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for a few weeks now my 01 ssei has been feeling like it has a misfire. a lifter on cyl 4 has been making some noise but i ran a can of BG109 before a oil change and that noise went away.. also sticking lifter was creating a P0304 misfire on cyl 4(hense p0304). that code has not came back since motor "flush". but the P0102 mas air flow curcuit low code is still active twice. i cleaned it out today but still has code and still drives horrible. i asume mass amounts of fuel are being dumped cuz tail pipes has alot of sut build up even on the bumper above.. any sugestions on if replaces MAF sensor will fully fix misfire issue.. it really only feels like its missing when idleing and cruising on any road with throttle pressed 5-10% specially going up hill.. hoping MAF will fix but not sure if i should go n buy it and it not fox my issue then have to dump more cash into it like the acc belt tentioner bouncing during idle but not sure if just cause of initial problem.. any suggestions would help.. a friend of mine said valve springs are notorious for breaking on GM 3.great motors so im hoping i dont need to dig those outa the back. car is my DD i dont mind a rough ride jus want it fixed asap. thx

also during idle the acc belt tentioner is bouncing all over but not sure if due to it almost dying during idle after trip or if adding to create bad maf problems worse

You could try unplugging the MAF sensor, and see if it runs properly. If so, then MAF should be your problem... Did you clean it till it was shiny chrome on the two pins that support the sensor element? Took me about 18 sprays to get mine really clean, using MAF cleaner (about $8.00 at NAPA).

Good luck,

MW

its been unplugged for a while and still runs like *shoot*. suspicious of a dead cyl. or bad valve component. just feels very stumbly and choked but THEE only dtc is a MAF sensor

01ssei wrote:its been unplugged for a while and still runs like *shoot*. suspicious of a dead cyl. or bad valve component. just feels very stumbly and choked but THEE only dtc is a MAF sensor

Did you try knocking on the Cat, and if so, did you hear a rattle within?

A bad/blocked Cat might cause symptoms as you described.
Also, seems like I read recently in another thread that a bad Cat/O2 sensor could also post a MAF code...

MW

it has a terrible rattle from underneath sounds like loose cat pieces probably. wat does the average cat cost and skill level to replace? and could it be a combination of MAF and bad CAT/ O2 sensor? i dunno im not the greatest diagnoser but i can hang parts pretty well

01ssei wrote:it has a terrible rattle from underneath sounds like loose cat pieces probably. wat does the average cat cost and skill level to replace? and could it be a combination of MAF and bad CAT/ O2 sensor? i dunno im not the greatest diagnoser but i can hang parts pretty well

Well now!
There is your starting point. Replace the Cat immediately, and then see if your symptoms disappear.
Have them clear all codes after the new one is installed, and drive it for awhile, MAF cleaned and reconnected. That should go a long way in restoring your performance.

As to Cat costs, etc, do a search here in this forum, as there are numerous threads with explicit details, far above my pay grade.
;-)

Good luck,

MW

have you pulled the spark plug from that cyl? what does it look like? If you had a broke valve spring you would have way more problems..

when was your last plug/wire change? check the connections on the wire to the coils to see if they are all crusty..

i have recently replaced plugs and wires in last 12k.

do they make direct fit bolt on cats or would i have to cut n weld a new one in?