|
Software Tuning Discuss all software tuning topics. |
|
Thread Tools | Search this Thread |
03-27-2019, 04:28 PM | #1 |
Junior Member
Join Date: Mar 2019
Drives: 2014 Scion FR-S
Location: Riverside ca
Posts: 6
Thanks: 0
Thanked 0 Times in 0 Posts
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
|
short term fuel trims high at idle and and partial throttle
Hi all I recently installed a Jackson racing supercharger kit on my car and a delicious flash and go tune. I have borla uel headers, and am experiencing high stft at idle and partial throttle especially on start up. they start to trend lower to around 8-12 after driving for awhile but are still positive. I have checked the pcv valve, the map sensor orientation and don't believe I have an exhaust leak as I used 2 grimspeed gaskets where the header meets the engine. I am stumped and I cannot get my tune dialed in until I figure this out thanks. its worth noting that the idle and driving feels fine maybe a little on the high side for idle around 900. otherwise the car drives great, id appreciate any ideas or feedback on what went wrong.
|
03-27-2019, 04:38 PM | #2 |
Senior Member
Join Date: Jul 2014
Drives: 14 BSP Edelbrock BRZ
Location: Lon Gisland
Posts: 806
Thanks: 113
Thanked 450 Times in 256 Posts
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
|
A small intake leak will be about 15% STFT, a large one will max it at 29.7 and the car will run like shit.
I've never done a Jackson install but if you went into boost I would make sure the cap and the hose under the throttle body are still attached. Other places beside PCV would be the block nipple under the AC compressor. |
03-27-2019, 04:41 PM | #3 |
Junior Member
Join Date: Mar 2019
Drives: 2014 Scion FR-S
Location: Riverside ca
Posts: 6
Thanks: 0
Thanked 0 Times in 0 Posts
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
|
thank you for the suggestion I will check those out, is it possible that if the tne he sent me doesn't account for my catless headers it could cause me to run lean at idle?
|
03-28-2019, 01:11 AM | #4 |
Banned
Join Date: Dec 2013
Drives: FT86
Location: Australia
Posts: 7,998
Thanks: 1,035
Thanked 4,987 Times in 2,981 Posts
Mentioned: 598 Post(s)
Tagged: 2 Thread(s)
|
Also check idle vaccuum.
Engine off manifold pressure should ve 1 bar ie atmospheric Engine idle should be about 0.3 to 0.4 bar if its closer to 1 bar you likely have intake leak or bov leak |
03-28-2019, 01:55 AM | #5 |
Senior Member
Join Date: Jul 2018
Drives: 2017 Toyota 86
Location: CA, USA
Posts: 231
Thanks: 21
Thanked 33 Times in 29 Posts
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
|
Idle vacuum should be like -10 psi right? If it's sometimes weaker, like at -7 psi, is that normal?
|
03-28-2019, 05:53 AM | #6 |
Banned
Join Date: Dec 2013
Drives: FT86
Location: Australia
Posts: 7,998
Thanks: 1,035
Thanked 4,987 Times in 2,981 Posts
Mentioned: 598 Post(s)
Tagged: 2 Thread(s)
|
|
|
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Extremely jumpy short term fuel trims all of a sudden | silverbullet | Software Tuning | 5 | 02-17-2016 04:31 PM |
Sudden high fuel trims - help please! | cawith | Issues | Warranty | Recalls / TSB | 13 | 10-15-2015 04:30 PM |
Negative Short term fuel trims at idle w/ no obvi leak | IBill4You | Forced Induction | 21 | 05-29-2015 09:49 AM |
Fuel Trims - Long term and short term | victorb | Engine, Exhaust, Transmission | 6 | 03-27-2013 02:18 PM |
Short Term and Long Term Fuel Trims | naikaidriver | Engine, Exhaust, Transmission | 3 | 03-18-2013 09:55 PM |