Ok so awhile ago I noticed my car was getting slightly richer as the temperature dropped. Well right now California experienced about a 30F drop in weather so in this nice 40F degree morning my car is running so rich i had to literally switch to my non e85 map to make it to work.

Something is definitely wrong its not just a few AFR points now its like running into the 9's for AFR when its cold. Need opinions on if this is a function of me having the air temp sensor both on the upic and it being connected to the fuel temp spot on the ECU rather than the air temp spot on the MAF.

Probably going to have to unmod now so i can get my car driving for the cold weather.

 

Is there a cold weather table that will compensate the fuel for various temperatures?

SD is supposed to not have issues with temperature variances. Makes me glad I havn't made the switch just yet.

 

That definitely sounds very weird. I would have guessed that you would start running lean, if anything.

So, you have your temp input into the fuel temp sensor adc and you have your ROM flashed to use the fuel temp adc?

When you log your temp sensor, what values are you getting? You aren't getting any ridiculously low temps are you? Is the richness just during initial start and warmup or all the time?

Did you ever change any of your temp tables in any way? Any baro/IAT table or anything remotely close to that? Any table that deals with the pv=nrt forumla or anything like that? I remember from several different threads where tables were posted that dealt with this kind of stuff. I think it was mentioned not to change them, but I think several people were experimenting with them. Did you happen to change any of these tables?

The temp compensation should follow the pv=nrt formula, so if nothing was changed in that respect, your fueling should stay in check, as long as your temp sensor is reporting accurate values. Maybe your IAT sensor is recording lower IAT values than your actual intake temps (like the IM heatsoaking) and thus resulting in a rich AFR. If that's the case, then it should lean back to normal once you start moving.

 

Yeah i would have guessed it going lean as well but it didn't. I haven't touched any of the baro or air temp tables. The values I read in evoscan look perfectly normal to me.

Fuel problem stays the same no matter if the car is moving or not, if anything it gets a little worse when its not idling. I do have a spare air temp sensor i can see if the sensor somehow got damaged and is reading erratically.

 

I think we will start to see more of this...sorry to hear roadspike...hopefully there is a fix

 

Think i may have found my problem..

It appears my MAT scaling for IAT scaling table is completely buggered..

God this is going to suck retuning it but i have hope it will work!

Left is mine right is stock banks scaling.. (scaling is set to hex 8) so i can see it

 

what is the reasoning for this? how'd it happen?

 

I copied it from an older rom likely its just old scalings or something

 

how come it never mattered until it got colder?

 

Probably was in a range that didn't change that much i wager

 

I was about to tell you to check that...glad you figured it out. But why don't you have the correct scaling?

 

I'm paranoid now that mine's messed up and I haven't driven my SD car in wide temp swings yet. I'm not sure what you mean by the "MAT scaling for IAT scaling table"? I have an SD IAT ADC Scaling table under "SD Programming" and a "MAT Scaling" under "MAT Patch." They match in my ROM. What do I need to check? Mine aren't in hex BTW.

Many thanks.

 

It was under the speed density programming table it probably was the IAT scaling table. I'm using the 94170015 rom patched for speed density.

Results:
So I put in the new temp scaling and it really did help tremendously but i found a secondary problem while i was under the hood. I noticed my o2 sensor stopped working well it was just loose from being tugged around when i replaced the crank sensor yesterday so easy fix.

Car seems to idle pretty darn well now and I'll get more info if the driving improved on this next cold morning.

Once the car is running properly I plan on submitting the file again in the thread for speed desnity patches.

 

I was going to add in that I recently took a trip in my car going from 110 degree temps at 2200 ft, to 60 degree temps at 9000 ft(in the course of a little over an hour) and I had zero issues with my SD map.

 

Ive had my car SD now for 2 weeks and have seen a 35* change and my car hasnt gone threw any noticable change in AFR since Ive been doing this. Ill keep everybody posted but all seems good here and banks said he saw a 40*C change in temps with lil to no change in AFR.

I guess time will tell as we get more feedback from peeple. I will be checking this extensively.