WELCOME!
   

Go Back   PY Online Forums - Bringing the Pontiac Hobby Together > Classic TECH- specs, codes, resto issues FORUMS > General Late Model Tech

General Late Model Tech All LM technical discussions except GTO, G8 and TA here!

Reply
 
Thread Tools Display Modes
  #1  
Old 02-27-2022, 06:29 PM
jamaca85 jamaca85 is offline
Ultimate Warrior
 
Join Date: May 2004
Location: nampa id
Posts: 1,088
Default Idle problems in 5.0 99 ford

So I seem to have an idling problem in my 5.0 when the motor starts up motor starts shaking like it's missing but it clears up after 12 1300 RPMs and you give it gas but when it comes back down to idle it starts sputtering and trying to stall again we have changed everything from EGR valves cam sensors checked every fuel injector did voltage readings on everything compression check and it still has the same problem . We also checked the fuel pressure fuel filters and everything is okay
__________________
1970 firebird, 468, e heads,

Last edited by jamaca85; 02-27-2022 at 06:36 PM.
Reply With Quote
  #2  
Old 02-27-2022, 06:43 PM
HoovDaddy's Avatar
HoovDaddy HoovDaddy is offline
Senior Chief
 
Join Date: Jan 2022
Location: Michigan
Posts: 271
Default

Vacuum leak?
Reply With Quote
  #3  
Old 02-27-2022, 06:47 PM
jamaca85 jamaca85 is offline
Ultimate Warrior
 
Join Date: May 2004
Location: nampa id
Posts: 1,088
Default

We already covered that no vacuum leaks actually replaced all the vacuum lines on the motor but thanks
__________________
1970 firebird, 468, e heads,
Reply With Quote
  #4  
Old 02-27-2022, 07:09 PM
ID67goat's Avatar
ID67goat ID67goat is offline
Senior Chief
 
Join Date: Nov 2007
Posts: 410
Default

Wasn’t the last year for 5.0 in 95?

A couple ideas…. have you verified your timing? Have you checked the idle air bypass valve for proper operation? They can get plugged up. Also mass airflow meter can have issues….
Reply With Quote
  #5  
Old 02-27-2022, 07:47 PM
jamaca85 jamaca85 is offline
Ultimate Warrior
 
Join Date: May 2004
Location: nampa id
Posts: 1,088
Default

yes we have checked both..the idle valve is working and not plugged, mass air sensor has been replaced...thats whats so weird about it. we have gone from gas tank to injectors still has the issue. ran fine till he parked it for a week then issue started. the odd thing is it hasnt thrown no codes
__________________
1970 firebird, 468, e heads,
Reply With Quote
  #6  
Old 02-28-2022, 01:49 PM
FrankieT/A's Avatar
FrankieT/A FrankieT/A is offline
Ultimate Warrior
 
Join Date: Jun 2011
Location: USA
Posts: 2,556
Default

Did you replace the battery or disconnect it recently? If so it may need to relearn the idle strategy and may require about 20 key starts.
__________________
1978 Black & Gold T/A [complete 70 Ram Air III (carb to pan) PQ and 12 bolt], fully loaded, deluxe, WS6, T-Top car - 1972 Formula 455HO Ram Air numbers matching Julep Green - 1971 T/A 455, 320 CFM Eheads, RP cam, Doug's headers, Fuel injection, TKX 5 Spd. 12 Bolt 3.73, 4 wheel disc. All A/C cars
Reply With Quote
  #7  
Old 03-01-2022, 07:45 PM
jamaca85 jamaca85 is offline
Ultimate Warrior
 
Join Date: May 2004
Location: nampa id
Posts: 1,088
Default

thanks i will ask him
__________________
1970 firebird, 468, e heads,
Reply With Quote
  #8  
Old 03-01-2022, 08:51 PM
jamaca85 jamaca85 is offline
Ultimate Warrior
 
Join Date: May 2004
Location: nampa id
Posts: 1,088
Default

Yeah I'm hoping that somebody has run into this issue with the same symptoms with with no check engine light and has solved it
__________________
1970 firebird, 468, e heads,
Reply With Quote
  #9  
Old 03-01-2022, 10:11 PM
Jay S's Avatar
Jay S Jay S is offline
Ultimate Warrior
 
Join Date: May 2018
Location: Nebraska City, Nebraska
Posts: 1,660
Default

That is a pretty common problem on fords that era. Been a while since I worked on those but if I recall correct the issue is up by the throttle body at the AIC. It requires disassembly and cleaning. There should be how to videos on you tube. Look up Ford idle air control valve. It causes a big dead spot coming off idle if it doesn’t work or is slow. If it is bad a check engine light will come on. If it is gummed up and slow the check engine light will likely not come on.

Last edited by Jay S; 03-01-2022 at 10:21 PM.
Reply With Quote
The Following 2 Users Say Thank You to Jay S For This Useful Post:
  #10  
Old 05-25-2022, 06:41 PM
necdb3's Avatar
necdb3 necdb3 is offline
Ultimate Warrior
 
Join Date: Jul 2004
Location: Mt. Laurel NJ, now Melbourne, FL
Posts: 1,369
Default

Stupid question, is there a K&N filter on there? The reason I ask, I worked at a Ford dealer for years and the open K&N filters would disturb the MAF sensor because of the turbulence from the radiator fan. If there is, try installing the factory filter box and see if it corrects the issue. You could put cardboard to block the wind turbulence to test it.
Reply With Quote
  #11  
Old 06-01-2022, 08:24 AM
necdb3's Avatar
necdb3 necdb3 is offline
Ultimate Warrior
 
Join Date: Jul 2004
Location: Mt. Laurel NJ, now Melbourne, FL
Posts: 1,369
Default

What wound up being the problem?
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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

Forum Jump


All times are GMT -4. The time now is 11:46 PM.

Featured Vendors


Advertising Info