misfire
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07-13-2006, 10:29 PM
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misfire
i've seen lots of posts in here regarding the notorious misfire. i'm just looking for a little reassurance so i don't keep throwing money down the drain.
right now...it only happens when the engine is cold.
once it goes from open loop to closed loop is when it misfires.
after about a minute or so it goes away.
the worst of it happens below 2k rpm.
once it goes to WOT it starts to clear up.
after the engine has sat long enough...not cold...it will idle rough.
replaced...plugs, dist cap, rotor, coil, wires, & engine coolant temp sensor and thermostat.
fuel pressure is good and copmression on all 6 is 180+.
P0300(ALONE), P0300 0301 0303(TOGATHER), &P0172. now it doesn't even throw codes.
this weekend im gonna replace the intake manifold gaskets along with the plenum and t/b gaskets.
i think i have a leak between #1&3 cylinders but don't want to waste my weekend on unecessary work if this doesn't fix it.
can anybody make sense of this or at least let me know if im on the right track.
right now...it only happens when the engine is cold.
once it goes from open loop to closed loop is when it misfires.
after about a minute or so it goes away.
the worst of it happens below 2k rpm.
once it goes to WOT it starts to clear up.
after the engine has sat long enough...not cold...it will idle rough.
replaced...plugs, dist cap, rotor, coil, wires, & engine coolant temp sensor and thermostat.
fuel pressure is good and copmression on all 6 is 180+.
P0300(ALONE), P0300 0301 0303(TOGATHER), &P0172. now it doesn't even throw codes.
this weekend im gonna replace the intake manifold gaskets along with the plenum and t/b gaskets.
i think i have a leak between #1&3 cylinders but don't want to waste my weekend on unecessary work if this doesn't fix it.
can anybody make sense of this or at least let me know if im on the right track.
#2
07-14-2006, 01:31 AM
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07-15-2006, 11:12 PM
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#4
10-09-2006, 03:29 AM
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RE: misfire
well an update for anybody who comes accross this problem. i have finally solved the misfire that has been plaguing me for the past couple of months. its the O2 sensors. im not sure which one(s) so i replaced them all. along with the 0172, i got 0173, 0174, 0175. the 02 sensors were doing their job but not efficiently. it became sluggish. thats why it would swing from rich to lean. seeing how they are heated, also solved the other issue where i missfired until my engine was up to operating temp, ie the exhaust gas. they aren't cheap but it will stop the headache with about an hours worth of work. thanks for the help in the other posts as well.
#5
10-09-2006, 05:25 PM
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#6
10-09-2006, 05:27 PM
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#7
10-09-2006, 08:29 PM
Record Breaker
RE: misfire
before you change out all of your o2 sensors, i will quote steve00ram360:
well before you go plunkin down hard earned bux on a new sensor... you could go get some CRC electronic parts cleaner at the auto parts store, yank out the o2's and clean them. spray it liberaly into the openings and dont be stingy... I've cleaned about a dozen sensors so far and all of them worked excellent after the cleaning. on my wifes old '02 dak, hers was throwing a cat in-effecinecy code, cleaned the sensor, reset the pcm and it never came back.
as for telling if a cat is good or not, have someone behind the wheel rev it to 2000~2200 rpms to heat up the cats and while they are reving it, use a temp gun and measure the input & output temps of the cat... normal is the output's are hotter than the inputs. anything else and the cat is bad.
as for telling if a cat is good or not, have someone behind the wheel rev it to 2000~2200 rpms to heat up the cats and while they are reving it, use a temp gun and measure the input & output temps of the cat... normal is the output's are hotter than the inputs. anything else and the cat is bad.