5.0L (1979-1995) Mustang Technical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.

Black exhaust, unsteady idle, hesitation...

Old 03-01-2007, 06:42 PM
  #1  
BlazeGT
2nd Gear Member
Thread Starter
 
BlazeGT's Avatar
 
Join Date: Jun 2006
Location:
Posts: 151
Default Black exhaust, unsteady idle, hesitation...

Lately my car has been acting up a lot with the following symptoms:
-Black smoke from the exhaust
-smells like gas when i drive...waaay more than it should
-when i push the gas pedal i have to pump it once quickly or it dies
-when im stopped the idle goes crazy, from somewhere around 250 to 1500 just revving up and down

The car runs fine once it gets going, but i was wondering if any of you could diagnose the problem. Any guesses would be appreciated
BlazeGT is offline  
Old 03-01-2007, 06:46 PM
  #2  
HACKGT350
6th Gear Member
 
HACKGT350's Avatar
 
Join Date: Jan 2006
Location: new jersey
Posts: 6,635
Default RE: Black exhaust, unsteady idle, hesitation...

sounds like you are having a fuel/spark problem when was the last time you did a tune up?
HACKGT350 is offline  
Old 03-01-2007, 06:49 PM
  #3  
BlazeGT
2nd Gear Member
Thread Starter
 
BlazeGT's Avatar
 
Join Date: Jun 2006
Location:
Posts: 151
Default RE: Black exhaust, unsteady idle, hesitation...

My last tune up was actually pretty recent...id say probably 3000 miles back and this car sees about 250-300 miles a week
so around two or three months if my math is correct
BlazeGT is offline  
Old 03-01-2007, 07:03 PM
  #4  
91ford302
2nd Gear Member
 
91ford302's Avatar
 
Join Date: Mar 2006
Location: Connecticut
Posts: 188
Default RE: Black exhaust, unsteady idle, hesitation...

what year and engine/trans combo. need more info
91ford302 is offline  
Old 03-01-2007, 07:17 PM
  #5  
92hatchLX
6th Gear Member
 
92hatchLX's Avatar
 
Join Date: Feb 2005
Location:
Posts: 8,439
Default RE: Black exhaust, unsteady idle, hesitation...

It's a fuel delivery related problem. You're running horribly rich. Clean your MAF wires first. If the MAF cleaning doesn't solve the problem, run codes and see if anything pops up. I'd lean towards a dirty MAF or ECT sensor, possibly bad oxygen sensor(s).
92hatchLX is offline  
Old 03-01-2007, 07:25 PM
  #6  
shaners90lxhatch
3rd Gear Member
 
shaners90lxhatch's Avatar
 
Join Date: Sep 2006
Location:
Posts: 760
Default RE: Black exhaust, unsteady idle, hesitation...

ORIGINAL: 92hatchLX

It's a fuel delivery related problem. You're running horribly rich. Clean your MAF wires first. If the MAF cleaning doesn't solve the problem, run codes and see if anything pops up. I'd lean towards a dirty MAF or ECT sensor, possibly bad oxygen sensor(s).
^ + a billion. You be runnin rich man. Absolutely no doubt about it. Fuel pressure should be 30psi at idle and 40psi with the vacuum line off the regulator. Drive it without the MAF and evaluate. Typically they create lean conditions over rich, but anything is possible. If your PCM power (VPWR) is too low, it will run extremely fat. You oxygen sensor voltages may be stuck at zero, but you will go into open loop and never notice smoke. You could have bad gas, so keep that in mind if you can't find any rich contributors. IAT or ECT reading way too low shouldn't make it pour black smoke, but you need to validate their accuracy.
shaners90lxhatch is offline  
Old 03-01-2007, 07:45 PM
  #7  
BlazeGT
2nd Gear Member
Thread Starter
 
BlazeGT's Avatar
 
Join Date: Jun 2006
Location:
Posts: 151
Default RE: Black exhaust, unsteady idle, hesitation...

OH woops sorry i forgot, this is a 1994 gt so there ya go for whoever asked. Thanks for all of the help so far, ill definately check it out.
BlazeGT is offline  
Old 03-03-2007, 12:19 AM
  #8  
AlabamaCobra
2nd Gear Member
 
AlabamaCobra's Avatar
 
Join Date: Dec 2006
Location:
Posts: 450
Default RE: Black exhaust, unsteady idle, hesitation...

i have the same idle problem but my car is speed density...any ideas??!5.0 i 89lx conversion
AlabamaCobra is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
2007StangV6
2005-2014 Mustangs
30
01-28-2016 06:09 PM
Boostaddict
Lethal Performance
2
09-08-2015 09:56 PM
aleit2013
Archive - Parts For Sale
0
09-04-2015 11:58 AM
Luke9222
New Member Area
7
09-04-2015 06:46 AM
Emblazoned
General Tech
0
09-03-2015 10:45 PM


Thread Tools
Search this Thread
Quick Reply: Black exhaust, unsteady idle, hesitation...



All times are GMT -5. The time now is 03:27 AM.