Nietzsche

iTrader: (7)

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.

NmexMAX

iTrader: (22)

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.

95turbo gxe

iTrader: (25)

It does have to do with load! On my 6 speed if I try to pick up speed in a low rpm in 6th it will be a lot richer than say 3rd at the same throttle %

eng92

iTrader: (3)

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.

NmexMAX

iTrader: (22)

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

eng92

iTrader: (3)

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.

Nietzsche

iTrader: (7)

IPW seems to be fairly consistant with regards to gear. Timing is the same as it's rpm based.

Sorry for the ignorance but what is ECT?

nismology

iTrader: (8)

Engine coolant temperature.

Nietzsche

iTrader: (7)

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?

Maximus_95

iTrader: (8)

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....

NmexMAX

iTrader: (22)

You've read through the FSM as much s I have so you know it does play some role.
I have the same fluctuation as seen in my MAF mod thread. Perhaps try 'clocking' your MAF 15 - 30º and see what that does.

Nietzsche

iTrader: (7)

I know, I know, however my test conditions are consistant from run to run, And the temps don't vary in the hour I take logs. I could always log the ECT if it makes you happy just to make sure, but I highly doubt this is it.

eng92

iTrader: (3)

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.

Kevlo911

iTrader: (36)

That is what I always thought it was when I was doing my revlimit on the EU...

Nietzsche

iTrader: (7)

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.

nismology

iTrader: (8)

Why not try using a vehicle speed adjustment map to correct the a/f based on MPH?

eng92

iTrader: (3)

There is no problem correcting the afr. My issue is why is like that in the first place?

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.

Nietzsche

iTrader: (7)

Would it be a safe bet to take my IPW from a third gear pull and use it as a starting point for injector control?