Rough Idle when warm

Discussion in '95-older Toyota Truck Tech' started by dennisla, Feb 17, 2009.

  1. dennisla

    dennisla

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    I have a 94 22-RE, When it cold starts everything is smooth and normal, after about 3-4min it starts to miss from idle all the way thru high RPM. When driving I dont feel the miss only when in neutral. When I come to a light it doesn't idle great but its not bad. It is bad however when I turn the truck off and go into a store or something (not let it cool down) come back to start it and it idles real rough and low. Once I start driving it back to somewhat normal. I've checked TPS, EGR (valve and modulator), it has new ignition cables plugs, and rotor w/cap. Air filter is new. Any Ideas??
     
  2. raydouble

    raydouble

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    Timing and rpm adjustment
    and
    Coolant temp sensor, I would check that.
     
  3. MStars

    MStars

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    coolant temp sensor made a world of difference for me. $20 at Napa. I had a bit different symptoms than you but it resolved several things for me. Good luck
     
  4. raydouble

    raydouble

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    Valve adjustment also.
     
  5. dennisla

    dennisla

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    Well as far as valve adjustment, last december I replaced the head with a stock new OEM head and an LC engineering street performance cam. Since the install I have adjusted the cam to OEM spec twice. The street performance cam is set up to be as performance increasing as possible with out messing with the computer. LC engineering said to adjust it to manufactures spec. Each time I have gone in there to adjust the valves, I haven't noticed any valve being off too much. And the timing was adusted at the head replacement, though I'm going to check it again just incase it has moved on me.

    And as for the cooling system sensor. I noticed on the OBD II reader that the sensor was registering the temp of the coolant and it seemed to be accurate. When this temp sensor failed did it completely fail of give irronious readings??
     
  6. raydouble

    raydouble

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    Your 94 has a OBDII plug in the cab? :confused::confused:
     
  7. 2ndGenToyotaFan

    2ndGenToyotaFan Ice-Bound Moderator

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    It's complicated....
    There may be more than one temp sensor....
     
  8. dennisla

    dennisla

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    no, I used the diag port under the hood. A buddy of mine has a super fancy snap on OBD II conputer that had an adapter. The truck was hot, though the reader needed power to operate and I guess the engine has to be running to get power to the port. Even then I couldn't download any faults. It wasn't a whole lot of help but it gave me some good information. I didn't know either that there are trouble shooting steps for all kind of things porgrammed in that reader.
     
  9. dennisla

    dennisla

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    Well I was hoping that someone would mention what I think it may be. I'm guessing that when the engine is cold the cold start injector is operating and riching the mixture enough all of the cylinders will operate ok, but when the cold start shuts off then the miss begains to take place in one or more cyclinders, due to an injector running lean or being clogged. Does anyone agree or disagree? I haven't done a thing to my injectors as far as I know there original.
     
  10. dennisla

    dennisla

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    Anybody know how many coolant temp sensors there are and where they are on the 22RE?
     
  11. 2ndGenToyotaFan

    2ndGenToyotaFan Ice-Bound Moderator

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    It's complicated....
  12. Dano

    Dano

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    has anyone concidered about vaccum

    I dont know to much on the 22re, how ever I have noticed on both of my trucks 89 and 99 that toyota likes to use thermostatic vaccum switches. If one of these has failed or there is a hole in the vaccum hose after the switch it could potentially cause similar simptoms. might be worth checking out before spending any mony.
     
  13. dennisla

    dennisla

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    Well I am interested in situations that can cause a lean condition and methods to troubleshoot them. I don't want to replace all my injectors and find out it was a temp sensor or vaccume leak. Any Ideas. I'm thinking if a computer or some kind of module is being givin false information it may think its richer or what ever, and lean out the air/fuel mixture. I've gone thru my vacume system and dont hear or notice a vaccume leak. Thats not to say there is. Is there a sure fire way to test all of those little hoses??
     
  14. dennisla

    dennisla

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    I trouble shot the vaccum system and in doing so checked the EGR valve and modulator, no discrepancy's, but I also checked the Mass Air Flow sensor. I read the resistance to the pins and it called out for and the values didn't fall in spec with the book. I didn't pay too much attention because I figured if the thing is bad it would be throwing a code. And I didn't want to admit that it was bad because its stupid expensive. But I'd hate to replace injectors to find out it could be a fuel filter or MAF sensor.
     
  15. raydouble

    raydouble

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    The VAF meter on a 22RE has fuel pump connections inside, if it's out of spec, find one that is within specs.
    Are you using this page for testing?
    http://www.ncttora.com/fsm/1993/engine/33volumeai.pdf
     
  16. dennisla

    dennisla

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    Well I tested the Mass Air Flow meter, and using raydouble's handy spec sheet (thanx) and its all within spec, I musta been doing something wrong the first time or chelton had his head up his ass. well that is a releif. So I'm back to possibly vacuum switch, injectors, or fuel filter. I guess I know what I'm doing this weekend. Any good tips on replacing that thing other than removing the engine? I'm curious though about the in tank pump and filter element. Is that a good thing to tackle or are they relitively not an issue?
     
  17. Dano

    Dano

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    ether

    Warm the engine so it will run rough then use a can of ether to spray vac. modulators, vac switches, vac lines ect. the engine should rev up when and if the ether is sucked into the engine.
     
  18. morganism

    morganism SunkCostFallacy

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    are you at altititude ? the vac senor for the older ones has a breather on the bottom that should be cleaned, and the big mama would have bad hoses all the time.

    you should also try (after warmed up) shaking the pos wire off the battery to the main fuse block.
    it is a bad connection on all the 2nd gens, it may be braking down on yours too.
    also try tapping on the coil.

    check the vac hoses on your vac advance on the dist? they run over the top of your engine, if you have them, and go bad on other engines.

    don't use any plugs other than NGK
     
  19. elvi

    elvi

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    FYI; the 3.slo and 22RE AFM's are different. Chiltons may have had data for the V6 unit.
     
  20. CookieJR

    CookieJR

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    Im having a similar problem with my 3slow it runs for about 5 minutes till warm (-15 here now) then will idle down and up its enoying to drive when u stop. Especially when i was trying to get coffee at timmies because they thought i was revving the motor to be enoying....any ways i cleaned the TB and the filter which helped longgate the revving to a slower on and off i did mess around with the intake hoses and clamps prior to the problem.. for some reason if i pull the big vac line right before the TB, so its sucking more air it idles normal wtf? any help would be greatly appricaited
     
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