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Lean and hot

Discussion in '3rd Gen 4Runners (1996-2002)' started by Jesse.h, Aug 6, 2022.

  1. Aug 6, 2022 at 4:52 PM
    #1
    Jesse.h

    Jesse.h [OP] New Member

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    Just throwing parts at this 4runner with 186k. Replaced water pump and timing belt with aisin products. Replaced thermostat, fuel filter, fan clutch, and radiator. Engine is running smooth but slight loss of power. It still runs hot up grades but runs normal to cool just cruising and idling. Exactly the same as before the replacements. The smog test read high N.O. at double the max. I checked vacuum lines. No leaks. No water in oil and coolant looks clean. Head gasket is still good. Could a bad mass airflow sensor cause this? Usually a bad one causes the engine to run sporadically. Im about to replace fuel injectors as a last resort and then the fuel pump. I know that a lack of fuel can cause hotter combustion
     
  2. Aug 6, 2022 at 7:43 PM
    #2
    negusm

    negusm New Member

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    Injectors aren't going to fix overheating or a fuel pump. Never heard a failing MAF causing significant overheating either. They may fix the NOX issue if the NOX is not related to overheating.

    Did you get the TOYOTA thermostat and put it in the correct orientation? The OEM one has a hole with a dangle in it that I think goes at 6 o'clock?

    Before you do anything else, get a coolant test kit. Just a little exhaust gas in the coolant will make it run hot. You can't see it. But the kit will turn color and tell you right away.

    Pull your plugs and what do you see? Are they the correct OEM TOYOTA plugs?
     
    2Toys likes this.
  3. Aug 6, 2022 at 9:33 PM
    #3
    Jesse.h

    Jesse.h [OP] New Member

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    The thermostat is at 6 o'clock. Temp is running same as before. The plugs were changed by a toyota dealership a few years ago. I will pull one to.get.a look at the color. When I replaced the upstream 02 sensor it was white like it's burning lean. Good thinking on the coolant test. Would a vacuum leak be the cause? A bad egr or pcv valve?
     
  4. Aug 7, 2022 at 9:11 PM
    #4
    negusm

    negusm New Member

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    What engine do you have?
     
  5. Aug 8, 2022 at 10:46 AM
    #5
    Jesse.h

    Jesse.h [OP] New Member

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    5vz-e 3.4l v6. Im wondering if the oil cooler needs to be replaced. It's the only original part left in the cooling system
     
  6. Aug 9, 2022 at 7:57 AM
    #6
    Kwikvette

    Kwikvette New Member

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    Do a fan clutch test; use a roll of newspaper if you do so with the vehicle on.

    Otherwise, see if it moves freely by hand after the vehicle is fully warmed up and off.

    Can't comment on the lean issue.
     
    suaveflooder likes this.
  7. Aug 9, 2022 at 8:47 AM
    #7
    negusm

    negusm New Member

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    Not sure how those can go bad. I think it's just a heat exchanger between the oil and coolant. It's possible that it could get blocked but if it really failed I bet you'd get coolant and oil mixing.
     
  8. Aug 9, 2022 at 8:49 AM
    #8
    negusm

    negusm New Member

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    If it wasn't the 3.4L, I'd recommend burping it. But I've never had to burp mine or worry about air trapped in the cooling system.
     
  9. Aug 9, 2022 at 8:51 AM
    #9
    nimby

    nimby in the drink

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    Damn.

    I thought this thread was going to be about something totally different. :pout:
     
    suaveflooder, 4scooter19 and qcTRDct like this.
  10. Aug 9, 2022 at 8:53 AM
    #10
    SR5 Limited

    SR5 Limited New Member

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    3rd gens have a thermostat?
     
  11. Aug 9, 2022 at 9:03 AM
    #11
    Kwikvette

    Kwikvette New Member

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    Of course.

    Located in the area forward and below the diagnostic port.

    Held by 3 10mm or 12mm nuts, accessed by a six wall deep socket. A small swivel helps.
     
  12. Aug 9, 2022 at 9:11 AM
    #12
    Jesse.h

    Jesse.h [OP] New Member

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    I replaced the fan clutch with oem-aisin. Turns out the old one is still good. I hope it's not the head gaskets. I will have to do a coolant test
     
  13. Aug 9, 2022 at 9:27 AM
    #13
    Jesse.h

    Jesse.h [OP] New Member

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    So there is a bypass on the water pump that goes to the oil cooler. When I replaced the water pump I noticed the hose to the oil cooler was oily on the inside wall of the hose but the coolant was not contaminated.
     
  14. Sep 13, 2022 at 10:26 AM
    #14
    standard

    standard New Member

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    stock so far, what could he possibly need
    federal or ca emissions? can you see air/fuel on a screen? my 99 federal uses the same O2 sensor at B1S1 [bank1 sensor1] and S2, so i can't get SCANGAGE to post an A/F value, but I can see the fuel trims using Torque app on my phone and bafx obd2 interface. if you have a ca emissions the s1 sensor is different and does give the A/F ratio. you can test the sensors with a VOM [volt ohm meter] at the plug connectors. you can get a half dozen injectors off amazn for 76$, yeah, from china. I recently used three of them to get me home from Texas. they replaced some recently installed denso oem injectors, one of which failed at 2700 miles, and the other two broke off the nose cones when I pulled the bank 2 fuel rail. AAAaargh... so, 76$ is what the parts stores charge for one injector. buying 6 gives you lots of investigative options. ciao
     
  15. Sep 14, 2022 at 9:43 PM
    #15
    Jesse.h

    Jesse.h [OP] New Member

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    CA emissions. I threw in 6 newfuel injectors from Ebay. $60. In new original toyota boxes. They are identical to the factory injectors. Went from lean to rich. Now there is a hesitation problem snapping the throttle from idle. If it's revved above 2k it's responsive. It ripps under a load at full throttle. More.power than before. I had to remove the intake manifold to replace the injectors and looking for missed vacuum lines but they are good. It seems like a vacuum problem but it might be the new injectors or the fuel pressure regulator but it starts up right away and idles ok. I'm stumped but not gonna give up yet. Tempted to put the old injectors back and see if the hesitation problem goes away
     
    standard likes this.
  16. Sep 14, 2022 at 9:53 PM
    #16
    negusm

    negusm New Member

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    No way did you get 6 authentic TOYOTA injectors for $60.
     
  17. Sep 14, 2022 at 10:53 PM
    #17
    standard

    standard New Member

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    stock so far, what could he possibly need
    wish i could help you on this. in the spring i had lots of gremlins that i chased down one by one. i put those same factory injectors in and one seized up at 2500 miles. tested it with meter and it was Dead. One of the "new" coil packs also failed. gremlins.

    first thing with this truck i replaced the coils, wires and plugs. that moved the miss to another cylinder so i put in a new set of injectors. i finally got to the IAC valve, it was all coked up, and after I cleaned it and reassembled it the MISS WAS GONE. process of elimination. gotta love an engine that uses bicycle cable technology for the throttle and cruise control and transmission ! ;)

    I am going to use propane to hunt for vacuum leaks next. Hope it's that simple.

    ciao
     
  18. Sep 15, 2022 at 12:40 PM
    #18
    Jesse.h

    Jesse.h [OP] New Member

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    It's true. 6 authentic toyota injectors for $60. Check it out on ebay. There are multiple sellers. To good to be true? Maybe so and why I'm having a rich problem. I tested each one with an ohm meter and they all check out. It did fix the above normal temp under a load. Now the temp Guage doesn't budge at a notch below normal even With the ac on a hot day. Also replaced the IAC. Fixed the low idle problem but now it's idling high. Again seems like a vacuum problem and I checked lines several times. Going to replace fuel regulator while I'm in there
     
  19. Sep 15, 2022 at 6:17 PM
    #19
    negusm

    negusm New Member

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    No way, no how. That's $10 per injector. And yes, they print boxes to fool buyers. Plenty of youtube vids on spotting the slight differences.

    Running rich is a typical problem of the knockoffs.
     
  20. Sep 15, 2022 at 6:19 PM
    #20
    negusm

    negusm New Member

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  21. Sep 15, 2022 at 7:39 PM
    #21
    Ahdofu

    Ahdofu New Member

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    I wish a Toyota injector was $10 but that is way too good to be true. The one that I bought from McGeorge went for $168
     
  22. Sep 16, 2022 at 5:58 PM
    #22
    Jesse.h

    Jesse.h [OP] New Member

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    The dealer sells them for 240 a pop. I should have known. Thanks for the thread. At least I know what the problem is now. Anyone know of a decent injector that's not oem?
     
  23. Sep 16, 2022 at 6:03 PM
    #23
    negusm

    negusm New Member

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    Best thing I have seen is to send your injectors out to be flow tested or have them swapped for a flow tested refurbished OEM set. It'll run north of $200 to do all 6.

    You can get a replacement at a big box auto store and they should be ok but they won't be Toyota quality... Better than ebay though.
     
  24. Sep 16, 2022 at 6:08 PM
    #24
    Jesse.h

    Jesse.h [OP] New Member

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    They fooled me good. They look identical to the original. Part# on the side and same colors
     
  25. Sep 16, 2022 at 6:11 PM
    #25
    Jesse.h

    Jesse.h [OP] New Member

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    I will try cleaning the old ones first. They were just not flowing enough. Maybe just dirty
     
  26. Sep 16, 2022 at 6:14 PM
    #26
    negusm

    negusm New Member

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    There are some good YouTube videos on cleaning and flow testing on a bench.

    Good thing is you have 2 sets...so the car isn't immobile.
     
  27. Sep 16, 2022 at 6:15 PM
    #27
    negusm

    negusm New Member

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  28. Sep 16, 2022 at 6:21 PM
    #28
    Jesse.h

    Jesse.h [OP] New Member

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    I'm afraid to run those Ebay injectors. Plus I'm in CA and don't want to burn out the cat. Thank you these threads are very helpful
     
  29. Sep 16, 2022 at 6:52 PM
    #29
    Ahdofu

    Ahdofu New Member

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    I have used Motorwest Performance in the past. They're in CA and their rate was quite reasonable. They cleaned my injectors, flow tested them and furnished me with a report afterwards. The issue that I had with the missing #4 cylinder went away after the cleaning. Unfortunately after a year one of the injectors failed so I ended up replacing that with a new Toyota injector. Knowing what I know now, I should have replaced all of them with new Toyota injectors. McGeorge Toyota probably has the best price for them.
     
  30. Sep 16, 2022 at 7:04 PM
    #30
    Jesse.h

    Jesse.h [OP] New Member

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    If cleaning the original injectors doesn't solve the problem I will get toyota injectors. The engine is worth it
     

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