM
#16
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This only happens during closed loop, so not when you are into the throttle enough to close the WOT switch to put it into open loop and go on the maps.
The O2 sensor sets a specific mixture value. When compared to the MAF values, the LH provides a pulse width equivalent to that which is required to satisfy the mixture ratio.
Provided you are taking in more air with the new cams, it will be sensed by the MAF(that is it's job), and the LH will widen the pulse width to maintain the correct F/A ratio so that the emissions are correct.
Which is a long way of saying; 'yes it does'. However, in my first post I did qualify the statement that it falls within the parametric limits on the original LH.
You actually confirmed this with your 'butt dyno' statement. If you are getting more air(new cams), you are either getting more fuel with it, or you are running a super lean mixture. Since the LH will not allow a too lean mixture to affect the CO and NOx, it will calibrate the injector pulse width accordingly.
Provided you are taking in more air with the new cams, it will be sensed by the MAF(that is it's job), and the LH will widen the pulse width to maintain the correct F/A ratio so that the emissions are correct.
Which is a long way of saying; 'yes it does'. However, in my first post I did qualify the statement that it falls within the parametric limits on the original LH.
You actually confirmed this with your 'butt dyno' statement. If you are getting more air(new cams), you are either getting more fuel with it, or you are running a super lean mixture. Since the LH will not allow a too lean mixture to affect the CO and NOx, it will calibrate the injector pulse width accordingly.
12-24-2011, 04:52 PM
#17
Nordschleife Master
Doc,
The new cams run a touch leaner (still safe) in the mid range than I like, but pig rich in the top end from observing two other cars. I doubt Danny's is any different.
The problem with the stock map and adjusting it is that the mid range has to come up so high that the upper RPM gets bumped too.
Keep in mind the O2 isnt used at WOT.
The new cams run a touch leaner (still safe) in the mid range than I like, but pig rich in the top end from observing two other cars. I doubt Danny's is any different.
The problem with the stock map and adjusting it is that the mid range has to come up so high that the upper RPM gets bumped too.
Keep in mind the O2 isnt used at WOT.
12-24-2011, 05:29 PM
#18
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I have seen a full three point difference in the AF ratio in open loop between a old MAF, and a new one, so it depends a lot on the degradation of the MAF as to what you actually are going to get, the bottom line is you will not know until you get a wideband on it.
You can adjust the map to get what ever you need at different RPM's, just because the mid range goes up does not mean the upper RPM's will do the same on AF ratio's.
So I am not sure what you are trying to say there?
You can adjust the map to get what ever you need at different RPM's, just because the mid range goes up does not mean the upper RPM's will do the same on AF ratio's.
So I am not sure what you are trying to say there?
Doc,
The new cams run a touch leaner (still safe) in the mid range than I like, but pig rich in the top end from observing two other cars. I doubt Danny's is any different.
The problem with the stock map and adjusting it is that the mid range has to come up so high that the upper RPM gets bumped too.
Keep in mind the O2 isnt used at WOT.
The new cams run a touch leaner (still safe) in the mid range than I like, but pig rich in the top end from observing two other cars. I doubt Danny's is any different.
The problem with the stock map and adjusting it is that the mid range has to come up so high that the upper RPM gets bumped too.
Keep in mind the O2 isnt used at WOT.
12-24-2011, 05:56 PM
#20
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You'll find, or you already know that the basic fuel pulse is a function of the MAF, RPM, thermo, and O2 inputs(I think that's all), and when not in WOT the O2 keeps it in stoich. However, during WOT, the enrichment is still a percent over the basic pulse width defined by the MAF, etc.
12-24-2011, 06:15 PM
#21
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Voltage is also a factor, since the LH makes adjustments to the pulse width to compensate for longer injector opening times that occur with lower voltage. Disconnecting and then reconnecting the battery may very well give a better connection, raising the voltage that the LH sees, and changing the compensation that it uses based on that voltage going to it.
12-24-2011, 06:19 PM
#22
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If you are saying that the O2 sensor has no effect on AF ratio during open loop on the WOT map, then I agree.
(or very little)
A stock NB O2 is only really good for measurement at or very near 14.7 to one, so is useless at areas very far from that other than to tell that is is rich or lean.
(or very little)
A stock NB O2 is only really good for measurement at or very near 14.7 to one, so is useless at areas very far from that other than to tell that is is rich or lean.
The added enrichment during WOT is in addition to the pulse metered by the MAF which is valid in all throttle positions including WOT. After re-characterization, the pulse width will be greater, provided the MAF is reading right, and the O2 sensor is putting out a signal. Then, the enrichment from WOT occurs during the times that the flappy valve opens and changes the intake runner length(S4).
You'll find, or you already know that the basic fuel pulse is a function of the MAF, RPM, thermo, and O2 inputs(I think that's all), and when not in WOT the O2 keeps it in stoich. However, during WOT, the enrichment is still a percent over the basic pulse width defined by the MAF, etc.
You'll find, or you already know that the basic fuel pulse is a function of the MAF, RPM, thermo, and O2 inputs(I think that's all), and when not in WOT the O2 keeps it in stoich. However, during WOT, the enrichment is still a percent over the basic pulse width defined by the MAF, etc.
12-25-2011, 02:21 AM
#24
Burning Brakes
Danny , I went from GT cams to the stage 2 triflow . on the dyno we did 3 runs with both the stock cams and the triflow . The car would pick up about 10hp by the 3th run as the cats tryed to clean out. both sets of cam runs showed too rich at the top end
12-25-2011, 02:50 AM
#25
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I guess you were already running GT cams where I had the stock S4 so naturally the difference is more pronounced in my case. It will be interesting to put it on the dyno and see now real WHP.
12-25-2011, 07:23 AM
#26
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12-25-2011, 01:50 PM
#28
Nordschleife Master
I have a number of cells at 127 in the mid range. I also had to adjust the injector size (60# set at 52) to bring the map range down so I could achieve full range. The other thing I did was to increase the mid range WOT numbers from being all zero to pull the range up.
I am able to achieve a good line through there now. But it has not been the easiest
SMTP,
Tri-Flow is the staggered opening of the intake valves. It has been shown to help increase mid range power, throttle response, and has a few other benefits.
12-25-2011, 03:23 PM
#29
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Ok Colin,
A little more complicated than stock but the end result is good.... it's not unusual to have to adjust the injector size to center the range, due to variables like MAF and other tolreances from car to car.
[QUOTE=Lizard931;9130294]John,
I have a number of cells at 127 in the mid range. I also had to adjust the injector size (60# set at 52) to bring the map range down so I could achieve full range. The other thing I did was to increase the mid range WOT numbers from being all zero to pull the range up.
I am able to achieve a good line through there now. But it has not been the easiest
QUOTE]
A little more complicated than stock but the end result is good.... it's not unusual to have to adjust the injector size to center the range, due to variables like MAF and other tolreances from car to car.
[QUOTE=Lizard931;9130294]John,
I have a number of cells at 127 in the mid range. I also had to adjust the injector size (60# set at 52) to bring the map range down so I could achieve full range. The other thing I did was to increase the mid range WOT numbers from being all zero to pull the range up.
I am able to achieve a good line through there now. But it has not been the easiest
QUOTE]
12-25-2011, 04:54 PM
#30
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John,
I have a number of cells at 127 in the mid range. I also had to adjust the injector size (60# set at 52) to bring the map range down so I could achieve full range. The other thing I did was to increase the mid range WOT numbers from being all zero to pull the range up.
I am able to achieve a good line through there now. But it has not been the easiest
SMTP,
Tri-Flow is the staggered opening of the intake valves. It has been shown to help increase mid range power, throttle response, and has a few other benefits.
I have a number of cells at 127 in the mid range. I also had to adjust the injector size (60# set at 52) to bring the map range down so I could achieve full range. The other thing I did was to increase the mid range WOT numbers from being all zero to pull the range up.
I am able to achieve a good line through there now. But it has not been the easiest
SMTP,
Tri-Flow is the staggered opening of the intake valves. It has been shown to help increase mid range power, throttle response, and has a few other benefits.
What is your fuel-pressure, and what is the actual flow rate of the injectors? The "marketing" and actual flow-rates will vary, also opening time will be different for different injectors-- this has a big effect particularly with large injectors and small pulse-widths at light/moderate loads.
ST does a good job with the injector-size calculation, the problem is that getting the actual specs is not simple-- even the stock "19#" injectors don't really flow 19 lb/hr, at the actual fuel pressure.
If you want to PM me the injector spec's, I'll see what I can find out. I am trying to collect some numbers that will give us all better starting points.
Cheers,