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Still learning this ecu and software and I was logging my friend's stock 07 trailblazer ss. I was seeing numbers populating the KR table as we drove. Does KR have the ability to ADD as well as subtract timing like in some ecus or was his truck really pulling up to 7* of timing?
Was pulling timing, better stop and have a look!
So I guess it is not able to add tiiming through KR? Like in Subarus positive the ecu has learned to add and negative means it is pulling timing.
anything that shows up as KR is pulling timing. This does not add.
Positive retard is negative advance.
Gotcha. Amazing that him adding an open filter element instead of the stock box could cause 7 degrees of timing to be pulled! Of course it did throw off his fueling by 15+ percent.
I'd suspect this had to do with the IAT sensor, myself. Where's that, in all this?
Maybe dangling someplace hot?
I don't remember, but thought it was integrated into the maf on those wasn't it? Will timing pulled from intake temp tables show up as KR?
the iat is in the maf. You can purchase a iat breakout harness and mount the iat in a better place if needed. i do know that putting an intake on a trailblazer ss without a tune does cause a power loss.Quote:
Originally Posted by sarg
Nah, since it is a NA motor, I am pretty sure that where it is located is perfectly ok. IAT were pretty similar before and after he did the intake. In fact, they actually cooled off a bit as he mounted it in a location where it is now getting a nice cool charge.
Monitor your IAT temps, If it is an open style CAI, it may be sucking the hot air from the radiator. I like to calibrate my IAT. What I did was start up the engine after sitting all night <<<< IMPORTANT, I looked @ the outside air temp, then the IAT. You would not believe how far these things are off. Mine was off almost 27% !!!!!!!!!!!!
EX: outside air temp 55, and IAT was reading 76 degrees. Some of these cars are realy far off from the factory, I think it is the sensors themself, not so much the tune.
First you find out the % it was off by, using my example take 55/76 to convert to %. Use your numbers obviously.bbIn my case, it was off by a value of 26.73%. So you highlight the whole IAT sensor calibration table and multiply by .7237 (the inverse of amount off) Then your IAT will read the correct temperature. Remember, you can only do this first thing in the morning as the fan wash will throw off the IAT by causing the intake to suck in the warmer air being heated as it moves through the radiator and gets blown towards the air filter. If yours is off like mine was, it will cause timing to be pulled.
Thanks for the tip! I'll take a look into that the next time my friend comes by with his TBSS.
If you look at it, it has to be cold, not heat soaked after he drives over. So when you do it, make sure its you that goes to his place, and it sat overnight. Any driving at all will have put heat into the radiator, and skew the readings as it will be sucking warmer than ambient air from the radiator wash. ;-)
Ya, I figured I would go over there one day.
There's a table of thermistor value vs temperature in the
shop manuals and a glass of ice water is a plenty good
reference.
But an in-MAF IAT with the hood closed at idle and the
fans not running, can easily be jacked by 10-20 degrees
by the heat pickup of the MAF body.
Just to update this, we boxed in the filter some and ran some ducting to get fresh air to it. Temps went down a good bit. Before doing this we noticed that it pulled a ton of timing as temp went up. We have dialed in fueling and all seems good, but still on a 90 degree day with 94 degree iat we are seeing KR. Still on stock timing table. Is this normal? I tried giving it a bit more fuel and it still was. Showing KR. Do these ecus generally see KR on the factory tune when it is hot out straight from GM?