Page 1 of 2 12 LastLast
Results 1 to 10 of 12

Thread: Cold start idle help

  1. #1
    Lifetime Member oztracktuning's Avatar
    Join Date
    Nov 2005
    Posts
    596

    Default Cold start idle help

    Since fitting the BBK TB i have had great gains in power BUT its changed the cold idle behviour dramatically what worked before doesnt work anymore.

    What can i do to dial this in accurately again. It is simply starting and stalling - i need to push the throttle and keep the revs up well above 1200rpm or it will stall. After 30s or so it is OK.

    If i check the AFRs what should i be aiming for at idle. I am not sure if the car has too much idle air or doesnt have enough??

    Have been stuffing around for a few cold starts now trying to get it right.

    The PLX wideband takes time to calibrate and settle - this is masking the ability to get accurate afrs. But i can plug it into an external power source and have it ready before the car is started. If this is the way to go.

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

    Default

    Hey dude, check out the "idle transition sticky" you will want to log RAFIG which is a calc pid and RAFPN they show you what air the car is trying to add to get the car to your required idle speed. If you then add that to your desired air table things start working well again.
    What was your old idle speed? You might be getting too much air with the larger tb making it lean, opening tps adds fuel.
    Check out that sticky anyway it helped me.
    .. sounds like I might want a 80mm bbk myself

    Ok, so its no longer sticky.. try here instead http://efiforum.iqd.co.nz/showthread.php?t=149
    Get EFILive in europe (http://www.efilive.eu).
    2007 Escalade ESV L92 6.2L VVT.
    2014 VF SV LS3 Maloo.

  3. #3
    EFILive Crew Site Admin Tordne's Avatar
    Join Date
    Oct 2004
    Posts
    3,870

    Default

    Also once you achieve normal temp check what the IAC Steps sits at when at idle. Mine sits at around the 60 mark at warm idle.

    I'd say if the car is stalling you don't have enough air.

    Did you change the IAC Effectice Area table at all? From what I've been reading most recently it is not required. I have had best results with a stock table.

    As Richard says, log the RAFIG from cold through to warm and apply to the Desired Airflow table.

    I'd also be inclined to disable idle learning, set B4501 to max setting (140*C). At least while tuning the idle.
    Andrew
    EFILive Crew


  4. #4
    Lifetime Member oztracktuning's Avatar
    Join Date
    Nov 2005
    Posts
    596

    Default

    Thanks guys
    All set to do the logging and some changes tommorrow.

  5. #5
    Lifetime Member Doc's Avatar
    Join Date
    Oct 2005
    Posts
    744

    Default

    I have a 80mm BBK. Ditto on the RAFIG / RAFPN from cold start. Sounds like not enough desair + TB set screw to get IAC to ~60 PN ~100 IG.

    2000 Silverado Full Size 4x4: Forged 6.2, H/C F1R Procharger
    98A4 Z28: 02 PCM H/C Forged 347, 9" Moser 3.73
    V1 V2 99+up RR COS #5 OLSD Dual Stg N20
    www.efialchemy.com
    www.greatamericancarwar.com

  6. #6
    Lifetime Member
    Join Date
    Mar 2005
    Posts
    355

    Default

    Hi there from New Zealand.
    I've just solved this issue this week for a customer of mine. As an after market tuner you often inherit a job after the mods are all done and as such don't always know the exact details, brands and in the and outs of the components used. Theirin can lie the problem....

    After hours of wracking ones brain cells using EFILIVE and altering every possible idle paramater it became very apparent to me that the problem was a physical one not a programming one. The car would surge when cold from 200 rpm to 900rpm and stall at intersections until it warmed up to 60 degree C.
    Hot idle and startup where fine.
    I removed the idle actuator for a look see to check that it was moving correctly using EFILIVE Scantool to activate the stepper motor during idle control. It seemed to be working fine but as I was re fitting it I noticed that the idle bypass drilling into the manifold side was very small, 5 mm in fact and yet the intake from the Atmo side was approx 12mm in diameter.

    mmmmmmmmmm I thought. Obviously the engine simply wasn't getting enough air on cold start and idle up. To prove this I set the throttle stop so the stepper motor was on ZERO steps and the car idled at 900rpm and sent the customer on his way to report back in the morning...
    Next morning I got the phone call at 8am, I had barely walked in the front door, " A PERFECT START THIS MORNING! " he said.
    Back into work he came and we drilled out the bypass to 12mm, the same as the inlet, and reset the TB stop so the stepper motor had 30 steps or so and tried it again in the morning.
    Perfect cold start again... GREAT!
    This solved the cold start problem but introduced several other idle issues often discussed elsewhere in these forums. These were easily tuned out with the EFILIVE software after a few trial and errors leaving the car idling like a stocker under all conditions.
    Caused a few grey hairs though

    Mike

  7. #7
    EFILive Crew Site Admin Tordne's Avatar
    Join Date
    Oct 2004
    Posts
    3,870

    Default

    Hey, another Kiwi. Cool
    Andrew
    EFILive Crew


  8. #8
    Lifetime Member oztracktuning's Avatar
    Join Date
    Nov 2005
    Posts
    596

    Default

    It seems to be getting better - will find out tommorrow when really cold again. What i did today after a disaster this morning was set the settings back to the way they were when idling good just before i put on the TB and then i added 13.77% to all the readings in B4403 and things seem to be alot better. Maybe its not the way - i read about this simple solution in another (competitors) forum !
    Oztrack
    EFILive Tuning Consultant

    Worldwide Remote Tuning Service

    2006 NSW Super Street Drag Racing Champion

    www.oztrack.com.au


  9. #9
    EFILive Reseller ringram's Avatar
    Join Date
    Oct 2005
    Posts
    1,411

    Default

    Yeah they are good for hack jobs. Read the real way to do it here

    Mine was a case of too much air. I had so much air initially that spark was down to 9 deg to slow the mother down. Of course it was shuddering like crazy. Slight throttle caused it to stall due to crap spark timing. Anyway it was fun to sort it out.

    I think I need a massive cam to tune now. Tordne get a TRex, it will be more fun!
    Get EFILive in europe (http://www.efilive.eu).
    2007 Escalade ESV L92 6.2L VVT.
    2014 VF SV LS3 Maloo.

  10. #10
    EFILive Crew Site Admin Tordne's Avatar
    Join Date
    Oct 2004
    Posts
    3,870

    Default

    Nah I think mind mind is made up on a FM13 on a 112+2. That will be enough fun
    Andrew
    EFILive Crew


Page 1 of 2 12 LastLast

Similar Threads

  1. Cold start perfect, Warm start flares high
    By samh_08 in forum Gen III V8 Specific
    Replies: 1
    Last Post: May 12th, 2009, 08:36 PM
  2. Cold start great but warm start sucks."Idle
    By mvvette97 in forum Gen III V8 Specific
    Replies: 11
    Last Post: October 25th, 2008, 11:22 PM
  3. wont cold start
    By dlove in forum Gen III V8 Specific
    Replies: 5
    Last Post: October 21st, 2008, 12:30 PM
  4. Rich at cold start.
    By jorge in forum Gen III V8 Specific
    Replies: 0
    Last Post: August 9th, 2008, 03:55 AM
  5. Cold Start
    By pomona in forum General (Petrol, Gas, Ethanol)
    Replies: 5
    Last Post: April 28th, 2005, 06:11 PM

Posting Permissions

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