vacum leak
02-11-2010, 12:30 AM
#2
4th Gear Member
Join Date: Jul 2008
Location: alabama
Posts: 1,812
When i have ran into one of these sob`s i usaually had a loss of low end, with a backfire in the plenum have you removed any lines lately start there first make sure there not loose or torn, any hose with dry cracks thro them away and get new ones! There might not be visible holes but if threre are cracks could be getting in somehow and unmetered air is a bad thing with efi!
unmetered air can make a car run lean (or so the ecm thinks) and the ecm over compensate on fuel from a reading from the o2s. causing fuel puddles in the intake and you get backfiring through the intake into the plenum. poping out of the exaust is afterfiring people tend to get the 2 confused!
unmetered air can make a car run lean (or so the ecm thinks) and the ecm over compensate on fuel from a reading from the o2s. causing fuel puddles in the intake and you get backfiring through the intake into the plenum. poping out of the exaust is afterfiring people tend to get the 2 confused!
02-11-2010, 09:15 PM
#5
4th Gear Member
Join Date: Jul 2008
Location: alabama
Posts: 1,812
Make sure all you clamps are tight and not seeping air, did you unplug the maf make sure it is plug all the way back in, make sure your other sensors are in also. by jumpy idle you mean up and down or like it ships or what exactly? when you cleaned the air filter was it dry when you started the car? if it was wet you may have wet the maf vanes uh oh!
02-12-2010, 12:53 AM
#7
4th Gear Member
Join Date: Jul 2008
Location: alabama
Posts: 1,812
Take the iac off and spray some carb cleaner into it and if you want take the 2 screws out of the cylinder and make sure the plunger isnt sticking, a simple working sensor, if it is oil and dirt covered it can make them not work properly, will cause your idle problem.
02-12-2010, 08:26 AM
#8
3rd Gear Member
Join Date: Feb 2008
Location: IL
Posts: 877
Hi,
Is the CEL on?
If not, like posted above, look at the IACV. I would also recomend cleaning the throttle plate as they like to get gummed up with carbon deposits.
I would also recomend doing a base idle reset (covered many times on this board) as well as checking idle voltage at the tps (should be around 0.98).
Other than that, you could use propane to find vacuum leaks or carb/starter fluid but be extremely careful if you do that. You would be using the propane or starter fluid on vacuum lines and intake gaskets and so forth.
You also might want to take a peek at the EGR and see if its not stuck open, but that would cause more of a misfire than a loopy idle.
If all else fails, block off the vacuum line going to the brake booster. If your idle improves, then you have a leaking brake booster (usually felt by a hard brake pedal).
Hope this gives you a head start....
Is the CEL on?
If not, like posted above, look at the IACV. I would also recomend cleaning the throttle plate as they like to get gummed up with carbon deposits.
I would also recomend doing a base idle reset (covered many times on this board) as well as checking idle voltage at the tps (should be around 0.98).
Other than that, you could use propane to find vacuum leaks or carb/starter fluid but be extremely careful if you do that. You would be using the propane or starter fluid on vacuum lines and intake gaskets and so forth.
You also might want to take a peek at the EGR and see if its not stuck open, but that would cause more of a misfire than a loopy idle.
If all else fails, block off the vacuum line going to the brake booster. If your idle improves, then you have a leaking brake booster (usually felt by a hard brake pedal).
Hope this gives you a head start....
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