Bringing TBI and Multi Port Fuel Injection to a New Level.     EFI Conversions and Tuning! Seattle to Portland! E-mail Tuning Consultant!
Page 1 of 2 12 LastLast
Results 1 to 15 of 28

Thread: TBI with High Idle in PARK

  1. #1
    Electronic Ignition!
    Join Date
    Jul 2019
    Location
    Gilbert, AZ
    Age
    50
    Posts
    12

    TBI with High Idle in PARK

    Hi folks I'm working on a TBI to Vortec (L-31) conversion into an 1983 Chevy K10 and it seems that the tuner I'm working with is having a hard time get the idle down when the truck is in park. I'm hoping someone has some suggestion as I have tried everything and the only way I can get it to idle slower in park is to jumper the A&B pin and force the IAC closed then unplug it and adjust the throttle blades open and she idles nicely at 700 rpms. I have followed the base idle setup procedure but as soon as I plug the IAC back in it opens up and the Idle goes to 850... The tuner tells me the target idle is set at 600rpms in the chip but it just doesn't get there. Now a bit of history on the truck! it started it life as a 6.2 diesel and when I purchased the truck the guy told me he purchased a wrecked 1987 with a TBI and moved all the components over to the 1983... in all fairness it looked as though he did a great job, everything was nicely done..... but even with previous motor and a different tuner the truck idled high in park. With the new GE crate L-31 I replaced about everything except wiring! could it be a wiring issue with P/N switch? Or a tuning issue? The BLM's are running about 117 in Park...... I'll try to attach the Tunerpro log but currently its not working. Thanks Much
    Last edited by JJK10; 07-25-2019 at 07:45 AM. Reason: Trying to attach data log

  2. #2
    Fuel Injected! PlayingWithTBI's Avatar
    Join Date
    Dec 2018
    Age
    66
    Posts
    136
    Check your grounds to D1 and A12. On one of the electrical service manuals (can't remember which one) for a GMT400 truck it said high idle can result due to a bad ground there.

    http://www.gearhead-efi.com/gearhead...ng/747ecm1.jpg

  3. #3
    Fuel Injected! brian617's Avatar
    Join Date
    Apr 2013
    Location
    Arkansas
    Age
    40
    Posts
    589
    What is your IAC value when this occurs?
    89 K1500 Scottsdale 5.7L 5spd 3:42

    Build specs: 97 4 bolt main block 350ci, Eagle rotating assembly with flat tops and 4 valve reliefs, Dart 165cc/67cc Iron Eagle heads, Manely SS valves and springs 110lbs seat @1.7, GM Ram Jet cam 196/206 @.50 .431/.451, stock intake and throttle body, heads and intake gasket matched, Delco EP377 fuel pump @ 22 psi, 427 PCM.

  4. #4
    Electronic Ignition!
    Join Date
    Jul 2019
    Location
    Gilbert, AZ
    Age
    50
    Posts
    12
    44 in closed loop... engine temp about 200. Thanks, Jason

  5. #5
    Fuel Injected! sturgillbd's Avatar
    Join Date
    Jun 2012
    Location
    Big Stone Gap, VA
    Age
    45
    Posts
    475
    Do you have any error codes stored? 7747 idle logic isn't as good as the later PCM's. On the 7427, if you don't have a VSS connected, it will do the same thing. You have to disable the error code for the VSS and the problem goes away. You may try that and see if it helps the high idle.

  6. #6
    Fuel Injected!
    Join Date
    Apr 2017
    Posts
    72
    700 seems high for base idle to me. I aim for around 500-550 when I set that, Should be lower than target idle, not higher. If it’s higher, ECM will be trying to lower rpm with the IAC, but it can’t. And I think you can actually damage the IAC that way. But I might be misreading your post on this....

    Another thing to look at in the tune... there’s a setting for IAC differential between neutral/park and drive. Perhaps that is set wrong, i.e. it doesn’t drop it enough when you go to park.

  7. #7
    Fuel Injected! brian617's Avatar
    Join Date
    Apr 2013
    Location
    Arkansas
    Age
    40
    Posts
    589
    What is your TPS voltage at idle?
    89 K1500 Scottsdale 5.7L 5spd 3:42

    Build specs: 97 4 bolt main block 350ci, Eagle rotating assembly with flat tops and 4 valve reliefs, Dart 165cc/67cc Iron Eagle heads, Manely SS valves and springs 110lbs seat @1.7, GM Ram Jet cam 196/206 @.50 .431/.451, stock intake and throttle body, heads and intake gasket matched, Delco EP377 fuel pump @ 22 psi, 427 PCM.

  8. #8
    Electronic Ignition!
    Join Date
    Jul 2019
    Location
    Gilbert, AZ
    Age
    50
    Posts
    12
    Quote Originally Posted by PlayingWithTBI View Post
    Check your grounds to D1 and A12. On one of the electrical service manuals (can't remember which one) for a GMT400 truck it said high idle can result due to a bad ground there.

    http://www.gearhead-efi.com/gearhead...ng/747ecm1.jpg
    Thank you... I will double check the grounds

  9. #9
    Electronic Ignition!
    Join Date
    Jul 2019
    Location
    Gilbert, AZ
    Age
    50
    Posts
    12
    Quote Originally Posted by Daveo91 View Post
    700 seems high for base idle to me. I aim for around 500-550 when I set that, Should be lower than target idle, not higher. If it’s higher, ECM will be trying to lower rpm with the IAC, but it can’t. And I think you can actually damage the IAC that way. But I might be misreading your post on this....
    With the ODB1 jumped and the IAC forced closed I set the idle on the throttle blades at about 525..

    Another thing to look at in the tune... there’s a setting for IAC differential between neutral/park and drive. Perhaps that is set wrong, i.e. it doesn’t drop it enough when you go to park.
    You could be on to something! but I have no ability to check that... Thanks much for the input!
    Last edited by JJK10; 07-26-2019 at 06:06 AM.

  10. #10
    Electronic Ignition!
    Join Date
    Jul 2019
    Location
    Gilbert, AZ
    Age
    50
    Posts
    12
    Quote Originally Posted by brian617 View Post
    What is your TPS voltage at idle?
    about .9 with the RPM at 825 and a BLM of 115 when I first put it in park after a long drive.... IAC count 44

  11. #11
    Super Moderator dave w's Avatar
    Join Date
    Feb 2011
    Posts
    4,162
    Maybe the information in this link will be helpful: http://www.gmcmidwestclassics.org/We...0the%20TBI.pdf

    dave w
    Attached Files Attached Files

  12. #12
    Electronic Ignition!
    Join Date
    Jul 2019
    Location
    Gilbert, AZ
    Age
    50
    Posts
    12
    Quote Originally Posted by dave w View Post
    Maybe the information in this link will be helpful: http://www.gmcmidwestclassics.org/We...0the%20TBI.pdf

    dave w
    Yes Sir! that's the direction I followed. it just idles up once you plug the IAC back in. Thanks

  13. #13
    Fuel Injected! brian617's Avatar
    Join Date
    Apr 2013
    Location
    Arkansas
    Age
    40
    Posts
    589
    Quote Originally Posted by JJK10 View Post
    about .9 with the RPM at 825 and a BLM of 115 when I first put it in park after a long drive.... IAC count 44
    Try adjusting the voltage down to somewhere between .50 and .65
    89 K1500 Scottsdale 5.7L 5spd 3:42

    Build specs: 97 4 bolt main block 350ci, Eagle rotating assembly with flat tops and 4 valve reliefs, Dart 165cc/67cc Iron Eagle heads, Manely SS valves and springs 110lbs seat @1.7, GM Ram Jet cam 196/206 @.50 .431/.451, stock intake and throttle body, heads and intake gasket matched, Delco EP377 fuel pump @ 22 psi, 427 PCM.

  14. #14
    Fuel Injected!
    Join Date
    Jan 2017
    Posts
    223
    In post #1 you said tuner set idle target to 600 rpms. As already mentioned twice, You need to set minimum idle 125 rpms below 600 rpms.

  15. #15
    Electronic Ignition!
    Join Date
    Jul 2019
    Location
    Gilbert, AZ
    Age
    50
    Posts
    12
    Quote Originally Posted by brian617 View Post
    Try adjusting the voltage down to somewhere between .50 and .65
    I'm sorry I missed up the Absolute pressure volts is .9 the TPS is .55... Thanks

Similar Threads

  1. LT1 High Idle
    By ReidB in forum GM EFI Systems
    Replies: 27
    Last Post: 09-25-2016, 07:00 PM
  2. Looking for cause of high idle in Datalog
    By sgtbilkodle in forum GM EFI Systems
    Replies: 6
    Last Post: 02-08-2015, 05:57 PM
  3. Park idle rich, in gear at same rpm/map not
    By TheApocalyptican in forum GM EFI Systems
    Replies: 12
    Last Post: 04-09-2013, 07:36 PM
  4. Replies: 3
    Last Post: 09-19-2012, 05:09 PM
  5. Trouble with idle speed in park
    By srobertsfsj in forum GM EFI Systems
    Replies: 80
    Last Post: 09-05-2012, 09:09 AM

Bookmarks

Posting Permissions

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