Exhaust leak
What type of data would a scanner be showing if I had an exhaust leak at the headers or y-pipe? I'm trying to troubleshoot a p0300 dtc code.
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97' SS #497 1 of 50 White Hardtop M6,stock TB reworked to 52mm,SLP CC shorties, Random Tech DC Y-pipe, LT4KM, Taylor Spiro's and NGK's, BMR Adj Lcr's, TA, Boxed SFC's, Adj PHR, Floorpan brace w/ driveshaft loop, STB, GM 4:10'S, 1LE alum DS, Eibach 35mm front swaybar and Pro-Kit Springs, Bilstein HD's, Lou's speed stick with Hurst ball,LS1 front brakes, Earl's lines, Hawk Pads, BMR relocation brackets. -
Generally an exhaust leak prior to the 02 sensor will show up as a flase lean as the sensor picks up the presence of extra oxygen that was not a part of the combustion process. This in turn signals the computer to compensate by adding additional fuel. The scanner would show a increase in injector pulse width on the offending bank, the short term and long term fuel corrections would most likely show the computer is adding fuel by a plus percentage. Each fuel trim cell will most like be affected, all across the rpm and load board.
What all that means is that the computer is going to add fuel on the same side that the exhaust is leaking to compensate for the additional oxygen picked up by the sensor and will now be rich on that bank.
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What if it's an exhaust leak after the O2 sensor (header collector); would the results be the same? My LIFTB2 reading at idle is +17% 145; could that be the result of an exhaust leak or bad plug wire?97' SS #497 1 of 50 White Hardtop M6,stock TB reworked to 52mm,SLP CC shorties, Random Tech DC Y-pipe, LT4KM, Taylor Spiro's and NGK's, BMR Adj Lcr's, TA, Boxed SFC's, Adj PHR, Floorpan brace w/ driveshaft loop, STB, GM 4:10'S, 1LE alum DS, Eibach 35mm front swaybar and Pro-Kit Springs, Bilstein HD's, Lou's speed stick with Hurst ball,LS1 front brakes, Earl's lines, Hawk Pads, BMR relocation brackets.Comment
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No. Your secondary sensors which monitor catalyst effeciency would show leaner in the offending bank. The difference is the computer won't add fuel to compensate. You may get a code for catalyst effeciency though.Originally posted by 97ss497
What if it's an exhaust leak after the O2 sensor (header collector); would the results be the same?
Can't tell, how does it compare to the other bank?Originally posted by 97ss497
My LIFTB2 reading at idle is +17% 145; could that be the result of an exhaust leak or bad plug wire?Comment
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Joe,
The other bank LIFTB1 is +1% 125.
I'm confused about your first responce; the only possible leak prior to the front O2 sensor would be at the header to head gasket; the header collector gasket (header/y-pipe) is after the front 02 sensor; would a leak at either joint cause the same problem?97' SS #497 1 of 50 White Hardtop M6,stock TB reworked to 52mm,SLP CC shorties, Random Tech DC Y-pipe, LT4KM, Taylor Spiro's and NGK's, BMR Adj Lcr's, TA, Boxed SFC's, Adj PHR, Floorpan brace w/ driveshaft loop, STB, GM 4:10'S, 1LE alum DS, Eibach 35mm front swaybar and Pro-Kit Springs, Bilstein HD's, Lou's speed stick with Hurst ball,LS1 front brakes, Earl's lines, Hawk Pads, BMR relocation brackets.Comment
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No they don't cause the same problem. If the leak is prior to the primary sensor, the computer compensates. If the leak is after the primary but prior to the secondary, the sensor will still read additional oxygen, it's just the computer will not try to compensate. The secondary sensors are there for one purpose: To help measure the effeciency of the catalytic converter(s).Originally posted by 97ss497
Joe,
The other bank LIFTB1 is +1% 125.
I'm confused about your first responce; the only possible leak prior to the front O2 sensor would be at the header to head gasket; the header collector gasket (header/y-pipe) is after the front 02 sensor; would a leak at either joint cause the same problem?
You definately have a fuel imbalence. There could be several reasons. Fouled/leaky injectors, bad plugs, bad plug wires, optispark, the list can go on and on. It's been my experience that first you make sure the ignition is 100%, then look to fuel issues after that.
In any case, P0300 - Random/Multiple Cylinder Misfire Detected
That means ignition. Something isn't right. Plugs, wires, optispark......Comment
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