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SOLVE THIS PROBLEM!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by greg83k5, Jan 29, 2002.

  1. greg83k5

    greg83k5 1/2 ton status

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    truck's an 88 K5, 200,000 miles on the odometer....

    i haven't gotten him to get the error code out of the computer yet, but i wanted to see what you guys thought-

    here's what he told me- (PS our friend eric has a poorly running toyota, that's what the reference is to)

    "on three separate occassions while driving, the engine has suddenly
    become punkish and feels feeble, weak and powerless, (like eric and his
    toyota). with my limited understanding it seems like its not firing
    correctly. now here's what i don't understand - after doing this, the
    check engine lite comes on but if i turn off the truck and turn it back
    on, the light goes off and the truck runs fine. the only other clue
    i've noticed is at least twice when it starts running like [censored] i've
    been idling at a light and felt the engine either surge or almost die
    first and then commence to imitating the toyota."



    so?

    i'll have an error code tomorrow to work with.....


    greg


    * keep the greasy side down *
     
  2. Jed

    Jed Registered Member

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    Could be a connection to one of the various TBI sensors or a sensor itself is flakey. I vaguely recall that the Ultimate A1 project 4x4 (at least it was chevy powered ;) in Petersen's had flakey a manifold temperature sensor on a new crate Ram Jet that caused it to run like crap.
     
  3. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Read the codes. MAP sender could be bad. Bad O2, bad temp sensor, All could cause the problem and throw a light if it goes open.

    Women dig dents and flat paint!
    coloradok5.com/gallery/Grim
    75 Jimmy, Dollar
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  4. greg83k5

    greg83k5 1/2 ton status

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    word.....

    the part about turning it and off clearing up the problem....????!??!?!

    what do you think about that? same thing? maybe taking the current off the sensor kinda lets it act normal again???

    * keep the greasy side down *
     
  5. rampage

    rampage 1/2 ton status

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    I would guess it's the fuel filter. When you turn the truck off and back on, the fuel pump repressurizes the line so the problem temporarily goes away. I had a similar problem and I think the error code it gave out was 42 or 44 (it's been several years since that happened). When's the last time you replaced it?

    <P ID="edit"><FONT class="small">Edited by rampage on 01/29/02 04:56 PM.</FONT></P>
     
  6. Corey-88K5

    Corey-88K5 1/2 ton status

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    I think rampage is correct also. BUT, my truck acted like this RIGHT before the fuel pump went out!

    Corey
    88K5

    [​IMG]<font color=red>Girls Like Guys In Bow Ties
    <a target="_blank" href=http://www.geocities.com/corey_perez>http://www.geocities.com/corey_perez</a>
     
  7. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Well first you got to understand the FI is basic on that truck. There are 2 kinds of codes. Hard code is where there is a failure and the computer keeps the light on. A soft code is a code that may trip a light store in memory but if the problem goes away it will come back off. It will still remember it for a while. Now like I said, thats a pretty early system and not that smart. When you shut the truck down it may kill the light and not throw it till it see's the failure. May not have a true "Hard code". So if something is intermitantly failing the computer looses track of what it's supose to be doing. When you restart the cumputer is back at a known point so it will run till it has that intermitant failure again.
    Read the codes. Even with the light out it should be stored till you reset the computer. It will give you an idea of what to look for. With out the code your going to have to keep trying parts till the problem goes away. Atleast having a code is going to give you a starting point. I will warn you that if you have a code for say something like a Map sensor don't just asume it's the map sensor. It could be a wiring problem, could be a conflict in the computer and thats where it figured out something was wrong is when it refferenced the Map sensor.
    I will tell you this...If I had to guess I would guess fuel related. You would get the light as it died form fuel starvation. When you restart it everything would be fine till it went lean again fron fuel starvation. Most sensors do not go intermitant...they just go. Fuel pump or a fuel pump relay will start building heat and go open. Then when the cool a little they will work till the get hot again. ANd it may be something as simple as a dirty fuel filter is putting excessive load on the pump. It may be to the point the pump is failing.
    Now you know you can read the codes with a paper clip don't you? Go get you a shop manual and it will have the procedure on how to do it and what the codes mean. For what it would cost to have the dealer read the codes you could buy the book.

    Women dig dents and flat paint!
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    75 Jimmy, Dollar
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  8. rampage

    rampage 1/2 ton status

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    Just an FYI: The codes will be lost after the battery is disconnected for 10 mins or if you've started the truck 50 times from what I remember.
     
  9. greg83k5

    greg83k5 1/2 ton status

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    word!

    i have the manual, i always just like to get a premonition from those who may have experienced the same symptoms.....

    i'll be sure to post back what i find out when he retrieves the codes....

    thanks.

    greg



    * keep the greasy side down *
     
  10. BurbinOR

    BurbinOR 3/4 ton status

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    Greg, truly the best way to figure this out is to get a scanner..........AutoXray makes good ones for $150 that will pull codes, take 'snapshots' of operating parameters, and give real time data from each and every sensor in your FI system. Any ideas we give you are all meant in good spirit, and may actually solve the issue, but for now and for the future you will use the scanner. I have figured out a number of issues with mine that were drivability related, not even code issues, and codes are even easier - the computer tells you what happened.

    Guess for anyone with an FI motor I would recommend either getting one yourself or splitting the cost with a buddy.

    ONE TON</font color=blue> <font color=green>TPI'd</font color=green><font color=red> BEAST<font color=red>
     
  11. MR.GADGET

    MR.GADGET Registered Member

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    Greg,
    I had the same problem with mine or so it sounds. I took it to two different Chevy shops and came out the same way. What I found after a lot of reading was there is a sensor called a Spark Knock Sensor above the starter on the block and looks like a oil sender unit. That sends info to the computer to tell what fuel air mix and timing to use it gave a code but was the map and o2 code. When I changed it it ran like a new truck it was 15-20$ at Auto Zone. Mine is a 89 with 180,000 on it and should be the same FI setup. Hope it works!!!!!!!! Jon

    IF IT'S NOT AS BIG AS YOU ARE DRIVE OVER IT!!!!!!!!!!
     
  12. k5king

    k5king 1/2 ton status

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    ok,,my guess,,throttle position sensor. they don't always go bad right away,,and they do that funny stuff to,,make it run sluggish when you got yur foot to the floor.

    who will win the cookie ? [​IMG]

    <font color=purple>ANYBODY LOSE THEIR JEEP????????[​IMG]
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  13. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Mr. Gadget:
    While I can fully understand that a bad knock sensor cause the problems you experienced I would like to explain what it does and how it will influence the computer.
    What it does is listens to the engine for Detonation/spark knock/ping.... What this is the fuel has started to burn to soon/fast or spontaniously combusted without the plug being the ignition source.
    The condition typicaly known as "spark knock", manifest itself by the noise created by driving the rod into the crank before the crank has rotated past top dead center.
    Ping and detonation usualy go hand in hand. Fuel starts burnning hot spots into the piston, fuel is burning to fast (lean) or ignighting without spark for various reason including carbon hot spots, lean air fuel mix etc. Both bassicly "ring" the piston. It can even burn diviots into the pistion, head, It's possible to happen with or without ignition and it can happen early enough to act like "spark knock" but doesn't have to.
    On every FI I have ever taken the time to read up on (Bosch of various designs, Toyota, GM) the computer relies on the O2 sensor, preset fuel map (pre O2 equipped or closed loop), MAS/Map/speed density (what ever one that particular FI uses) and the throttle position sensor to calculate the fuel mix. Full throttle usualy goes "open loop" (ignores O2 sensor) to a pre calculated rich condition to help combat ping/detonation.
    The knock sensor will not dirrectly effect the air fuel mix. What the knock sensor will do is trigger the computer to back off the timming advance when it hears Spark knock/ping/detonation. It can't tell what one is happening but each will trigger the same responce. Asuming the fuel maps or O2 sensor are giving acurate information the computer would think it's firing the plug to early. This will however indirrectly effect the mix the O2 sensor reads because of a different timming and the computer may adjust the mixture as a result of the timming change. But it's the reading off the O2 sensor that is going to govern it if it's in a "closed loop" conditon (using O2 for mixture readings) or the pre calculated fuel map if it's "open".
    There are several things that need to be checked /listen for on FI vehicles. One is most manufactures recomend O2 sensors be replaced at 60k intervals. If it's bad you can get into lean conditions that can burn valves, pistons, valve seats and be really expensive to repair. If your Knock sensor is bad you can have real bad things happening. I got a nice piston from My supra with a hole clean through it from a injector going lean. The knock sensor was also toast. I bought the car with the blown engine. I year later after I dropped a used engine in it burned a couple valves (multi valve head) in the same cylinder. That is when I discovered what really was wrong. Bad injector , bad knock sensor. Replaced the injectors and got a good knock sensor and gained 2.5 mpg.
    Now I don't think this is the cause of the particular problem this guy is having. It's an intermitant problem of the engine just dying. If it was the knock sensor it would retard the timming but it would still run just have minimal power. Or it would alow the engine to spark knock/ping/detonate unchecked but it would again run and the problem would probably only happen under load.
    Class dismissed!

    Women dig dents and flat paint!
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    75 Jimmy, Dollar
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