S.o.s
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On The Tree
Joined: Feb 2008
Posts: 131
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S.o.s 99 camaro SS>
car runs fine when it starts up and when it reaches normal operating temp. but then after driving awhile i get a hesitation or a really bad miss upon take off i've replaced the MAP sensor, the o2 sensors, the coils and the plugs and wires and the no. 4 plug is darker than the other plugs, where as the other plugs are showing normal wear the no. 4 is dark around the ceramic part of the electrode, now i scanned the computer : 0 codes but i got an incomplete condition reading on the screen that read EVAP im thinking i may have kinked a line when i changed the fuel pump but i want to hear you guys opinions!
car runs fine when it starts up and when it reaches normal operating temp. but then after driving awhile i get a hesitation or a really bad miss upon take off i've replaced the MAP sensor, the o2 sensors, the coils and the plugs and wires and the no. 4 plug is darker than the other plugs, where as the other plugs are showing normal wear the no. 4 is dark around the ceramic part of the electrode, now i scanned the computer : 0 codes but i got an incomplete condition reading on the screen that read EVAP im thinking i may have kinked a line when i changed the fuel pump but i want to hear you guys opinions! Last edited by ODAWG; Sep 27, 2009 at 09:40 AM. Reason: left out something i've replaced on car to help diagnose problem.
I would think if it was EVAP there wouldn't be just one (#4) plug looking bad. Plus, I don't think EVAP problems cause misfires. ?????
Make sure that #4 plug wire is not touching any part of the exhaust pipe manifolds. If it is, or if any of them are......it will misfire. But you will not get misfires usually until your in the mid-to-upper rpm's and it will be worse after its hot. Most people get codes when it misfires, but I've learned that all PCM's do not act the same, so you might not get one.
If thats not it, swap that plug wire with a new one. Make sure its "snapped" on at both ends. If its loose it'll still fire sometimes, but it will also misfire.
You could swap coils to see if the problem moves with it, but you're not getting codes to tell which cylinder is missing.
.
Make sure that #4 plug wire is not touching any part of the exhaust pipe manifolds. If it is, or if any of them are......it will misfire. But you will not get misfires usually until your in the mid-to-upper rpm's and it will be worse after its hot. Most people get codes when it misfires, but I've learned that all PCM's do not act the same, so you might not get one.
If thats not it, swap that plug wire with a new one. Make sure its "snapped" on at both ends. If its loose it'll still fire sometimes, but it will also misfire.
You could swap coils to see if the problem moves with it, but you're not getting codes to tell which cylinder is missing.
.
Are you sure its related to the engine temperature? Does the mis only happen in certain RPM ranges? Is it only when you gun the gas? What transmission do you have? Have you scanned for codes?
Thread Starter
On The Tree
Joined: Feb 2008
Posts: 131
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its a stock maf and yes it is descreened , custom tuned also and my mistake its the no. #3 plug, m6. it will idle normally if i sit and watch it idle it idles at 900 rpms and 17 inches of vacuum, then it will start acting funny after a few minutes and when i give it gas it hesitates, but then if i cut the car off and restart it it s fine for another few minutes, and then it will do it again.
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