Rough Idle/fuel smell
05-17-2019, 03:58 PM
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Rough Idle/fuel smell Hello everyone I hope the very knowledgeable people here can help me out. I have a rough idle problem that has been driving me crazy for some time now. I have a 99 firebird trans am m6 with 69k miles. It has a K&N cold air intake and a borla cat back (those are the only mods to that i know of). In trying to fix this issue i have replaced the spark plugs twice (right now ngk tr55 ix's are in there) i have MSD wires, which i bought new. I have replaced the fuel filter, both front 02 sensors, pcv valve and the IAC. I have cleaned the MAF multiple times and cleaned the throttle body to the best of my ability twice. I have also disconnected the Maf and let it run and it may have small difference but if it did it was almost not noticeable. I have also cleaned the IAT sensor as well and checked the coolant temp sensor, (wires looked fine, didnt see any cracks in the connector). I have also checked for vacuum leaks multiple times and found none so far. I also had the drivers side cylinder head replaced (intake manifold bolt snapped off into the head)
I have hooked up my scanner multiple times (bluetooth obd2 and the torque app)
Im not throwing any codes but i will let you know what i have noticed.
When the MAF was disconnected i threw a code but my dash never lit up (i know the light works because i had to replace the led for it and i see it light up when the car starts.)
During some live data monitoring i have noticed cylinder 6 and 8 have 2 misfires each incredibly briefly and then none for a extended period of time. (iv only seen this once) After running some data logs i have also noticed misfires in cylinders 2 and 5 again a count of only 2.
I have also noticed some failures in the mode 6 data however it being mode 6 data its accuracy is questionable. (TID: $0c CID:$20 misfire counts for last/current driving cycles(calculated) max:278, current: 53000 TID: $0c CID:$30 misfire counts for last/current driving cycles(calculated) max:153 current:63000)
I have also started noticing a fuel smell, which is new, its normally only at startup and i smell it occasionally going down the road (i dont see any leaking fuel around the injectors and the ohms reading was accurate)
i am at about 21hg vacuum i believe (which from the research i have done, that is about right)
The idle is not steady, it floats up and down from about 790 to around 805
I appreciate any help that is provided, i also apologize in advance if this is in the wrong place.
Logs are also attached for those who wish to view them, if they can be useful.
Mike
I have hooked up my scanner multiple times (bluetooth obd2 and the torque app)
Im not throwing any codes but i will let you know what i have noticed.
When the MAF was disconnected i threw a code but my dash never lit up (i know the light works because i had to replace the led for it and i see it light up when the car starts.)
During some live data monitoring i have noticed cylinder 6 and 8 have 2 misfires each incredibly briefly and then none for a extended period of time. (iv only seen this once) After running some data logs i have also noticed misfires in cylinders 2 and 5 again a count of only 2.
I have also noticed some failures in the mode 6 data however it being mode 6 data its accuracy is questionable. (TID: $0c CID:$20 misfire counts for last/current driving cycles(calculated) max:278, current: 53000 TID: $0c CID:$30 misfire counts for last/current driving cycles(calculated) max:153 current:63000)
I have also started noticing a fuel smell, which is new, its normally only at startup and i smell it occasionally going down the road (i dont see any leaking fuel around the injectors and the ohms reading was accurate)
i am at about 21hg vacuum i believe (which from the research i have done, that is about right)
The idle is not steady, it floats up and down from about 790 to around 805
I appreciate any help that is provided, i also apologize in advance if this is in the wrong place.
Logs are also attached for those who wish to view them, if they can be useful.
Mike
Last edited by mbarb55; 05-17-2019 at 05:00 PM. Reason: updating
05-17-2019, 10:56 PM
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Update:. I ran a second pass of logs and I saw more misfires. I'm now showing misfires in every cylinder but cylinder 4.
I decided to unplug the maf and run the same route and data log as well. No misfires and the idle was definitely better. I know that just because it ran better with the maf disconnected doesn't mean I have a bad maf. I am open to suggestions.
Anyone?
I decided to unplug the maf and run the same route and data log as well. No misfires and the idle was definitely better. I know that just because it ran better with the maf disconnected doesn't mean I have a bad maf. I am open to suggestions.
Anyone?