What are the issues to beware of with tuning in the heat?

If you tune in 90 degree temps, what is likely to be off in the tune when you are in 50 degree temps?

I guess in cooler temps you can run more timing? Not sure about how temps affect AFR.

How many people have separate maps for different seasons?

Thanks.

p.s. I really want a remote map switch if anyone has one to sell.

 

If you are tuning with the UTEC you shouldn't really have to worry about that becuase you are only changing the base ign timing or fuel table, these are the base tables and they do not take into account any of the trim tables from my understanding. So all of your trim factors will still function as normal which is a good/safe point of the UTEC so there should be no worries. Testing is always good though once the weather changes.


Hope it helps.

 

I thought the timing numbers were absolute, except to the extent that you set the "parameters" to pull timing over a certain temp? I'm a little less certain about fuel, but the MAF should help to keep those in line, provide that Karman values reflect air density changes.

 

Yes, the timng numbers are absolute. In my case, I see my AFR goes a little leaner in cold nights (I tunes mine during hot days). It got as high as 0.3 points AFR in difference. But I don't get knocks becuase of it though. I guess it has to do with the colder intake air, which is also less likely to cause knocks. And I think it is another reason why you don;t want to tune your car to the knocing threshold.

 

For the most part, if your using the MAF signal, the cells you tune will be relative to the actual air your car is ingesting, You will probably find slight variations due to temp, but usually you are more likely finding yourself in a different range of cells that need slight adjustment still.

Timing is absolute, but the path the car takes through your timing and fuel maps will depend on your maf frequency, which changes slightly as conditions change..

 

Obviously colder air temp charges are much more dense. Therefore, at the same point in a map on a cold day vs a hot day, you will be taking in more O2 making the 02s leaner. By them being leaner... if you tune your car on a cool night you should be ok to run it on a warm day in spurts perfectly fine. The other problem with very hot days is the temps start to heat up EVERYTHING too much making it knock much more than it normally would. This is the reason there are provisions for things like coolant temp enrichment. I would think you could use this to compensate for hot days. I dont really care enough to use it but if you wanted you could. I am sure with enough screwing around you could probably wire up a different sensor to it (Perhaps an intake temp sensor) and use it to add fuel or retard timing when it gets real hot... I havent used it or looked into it and I dont think it would work great because I am assuming it is an on/off type thing making it at 54 degrees celsuis it uses the normal table and 55 it changes the tune. Im not sure if you could set it to be progressive of not. Honestly... it is too much tuning for me.

From what I have learned about tuning is this.... For track day type tunes you set them on the limit of what you think you can get away with. Run it and tune from there. For normal driving... shoot real safe numbers at it and leave it be. If you lose 20-30 horses who cares. Its safe and you wont need to worry about it.

 

And M Jack is right... the MAF sensor has an intake temp sensor as a part of it that changes the 'hertz' readings it produces. It SHOULD be accurate (Lower Karmens on a hot day than cool day) but it isnt perfect. The utec will probably move over to a higher load point when its cool out but it may not... Im not sure the algorythm the utec uses to decide what map point your in. I am assuming 100 load point is 90-100%, 90 load point is 80-90%, etc... but i dont know

 

Yes, but when you are in 100% load (at around 5500RPM+ in my case), there is no room for the MAF signal to fall into different load site. So the AFR may be off a little more in WOT at high RPM when it reached the 100% load site... As I am writing this, I am thinking if I should increase my MAX MAF signal to higher so I see fewer rows of 100% load in a full third gear run.

 

Correct, if you are in 100% load site, but remember, the cells are "Tweened" so depending on where you are, it could be slightly different (this basically makes for smooth transitions between cells)

Also, TurboXS actually recommends that you set your max MAF setting to be in excess of what you hit, therefore you should only rarely hit 100% The way my car is set up, I have the max maf set for 20 (2000hz, I will hit 100% load site on occasion, but it will mostly be within 90%) Only recently did I find I needed a retune after noticing my MAF reading changed a bit and I had to up the number, early on I had it set to 17 and it was at 100%, and I could see your point when my maf reading was at 1900 when the 100% cell was configured at 100%.. But thats in reality a configuration setting, and you should actually set your max maf setting to be greater than what you'd typically hit and do most of your tuning in the 90% or lower columns.

 

My EMS was tuned in the winter on C-16. Speed Density. What should I expect on these HOT 100% humidity days? I'm sure power will fall off but how much?? 5-10%?

 

hard to say, turbo cars are just so tempermental in heat/humidity, I wouldn't be surprised if your down at least 15%..

My car runs fine in the hot humid weather, but it definitely feels pretty down on power compared to cooler nights.

 

We got a couple of cool nights (relatively speaking) here recently and I noticed that my car ran leaner in the cooler temps when I had done most of my tuning in higher temps. Does this make sense? I think it does because the heat doesn't seem to change the Karman readings much but the air is surely more dense. So maybe tuning in the heat and then running in the cold isn't necessarily the most conservative approach. The car may be more knock prone in the heat and therefore it's a good time to dial in timing, but maybe you need a cold day to dial in AFR?

 

look at your logs, you may find the path through the cells is a little different.. There are three components that affect your MAF reading, Air density, temp, etc.. Also, our cars have a Baro sensor, it samples the air pressure when you start the car, it determines the offset the MAF would normally get.. But the UTEC may not utilize all three sensors at the moment, so it may just use MAF reading without temp/baro info.. I started realizing that the other day.

 

Okay, car definitely runs leaner in cooler temps and it's not due to shifting cells. Tonight was in the low 70s and I've dialed in my AFR in temps in the mid-80s. Car ran about 2-3 tenths leaner on boost. It took a good size correction to get AFRs back into the low 11s. Happily the lower temps allowed me to run more timing at the same boost level and that picked up a bunch of power. I think that I am planning to have multiple maps for different temp ranges based on what I'm seeing.