OnOiShNo0dl3Z

iTrader: (2)

Details on Car:
The car is an 02 3.5 6MT.
The codes I have are p0420, p0430, and p0442.
The car idles fine at around 650 rpm.
The car shifts fine.
According to a few mechanics, transmission looks pretty new as of last year and I have filled the transmission with Amsoil Gear Oil for about a year.
I've had all these codes prior to this new problem.
No leaks anywhere.
Car starts fine.
NGK IX Iridium Spark plugs for less than 15000 miles.
Fuel filter and O ring done less than 8000 miles ago.

Many of you might know the p0420 & p0430 are for bad precats/O2 sensors.
The p0442 is for a small evap leak (had code for about two weeks now).

Problem:
Out of nowhere, last night while driving in 1st and second gear, if I accelerate slowly, or sometimes just trying to hold speed, the car bucks while driving.

This morning, I noticed it in 2nd, 3rd, and 4th gear. I noticed if I'm on the throttle hard enough, the bucking doesn't happen. I don't really drive the car hard so I haven't yet tried pushing the car past 2500 rpm.

If I try to drive at a constant speed in 2nd to 4th gear or accelerate slowly, I get this bucking issue. It didn't always happen this morning, but it happened often.

I also noticed that it tends to happen between 1500 to 2000 rpm. (The way I drive, I usually shift by 2000 - 2200 rpm.)

In Both instances (last night and this morning) I noticed it when the car was warmed up.

Can anyone please help me. Right now I'm suspecting the MAF, or possibly the tranny.

Rochester

iTrader: (3)

"bucking" is a phrase I'd associate with misfire behavior from a failing coilpack.

02whitemaximase

iTrader: (38)

Does the cel flash? It flashes on and off for misfires.

knight_yyz

iTrader: (40)

if you can't get above 3k rpm I would suspect the MAF

OnOiShNo0dl3Z

iTrader: (2)

It could be a misfire, I've had a p0302 in the past and have replaced the ignition coil. I pulled my codes last night by watching the blinking CEL. I don't know if bucking is the right phrase, maybe jerking?

It's that feeling you get when you experience the fuel cut off when you try to take your foot off the gas in first gear which I'm sure the 6MT owners are familiar with. It usually is less pronounced in higher gears (3 and 4) and barely noticeable in 5 and 6 and only happens once, whereas my issue sorta jerks maybe 3-5 times.

I get this 'jerking' that happens for a few seconds when trying to hold the car at say 27 mph or so in 3rd gear, or about 35 ish mph in 4th gear (within that 1500-2000 rpm window).

OnOiShNo0dl3Z

iTrader: (2)

I'll definitely try pushing it a bit more later past 3000 rpm, but from what I saw this morning, I wasn't experiencing loss of power.

No CEL flashing from what I noticed.

I haven't had a chance to look under the hood yet due to it being too dark last night and raining this morning.

Does this sound like a transmission issue at all? I sure as heck hope not...

02whitemaximase

iTrader: (38)

Transmission does not sound like the problem. I have had two separate issues that somewhat caused the "surging" feeling. The first was for a general misfire which had a flashing cel. I attributed it to either a failing coil or bad gas. Only lasted a couple days and now a few months later the car is running perfectly fine. The other was a failing throttle body (the drive by wire sensor for the butterfly). Again this gave me a cel.

ImStricken

does your speedo have a problem?
if you have a CEL and your speedo is unplugged- you will get this under acceleration.

also check your MAF

OnOiShNo0dl3Z

iTrader: (2)

I'll look for it again, but I don't recall seeing the CEL flash.

The speedo seems to be working fine as well. I'll pay attention to these and also check to make sure no wires are loose or broken on the connector to the MAF after work.

Seems like most are thinking this is a misfire issue or the MAF. I'm leaning toward's MAF as well since I didn't see a CEL flash, but I'll pay attention on my 25 mile commute home.

Hope mine goes away in a few days as well..

PS: Just realized that i might have caused some confusion about blinking CEL. I used the procedure that is similar to resetting your ECU to pull the codes. So far, while doing regular driving, the CEL IS on, but not blinking as in the case of a really bad misfire.

Bufflomike

If the CEL light is lit, knowing the code would help diagnose this problem. I am guessing a bad MAF

OnOiShNo0dl3Z

iTrader: (2)

So I had to drive the car after work stuck in traffic for a good 2 hours...

I'm much more certain that it's the MAF now, but if some experts can confirm that these issues are all MAF related, that'd be great:

When accelerating, once I get to about 2300 or 2400 rpm, the car no longer accelerates. I just keep getting this feeling like the car is being yanked back if it tries to go above 2400 rpm.

With sudden changes in throttle application, the car kinda surges or has hiccups.

My idle RPM is now at about 1000 rpm. With the defroster on, it sometimes go to 1100, and at times dips down to about 900 rpm.

The car feels slow, definite loss of power.

All of these seem to me like it's a problem with the MAF if not the connector To the MAF.

I'll try to clean the MAF sensor when I have a chance (break from work and the rain) and if that doesn't do it, I guess I'll try and do the 2k2 to 2k1 MAF swap.

Can someone check to confirm that all of those symptoms sound normal for a bad MAF sensor, or mention anything else it could be if it isn't the MAF sensor.

Mr. Blue Sky

iTrader: (1)

from what I know, that is a symptom of the MAF going bad. Your car is probably in limp mode, not allowing you to go above 2400-2500 RPM

OnOiShNo0dl3Z

iTrader: (2)

Alright. How about the high idle thing? That's the only thing I'm uncertain of. I'm not sure if that's related to the bad MAF. I've seen bad MAF's cause unstable idles, but not sure about the high idle. Either way, I'll have to try and clean/replace the MAF this weekend.

nsnrider

iTrader: (59)

try cleaning the maf and performing the idle air volume learning procedure to try to correct your idle.

nsnrider

iTrader: (59)

also, as a side note, if your cats have been clogged up for a while and at one point you had a misfire, you cats might be clogged up to a point that they barely allow exhaust flow, i've seen cars that would completely die after warming up and then won't start at all all due to clogged up cats.

But based on you symptoms described above, I'm leaning towards a bad maf.

OnOiShNo0dl3Z

iTrader: (2)

As pretty much everyone expected, the issue was indeed the MAF.

After leaving it sit for about 3 days, I had a chance to drive it around the block and thought the issue corrected itself. Right after I thought it was fixed, it happened again.

I went ahead and used some MAF cleaner I had lying around on it and sprayed it down following the instructions on the clean your maf for under $10 thread. It worked until i got down the block.

I took it back out, read the instructions on the bottle (which say to spray it about 7-8 times), and blasted the heck outta the dam thing. Drove around for a good 20-30 minutes and everything seems good. Hope it stays that way.

Thanks for the help everyone.

Edit: I suppose I spoke too soon. Went for a drive about an hour later and the MAF is acting up again. Guess I'll move onto trying the 5.5 gen to 5th gen MAF swap.

Edit 2: Issue fixed after replacing MAF with an 01 MAF w/ thermistor swap.