Notices
Engine & Drivetrain VQ Power and Delivery

Idle AFR slowly drops to 10.5 while warming up

Thread Tools
 
Search this Thread
 
Old 07-14-2018, 07:41 PM
  #1  
Faasnu
New Member
Thread Starter
 
Faasnu's Avatar
 
Join Date: Aug 2016
Location: WA
Posts: 51
Received 0 Likes on 0 Posts
Default Idle AFR slowly drops to 10.5 while warming up

When starting my car, the idle AFR is at 14.7, but as it warms up, it slowly drops until it reaches 10.5.

I noticed both the upstream O2 sensors were always reading 0.01V at idle so I replaced both of them. The car still runs rich and the O2 sensors still read 0.01V.

I tried:

Cleaning the throttle body
Cleaning the MAF sensor
Checking the PCV valve
Idling with the air filter off

The spark plugs and ignition coils are only a year old.

I also tried idling with the PCV hose disconnected to introduce a vacuum leak. The idle afr went to 14.7 and the rpm jumped to about 1200.

This issue just came up while driving and will try to bog the engine down to 400 rpm when at a stop in drive so I need to give it gas so the car doesn't shut off.

This happened a day after I fixed my transmission slipping issue:
https://my350z.com/forum/2003-2009-n...-slipping.html

I don't see any way it could be related but this issue did happen a day after fixing the transmission issue.

I noticed my vacuum at idle in drive is reading at 13.7hg with an OBD scanner and 17hg on my boost gauge.

Last edited by Faasnu; 07-15-2018 at 04:19 PM.
Old 07-15-2018, 04:20 PM
  #2  
Faasnu
New Member
Thread Starter
 
Faasnu's Avatar
 
Join Date: Aug 2016
Location: WA
Posts: 51
Received 0 Likes on 0 Posts
Default

I bypassed the supercharger and idle afr went to normal so it seems like a blow off valve issue

Edit:

Took off blow off valve, issue still present

Last edited by Faasnu; 07-15-2018 at 05:51 PM.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
StuNyce
Maintenance & Repair
7
07-13-2023 04:04 AM
05SickSer
Forced Induction
50
08-25-2012 01:34 PM
m808six
Maintenance & Repair
8
08-31-2011 03:56 PM
ZKansasZ
Maintenance & Repair
9
03-26-2010 06:23 PM
Cloud
Engine & Drivetrain
2
06-20-2007 10:45 AM



Quick Reply: Idle AFR slowly drops to 10.5 while warming up



All times are GMT -8. The time now is 08:37 AM.