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Engine Hesitation under Medium Acceleration (Ignition Coil?)

Discussion in '2nd Gen. Tacomas (2005-2015)' started by geogecko, May 12, 2017.

  1. May 12, 2017 at 12:28 PM
    #1
    geogecko

    geogecko [OP] Well-Known Member

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    For the past year or as long as I can remember, I've had a fairly consistent engine hesitation with my 2005 Tacoma (V6 with 180k miles), but have yet to figure out what exactly is causing the problem (I'm not getting a CEL.) I am currently leaning towards a bad coil pack on one of the cylinders, and below I will list out the conditions, and why I think this. My problem is, since I want to go with OE parts, is there a way to determine, reliably, which one is bad, since these are $50+ a piece?

    Symptoms:
    Idle and WOT acceleration seems normal 100% of the time.
    Hesitation seems to happen the most, when getting on the highway via on-ramp, under medium acceleration, meaning not full throttle downshifting, but somewhere in the middle, where it stays in a higher gear, but the transmission is on the verge of downshifting.
    Hesitation happens while the accelerator is in a constant position.

    Maintenance that has had No Effect:
    Spark Plugs have been changed regularly every 30k miles (OE plugs).
    Air Filter has been changed every 30k miles.
    MAF sensor and Throttle Body have both been cleaned 3 times over the 180k miles.
    Driver's side heated A/F ratio sensor was replaced (CEL code indicated).
    I have not done any fuel related maintenance (i.e., fuel filter, injector cleaners, etc)

    Ruled Out (possibly?):
    Fuel related, because WOT and idle seem to be okay, so does not seem like a fuel pressure, fuel filter, fuel pump, or injector clogged issue (perhaps the electronic part of an injector is bad?)
    Spark plugs, as they have been changed since I noticed the issue.

    I did notice that when I replaced the spark plugs, that it looked like the potting on one of the coil packs was cracked across the top. I couldn't determine if it was really cracked, or if it was cosmetic, but when I tried to pull apart the potting with my fingers, it did not seem to pull apart into two halves.

    That being said, is there any way to determine if a coil pack is bad? Since this problem does not seem to exist at idle or WOT, I would think the resistance checking method may not work, as it may check out fine, and then have a failure/short when under heavy load... I was thinking of just buying one new coil pack, and rotating it through all 6 cylinders, driving around for a few days with it in place, until I notice the problem going away, but that just seems like it could take a while... Has anyone had this issue? Do injector electronics go bad? How can you test those?
     
  2. May 12, 2017 at 6:22 PM
    #2
    cliffyk

    cliffyk Well-Known Member

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    Get one of these ($9 on Amazon), some FLAPS stock them also, set the gap to 10 to 12 mm, and test each coil.

    [​IMG]

    1. Stop engine;
    2. Pull COP;
    3. insert tool into COP and connect tool ground;
    4. Have an assistant start the engine while you observe the spark
      (do not let the COP fire across the large gap for more than 5 to 7 seconds as it might overheat);
    5. Move on to the next COP;
    A good coil should easily fire across a 10-12 mm air gap--look for consistency in the spark across all the coils, If one seems weak open up the air gap to 15 mm and see what happens--again do not let it fire for more than 5 to 10 seconds.

    Here is what you will see:
    http://www.paladinmicro.com/images/CIKCOPTester01.mp4
     
    TRDSport10 and Biscuits like this.
  3. May 13, 2017 at 9:17 PM
    #3
    geogecko

    geogecko [OP] Well-Known Member

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    Wow, thanks Cliff, I like the price on that too. I'll give that a try. Seems like whatever the problem is, it's getting worse, so need to get it fixed soon.
     
  4. May 22, 2017 at 1:24 PM
    #4
    geogecko

    geogecko [OP] Well-Known Member

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    Well, ordered one of the Denso ignition coils, and decided to just try swapping the easiest coil, which happened to be the one that has the cracked potting on the back. Initially, it seems to have solved the problem, but going to give it a few days to make sure. Seems to be a lot smoother.
     
  5. Jul 28, 2018 at 9:23 AM
    #5
    scootter82

    scootter82 Well-Known Member

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    What was the outcome of this? I'm replacing my spark plugs soon, and was looking into proactively replacing the ignition coils. Did you end up replacing the rest, and did you see a noticeable difference? I only have 60k miles on the truck, but I'm the second owner and it has a supercharger. Not sure if the plugs have ever been changed.
     
  6. Jul 28, 2018 at 10:46 AM
    #6
    Torspd

    Torspd Tor-nication

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    Vacuum hoses and new fuel filter. OP hasn't been on since Feb., though....
     
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  7. Jul 28, 2018 at 10:52 AM
    #7
    b_r_o

    b_r_o We need to talk about your flair

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    Just some advice for anyone who stumbles across this thread.. if you think you have a cracked coil, spray it with some soapy water mixture when the engine is running. The water will go down in the crack and you may see some arcing. The soapy water mixture helps draw the "spark leak" out into the daylight where you can see it
     
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  8. Jul 28, 2018 at 3:14 PM
    #8
    geogecko

    geogecko [OP] Well-Known Member

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    Hi, yep, been a while. I will say that the coil pack, at least, in the position I put it in, has not fixed the issue. I’m leaning more towards the vacuum hoses. That will be a chore, but probably needs to be done anyway, along with the coolant hoses...still at a loss as to what the issue is, but really don’t want to take it into the dealer.
     
  9. Jul 29, 2018 at 5:13 AM
    #9
    blacktaco07

    blacktaco07 Active Member

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    Hope this helps, I had the exact same problem in my 2007. Just like you I tested most ignition parts etc... then I decided to get a friend of mine connect his Scan tool to the truck while driving. All we watched was the fuel pressure while driving. At the exact time it would(surge/cut-out) the fuel pressure would drop to 30 PSI and then immediately recover to 50+. Changed the fuel pump and never had a problem since.

    Good luck, hope this helps
     
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  10. Jul 31, 2018 at 6:45 PM
    #10
    geogecko

    geogecko [OP] Well-Known Member

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    Interesting, I have a scanguage hooked up permanatly, will have to look in the manual to find out which gauge that is, unless you happen to know off hand. Thanks for that, I’ve checked the TPS, and it’s reading seems to remain pretty constant during the surging...
     
  11. Jul 31, 2018 at 10:09 PM
    #11
    Junkyardog

    Junkyardog Well-Known Member

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    I'm having the same hesitation no cel just no throttle response and it's back, I have replaced the tps and throttle body from another Tacoma and still have the problem, I'm going to hook up my scanner n hope this is the problem. Thanks in advance

    Anyone ever have problems with the gas pedal drive by wire??
     
  12. Jul 31, 2018 at 10:39 PM
    #12
    geogecko

    geogecko [OP] Well-Known Member

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    Well, my SGII isn’t picking up the fuel pressure that is built in. I entered an x-gauge setup for it, and it’s returning some values, but it’s jibberish right now. The code I found says it only works with a newer version of firmware I don’t have...would have to send the unit in to be flashed. I may end up doing that anyway, just to get it updated. Sure wish they had field updating available for these things...
     
  13. Aug 1, 2018 at 2:32 AM
    #13
    blacktaco07

    blacktaco07 Active Member

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    Your other option, which may be better is to connect a fuel pressure gauge, (lots of info on this Forum on how to connect to the fuel line) and run the gauge inside and take it for a drive. I know in. My case, I could predict when it was coming to happen, as it was always up a ramp getting up to speed and at approximately 40 Mph. good luck
     
  14. Aug 1, 2018 at 4:23 AM
    #14
    craigs1

    craigs1 Well-Known Member

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    While you're scanning, check the Long Term Fuel Trim values for bank 1 and bank 2 during idle and steady-throttle cruising. They should be closely balanced, and should range from -3% to +3% based on what I've seen with other V-type engines. On my 4Runner, the values change in increments of 0.78%, hot idle ranges from -0.78% to +1.56% on both banks. Highest value I've seen has been +2.34% (0.78 * 3).

    If they're imbalanced significantly, it's likely an injector issue. If they're balanced but unusually high (positive trim values) it's likely a fuel delivery issue e.g. fuel pump, clogged filter, fuel pressure regulator weak.
     
  15. Aug 1, 2018 at 3:51 PM
    #15
    michael636

    michael636 Well-Known Member

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    My truck seems to hesitate from stop signs on regular occasion... Any ideas?
     
  16. Aug 3, 2018 at 9:16 AM
    #16
    Junkyardog

    Junkyardog Well-Known Member

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    Follow this thread closely, this is what’s happening to our trucks as well!!
     
  17. Dec 4, 2018 at 6:52 AM
    #17
    Jamers99

    Jamers99 Well-Known Member

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    So why would it hesitate around 40 mph? Could you describe what it felt like. I'm getting something weird around 40-45 mph under very light acceleration. Did you have to replace the fuel pump? If so, how much was it?
     
  18. Jan 6, 2020 at 3:54 PM
    #18
    ToyotaTod98

    ToyotaTod98 Well-Known Member

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    Hey guys, I'm trying to change my spark plugs on my 98 taco and everything is dry rotted and cracking and pulling apart. I got the spark plugs replaced on the driver's side ( which I had a end of a boot break off down in there and had to dig it out with a hanger) and it was the one against the fire wall. But got that side done after several hours of fighting with all the broken plastic pieces on the boots and the boots tearing apart themselves. But when I got to the other side I took out the bolt on the first coil pack and unhooked everything and lifted straight up while wiggling and the darn thing came apart. Like it was a two piece, the head came right off and the boot was stuck on the valve cover and spark plug. So I tried pulling the boot but it started to year, and so I pulled a little on the metal center piece and it came right out with the spring!!! So after shitting down both legs I put it back together and prayed like hell. Luckily it runs fine and there is no engine light on. So I'm going to have to get the spark plugs changed. But I had to take a break, so I'll do it when I can get a backup coil pack, in case I tear one all to hell. Has anyone ran into this? And have you pulled it apart like I did? And is there a way to get that fragile dry rotted shit off without tearing them up? I have a 98 taco limited with 220,000 miles and I got it 4 months ago and I have just been doing preventive maintenance on it. Cause it's obvious that no one has done anything to the truck, but it has been taken care of and has probably never seen a gravel road. I'm the 3rd owner and the guy I got it from only put 25000 miles on it and he parked it for a year cause deisiel went back down so he was going to give it to his grandson when he got old enough, But I talked him out of it and I feel pretty lucky cause it's a limited and everything worked on it. Power mirrors and all!! It just had tree sap all over it and was black. Even though it's white. But I guess the sap saved the clear coat cause after washing and waxing it, it looks brand new!! And the first owner lived in California but was a nerd, from what the guy told me and never did anything to the truck but had all of the paperwork where he had the dealership in alburn Cali. Change the oil! So I feel I got a great truck, but as with all old ones there are some things that need replacing. I replaced the clutch , which was original. And the CV axles, cause the boots tore when I started driving it. But everything is original except the water pump and timing belt and rebuilt alternator, and steering pump, which the previous owner did before he parked it. And I put a lift and wheels and tires on it but other than that I'm just trying to take care of it cause it's my only vehicle. I've done all the fluids and change the oil every 4000 no matter what. So I'm to the spark plugs and wires. And then I'm going to do the valve cover gaskets and all of that stuff that goes with it, as many on here have done. But I wanted to do the plugs and wires before I did the gaskets so incase when I do , if it doesn't run right then that will be easier to diagnose! So if anyone has ran into this where someone didn't use elec.lube or as my case maybe not had them done in a while to where their a bitch, then let me know how you went about it? Cause I know someone if not many has had to on here. This site is the shit for Taco's.
     
  19. Apr 19, 2021 at 1:23 PM
    #19
    RocketTaco808

    RocketTaco808 Active Member

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    Anyone solve their hesitation?

    @Torps, I’ll take your advice and chew through the bacon system. *Vacuum system, not bacon system Thanks!
     
  20. Apr 19, 2021 at 1:28 PM
    #20
    RocketTaco808

    RocketTaco808 Active Member

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    Glad you got things back together.. agree with getting a replacement coil pack.

    You should start a new thread on the forum for first gen Tacoma’s, not hijack a thread for second gen Tacomas with a specific issue. Also, do this for each individual issue you’re experiencing, otherwise it gets way to confusing. I appreciate details, but soooo many words!
     

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