Plz HELP!!!!!!!!! Random Misfire code still
11-21-2012, 06:20 PM
#1
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Plz HELP!!!!!!!!! Random Misfire code still i have 02 firebird formula stock except borla catback exhuast and slp air intake system, on cold starts idles real rough till reaches normal operating temp, no loss of performance at all, i changed coolant temp senor, all 02 sensors,tps sensor, mass air flow sensor, had intake gasket changed, and the fuel injectors cleaned, and put new ngk spark plugs, with new wires, plz any more suggestions???
11-21-2012, 07:36 PM
#2
i have 02 firebird formula stock except borla catback exhuast and slp air intake system, on cold starts idles real rough till reaches normal operating temp, no loss of performance at all, i changed coolant temp senor, all 02 sensors,tps sensor, mass air flow sensor, had intake gasket changed, and the fuel injectors cleaned, and put new ngk spark plugs, with new wires, plz any more suggestions???
I think the gear in your headlight motor is stripped......lol
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11-22-2012, 09:03 PM
#5
Make sure NONE, I mean no part of any spark plug wires are touching any of the metal exhaust piping......that caused misfires.
Spinning the boot that attaches to the coil is the best way to get a wire into a position where its not touching the pipe. Just spin it slowly till the wire is clear of any metal.
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Spinning the boot that attaches to the coil is the best way to get a wire into a position where its not touching the pipe. Just spin it slowly till the wire is clear of any metal.
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11-22-2012, 09:23 PM
#6
you are getting P0300 and never a specific cylinder misfire P0301-P0308?
http://repairpal.com/OBD-II-Code-P0300
when you say only when cold and at idle, that makes me think rings and valves.
how's your oil look and smell, and how is oil pressure? Any valve train noise?
And is the car an automatic or a manual ?
ever hit the rev limiter or miss a shift if it's a manual? might want to check pushrods for straightness.
dry doing a compression test when hot and when cold and see what you get.
you need to put a scan tool or scope on it and monitor engine data before the misfire code so you can better diagnose what's happening rather than throwing parts at it. after your list of parts that you've changed, only other one i can think of is crank sensor,,, not sure if at idle it could be faulty but at higher rpms is ok.
http://repairpal.com/OBD-II-Code-P0300
when you say only when cold and at idle, that makes me think rings and valves.
how's your oil look and smell, and how is oil pressure? Any valve train noise?
And is the car an automatic or a manual ?
ever hit the rev limiter or miss a shift if it's a manual? might want to check pushrods for straightness.
dry doing a compression test when hot and when cold and see what you get.
you need to put a scan tool or scope on it and monitor engine data before the misfire code so you can better diagnose what's happening rather than throwing parts at it. after your list of parts that you've changed, only other one i can think of is crank sensor,,, not sure if at idle it could be faulty but at higher rpms is ok.
Last edited by 1 FMF; 11-22-2012 at 09:34 PM.
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11-23-2012, 09:16 PM
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I'll bet you have a vacuum leak someplace.....reason it smooths out as it warms up is it starts running off the o2 sensors. cold its running on the cold start program. Find yor leak.
Try this stone cold, have someone start the car for you as you take a UNLIT propane torch around the edges of the intake manifold.
Try this stone cold, have someone start the car for you as you take a UNLIT propane torch around the edges of the intake manifold.
