bounceing idle issue - Forums at Modded Mustangs
 1Likes
  • 1 Post By Eagle2000GT
 
LinkBack Thread Tools
post #1 of 10 Old February 26th, 2017, 12:47 PM Thread Starter
Newbie
 
Join Date: Dec 2016
Posts: 8
 
iTrader: 0 reviews
bounceing idle issue

got a issue that started back a couple months ago, been trying to figure it out, here's what ive done so far , replaced maf, iac oxygen sensors ,coils, and new accell injectors, fixed a vacuum leak on egr valve gasket yesterday but still have the issue , when i get in car after it sets for more than a hour and crank it up idles fine other that the rpms tend to hang a bit seems like , but anyway when i go to put the car in reverse and pull out of yard the rpms start to bounce way up to like 1500 then down to like 500 ,if i dont get on the gas pretty quick it stalls ,yesterday it did this and stalled and was kinda yard to restart , starting to think it may be fuel pump failing ?

---------- Post added at 11:47 AM ---------- Previous post was at 11:44 AM ----------

also replaced fuel filter
Vann Penny is offline  
Sponsored Links
Advertisement
 
post #2 of 10 Old February 27th, 2017, 02:50 AM
US Air Force (retired)
 
Eagle2000GT's Avatar
 
Join Date: Aug 2007
Location: Indiana
Posts: 13,461
                     
Garage
iTrader: 1 reviews
If I read that correctly, with the motor cold it idles OK in high idle (1100-1200 rpm) until you apply a load (put it in gear) then the idle drops to 500 rpm and stalls if you do not work the gas. I believe you said you replaced the IAC. Did you adjust the TB butterfly valve?

New TBs and even old TB with some wear and tear need to be adjusted. The IAC requires a certain amount of by-pass air in order to work properly. If the butterfly valve closes too tight then the IAC doesn't have enough time to react to changing idle conditions and the car will die.

ProCharger P-1SC, 9 psi, STD 396/383; Uncorrected 388/375; SAE 383/370.
Ret. USAF 1969-1973,1980-1996: Vietnam veteran. Aircraft maintenance. R & D, ICBM Operations.
Also own: 1997 Harley FXDWG, 1998 F-150, and 2002 Corvette LS1
Eagle2000GT is offline  
post #3 of 10 Old February 27th, 2017, 11:00 PM Thread Starter
Newbie
 
Join Date: Dec 2016
Posts: 8
 
iTrader: 0 reviews
yeah right now the idle is kinda high itll stay at like 1500 rpms or so when cold then drops down to maybe 900 rpms bama tuneing guy said my idle duty cycle needed to be at 0.35 , its currently at like 0.25 ,only way i can get it to hold a 0.35 value is to lower the idle but when i did that even after a idle relearn , it wants to lung foward hard when put in gear its a auto
Vann Penny is offline  
Sponsored Links
Advertisement
 
post #4 of 10 Old February 27th, 2017, 11:07 PM Thread Starter
Newbie
 
Join Date: Dec 2016
Posts: 8
 
iTrader: 0 reviews
the idle speed valve duty cycle i mean >>bounceing idle issue-2017-02-27.jpg
Vann Penny is offline  
post #5 of 10 Old February 27th, 2017, 11:12 PM Thread Starter
Newbie
 
Join Date: Dec 2016
Posts: 8
 
iTrader: 0 reviews
bounceing idle issue-2017-02-27.jpg
Vann Penny is offline  
post #6 of 10 Old February 27th, 2017, 11:19 PM
US Air Force (retired)
 
Eagle2000GT's Avatar
 
Join Date: Aug 2007
Location: Indiana
Posts: 13,461
                     
Garage
iTrader: 1 reviews
Hell, I don't know data logs. If the car runs good then OK. What I know is that I adjusted the throttle body stop screw and it fixed my problem. If you wish to investigate further then that is up to you but I've been a member of this forum a long, long time. Adjusting the set screw has fixed a lot of problems.
Vann Penny likes this.

ProCharger P-1SC, 9 psi, STD 396/383; Uncorrected 388/375; SAE 383/370.
Ret. USAF 1969-1973,1980-1996: Vietnam veteran. Aircraft maintenance. R & D, ICBM Operations.
Also own: 1997 Harley FXDWG, 1998 F-150, and 2002 Corvette LS1
Eagle2000GT is offline  
post #7 of 10 Old February 28th, 2017, 07:31 AM
1C2
Regular
 
1C2's Avatar
 
Join Date: Jun 2016
Location: Sonora CA
Posts: 270
 
iTrader: 0 reviews
Does your gas pedal kinda stick at first when you press it?

91 GMC Syclone
95 Taurus SHO mtx
99 Mustang GT-Sold
94 Probe GT
03 Mustang GT
1C2 is offline  
post #8 of 10 Old February 28th, 2017, 07:36 AM
6 Cylinduh, Really Bruh?
 
TheOdessa's Avatar
 
Join Date: Jun 2011
Location: Tampa, Florida
Posts: 5,215
           
iTrader: 4 reviews
Lol eagle. It's the way of the future man!

Hell I can't read them either. I go the old school route
TheOdessa is offline  
post #9 of 10 Old February 28th, 2017, 08:50 PM Thread Starter
Newbie
 
Join Date: Dec 2016
Posts: 8
 
iTrader: 0 reviews
yeah i think setting the tb screw will solve the issue also ,from what i hear theres a sweet spot for them, like i said its kinda of a high idle, but in gear its a low idle, also theres a pattern to it when it does it ,maybe 3 times itll rev up and down and about third time it stalls out

---------- Post added at 07:50 PM ---------- Previous post was at 07:47 PM ----------

also the dataloggs are pretty simple to read ,i just pay attention to the values and tells me alot, had a issue not to long ago after header's installed , one of the up stream o2's was bad and the live data really helped alot! noticed one had no value at all and was like yeah that 1's shot and sure enough was!
Vann Penny is offline  
post #10 of 10 Old March 1st, 2017, 12:04 AM Thread Starter
Newbie
 
Join Date: Dec 2016
Posts: 8
 
iTrader: 0 reviews
correct me if i wrong ,but shouldnt my tps volts be at aleast 1.00 or tad lower on the 4.6 2v? and not 1.12
Vann Penny is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Forums at Modded Mustangs forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome