Notices
EcuFlash

Idle Surging.

 
Old Feb 11, 2008, 09:40 PM
  #1  
Evolved Member
Thread Starter
iTrader: (30)
 
Inprogress's Avatar
 
Join Date: Jun 2004
Location: Houston, TX
Posts: 1,947
Likes: 0
Received 0 Likes on 0 Posts
Idle Surging.

Everytime I start slowing down to come to a stop and put the car in neutral and start braking, the RPMS surge. they'll fall to where they should be initially, but then they'll surge to 1500-1650 and come down to 1100-1200 rpm then bounce back once more before eventually stabilizing.

Why would this be happening? I initially thought it was because of the cold weather but it was 75*F today and it still did it.

Also to note, I did do a 25psi boost leak test today and am still getting the same problems. Also, I am having very rich idling, around 10.9-12.0. I don't understand how this could be happening, my tune is fine and the idle tables are fine too.

Could it be me idle air control on its last legs? I really don't want to buy one as a) it's expensive b) if I end up not needing it I can't even return it

Any suggestions?
Inprogress is offline  
Old Feb 11, 2008, 10:25 PM
  #2  
EvoM Guru
iTrader: (6)
 
Join Date: Feb 2007
Location: Melbourne, Australia
Posts: 9,486
Received 57 Likes on 38 Posts
what are your fuel trims like?

if you fixed a boost/vacuum leak then you fuel trims would be way out...

anyways if your fuel trims are way out then reset the ecu and see if that fixes your rich idle..
tephra is offline  
Old Feb 11, 2008, 10:31 PM
  #3  
Newbie
iTrader: (5)
 
bigturboevo8's Avatar
 
Join Date: Jan 2008
Location: COLD
Posts: 66
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by tephra View Post
what are your fuel trims like?

if you fixed a boost/vacuum leak then you fuel trims would be way out...

anyways if your fuel trims are way out then reset the ecu and see if that fixes your rich idle..
+1
bigturboevo8 is offline  
Old Feb 11, 2008, 10:35 PM
  #4  
Evolved Member
Thread Starter
iTrader: (30)
 
Inprogress's Avatar
 
Join Date: Jun 2004
Location: Houston, TX
Posts: 1,947
Likes: 0
Received 0 Likes on 0 Posts
Well since we did the boost leak, we disconnected the battery afterwards anyways (since we disconnected the MAF and had the car on to power the boost gauge to watch it)

Anything else?

Thanks for the input!
Inprogress is offline  
Old Feb 13, 2008, 09:56 AM
  #5  
Newbie
iTrader: (1)
 
fas-n-furyus's Avatar
 
Join Date: Dec 2006
Location: in my car
Posts: 63
Likes: 0
Received 0 Likes on 0 Posts
If the car was running ok before, i would assume that maybe one of your sensors are not working properly. The sensor is probably is back a voltage signal thats not correct.

Example: your car is warmed up but your coolant temp sensor is still showing that the car is cold. thus no check light since there is feed back from the sensor.

sensors that affect AFR are:
- oxygen sensor
- coolant temperature sensor
- air temperature sensor which is part of the MAF

Monitor your sensor readings and see if any are out or acting weird

also check to see if the vacuum that the car pulls at idle is the same or if it has dropped off. if its low make sure your timing is ok or maybe you have hurt your engine
fas-n-furyus is offline  
Old Feb 13, 2008, 10:40 AM
  #6  
Evolved Member
Thread Starter
iTrader: (30)
 
Inprogress's Avatar
 
Join Date: Jun 2004
Location: Houston, TX
Posts: 1,947
Likes: 0
Received 0 Likes on 0 Posts
I've had a bad o2 in my STI before and it's easily noticeable and the car drives like ***, but this isn't the case. While coming to a stop as soon as I put my car into neutral (it's still coasting) it'll go extremely rich until it finds its way and will then idle between 13.5-15.4

Sometimes it'll struggle and dip to around 600-700 rpm and go real, real lean, but most of the time it's just rich, like when the idle rpms start to come up it'll start getting rich then fall back to where it should.

The vacuum is the same, the car still makes good power and everything it's just the idle. It's not eating oil or losing oil for that matter.
Inprogress is offline  
Old Feb 13, 2008, 12:40 PM
  #7  
Evolved Member
iTrader: (4)
 
bnice01's Avatar
 
Join Date: May 2007
Location: Hurlburt Field, FL
Posts: 688
Likes: 0
Received 0 Likes on 0 Posts
Sounds like your maf is bad, try switching with some else. Like everyone else said post up a log of your fuel trims @ idle and cruise. For idle your going to select low fuel trim and cruise select mid fuel trim, also make sure to select o2 feedback as well for both trims. I found using mitsulogger the best for logging fuel trims.
bnice01 is offline  
Old Feb 13, 2008, 12:46 PM
  #8  
Evolved Member
Thread Starter
iTrader: (30)
 
Inprogress's Avatar
 
Join Date: Jun 2004
Location: Houston, TX
Posts: 1,947
Likes: 0
Received 0 Likes on 0 Posts
I just had the MAF cleaned yesterday. I'll make some logs at idle and cruise soon and post them.
Inprogress is offline  
Old Feb 13, 2008, 01:53 PM
  #9  
Evolved Member
iTrader: (4)
 
bnice01's Avatar
 
Join Date: May 2007
Location: Hurlburt Field, FL
Posts: 688
Likes: 0
Received 0 Likes on 0 Posts
make sure you give it some time when you log trims. I say about 5min for idle and 10 min for cruise.
bnice01 is offline  
Old Feb 13, 2008, 01:58 PM
  #10  
Evolved Member
Thread Starter
iTrader: (30)
 
Inprogress's Avatar
 
Join Date: Jun 2004
Location: Houston, TX
Posts: 1,947
Likes: 0
Received 0 Likes on 0 Posts
Like 5 min after I turn the car on or 5 min of logging?
Inprogress is offline  
Old Feb 13, 2008, 02:37 PM
  #11  
Evolved Member
iTrader: (4)
 
bnice01's Avatar
 
Join Date: May 2007
Location: Hurlburt Field, FL
Posts: 688
Likes: 0
Received 0 Likes on 0 Posts
5 min after logging I would do 10 min on both idle and cruise to get good #'s. Fuel trims cycle every 4 mins.
bnice01 is offline  
Old Feb 13, 2008, 02:39 PM
  #12  
EvoM Guru
iTrader: (6)
 
Join Date: Feb 2007
Location: Melbourne, Australia
Posts: 9,486
Received 57 Likes on 38 Posts
so you cleaned it and then your car started acting up or vice-versa?

basically if you are getting funny lean/rich conditions at idle (when warmed up) then it can only be a few things, o2/maf/injector scalings/fuel filter?
tephra is offline  
Old Feb 13, 2008, 02:47 PM
  #13  
Evolving Member
iTrader: (2)
 
spdracr's Avatar
 
Join Date: Feb 2006
Location: LA
Posts: 495
Likes: 0
Received 0 Likes on 0 Posts
i had a similar problem a while ago but i changed my tune and it went away lol idk wat i changed but it fixed itself i guess
spdracr is offline  
Old Feb 13, 2008, 03:07 PM
  #14  
Evolved Member
Thread Starter
iTrader: (30)
 
Inprogress's Avatar
 
Join Date: Jun 2004
Location: Houston, TX
Posts: 1,947
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by tephra View Post
so you cleaned it and then your car started acting up or vice-versa?

basically if you are getting funny lean/rich conditions at idle (when warmed up) then it can only be a few things, o2/maf/injector scalings/fuel filter?
No, I cleaned the MAF after it started acting funny in hopes of curing it. I don't think it's injector scalings because it's been left un-touched as I'm on the stock injectors. Fuel filter is interesting, how often should the be changed? And as for the o2, wouldn't more severe symptoms show up if it were on its way out or already out?

Thanks for all the help everyone!
Inprogress is offline  
Old Feb 13, 2008, 03:09 PM
  #15  
Evolving Member
iTrader: (2)
 
spdracr's Avatar
 
Join Date: Feb 2006
Location: LA
Posts: 495
Likes: 0
Received 0 Likes on 0 Posts
i'm at 52k and i've never changed my fuel filter lol infact i havent even seen it lol someone wanna touch on where it is for op and myself
spdracr is offline  

Thread Tools
Search this Thread
Quick Reply: Idle Surging.


Contact Us - About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.