GuitsBoy

iTrader: (4)

Theres a couple tables that dictate the Cylinder Charge Temperature:

Charge Temp Bias vs. ECT: This table determines how much the charge temperature is biased towards the ECT or IAT. Higher numbers bias the resultant temperature towards ECT.

Charge Temp Filter vs. Airflow: This table determines the rate at which the temperature moves to the new bias temperature. At low airflows the temperature change is slower than at high airflows.



Im experiencing a problem with stalling when I pull into the parking garage at work. I guess it has to do with the cooler air in the shade screwing with my idle airflow. Do these tables look like the answer?

Thanks, -T

GuitsBoy

iTrader: (4)

anybody?

soundengineer

iTrader: (16)

you should look at your LTIT's and STIT's and all your idle stuf.... something is not right there....teh charge bias is very loosely based...its mostly towards ECT cause your sensor gets skewed easily... my example being that teh sensor on my car reads sometimes 100* just sitting at idle...and I know teh air is actually 80* outside...when I start driving it cools back down...an dwhen I come to a stop it slowly creeps back up...
at higher g/cly it is biased towards the iat...at less it is biased towards the ECT...
so being biased towards teh ect at Idle and crawl speeds means that it is not your IAT causing this problem and teh difference between outside and garage would change IAT temps....

I would consider looking at you MAF table... as being ported they need recalibration...and I see a lid so teh intake track is changed a well....I dont think i would be enough to cause the car to stall out..but it might??
something else to do to eliminate the problem is to put the car in SD....and try driving into the same parking garage that you are having problems in...

we need to eliminate otherthings first....

hell..even just try putting soem ice infront of the intake to see if a cool charge causes it....then you can sit at home and do it and try to reprogram and try different things to see what is really causing the problem

GuitsBoy

iTrader: (4)

Thanks soundman.

Im currently running SD - so the maf is out of the equation, although while i do have the MAF enabled the same thing happens.

My idle LTFT seems to be pretty stable, noting more than a click or two. I have not really scrutinized the STFTs.

I am however seeing a 10º to 20º IAT difference which results in the the STIT jumping about .5 or .75 g/sec higher. The problem is when coming to a stop before the STITs can react, the engine tries to stall 2 or 3 times. It usually only drops down to 400 or 500 RPM but its still a bit embarassing and hard to drive around.

I dont know what other variations besides IAT there are between the parking garage and the outside.

Thanks again.

soundengineer

iTrader: (16)

have you played with th ethrottle follower/cracker tables at all?? a lot of cams need some adjustment in this area

MeentSS02

iTrader: (11)

If your car is stalling while the STITs are trying to react, doesn't that mean that your idle trims are going outside of their learning limits? As in, you need to set the learning limits higher? I'm just wondering because from what I understand, the idle trims can correct beyond their learning bounds, but when returning back to idle, they will have to essentially learn again from their highest value (which will be the upper end of the learning limit, and that may not be high enough).

GuitsBoy

iTrader: (4)

Sound - I recently went back to stock cracker table. I didnt see any difference there, but then again, i didnt read up on it as much as i could have.

MeentSS02 - No, im not running out of limits. For simplicity'd sake, lets say that Im cruising around and my LTITs are 0 and my STITs are also hovering ~0. Now I pull into the parking garage and at the first stop sign Ill come to a complete stop and watch the rpms drop down for a split second while the STITs shoot up ~1.5 g/sec then back down and back up eventually settling on about .75 g/sec.

MeentSS02

iTrader: (11)

Hmmmmmmmm...I guess you could try biasing the calculations more towards the ECT...if you adjusted it wrong, I guess you'll know where you went wrong

gameover

generally this kind of issue is caused by incorrect settings in the Base Running Airflow as the engine warms up. Starting driving with the engine cold then stopping once its warmed up can cause issues due to the STIT having to do a quick catchup. This is also usually compounded by the LTFT's quickly adjusting down (rich stumble) if you drove a long way before idling in closed loop and your VE table isn't quite right.

After this initial hiccup is it fine from then on?

The charge temperature tables are used to predict the temperature of the air entering the cylinders becuase the IAT sensor is not located close to the engine. You could try changing it, but i have never had to except on supercharger/turbo setups that mount the IAT sensor on the boost side (then i set the switch so that the complex charge temperature model is not used, it just reads the IAT directly).

Chris...

GuitsBoy

iTrader: (4)

Well, my morning commute is about an hour, I figure the engine is as hot as its gonna get. Sitting at the light right before I get to work, the car will idle just fine. Once im in that damn garage though! I swear it must be made out of some rare magnetic ore screwing with my sensors. Or maybe they pump out the oxygen. Or maybe my simply car dreads going to work.

gameover

that is very weird. reminds me of a 750 holley float problem i had back in the day... if i went over a bump at just the right angle the car would stall

solution: don't go to work

GuitsBoy

iTrader: (4)

I wonder if it could have something to do with accessory drag instead? Seems like when I come to a stop inside the garage, im always at the start of a sharp turn. Maybe the power steering is bogging the motor?

P Mack

iTrader: (6)

You never said if your stft/ltfts change when this happens. If it has to do with charge temp bias then it would be a fueling issue and you'd see it in the trims. If it's an airflow issue you'd see it in the idle trims (which you are). Do your stit's stay high when you're not turning? It could be something weird like the air in a parking garage is full of exhaust so there's less oxygen in the air.

GuitsBoy

iTrader: (4)

The LTFTs dont change more than one or two. I havnt watched the STITs but i dont think they change much. Ill look into that though.

I dont really think its a lack of oxygen issue either, as the garage is above ground and the sides are open to the air.

gameover

yeah most engines bog slightly if the power steering is on full lock. The PCM does not compensate for this and if you are moving above the throttle cracker enable speed or have just used the throttle and adaptive idle hasn't engaged again then RPM's will dip. AFAIK, there is no way to calibrate for this except maybe raise the throttle cracker speed a little.

Chris...

GuitsBoy

iTrader: (4)

The power steering is not nearly at full lock, its just slightly into a turn. I dont really know if it would have to do with the cracker since it dosnt happen really anywhere else. I doubled the accessory drag in torque management and that seems to have helped a little. Ill give it a few days to learn before I accept this as a fix.

Thanks,
-T

My90Iroc

iTrader: (26)

What's the difference in ECT (and/or possibly IAT) between getting off the highway to pulling into the parking spot (after sitting at the light and putting through the parking lot)?
Sitting at the light and putting around the parking lot may give the motor time to heat up a little and if you're running say a tad rich it may create a situation where the car is slightly flooding itself at idle due to the hotter engine temps. Just and idea.

GuitsBoy

iTrader: (4)

Whats up dude!

There really isnt a difference in ECT, but IAT has a difference of atleast 10 degrees. Im just using sitting at a light as an example of coming to a stop. So far doubling the accessory torque has made the biggest stride towards eliminating the effects. I can almost drive around the stalling effects now, but its still a bit of a PITA, and a little embarassing from time to time..

GuitsBoy

iTrader: (4)

This morning my car threw another curveball into the mix.

I was stuck in traffic on the road my building is on, so i loaded my idle config into HPTuners scanner. My ltit was around -.40 g/sec, and my stits were hovering around 0. After pulling into the garage, my car did its usual almost stall a couple times until i parked. Once I parked, I saw that the stit was around +.40. I watched the ltit climb until both hovered around 0. Both ECT and IAT temps were within a couple of degrees both inside and outside the garage. It was cloudy outside so the sun wasnt really beating down on the asphault outside. I cant think of a single reason why my car requires .40 g/sec more airflow inside the garage as opposed to outside.

WTF?!?

Steel Chicken

iTrader: (3)

is it only the garage this happens? does it happen anywhere else? redlight or stop sign?