Notices
86-95 Trucks & 4Runners 2nd/3rd gen pickups, and 1st/2nd gen 4Runners with IFS

Bad AFM ?

Old 02-19-2019, 10:18 PM
  #1  
Registered User
Thread Starter
 
Join Date: Oct 2010
Location: Vegas
Posts: 114
Likes: 0
Received 0 Likes on 0 Posts
Unhappy Bad AFM ?

Been having a lean misfire once warmed up lately, does fine when cold... closed loop. Was advised to change AFM, figure after 30 years and 800k plus miles couldn't hurt, right ? Got the remanned unit today put it in, start it up and its missing belching black smoke ,,,,, WTF ? Even thru the CEL ! Swap the original back on, no smoke, CEL goes out on its own ! What am I missing. have another AFM coming in Thursday .
Blue 89 Runner is offline  
Old 02-20-2019, 01:27 AM
  #2  
Registered User
 
87-4runner's Avatar
 
Join Date: Mar 2012
Location: Oklahoma
Posts: 435
Received 43 Likes on 41 Posts
Advised to change the AFM ... why?
87-4runner is offline  
Old 02-20-2019, 01:30 AM
  #3  
Registered User
 
87-4runner's Avatar
 
Join Date: Mar 2012
Location: Oklahoma
Posts: 435
Received 43 Likes on 41 Posts
What are the symptoms of your miss... at idle, certain rpms coasting down hill and barely touching thre accelerator?
what engine 22re or 3vze

Last edited by 87-4runner; 02-20-2019 at 01:36 AM.
87-4runner is offline  
Old 02-20-2019, 05:15 AM
  #4  
Registered User
 
Paul22RE's Avatar
 
Join Date: Feb 2018
Location: NNJ
Posts: 200
Received 20 Likes on 16 Posts
I don't think they change the circuit board on remanned ones. I just ordered one since I had some dead spots on the restrictive strip on my orig one. Remanned one had more dead spots than mine so it is going back. Here is how you test you AFM: http://htftp.offroadsz.com/marinhake...33volumeai.pdf
Paul22RE is offline  
Old 02-20-2019, 05:18 AM
  #5  
Registered User
Thread Starter
 
Join Date: Oct 2010
Location: Vegas
Posts: 114
Likes: 0
Received 0 Likes on 0 Posts
Once warmed up and goes into open ? Loop. Coasting downhill it gets a barely noticible back fire once in a while, Does not throw a cel. On a 22 re , when cold it does not have the misfire, sounds nice and even out exhaust .
Blue 89 Runner is offline  
Old 02-20-2019, 05:24 AM
  #6  
Registered User
Thread Starter
 
Join Date: Oct 2010
Location: Vegas
Posts: 114
Likes: 0
Received 0 Likes on 0 Posts
A
lso, once warmed up it has the pop pop out the exhaust, can feel and hear it as well, cold nice and even
Blue 89 Runner is offline  
Old 02-20-2019, 05:38 AM
  #7  
Registered User
 
87-4runner's Avatar
 
Join Date: Mar 2012
Location: Oklahoma
Posts: 435
Received 43 Likes on 41 Posts
When was the last time you adjusted your valves?
87-4runner is offline  
Old 02-20-2019, 08:17 AM
  #8  
Registered User
Thread Starter
 
Join Date: Oct 2010
Location: Vegas
Posts: 114
Likes: 0
Received 0 Likes on 0 Posts
3000 miles ago when new head was installed
Blue 89 Runner is offline  
Old 02-24-2019, 09:09 AM
  #9  
Registered User
Thread Starter
 
Join Date: Oct 2010
Location: Vegas
Posts: 114
Likes: 0
Received 0 Likes on 0 Posts
Put second replacement on, runs better then it was. this one however has some kind of adjustment on it. original and first one did not, any ideas ?
Blue 89 Runner is offline  
Old 02-24-2019, 11:27 AM
  #10  
Registered User
 
wallytoo's Avatar
 
Join Date: May 2013
Location: nh
Posts: 843
Likes: 0
Received 35 Likes on 35 Posts
Originally Posted by 87-4runner View Post
what engine 22re or 3vze
sig says 22re
wallytoo is offline  
Old 03-04-2019, 04:29 PM
  #11  
Registered User
 
Join Date: Apr 2015
Posts: 68
Likes: 0
Received 2 Likes on 2 Posts
Idle control air valve would be my guess.
yota tay is offline  
Old 03-04-2019, 05:54 PM
  #12  
Registered User
Thread Starter
 
Join Date: Oct 2010
Location: Vegas
Posts: 114
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by 87-4runner View Post
What are the symptoms of your miss... at idle, certain rpms coasting down hill and barely touching thre accelerator?
what engine 22re or 3vze
Originally Posted by Blue 89 Runner View Post
Once warmed up and goes into open ? Loop. Coasting downhill it gets a barely noticible back fire once in a while, Does not throw a cel. On a 22 re , when cold it does not have the misfire, sounds nice and even out exhaust .
Seems like it is slightly getting worse.... IAC was changed out a while back due to not returning to low idle, could it cause the erratic misfire at idle somehow ?
Blue 89 Runner is offline  
Old 03-05-2019, 04:59 AM
  #13  
Registered User
 
Join Date: Apr 2015
Posts: 68
Likes: 0
Received 2 Likes on 2 Posts
Originally Posted by Blue 89 Runner View Post
Seems like it is slightly getting worse.... IAC was changed out a while back due to not returning to low idle, could it cause the erratic misfire at idle somehow ?
I would take it out and soak it in carb fluid and re-spec the tps.
yota tay is offline  
Old 03-05-2019, 10:39 AM
  #14  
Registered User
 
Kolton5543's Avatar
 
Join Date: Mar 2013
Location: Safford, AZ
Posts: 363
Likes: 0
Received 13 Likes on 13 Posts
Open loop is when the engine is cold and closed loop is when the engine is warm. Unplug the O2 sensor and see if it still has the same symptoms. Unplugging the O2 will force it into open loop and will determine if the problem is related to corrected fuel trims.
Kolton5543 is offline  
Old 03-05-2019, 12:20 PM
  #15  
Registered User
 
old87yota's Avatar
 
Join Date: Jun 2013
Location: Portland, Oregon, USA
Posts: 1,997
Received 121 Likes on 112 Posts
Oxygen sensors do wear out, so that is a good place to look.

Lets go back to the Air Flow Meter for a moment. I am unsure how much the AFM plays a role in the problem you are experiencing (there are many potential causes), but it would be good to know if the Air Flow Meter is working properly.

Do you have a multimeter and know how to use it?

If so, the Air Flow Meter can be electrically tested to make sure it works as it should.

Here is a good write up on testing the Air Flow Meter using the Factory procedure: http://www.4crawler.com/4x4/CheapTricks/AFM/index.shtml

old87yota is offline  
Old 03-05-2019, 05:05 PM
  #16  
Registered User
 
Join Date: Jul 2017
Location: West Texas
Posts: 107
Likes: 0
Received 3 Likes on 3 Posts
Check your intake tube between the AFM and throttle body for cracks or tears. Leaks can cause missing and rough running. It is a quick and easy check. Then test the AFM as old87yoda has recommended.
amamike91 is offline  
Old 03-12-2019, 03:55 PM
  #17  
Registered User
Thread Starter
 
Join Date: Oct 2010
Location: Vegas
Posts: 114
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Kolton5543 View Post
Open loop is when the engine is cold and closed loop is when the engine is warm. Unplug the O2 sensor and see if it still has the same symptoms. Unplugging the O2 will force it into open loop and will determine if the problem is related to corrected fuel trims.
Unplugged it and still acts the same... with the addition of the CEL of course. So, this tells me what now.... o2 sensor is good, correct ?
Blue 89 Runner is offline  
Old 03-12-2019, 04:30 PM
  #18  
Registered User
 
Join Date: Apr 2015
Posts: 68
Likes: 0
Received 2 Likes on 2 Posts
Originally Posted by Blue 89 Runner View Post
Unplugged it and still acts the same... with the addition of the CEL of course. So, this tells me what now.... o2 sensor is good, correct ?
Yep.

Check the iacv and both coolant sensors and make sure they are functioning properly. If you're having a cold loop hot loop problem that's where I would start.
yota tay is offline  
Old 03-12-2019, 04:42 PM
  #19  
Registered User
Thread Starter
 
Join Date: Oct 2010
Location: Vegas
Posts: 114
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by yota tay View Post
Yep.

Check the iacv and both coolant sensors and make sure they are functioning properly. If you're having a cold loop hot loop problem that's where I would start.
All the IACV does on these is speed up the idle when cold, correct? What is the proper method for testing these. Packed up repair manual in storage till I get moved , TIA
Blue 89 Runner is offline  
Old 03-12-2019, 04:49 PM
  #20  
Registered User
 
Join Date: Apr 2015
Posts: 68
Likes: 0
Received 2 Likes on 2 Posts
Originally Posted by Blue 89 Runner View Post
All the IACV does on these is speed up the idle when cold, correct? What is the proper method for testing these. Packed up repair manual in storage till I get moved , TIA
Something like that. But if stays stuck in the open position it messes with idle. Take it off and put in boiling water and verify mechanism is opening and closing. Also check the green coolant sensor. It tells the cpu info for the loops.
yota tay is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
PapaChulos4U
86-95 Trucks & 4Runners
7
09-02-2014 06:48 AM
KODE
86-95 Trucks & 4Runners
1
05-07-2012 12:22 PM
Beefy_heafy
Staging Area For Tech Article Submissions
0
09-19-2011 12:30 AM
Kyle95sr5
86-95 Trucks & 4Runners
1
01-19-2006 01:54 PM


Thread Tools
Search this Thread
Quick Reply: Bad AFM ?


Contact 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.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: