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Thread: Misfire codes again P0300, P0301, and P0302

  1. #1

    Misfire codes again P0300, P0301, and P0302

    Hi all,

    Back in 2012 I was replacing my Lower control arm bushings and encountered two PO300 codes (P0303 and PO304). Link is here: http://www.ultimateyota.com/showthre...ighlight=p0300

    Anyways, on my drive down to get a new catalytic converter installed (per my smog guy's 4 year insistence!), the dreaded blinking check engine light started to go off. Greaat. I had the cat installed no problem, but on the drive up, my scan tool pulled up another code. So as of today, its P0301 and P0302 (note: If you pull more than 2 of these misfire codes, P0300 will show up too; it indicates more than 1 cylinder is misfiring).
    Well as you can imagine, it runs rough. I hardly drive the 4runner and I don't think I've put more than 10,000 miles on this since 2012. No joke because I've been driving Das Gross Polluten machine, my 2013 Golf TDI. So yes, not happy. Because back in 2012, I did the following (in order):

    - Cleaned MAF wire (just by spraying it down w/ MAF cleaner)
    - Switched coil packs around (no effect)
    - Replaced spark plugs and wires
    - Cleaned throttle body but NOT Idle air control valve (I really need to do the IACV)
    - Had injectors rebuilt by Witchhunter

    The injector rebuilds helped solve the problem up until now. So I contacted Witchhunter just now to see if that's common for the rebuild to fail so soon (assuming its the injectors of course). But no response yet.

    So I'm going to do the following again:

    - Cleaned MAF wire (just by spraying it down w/ MAF cleaner)
    - Cleaned throttle body but NOT Idle air control valve (I really need to do the IACV)
    - Switched coil packs around
    - Retest

    - If no change, I'm going to change out the spark plugs.
    - If no change, then going to buy new plug wires
    - If no change, then new coil packs
    - If no change, buy new injectors or rebuilt injectors

    Am i missing anything?


    The suck ass part is that I don't have a garage anymore and I know some busy body will freak out in my apt complex if they see me doing car repairs in my garage port. So either I do this street side or need to find a garage.

    With VW and the gub'ment announcing in late April that VW will need to buy back my Golf + $5000, I'll have some money to re-invest back into the 4Runner as I don't want to buy a new car right away (or at all---but we'll see, b/c that Tesla sedan looks mighty tempting)

  2. #2
    How often between sittings are you driving it? I wonder if the fuel is begging to go bad.
    Also have to changed your fuel filter yet? Maybe there are contaminants getting past and could be gumming up the works up ahead?

    I had a few other responses in my e-mail to you regarding fuel type and the use of a treatment, something to consider.

    That sucks that VW has to buy back the vehicle, end of the TDI forever -_- (Sorry for the Off topic just had to shed a tear for that for a second)

  3. #3
    I'd say it gets driven about every weekend for a few hours. Fuel filter: good thought. Haven't changed that since...long ass time. I'd have to look at the date of my write up! And I'll take a look at your email.

    TDI- it's a really great car. Handled well, excellent mpg, got decent pickup...have to cheat to make it perform so well. Well I'll consider it a win depending on how much I get back!

  4. #4
    Like Avi, I'm wondering about the fuel as well. I'm sure it's not too old if you're driving it every weekend. Besides old fuel, water in the fuel will cause a lot of problems that are hard to diagnose.

    You mentioned it runs rough but how does it idle? And under load?

  5. #5
    Alrighty time for an update: I decided to bust out the official shop manual and see what might've been missed. Quite a list of things I've never done before (including items NOT included in the list above), but seem easy enough. So I'm going to put some tech together that follows this process. Most onerous will be the fuel injectors which I will go out of order and save for last given the tear down.

    Remember, i do NOT have a garage now!

    So i ended up taking off the following parts for cleaning and inspection:

    1) Coil packs and wires
    2) Spark plugs. That damn bar that gets in the way of #6 has a rounded bolt. I need to do something about that.
    3) air cleaner hose
    4) Throttle body (disassembled the IACV from it)

    So the manual specifies for a lot of resistance testing. Unfortunately for me, my multimeter's fuses were blown and I spun my wheels for 2 days straight. Need to find a parts store soon and get those fuses.

    So regarding item #4: curiosity got the best of me and I wanted to see how dirty a never-been-cleaned IACV looked like. Wow, looked pretty sludgy! So since I had an hour before sun down, I took to it and cleaned it up as best I could. I'll give it another go. However in the process, I mangled one of the brass screws. Now talk about a b###h to find in a hardware store or on-line. I think I'll try calling a few Toyota parts dealer via email with pics. I don't think they have these, so I may have to go back to the drawing board and find a seller online for these M5 x .8 screws.

  6. #6
    Mike, I'm going to replace the fuel filter. It sits about 6 to 13-ish days undriven.

    Idling: it does jump around a little bit. Like its hunting for stable idle. I forget the range my OBDII reader pulled up. Under load = rough but still moves. But the blinking light means bad news for the cat...the new cat I don't want to damage so quickly.

  7. #7
    I hear ya on not toasting the new cat.

    Coming home from the Joshua Tree trip years ago was when my IAC started acting up. Every time I'd turn the truck off it would be hell to get it going again. Basically a low garggly idle and even when I'd give it gas it would hiccup and die until I repeated the process two or three times.

    I've replaced all the brass screws I've come across with stainless hex head fasteners. Off the top of my head that's the MAF, TPS and IAC. The brass/zinc coated whatever grabs so hard and the metal is so soft they self destruct. Not to mention the TPS mounting screws are only a few inches from the firewall and even with a short stubby screw driver you're destined to muck them up. If I were you I'd head down to an ACE or even Home Depot and pick up a handful of hex head screws and the thin stainless lock washers. I keep a few extra along with an extra hex wrench in the glove box.

  8. #8
    Mike,

    Thanks for the advice on a replacement type. I actually did that last night and bought a socket head and cheese head hex screws. They're a little shorter. That said, I finally found a toy online dealership that had them in stock. I did a little reading too as to when to use brass over other metal types and it comes down to conductivity and malleability. Make sense since there's coolant passing through the IACV.

    In the meantime, gonna take some time to clean off and label the rest of the pulled parts tonight and start my resistance testing tomorrow when I get the fuses via Amazon.

  9. #9
    You blew the fuse in the meter because you ran power thru it when you had it set to ohms setting. When in ohms. It actually uses the power in the meter to run thru the test leads to figure out ohms. So power to power will blow the fuse.
    88 4Runner LT
    04 Tundra

  10. #10
    I probably did that by mistake when I was learning to use the thing Anyways, problem solved hopefully when I get the fuses.

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