2005 impala 3.4 missfire rich problems
Mar 29, 2012 | 08:59 PM
#1
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From: Crystal Springs, MS
2005 impala 3.4 missfire rich problems
Got this 05 impala thats throwing a p0300 and a rich code.
These two codes to me mean that its a spark problem. Right?
They took it to a shop and had the plugs, wires, and a coil changed. Then a MAF.
Still wont crank good. Takes about 3 tries for it to fire off and then idles like crap.
Ive hooked efi live to it and manually turned each injector off but not sure if there was a difference that i could tell.
Unhooked the pcm and checked the resistance. All 6 read 1754 ohms. So that should mean that its not a wiring problem nor a shorted injector under that condition.
Only thing else i could figure is the ign coil module is having problems? Dunno how to test it yet tho.
Ive read the intake gasket could be leaking coolant into the runners but it hasnt been using coolant and somebody did a pressure check to the coolant system and didnt show anything.
What yall think? They have throw bout $1k of parts/labor at this thing with no fix.
These two codes to me mean that its a spark problem. Right?
They took it to a shop and had the plugs, wires, and a coil changed. Then a MAF.
Still wont crank good. Takes about 3 tries for it to fire off and then idles like crap.
Ive hooked efi live to it and manually turned each injector off but not sure if there was a difference that i could tell.
Unhooked the pcm and checked the resistance. All 6 read 1754 ohms. So that should mean that its not a wiring problem nor a shorted injector under that condition.
Only thing else i could figure is the ign coil module is having problems? Dunno how to test it yet tho.
Ive read the intake gasket could be leaking coolant into the runners but it hasnt been using coolant and somebody did a pressure check to the coolant system and didnt show anything.
What yall think? They have throw bout $1k of parts/labor at this thing with no fix.
Mar 31, 2012 | 06:23 AM
#2
Generally with a spark issue you would get lean codes. This is due to the fact that the fuel isn't burned in combustion and passes along in its vapor form allowing the sensors to only read oxygen. Have you checked the fuel pressure and if so does it bleed down? Is the rich code for only one bank? If so first thing I would do is swap the o2 sensor from bank to bank then monitor your fuel trims.
Mar 31, 2012 | 07:33 AM
#3
From my experience, if you are getting rich code, you got a leak somewhere. Could be vacuum hose, intake manifold, exhaust manifold.
Did you check the fuel pressure? Check the battery? An insufficient battery in a Corvette causes ALL kinds of problems. An Impala has less electronics, but could still cause issues.
Did you check the fuel pressure? Check the battery? An insufficient battery in a Corvette causes ALL kinds of problems. An Impala has less electronics, but could still cause issues.
Mar 31, 2012 | 08:18 AM
#4
Take a look at the fuel pressure regulator on the front of the intake manifold. It should decrease fuel pressure at idle and then increase with demand. Fuel pressure will bleed down on the 3.4 regardless but you can time it.
However the symptoms honestly sound of that of a failing coolant temperature sensor. It won't always toss a code for it either. It's a cheap part and for something like this probably the first thing I would change. Since it is doing this on startup it's not the O2 sensors as they are not even part of the equation.
However the symptoms honestly sound of that of a failing coolant temperature sensor. It won't always toss a code for it either. It's a cheap part and for something like this probably the first thing I would change. Since it is doing this on startup it's not the O2 sensors as they are not even part of the equation.
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