a/f changes with weather

[Mellon]

I use the MAF-T and E-Manage and I'm noticing that my a/f is changing with the outside temperature

43 degrees this morning and I'm ok
61 degrees this afternoona and I'm pig rich

check out my overlay.. I thinking that the fixed temp in the maf-t is keeping the ECU from adjusting for temperature

what do you guys think? there were no changes in the tune made by me...this is driving me nuts. If I lean it out at noon for the warmer weather for say 11.5:1 it'll end up being damn near 13.0:1 in the morning when it's cold.. knock city.

what can I do about this?

You must be logged in to view this image or video.

 

[86MCSS]

Welcome to turbo tuning 101! This happens to all turbo vehicles. I say tune for the warmest weather during the day since this is your daily driver. This way you know the tune is always safe. I dont know if e-manage has the ability to save different tunes but maybe you could save different weather tunes?

 

[my_gst95]

This is why our cars have knock sensors. Outside temps have major effects on how a turbo'd car performs even in stock form. If your car is a daily, then I would do what 86MCSS said and tune for when your outside temp is 'most' likely to be. You'll have to deal with very rich and very lean conditions on certain days or certain parts of the global if you travel with it. Then at track time, retune.

GL,

my_gst95

 

[Mellon]

I'm going to borrow a stock MAS tomorrow and see if it helps or not since It'll have a working IAT sensor.

with the E-01 I can save up to 3 different tunes so if I can't fix this issues I guess I'll have to do these:

pump gas warm weather
pump gas cold weather
race gas track tune

I can understand it being a bit off but damn I had it dialed in last night 11.5:1 on pump gas and 0 knock and this morning that same tune was all over 13.0:1 and knocking 15 counts by 4000 rpm.. f'n rediculous.

 

[Mellon]

ok, I made no changes to the tune this morning and it's richer than ever @ a rainy 56 degrees outside.

You must be logged in to view this image or video.

the car was bogging hard.

I'm going to log:

rpm vs boost vs airflow and make sure that the airflow at say 4000rpm @ 16psi is always showing the same aifrlow. if it doesn't that suggests the issue is the MAF. If everything matches up pretty well then it might be something fuel related like the SX FPR.

 

[1LE]

Welcome to turbo tuning 101! This happens to all turbo vehicles. I say tune for the warmest weather during the day since this is your daily driver. This way you know the tune is always safe. I dont know if e-manage has the ability to save different tunes but maybe you could save different weather tunes?

You're backwards

Tune in the cold weather when the car wants to go lean. It'll run richer when it gets warm out. I tune when it's mid 40's out. If it's colder than that, I'm not likely to go WOT for lack of traction, plus the knock sensor can help me out a little if need be. Runs pretty good up until about 90 degrees. Once it hits the 90's, it's too rich, but those temps are so rare around here that I don't bother to re-tune.

 

[awdsm drft]

Are you using the emagane to tune your fuel?

If so it probably uses rpm based points rather than airflow points like the maft. Tune it once with the maft and it won't change in accuracy.

 

[Mellon]

 

[Hal]

Welcome to the world of "piggy back" tuning.

The MAF-T alters the MAF Hz signal.

This is one of the sensor values that the ECU uses to determine air mass.

When you take 10% hz out, you are leaning it out 10% for the current combination of air temp and barometric pressure.

When either of those two things change, your 10% hz adjustment no longer reflects a 10% change in air mass.

If your car as a properly operating air sensor metering system and a properly operating fuel system, the air fuel ratio (in closed loop operation) will remain fairly constant regardless of the weather.

The use of a piggyback like the MAF-T or AFC alters the maf hz signal, aka... it is no longer accurately reporting the amount of air entering the motor... so by definition, your air metering system is no longer operating properly.

 

[Mellon]

I don't do any correction with the MAF-T .. all done on the e-manage but of course that's still altering the airflow to the ECU.

I'm on the stock MAS now and did a log when it was ~ 32 degrees last night..when it warms up to 50's I'm going to post the log of that to see if it's any better.

here's the tune I ended up with last night. 11.7 on pump gas had me riding the ragged edge of knock so I tweaked it to 11.5 for a little more cushion. I still have to fine tune a few places but it's getting there. This was taken at 2am this morning @ 32 degrees

You must be logged in to view this image or video.

 

[Mellon]

2:30 pm 59 degrees now..no changes to the tune, here are the results from a near 30 degree increase in temperature with the stock MAS.

what a relief for me to see this.. finally I'll be able to drive around without dicking with the settings constantly to save the engine.

You must be logged in to view this image or video.

now, to figure out what's up with the MAF-T setup. I know voltage can cause fluctuations but it was consistently off so I don't think that's the issue. I'm looking into trying another MAF and MAF-T to see which is the culprit.

so clearly the stock MAS is doing an excellent job of compensating for weather where as the MAF-T is doing a horrible job.

Stock MAS 30 degree shift in temps = barely any deviation whatsoever
MAF-T 10 degree shift in temps = disaster (see below)

You must be logged in to view this image or video.