thewraith1971

I have a 2002 z28 with slp lid and K&N, long tube headers, 3" y into flowmaster exhaust, a 3k stall, and 160 thermostat....

Now the car has not been professionally tuned yet so i get the codes for the rear o2 sensors and a few others....i will post them when i find darn printout of the scan

anyways as of late the car runs fine about 95% of the time when its dry out only the occasional flash of check engine light for mere second, but if its raining out might as well forget it car stumbles, runs extremely rich, and the ses light flashes for multiple random misfires if i am giving it part throttle...now if i floor it car runs just fine and symptoms dissapear for a little bit then come back

am I experiencing a short somewhere with the wires, or is a coil pack going bad etc...

joecar

See this: https://ls1tech.com/forums/general-m...r-stories.html

thewraith1971

went to autozone today had it scanned came up with 7 codes....he only printed off 3 of them for me stating the others were for rear o2s which are not on the car due to LT headers.


codes were p0300 of course for the random multiple misfires which only occur when it rains, p0135 basically front o2 sensor bank 1 is toast, and front o2 sensor bank 2 said insufficient switching....

would I be correct in assuming that the misfires are coming from water getting into faulty connection or bad o2 sensor?

joecar

Not necessarily.

Fix the O2 problems and then start diagnosing the misfire.

thewraith1971

took car to get detailed today and so happens guy also had an hp tuner and said he could spray down the engine to force it to misfire and monitor the systems....he cleared the codes started car up and of course started to misfire while reading the o2 sensors bank 2 sensor 1 was stuck at 1107 mv and bank 1 sensor was all over the place from 200 to 400....what should be the parameters of o2 sensors at idle while being read on the scanner?

joecar

When in closed loop, the front O2 sensor voltages should continually swing from below 300mV to above 600mV and back again, at least three complete swings per second.

thewraith1971

ok update took it to the shop they said they would hook it up to scanner use misfire counter and etc...

their finding was cylinder 6 misfire with coil pack being bad...but when i have car scanned at autozone I have no code for specific cylinder misfire just p0300 and o2 sensor codes 4 of them just for front o2s alone....I do not know how they determined it was cylinder 6 but is it possible it is the coil pack


Also they said when they used their scanner nothing showed up for o2 sensors but yet it does at autozone...whom should i trust?

jam01

not bashing any one who works at these five and dime parts stores, but most dont know there butt from there nose. i would go with the shops diagnoses unless they didnt have the right equipment and it seems they do. if in doubt get a junk yard coil and see if that helps.