Misfiring - No codes
#1
09-05-2007, 10:32 AM
Misfiring - No codes
I have a problem, the SS sounds like it is misfiring, especially in the 1500 to 2000 RPM range, yet it is not throwing out any codes. My car sat for two-years, so one person told me it could be a bad fuel filter, another my cat-back system is screwing with the computer. But the car goes into 4-cyl mode awfully quick too.
When you punch it, it reacts just fine... the problem comes in when you are driving normal. It just feels and sounds funny. I have the mechanics looking at it right this minute, but these new mechanics are lost most of the time if the computer is not throwing a code that tells them the problem. With my wife's Malibu, they had it for 3-days and could not figure out the problem. So I took it to my regular mechanic and he popped the hood nad said it was the "Mass Air Sensor", all of 30-seconds. He replace the sensor and the car has been running great ever since.
What do you guys think -- oh, I only run Top Grade Premium Gas
When you punch it, it reacts just fine... the problem comes in when you are driving normal. It just feels and sounds funny. I have the mechanics looking at it right this minute, but these new mechanics are lost most of the time if the computer is not throwing a code that tells them the problem. With my wife's Malibu, they had it for 3-days and could not figure out the problem. So I took it to my regular mechanic and he popped the hood nad said it was the "Mass Air Sensor", all of 30-seconds. He replace the sensor and the car has been running great ever since.
What do you guys think -- oh, I only run Top Grade Premium Gas
#2
09-05-2007, 11:08 AM
RE: Misfiring - No codes
[align=center]Hi Craig,[/align][align=center]
[/align][align=center]Sorry that you are having problems with your SS [X(][/align][align=center]Good thing that it's still under warranty : ) 
[/align][align=center]I hope they can find your problems.[/align][align=center][/align][align=center]This is what I found in my Problem Engine file:[/align][align=center]It may help you with some idea's on what could be wrong,[/align][align=center]but sitting for two years can cause many issues:[/align][align=center][:-][/align][align=center]Car Engine Misfires Poor Running - Tune Up [/align]
[/align][align=center]Sorry that you are having problems with your SS [X(][/align][align=center]Good thing that it's still under warranty : ) [/align][align=center]I hope they can find your problems.[/align][align=center][/align][align=center]This is what I found in my Problem Engine file:[/align][align=center]It may help you with some idea's on what could be wrong,[/align][align=center]but sitting for two years can cause many issues:[/align][align=center][:-][/align][align=center]Car Engine Misfires Poor Running - Tune Up [/align]Engine Miss Fire and Rough Running Condition
There are three kinds of gasoline engine misfire scenarios, first there is the "under load" misfire and there is the "at engine idle" misfire, and finally there is misfire continuously. All engine misfires exist because one of three things has occurred. First, a cylinder has lost compression, a cylinder needs a certain amount of compression to operate correctly. Second, the ignition system has failed or is failing intermittently, spark is needed at the time of compression to ignite the fuel air mixture. Third, the fuel air mixture is incorrect, proper mixture is needed for the ignition system to ignite fuel properly. If any of these conditions occur in the engine, the engine will misfire.
1. Low or no compression can be caused by
a. burned or leaking intake or exhaust valves
b. worn or broken piston or piston rings
c. worn out camshaft
d. wrong weight motor oil was installed holding the cam followers from adjusting
e. broken valve spring
f.failed head gasket.
[align=center]2. Ignition system has failed or is failing[/align]There are three kinds of gasoline engine misfire scenarios, first there is the "under load" misfire and there is the "at engine idle" misfire, and finally there is misfire continuously. All engine misfires exist because one of three things has occurred. First, a cylinder has lost compression, a cylinder needs a certain amount of compression to operate correctly. Second, the ignition system has failed or is failing intermittently, spark is needed at the time of compression to ignite the fuel air mixture. Third, the fuel air mixture is incorrect, proper mixture is needed for the ignition system to ignite fuel properly. If any of these conditions occur in the engine, the engine will misfire.
1. Low or no compression can be caused by
a. burned or leaking intake or exhaust valves
b. worn or broken piston or piston rings
c. worn out camshaft
d. wrong weight motor oil was installed holding the cam followers from adjusting
e. broken valve spring
f.failed head gasket.
a. spark plug has fouled or is worn out
b. ignition coil has failed
c. spark plug wires have shorted
e. engine control module coil driver has failed
[align=center]3. Fuel/Air Mixture is incorrect[/align]b. ignition coil has failed
c. spark plug wires have shorted
e. engine control module coil driver has failed
a. vacuum leak at the intake manifold
b. fuel injector has failed
c. EGR valve is stuck open
d. mass air flow sensor has failed
e. oxygen sensor has failed
f. air intake boot is cracked
Most vehicles can monitor the cylinder misfire condition and will illuminate the "service engine soon" light if a cylinder misfire has been detected. A engine code reader is used to read the trouble codes and can isolate the cylinder malfunction. See Checking Trouble Codes after the repair is complete the "service engine soon" light must be reset with a code reader. The vehicle has to be driven thoroughly (30 to 60 miles) to let all computer monitors and relearn their system to deem the vehicle repaired.
common problems:
1. fuel injector has failed or is failing
2. spark plug wire has shorted
3. spark plug is worn out or is cracked
4. ignition coil has failed is failing
b. fuel injector has failed
c. EGR valve is stuck open
d. mass air flow sensor has failed
e. oxygen sensor has failed
f. air intake boot is cracked
Most vehicles can monitor the cylinder misfire condition and will illuminate the "service engine soon" light if a cylinder misfire has been detected. A engine code reader is used to read the trouble codes and can isolate the cylinder malfunction. See Checking Trouble Codes after the repair is complete the "service engine soon" light must be reset with a code reader. The vehicle has to be driven thoroughly (30 to 60 miles) to let all computer monitors and relearn their system to deem the vehicle repaired.
common problems:
1. fuel injector has failed or is failing
2. spark plug wire has shorted
3. spark plug is worn out or is cracked
4. ignition coil has failed is failing
Could be old gas that jelled up & is clogging up things ?
Let us know the results from your GM Tech's
Craig, I hope the above gives you
some information that you can use.
Good Luck,
`Space
Craig, I hope the above gives you
some information that you can use.
Good Luck,
`Space
#4
09-05-2007, 12:27 PM
Join Date: Apr 2006
Location: Woodstock, Ontario, Canada
Posts: 5,264
RE: Misfiring - No codes
it could be bad gas, but if you've been driving it you will have run through that tank that sat for 2 years, i would bet its something to do with the fact it sat for so long...maybe the fuel filter is no good
#5
09-05-2007, 02:13 PM
RE: Misfiring - No codes
I would run some Shell gas due to a cleaning addative they put in, any gas that runs 10% ethenol - I believe BP and Mobil's are doing this more often. Or put a gallons worth of E85 in a tank that is 3/4 full. That should blend in nicely to help clean the whole fuel system from the tank to the injectors. It will also clean the spark plugs a bit, and will do a GREAT job at cleaning your valves.
STP fuel injector cleaner will help as well. If this doesn't get fixed within the first 2 tanks or 2 weeks or so, then change the fuel filter especially if it gets worse. The E85 works so well it will actually clean up the gas tank itself and clog up the fuel filter on you, but then your filter will be new and your tank will be clean of any jelling.
STP fuel injector cleaner will help as well. If this doesn't get fixed within the first 2 tanks or 2 weeks or so, then change the fuel filter especially if it gets worse. The E85 works so well it will actually clean up the gas tank itself and clog up the fuel filter on you, but then your filter will be new and your tank will be clean of any jelling.
#6
09-05-2007, 07:49 PM
RE: Misfiring - No codes
I think these guys have it figured out. The gas is way past bad! It needsto be drained not ran through the car and the fuel filter needs to be replacedimmediately afterwards! I can't stress that enough. The other thing you are hearing is the same thing I hear on mine. It's got flowmasters too. They sound funny in four cyl mode. I bet there is nothing wrong with the DOD/EFM. Just flowmasters on a 4 cyl. It's like you can hear every cylinder hit in 4cyl mode with those type of mufflers.
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