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Calling Mechanics, hunching

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BLAZER F.F.JAPAN, Mar 6, 2000.

  1. BLAZER F.F.JAPAN

    BLAZER F.F.JAPAN Newbie

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    Hello,Guys.My Blazer is 90 350 with auto tranny.I asked about my rough idling on the previous board the other day, and then I was advised to clean TBI and IAC.So I did as I was told, but hunching has not been cured so far.According to the computer scanner,when in open loop,idling is stable but in closed loop there's surging and hunching between 500 rpm and 650-700 rpm when shifting in D. Block learn tells me
    108 at that condition, I think it's in too much fuel condition, right? I checked vacuum hoses there seems to be no leak, so I changed throttle position sensor, MAP sensor, O2 sensor so far to check if this bad condition is improved or not. As for the result, there's no improvement unfortunately.Except for the idling, the rest of the drivabilty is good. There's no trouble code.Water temp is always over 194F.TPS tells 0.7mV, MAP 1.5-8, O2 sensor fluctuates between 0.1-900mV normally at idling in D.I am so puzzled now.What should I do next? Somebody,please help me. Any advice will be greatly appreciated, Thanks.


    BLAZER FANATIC FROM JAPAN
     
  2. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    EGR is my best guess. They will give you all sorts of idle problems but be fine once under way. These are pretty prone to cloging/ sticking. A quick test to see if it's working is to apply vacum to the EGR if the idle gets poor then it's working...if the idle doesn't change then it's usualy an indication that it's stuck open.
    For a Ping problem If the valve seems to be ok and working the feed tube that runs through the intake could be carboned up. Ususaly when they plug it is right where the dump into the plenum divider directly under the carb or in your case under the throttle body. I had one so pluged up you didn't even know the port was there. it looked like an irregularity in the casting. If your carfull you can chip the carbon out and take a vacum to suck it clean without having to remove the intake. This is a cause of a ping problem if it is plugged up. The EGR on the newer vehicles has a position sensor and tied into the ECM. On yours I don't think the EGR is monitored so it would not throw a code.

    Now that I have sombody from Japan within my Cyber reach how about answering a question for me :)
    I am about to purchace a used engine for my Supra that was shipped in from Japan. The story I have been told is that over there you guys cannot install a used motor in your vehicles so many used motors are being shipped to the US. what I have been told is if your engine fails it has to be replaced with new. Is that true?
    Hay something else. My sisters Carolla has a stuck open EGR. They want $120 US here for it. what price are they there. What are you paying for a GM EGR over there? A EGR for that truck you have here is $40 US here.

    Diging it in the dirt with my K5's
    Grim-Reaper
     
  3. 6.2 man

    6.2 man 1/2 ton status Premium Member

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    Besides your egr valve , sounds like maybe your plug wires are maybe cutting out.This might explain why when you heat engine up the wires give out do too heat . Use an ohm meter and check each plug wire for resistance.
     
  4. BLAZER F.F.JAPAN

    BLAZER F.F.JAPAN Newbie

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    Thank you for the helpful advice, I'm really happy to hear from you. As for the EGR,I try to check it once again. I have a new EGR, so I'm going to change it to the new one.

    By the way, about your supra question, second-handed engine is also expensive here in Japan, so your friend told you that it would be better to get the new one with warranty I think.And there still isn't a custom to use the second handed engine to repair, so many cases they will choose to buy a new engine. Car parts are expensive here unfortunately. This time I ordered EGR from your country,but if I ordered the same one in Japan its price would be four times or more, that is 200-300 dollars.Surprised? So your sister's corolla EGR is also not cheap even in Japan,maybe.

    BLAZER FANATIC FROM JAPAN
     
  5. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    I guess not! Heck I was going to work you out a trade! Well thats strange about the engine. I'm getting a complete engine (used) for $1,000 US. It is supose to have the starter and all the FI gear on it. Most of the junk yards around me are wanting $1200 if it has low miles. This one is garanteed to have under 50 thousand miles. They even are putting a year warranty on it and the Junk yard here will only do 90 days.
    A new one from the dealer is listed at $4500 US here. I'll get the used one! Who knows maybe I will luck up and get one that has the Steel HKS head gasket on it.
    Thanks for the reply.


    Diging it in the dirt with my K5's
    Grim-Reaper
     
  6. blazerboy16

    blazerboy16 Registered Member

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    Strange problem you have there. If it’s not you’re EGR valve. You might want to check your PROM if you bought the blazer used someone might have changed the PROM or the ECM, it happened with my 89. A quick way to check is by reading the PROM ID, you can do this with a Snap-On Scan tool I’m not sure what you have for a scan tool but If you get the PROM ID number you can make sure it’s the right one. If you get the number and cant find out if it’s the right one send it to me and I’ll try to help you.
     

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