AFR 1st gear vs 3rd
#1
AFR 1st gear vs 3rd
So after many hours of logging and playing I've noticed my AFR through first is alot higher than in 3rd. If I do a launch my AFR is consistantly mid to high 13's but in a 3rd gear pull it's low to high 12's. Is this normal and if so why?
Thanks as always.
Thanks as always.
#2
Originally Posted by Nietzsche
So after many hours of logging and playing I've noticed my AFR through first is alot higher than in 3rd. If I do a launch my AFR is consistantly mid to high 13's but in a 3rd gear pull it's low to high 12's. Is this normal and if so why?
Thanks as always.
Thanks as always.
#4
Originally Posted by NmexMAX
Mine is the same. My guess is that there is more load on the engine. Both of our ECU's, though not the same, both have a calculated load feedback, but I'm not sure if it used with respect to fuel requirements. Most of the FSM dictates parameters with respect to IAT, ECT, but seldom load. Even then, our ECU's have always been programmed to be 'safe', so again, that would make sense re: more fuel @ higher load.
#5
As always, informative information from you
I saw that when I tossed a on the subject earlier.
http://www.powercardtuning.com/support/load.aspx
http://www.angelfire.com/pro2/rst/ai...uning_tips.htm
Originally Posted by eng92
Engine "load" is just the ratio of the current airflow to a pre-determined "peak" airflow number. It is independent of speed and only really depends on engine speed and throttle position.
I saw that when I tossed a on the subject earlier.
http://www.powercardtuning.com/support/load.aspx
http://www.angelfire.com/pro2/rst/ai...uning_tips.htm
#6
Originally Posted by Nietzsche
So after many hours of logging and playing I've noticed my AFR through first is alot higher than in 3rd. If I do a launch my AFR is consistantly mid to high 13's but in a 3rd gear pull it's low to high 12's. Is this normal and if so why?
Thanks as always.
Thanks as always.
Are you compensating for ECT in your UTEC? Typically (at this time of the year) it can be considerably higher from a launch condition.
#7
Originally Posted by eng92
You are using a UTEC. Do you have any differences in IPW for a given rpm/airflow for your two different gear runs? Also check for timing differences between the two runs as that will impact the afr picked up by your WBO2.
Are you compensating for ECT in your UTEC? Typically (at this time of the year) it can be considerably higher from a launch condition.
Are you compensating for ECT in your UTEC? Typically (at this time of the year) it can be considerably higher from a launch condition.
Sorry for the ignorance but what is ECT?
#9
Gotcha, I have never monitored this but don't think it would play a role. I always wait for the car reach operating temperature and wait between runs. Is it possibly just a function of how quickly the engine spins. When you do a third gear pull it's a slow and steady pace. With a start from a stop the engine revs up much faster. Could this lead to it not dumping fuel quick enough? Maybe something to do with the gearing?
#10
im having the same exact problem also..... just that when im 1st gear and i go wot, my car would hit 16's on the wideband 02 for a split second, i will feel a huge power loss then it picks up again after that.... but weird thing is, it only does it on 1st gear, and any gear after that, its ok.....
Man, this is really bugging me, not being able to go WOT on 1st....
Man, this is really bugging me, not being able to go WOT on 1st....
#11
Originally Posted by Nietzsche
don't think it would play a role.
Originally Posted by Maximus_95
just that when im 1st gear and i go wot,
#12
Originally Posted by NmexMAX
You've read through the FSM as much s I have so you know it does play some role.
#13
I did some data logging the other day for WOT runs in 1st, 2nd and 3rd gears.
I dialed the timing back for all the runs in order to be able to maintain traction in 1st and the top of 2nd.
Up to 3.5K and after about 6.2K, my afr was consistent in all three gears. In the range between those two rpm levels, 1st was between 0.5 and 1.0 points leaner than 2nd and 3rd.
Looking at airflow, the MAF voltage was pretty consistent vs rpm for all three gears (as expected).
On the other hand, the IPW curves pretty much told the story. The first gear data set was typically 1 ms shorter than that for 2nd and 3rd.
Now we need to figure out why the ecu would output a shorter IPW for a given rpm. Rght now the only difference between the runs, I can see, is the rate of change of rpms. First gear is over with pretty quickly.
I will post up some curves tomorrow.
I dialed the timing back for all the runs in order to be able to maintain traction in 1st and the top of 2nd.
Up to 3.5K and after about 6.2K, my afr was consistent in all three gears. In the range between those two rpm levels, 1st was between 0.5 and 1.0 points leaner than 2nd and 3rd.
Looking at airflow, the MAF voltage was pretty consistent vs rpm for all three gears (as expected).
On the other hand, the IPW curves pretty much told the story. The first gear data set was typically 1 ms shorter than that for 2nd and 3rd.
Now we need to figure out why the ecu would output a shorter IPW for a given rpm. Rght now the only difference between the runs, I can see, is the rate of change of rpms. First gear is over with pretty quickly.
I will post up some curves tomorrow.
#14
Originally Posted by eng92
I did some data logging the other day for WOT runs in 1st, 2nd and 3rd gears.
I dialed the timing back for all the runs in order to be able to maintain traction in 1st and the top of 2nd.
Up to 3.5K and after about 6.2K, my afr was consistent in all three gears. In the range between those two rpm levels, 1st was between 0.5 and 1.0 points leaner than 2nd and 3rd.
Looking at airflow, the MAF voltage was pretty consistent vs rpm for all three gears (as expected).
On the other hand, the IPW curves pretty much told the story. The first gear data set was typically 1 ms shorter than that for 2nd and 3rd.
Now we need to figure out why the ecu would output a shorter IPW for a given rpm. Rght now the only difference between the runs, I can see, is the rate of change of rpms. First gear is over with pretty quickly.
I will post up some curves tomorrow.
I dialed the timing back for all the runs in order to be able to maintain traction in 1st and the top of 2nd.
Up to 3.5K and after about 6.2K, my afr was consistent in all three gears. In the range between those two rpm levels, 1st was between 0.5 and 1.0 points leaner than 2nd and 3rd.
Looking at airflow, the MAF voltage was pretty consistent vs rpm for all three gears (as expected).
On the other hand, the IPW curves pretty much told the story. The first gear data set was typically 1 ms shorter than that for 2nd and 3rd.
Now we need to figure out why the ecu would output a shorter IPW for a given rpm. Rght now the only difference between the runs, I can see, is the rate of change of rpms. First gear is over with pretty quickly.
I will post up some curves tomorrow.
That is what I always thought it was when I was doing my revlimit on the EU...
#15
I guess I missed that but you are right, my IPW is longer in 3rd gear. I wonder if I should switch over to Speed Density from MAF control to see if this solves my problem. I'm kind of nervous controlling injector timing though, at least with MAF adjustment I can't go really out of control.
#17
Originally Posted by nismology
Why not try using a vehicle speed adjustment map to correct the a/f based on MPH?
The only thing I don't like about using vehicle speed correction is the adjustment it would apply at the top of first gear would be the same as the middle of 2nd gear.
I will experiment a little to see if I can come up with a good compromise.
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