Engine runs rough
09-15-2016, 04:07 PM
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Engine runs rough What I have: 1998 TA 5.7 LS1 6sp MT. Virtually stock. 110K miles.
Modifications (1): Deleted 1-port muffler for dual port pipe.
Issue: Last summer I had my exhaust guy replace my 1-port factory muffler. Upon my 1st trip out, the exhaust gave an extra "resonation or mini backfire" This immediately lit my "Check Engine"
I checked the code. "O2 sensor" so I replaced that corresponding sensor. That didn't cure anything.
I assumed there was too much exhaust flow for my O2s to properly read, so I added sensor extenders. That too did not fix the issue. When I disconnect the battery, this temporarily clears the code.
I do keep premium fuel in the car (usually 3/8 or better) Not always from the same station.
Lately the issue seems to be showing more frequently. If I'm cruising under 56 mph in 6th, the engine feels a vibration. Misfire? The only time the engine doesn't seem to lack power is high RPM, or sporty driving. In other words, the power seems to lack on the low end. I've heard that bad O2s can cause. I have replaced spark plugs & wires w/ A/C Delco
My Question: How likely is it that I should replace all 4 O2s? Maybe at least 2 at a time? (1-Left & 1-right bank)
I'd rather not throw out more $$$ to not fix this.
Other possible culprits:
Bad CAT? 110K @ 19yrs, anything is possible?
MAF sensor isn't so old. Replaced is also OE
(no K&N A/filter, but a paper one)
Bad Injector(s)?
Knock Sensor: I had a 2001 Camaro LS1 6spd.
I did replace that sensor & harness.
That offered more of a low end power loss.
Modifications (1): Deleted 1-port muffler for dual port pipe.
Issue: Last summer I had my exhaust guy replace my 1-port factory muffler. Upon my 1st trip out, the exhaust gave an extra "resonation or mini backfire" This immediately lit my "Check Engine"
I checked the code. "O2 sensor" so I replaced that corresponding sensor. That didn't cure anything.
I assumed there was too much exhaust flow for my O2s to properly read, so I added sensor extenders. That too did not fix the issue. When I disconnect the battery, this temporarily clears the code.
I do keep premium fuel in the car (usually 3/8 or better) Not always from the same station.
Lately the issue seems to be showing more frequently. If I'm cruising under 56 mph in 6th, the engine feels a vibration. Misfire? The only time the engine doesn't seem to lack power is high RPM, or sporty driving. In other words, the power seems to lack on the low end. I've heard that bad O2s can cause. I have replaced spark plugs & wires w/ A/C Delco
My Question: How likely is it that I should replace all 4 O2s? Maybe at least 2 at a time? (1-Left & 1-right bank)
I'd rather not throw out more $$$ to not fix this.
Other possible culprits:
Bad CAT? 110K @ 19yrs, anything is possible?
MAF sensor isn't so old. Replaced is also OE
(no K&N A/filter, but a paper one)
Bad Injector(s)?
Knock Sensor: I had a 2001 Camaro LS1 6spd.
I did replace that sensor & harness.
That offered more of a low end power loss.
Last edited by 1998WS6calasor; 09-19-2016 at 04:18 PM.
