Page 2 of 2 FirstFirst 12
Results 11 to 17 of 17

Thread: Open Loop VE IAT Multiplier Values

  1. #11
    Junior Member
    Join Date
    Jan 2004
    Posts
    22

    Default

    I have similar problems with IAT in SD open loop using a v3 OS. When the car has been idling or sitting in traffic for a while and warms up to 50*C+ IAT the result is a lean condition (17:1 or higher, way above commanded). I definitely believe the air under the hood is getting as hot as 70* and that the SD tune is not compensating. I have tried maxing out the IAT VE multplier at higher temps to 1.300 with zero success - it does not appear to help the mixture richen up at all.

    Help?

  2. #12
    EFILive Reseller ringram's Avatar
    Join Date
    Oct 2005
    Posts
    1,411

    Default

    I have had good results using 1% per 10*C close to the number mentioned by others in this thread. (eg) 0.99, 1.00, 1.01

    Im currently trying to find someone in Oz who wants to send me a OTRCAI in NZ. Delco is out of stock apparently. Im waiting on Orssom to get back to me at the mo. IAT temps must die!
    Get EFILive in europe (http://www.efilive.eu).
    2007 Escalade ESV L92 6.2L VVT.
    2014 VF SV LS3 Maloo.

  3. #13
    Junior Member
    Join Date
    Jan 2004
    Posts
    22

    Default

    Hmm, I've tried a full 30% added in the 50-70*C area and it didn't appear to have any effect on my warm idle lean condition. Perhaps I'll try again to see if I was on crack - maybe my VE value at idle was just too far off base. I guess I'll try to write my own PID to calculate what the airflow would be with this 30% added in, and compare to the grams/s that the PCM is measuring.

  4. #14
    Lifetime Member
    Join Date
    Apr 2003
    Posts
    379

    Default

    The IAT correction was added in like the Boost spark retard for the occasion when you need it.

    Do all your base tuning with it set at 1.0000 , same as the factory would have had it , if after doing all your tuning you see a AFR shift at different IAT values then dial in your IAT correction table as required.

    We found with blown combo's that this was required , not as essential with a N/A motor but it is another adjustment that can be used if and when requried.

  5. #15
    Senior Member
    Join Date
    Oct 2005
    Posts
    158

    Default

    Quote Originally Posted by McRat
    Just rambling about IAT's in general.

    Often the true IAT has nothing to do with what the sensor tells the engine. Sitting on the line in the summer, a Z06 will report over 150degF to the engine when the air going into the engine is only 80 deg.

    If cannot relocate your IAT sensor outside the engine bay, you should at least zero out any effects that are in the "stupid range". Anything over 90 degF should probably be ignored. For racing, I zero out all effects of IAT.

    The difference it made in 1/4mi ET was .48 seconds.
    .48 seconds is a helluva lot ! I would have to spend a lot of money to drop my et that much, or would be major league pissed if it went up that much !

    Maybe you mean .048 ?

  6. #16
    Lifetime Member GMPX's Avatar
    Join Date
    Apr 2003
    Posts
    13,148

    Default

    Quote Originally Posted by Draco
    Hmm, I've tried a full 30% added in the 50-70*C area and it didn't appear to have any effect on my warm idle lean condition. Perhaps I'll try again to see if I was on crack - maybe my VE value at idle was just too far off base. I guess I'll try to write my own PID to calculate what the airflow would be with this 30% added in, and compare to the grams/s that the PCM is measuring.
    How did the updated file go?
    I no longer monitor the forum, please either post your question or create a support ticket.

  7. #17
    Lifetime Member McRat's Avatar
    Join Date
    Nov 2005
    Posts
    280

    Default

    Quote Originally Posted by Extinct
    .48 seconds is a helluva lot ! I would have to spend a lot of money to drop my et that much, or would be major league pissed if it went up that much !

    Maybe you mean .048 ?
    No, in the case of the stock Z06, reported launch IAT was ~156°F, which pulled about 9 deg timing. It ran 12.46 @ 110, then I wiped out the IAT retard table and it ran 11.98 @ 114 with no other changes. I could have iced down the MAF and got the same effect, but I'm not into dripping water down the track. This is one explanation why some magazines say the Z06 runs high 12's.

    The LS6 MAF has the IAT sensor imbedded it in, and it's an aluminum body. The radiator heats it up to near water temp due to it's location. But the actual air going into the motor comes from in front the radiator in the empty nose, and is only a bit warmer than outside air.

    It wasn't a "gain" in horsepower, rather it was a recovery of lost HP. Any Z06 you see running 11's stock has addressed the issue one way or another.
    2005/2007 DHRA Western Drag Champion
    Bonneville A/DT & B/DT Land Speed Record Holder, 197mph best speed.

    Casper - 05 GMC 2500 Dmax LLY 10.59 @ 129, 916rwhp
    Big Blue - 04.5 GMC 3500SRW LLY 13.12 @ 104, 502rwhp sled puller
    Wendy - 06 GMC 2500 LBZ 12.50 @ 107.5 First LBZ into the 12's. 542rwhp.
    Blue Meanie - 02 Z06 11.40 @ 121 AFR H/C

Page 2 of 2 FirstFirst 12

Similar Threads

  1. How to REALLY shut of closed loop/ force open loop
    By Tomato in forum Gen III V8 Specific
    Replies: 6
    Last Post: June 17th, 2008, 02:37 AM
  2. program is changing open loop to close loop
    By louis in forum General (Petrol, Gas, Ethanol)
    Replies: 1
    Last Post: November 7th, 2007, 05:38 AM
  3. Open loop or semi open loop still?
    By louis in forum General (Petrol, Gas, Ethanol)
    Replies: 15
    Last Post: October 18th, 2007, 02:46 AM
  4. Semi-Open Loop Vs Just Open Loop
    By BowlingSS in forum Custom Operating Systems
    Replies: 16
    Last Post: April 14th, 2006, 04:25 AM
  5. Open Loop SD VS Closed Loop SD Advantages???
    By BowlingSS in forum General (Petrol, Gas, Ethanol)
    Replies: 1
    Last Post: August 4th, 2005, 11:25 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •