I understand the computer backs out a big chunk of timing when the IAT is above 96 degrees. Where is the table with those controls and what is the recommended fix?
I understand the computer backs out a big chunk of timing when the IAT is above 96 degrees. Where is the table with those controls and what is the recommended fix?
Originally Posted by seevi
totally vehicle dependent....
and it doesnt necessarily pull out timing at 96 degrees and above...
some do it earlier...some do it later...all based on a lot of things on the vehicle
for the most part you can leave it just like it is....it is there for a reason...
some people back out some of it...
I do not recommend zero-ing it out...
the airmass does change quite drastically when the temperature goes up or down...you need less timing for hotter air
-Scott -
agreed with him^^ vector motorsports sells a hsrk (heat soak reduction kit) check it out!! not sure if its worth the money. heard reports of 8 whp gain on g8 gts...
08 GMC rcsb 2wd. 4.8/4L80e with a dollar store turbo.
best so far of 7.25 @ 97.4 1/8 mile
We've came a long way from the 60s when there was no IAT table. Or any other table for that matter. And the cars back then ran just fine with the same timing at any temp.
Incidentally, my 08 Corvette starts to pull timing at 86*.
you are very right...we have come a long way...imagine how much better those old muscle cars would have ran with todays computers.....
-Scott -
The table is the Spark Control Section, IAT Spark/Base.
I would just tune the car with the temps available and find out how much timing it will take. Then you can have the pcm ADD/SUBTRACT timing at cooler or warmer temps.
If you are tuning a car in the middle of the summer with 120* IAT temps it is pretty safe to say that the 120* row could be zeroed out while tuning. Just have the pcm take timing out above that and add a little in below.
Just my 2 cents, but I would leave that table alone and do adjustments in the Main spark table. That table is setup that way for a reason like soundengineer said.
____________________________
2008 Convertible Corvette
Haltech CAI | Kooks Headers and X-pipe | 227/231 .613/.617 lift 115 LSA CAM | Tuned to death
It actually starts at 122. Take a look at the multiplier tables and you'll see that it is multiplied by 0 up until 140 on the ECT mult table and by 0 until 122 on the IAT vs rpm table.
With burst knock and a few other things pulling timing at given times/points.. Taking out the 122 column wouldn't be too dangerous.. especially since its multiplied by some rediculously low # on the mult2 tabke..
2006 Trailblazer SS - Stalled, Cammed, Tuned, Turbo'd, Built, and Stroked.
Runs on cash, blood, sweat, and tears...... and 93 octane.
2007 Cadillac STS-V - Stock.
I fixed my G8 IAT by relocating it to the air box inlet. Just bought a seperate LS1 IAT sensor and wired it in. The Mass Air IAT gets heat soaked and takes too long to cool off.
I had the same problem with my GTO but I relocated the IAT with this and now the IAT temp is much cooler.
http://www.vectormotorsports.com/ind...mart&Itemid=28
2000 Trans Am WS6, 383 RWHP 344 RWTQ
2006 GTO, LS2, Cyclone Gray, M6, 1 of 475
2009 Chevy Silverado
relocating the stock IAT is usually enough...
on LS1's I relocate it to the Intake just after the Throttle Body..its should work equally as well on any vehicle..
if IAT is built into the MAF...just buy an LS1 IAT ad grommet and the wiring kit to relocate it...or just buy that one listed...
I think theres a few places that advertise an"Omega sensor"...its a little faster responding than the LS1 sesnor...but I've never had any issue with response time once I moved the sensor itself
its important that the sensor is directly in the air stream at a high velocity point...
typically the airbox is not a high velocity area...but as all that air gets channeled down to a smaller tube it picks up a lot of velocity
-Scott -
No expert on IAT sensors but it does appear the factory is awfully slow responding. From my logs I'm a long way down the track before my IAT logged value comes down anywhere close to ambient. Seems to me once moving at WOT with an outside air collect filter the air injested into the intake/engine is virtually ambient. My log is a long way from ambient. Maybe that's why we can get away with reducing the amount of timing retard in our IAT table with no logged KR.
Also. because of the given multipliers, the amount you reduce it by, in most cases, turns out to be less than you think. Besides 1000-2000rpm, the actual timing retard is less (mult by <1) until 158 IAT @ 5500
2006 Trailblazer SS - Stalled, Cammed, Tuned, Turbo'd, Built, and Stroked.
Runs on cash, blood, sweat, and tears...... and 93 octane.
2007 Cadillac STS-V - Stock.
when you put in in the right location you will see that its not slow at all...
I've moved the IAT in several cars and you can see an instant change in IAT temp when you get the air moving..especially when you put in directly in the intake snout just behind the throttlebody
on LS1's theres a nice little hole that the EGR pipe goes in....its a perfect spot for the IAT sensor...
most of the Fast intakes have the same little ERG flat spot....just no hole for the EGR unless you order it with the EGR provision...
I've run 9sec 1/4 mile cars with my IAT mod and no ill effects.....and IAT temps are ambient temps within seconds of starting to move
-Scott -
I have an 08 Corvette. The IAT sensor is built into the mass air sensor. Don't know how I would move this one.
The Vector kit has a breakout harness that pulls the two pins from the stock IAT and wires them to their proprietary (faster) sensor. I noticed considerable differences in my LS2 GTO with their kit and relocating the sensor to the air box.
1970 Corvette LS1/T56
2001 Corvette Z06
IF you wish to relocate the IAT that is part of the MAF...you have to buy a seperate IAT and a wire harness...
the kit mentioned above is a perfect example...its designed to allow you to place the IAT in another location and not use the one built into the MAF
-Scott -
Thanks for the info. Certainly good to know but for now I'm going to keep the IAT in the stock position to avoid any warranty issues. I'm sure if the dealer saw some funny wiring they would make reference. Hard to do but as long as I keep the IAT down it shouldn't hurt performance in the stock location. And too this car is almost stock for now.
Having a faster IAT sensor in the stock spot (Talking about LSx Goats) helps out when the outside temps are cold, since the IAT temp can go lower faster to match the real temp oustside, but still won't prevent the performance reduction via IAT timing when the outside temps are above 86F (GTO application). like it was said before, having the IAT sensor relocated just behind the TB is pretty much ideal for a lot of applications, (FAST intake comes to my mind), cause you want to measure air temp moving inside the CAI tract, not faking the readings from a sensor placed in the airbox, if the whole deal is to get close to ambient as possible, why not place the IAT sensor just outside the engine bay right, which we know is totally wrong.
The problem with the Goats is IAT location, and the heat soak issues associated with having the sensor just above the radiator, the sensor readings are just fine, but when the CAI tract gets heat soaked, the sensor doesn't respond fast enough to bring the heat soaked IAT temps down to more real outside temps, and thus why people have been playing with Omega sensors and VMS kits to try to alleviate the problem. again, that works fine for outside temps <86F, but the stock GTO IAT table is pretty aggresive on its own.
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