bird2002

Prior to doing the mod I was experiencing up to 3.9* of kr at the top end of some of the gears. Put the 4.6k ohm 1/2 watt resistor now the iat thinks its getting 57* air and I only experience extreme small kr at 120mph.

I dont know how that works but if somebody could explain that to me and weather or not it is safe to continue this setup that would be greatlly appreciated.

Mods are
Ported n Polished TB and MAF, K&N kit, magnaflow catback.

superls1

Be curious to see what the results are when you drive in air that is cooler ('better') than 57*.

SSpdDmon

iTrader: (10)

x2...

bird2002

True, but I think the underhood temp sensors would be higher than 57* at the sensor.

brad8266

iTrader: (23)

All you did was a half *** band aid fix and actually reduced your timing anyway right off the bat. There is a table that pulls timing based of IAT and since you tricked the IAT its probably pulling some timing without logging KR.

SSpdDmon

iTrader: (10)

Half-*** band aid fix - yes.

PCM pulled timing because of resistor - no.

PCM increase fueling because it assumes cooler/denser air - most likely.

The PCM won't pull timing for lower IAT's according to my copy of a stock '02 tune. Only once the IAT's are above 86*F at part throttle and 95*F at WOT will the PCM begin pulling timing.

bird2002

It seemed to make my car run faster. I was able to hang with my buddies TA. I read an article that showed about a 1.5* timing advance with this mod.

Im assuming the proper way of fixing this problem would be to go get the car tuned to have them add in more fuel to help prevent the KR???

The main thing im concerned about right now is weather or not this a "safe" setup for the rest of the summer?? Am I putting anything at risk??

brad8266

iTrader: (23)

got ya, I knew it would add more fuel but i wasnt sure what the IAT timing table has in it, Im not infront of my tune file right now.

Thanks for clearing that up. Either way its still a bad aid fix.

bird2002

Any thoughts from people on weather or not they think its okay to run this way the rest of the summer??

2xLS1

iTrader: (25)

Show me the table in the calibration, any calibration, where it does this.

bird2002

Someone also suggested to me it makes the car go into open or closed loop, is that true?

brad8266

iTrader: (23)

i dont think so.

NoGo

iTrader: (2)

I agree with this. I run OLSD and I have a resistor in the IAT. I did it originally to cut down on the variables for tuning, but later saw that the fueling wasn't drifting as the ambient temperature changed.

If it does modify fueling it is a very very small amount.

joecar

PCM sees colder IAT, so it computes more airmass, so it adds more fuel... running richer may prevent knock.

joecar

It's a computation.

brad8266

iTrader: (23)

Yeah it adds fuel until the O2's tell the pcm its too rich due to the false IAT, so in turn the trims cut back fuel. Am I wrong here?

2xLS1

iTrader: (25)

Theory or fact?

ZL1Killa

iTrader: (17)

isn't there a table in efi live that has adding/subtracting fuel based on IAT temps... its a factor i believe

2xLS1

iTrader: (25)

Yes the table is there for PE mode but the GM Calibrators chose to populate that table with 0s in every calibration I've ever looked at. If they wanted to add fuel based on IAT, it would have been so easy for them to do it. They just chose not to.

SSpdDmon

iTrader: (10)

If IAT's have no effect on fueling, then please explain to me why my idle AFR richens up as IAT's drop and leans out as they increase?

When IAT's are 60's~70's, I idle at mid 14's on the WB. Once the IAT's are over 90*F, I start to see more 15's and some 16's on the WB.

That's in practice.

The part in the tune I'd like to draw your attention to is the dynamic airflow calculation from the VE table. It calculates fueling in part based on charge temperature, which comes from IAT and ECT. I know based on application that the VE does effect not only transitions, but idle as well. That's why you have to lop off 40% or more from the low RPM regions of the VE for a big cam'd car to idle right. If it was a pure MAF measured value providing an airflow measurement to the PCM, this wouldn't be necessary.

Even if it's a MAF only tune (where the dynamic airflow threshold limits are reduced to 1 RPM), I've seen IAT alter AFR. I wish I knew more of the details to answer your question. But, the fact is I only have my personal experience.