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Please Help! Rough idle...stalling...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Ignato, Oct 19, 2003.

  1. Ignato

    Ignato Registered Member

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    UPDATE!!!!!!!
    For any of you who followed this thread, here was the fix::::

    Timing was off a little. Moved the distributor a little, fixed the timing. BAM. Fixed. lol.
    This was, of course, AFTER I replaced the:
    fuel pump
    fuel filter
    ESC
    ECM
    Distributor
    Distributor control module
    70+ dollars in gaskets (took the timing chain cover off)
    soon the radiator (poked a hole in it)
    80 plus dollars on diagnostics.
    list goes on.....

    Guess all I needed was my grandpa to come down and whip me into shape. lol.

    The thought behind the distributor moving is well, for 1. the clamp must have been a little loose. and 2. I used some starting fluid on it, and that might have kicked it off or something.

    Oh well, lesson learned.
    "Check the simple things first, and then check them again"

    Thanks to all of those who gave a helping hand!

    ~Ian





    I have an 1988 Blazer with a 350 TBI & 700R4 which has been un-drivable for over two weeks now. And I have NO idea what it could be! It all started one day after running some errands. I came home, shut the blazer off and went inside, came back out and attempted to restart the blazer. It would crank fine, but wouldn't start. So after testing out a few things I decided it was the fuel pump. Naturally, I just filled up the fuel tank and had to siphon out almost 30 gallons. No fun at all! So I got that done, and also went ahead and replaced the fuel filter. I get in and start it up. It starts! woo hoo! BUT it runs horrible. The engine is shaking and it sounds like the timing is off. If you hit the gas, it starts to bog down, but then it seems to run fine untill it goes back to idle..er...attempting to idle. Two weeks later, after all the money that I've been putting into it. It still runs like crap. I am totally lost as to what it could be. I've had my grandpa (retired mechanic) look at it, my boss (mechanic) The crew at pep boys. And numerous amounts of UTI students and such with no luck.
    Here's what I've done to her so far::

    -Replaced fuel pump, strainer, and filter.
    -Spent well over an hour looking over the vacuum hoses and electrical connections and wires. Making sure there are grounds and no frays or extreme bends. Also included spark plug wires.
    -Inpected cap and rotor for wear
    -Taken distributor control module out and down to autozone 2-3 times to test.
    -Replaced ESC
    --Replaced ECM
    -Tested EGR valve and replaced gasket.
    -Checked old and new ecm's for codes (NONE)
    -Inspected TBI fuel spray pattern
    -Checked fuel pressure (pep boys actually did...they said it was ok)
    -Adjusted the timing. (Pep boys REALLY f*cked it up!! /forums/images/graemlins/angryfire.gif But thats another story. I'm never going there again) Whats weird about the timing is when I adjusted it. it would run fine, but then the timing mark would slowly move untill the engine died. I'm able to restart and have the timing reselt itself. Then over a series of 30-40 seconds move over again untill it would barely run or just die.
    Well, I think thats about it. Sorry for the long post, but I'm horribly confused, and I just don't know what to do.
    Any help would be truly appreciated!!!!
    ~Ian
     
  2. uglychevyZZ4

    uglychevyZZ4 3/4 ton status

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    you better read all of this cuz i cant type well, and i feel for you! i just went through the same thing, sounds like we need to trade parts that we KNOW are good /forums/images/graemlins/rotfl.gif

    Replaced fuel pump, strainer, and filter.
    GREAT
    -Spent well over an hour looking over the vacuum hoses and electrical connections and wires. Making sure there are grounds and no frays or extreme bends. Also included spark plug wires.
    CHECK THE PLUGWIRE RESISTANCE WITH OHM METER COLD, **AND HOT**
    -Inpected cap and rotor for wear
    CARBON TAB WORN? CAP CRACKS?
    -Taken distributor control module out and down to autozone 2-3 times to test.
    *****HERE IS WHERE YOU ARE MISSING SOMETHING, MODULE WONT SHOW BAD 9TIMES OUTTA TEN UNTIL IT IS WARM /forums/images/graemlins/wink.gifTHEN IT WILL FAIL. WHAT SHAPE IS THE MAGNETIC PICKUP IN???????<--* ALSO WHAT ARE THE MAGNETIC CONTACTS LIKE? /forums/images/graemlins/thumb.gif
    -Replaced ESC
    GOOD, I THINK MINES BAD??? SEND THE OLD ONE TO ME
    --Replaced ECM
    WONT MATTER IF A CHIP IS DAMAGED
    -Tested EGR valve and replaced gasket.
    THERE ARE 2 KINDS ON 87-91, A POSATIVE VACUME AND A NEGATIVE, WHICH DO YOU HAVE? WAS IT TESTED RIGHT? IF A PINTLE VALVE IS HUNG UP, YOU WONT KNOW IT EITHER WAY, ONLY IF ITS BLOWN.
    -Checked old and new ecm's for codes (NONE)
    POINTLESS ON A OBD1 SYSTEM
    -Inspected TBI fuel spray pattern
    IS THE PRESSURE REGULATOR PUKING THOUGH?...CLOGGED?...BLOWN? AND WATCH FOR INJECTOR GLICHES, ECM INJECTOR DRIVERS MAY BE DAMAGED IF A INJECTORS IS INTERNALLY GROUNDING
    -Checked fuel pressure (pep boys actually did...they said it was ok)
    THEYRE IDIOTS
    -Adjusted the timing. (Pep boys REALLY f*cked it up!! But thats another story. I'm never going there again) Whats weird about the timing is when I adjusted it. it would run fine, but then the timing mark would slowly move untill the engine died. I'm able to restart and have the timing reselt itself. Then over a series of 30-40 seconds move over again untill it would barely run or just die.
    SHEESH, DID YOU DICONNECT THE TIMING PLUG? YOU MUST DO THAT OR IT'LL READJUST, WHICH IT DOES ANYWAYS, BUT CORRECTLY.

    -My course of action would be the following, recheck timing the correct way, with timing plug unplugged, then set it, and if still bogging, check the amount of fuel coming out, sounds like overfueling now??? (replace the regulator)
    -next if thats no help replace the old mag pickup, and module. that is a distinct charechteristic of those 2,

    next line of diagnostics....
    -also, is the egr vacume relay working right?
    -is the IAC hung up? clogged? R&R it and clean it out.
    -map sensor working right?
    -O2?
    -TPS working right? is it going from .05-5.0 volts on pass?
    -tranny module having a vacume leak? power booster leaking vacume?
     
  3. Thunder

    Thunder 3/4 ton status

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    kinda sounds like a Dist module to mee too.
    When they tested it did they put a heat gun on it?
    No start. Bad running and no trouble codes are usually symptoms of a bad dist module or a magnetic pick up coil. The pick up coil will usually throw a code 42 but not always.
    A bad dist module can make you think you have a fuel problem because if the ECM sees no spark signal it shuts down the fuel to keep the engine from flooding.
     
  4. Ignato

    Ignato Registered Member

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    Thank you VERY much for your help and input! Today I've spent mainly playing around with the timing. My boss thought that the timing was somehow backwards, so I turned the distributor around by pulling it out. That sure didn't work! Put it back.
    I made sure I pulled apart the connector for the timing. Right now, it actually seems to run pretty good. (without the connector plugged in) Although I have to hold the gas to get it started. (On a TBI?!?!) It seems to idle fine, and when I hit the gas, it revs up like normal. I look at the timing and its not even on the marks! I turn the distributor and the closer I get the rougher the engine gets untill it stalls. (This was happening before I pulled the distributor, by the way)
    I'm not sure what the deal is with the timing, nor does my boss. I re-re-re-checked the distributor control module. /forums/images/graemlins/crazy.gif and made sure it was nice and hot. It passed over and over again. Tested the ignition coil for good measures. Also went ahead and got a new cap and rotor.
    I'll go ahead and give what you said a try tomorrow uglychevyzz4. I tested the egr valve by sucking on the tube and seeing if it would hold pressure. Seemed air tight to me. The little things that opens up at the intake also moves.
    My brother has the same vehicle so I tried out his esc and it ran no differently. So I still have my old esc..hehe.
    Any more input would be awesome. What do you think I should do with the timing?
    /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif
     
  5. Thunder

    Thunder 3/4 ton status

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    When you see the timing move does it advance or retard?
    Does it run bad both when its cold and when its hot?
    Does your Check engine light work?
    Have you checked the gasket on the base of the TBI? They can go bad and cause a big vacume leak and give a bad idle.
    You can check the Magnetic pickup coil by un pluging the green and white wires inside the dist and putting a ohm meeter acrost them. should have 500-1500 ohms resistance if out of specs the pickup coil is bad. Should check when warm.
     
  6. Kyle89K5

    Kyle89K5 1/2 ton status

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    Mine did the same thing. Pulled dist. went to salvage, got another one, put it in, runs fine.

    I had replaced everything except the dist. itself. I cut my losses and started driving again /forums/images/graemlins/grin.gif
     
  7. Ignato

    Ignato Registered Member

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    *sigh* I didn't even have time to open the hood on the blazer today. I was talking to my boss and grandpa about the timing some more. Boss thinks if we take off the valve cover and re-align the distributor rotor with where the lifters are supposed to be positioned one the number one cylinder, that the timing would be where it should be. I'm not exaclty sure how he plans on going about it. But my grandpa made a good point. If the chain jumped gears or something like that, the only way to fix it would be to take the cover off, and re-alingn the gears. I DO really think that the base timing is the problem, because thats the one thing that the computer doesn't control. And that would explain maybe why the computer sets no codes.
    I did make sure the check engine light works, and checked both computers for codes with my handy paperclip.
    I've had it pretty warm (just messing around with the timing and stuff) It seems to act the same cold and warm.
    I replaced the gasket on the egr valve for good measure. Those dang bolts are REALLY hard to get to! Almost as hard at the distibutor hold-down bracket bolt...hehe.
    I"ve LOOKED at the gasket on the tbi..hehe..not much else. The thing is, I can make it run not half bad, but the timing is WAY off. I didn't try driving it, it would probably bog down and stall.
    I wasn't for sure how to check that magnetic pickup coil, but now that I know I'll add it to my list of stuff to check.
    Oh..uh.. And the timing mark is...to the left of the degree counter. I think thats retarded..hehe. The closer it gets, the rougher it gets. Till it stalls.

    I do believe that the timing chain may have moved, perhaps due to the constant turning of the engine, trying to get it started, and/or all of the backfiring its been doing since the fuel pump replacement.
    Y'all know how much it might cost me if I did the timing gear/chain replacement myself? I've never done it, nor have ever seen it done, but it can't be THAT hard...right...? /forums/images/graemlins/crazy.gif
     
  8. detailer03

    detailer03 1/2 ton status

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    Replacing the timing chain is not too bad. The worst part is trying to seal up the oil pan to timing cover gasket. You should also use a balancer installing tool when you put the balancer back on. Don't beat it on with a hammer. It is not hard, just takes time. How many miles on the thing. If it jumped time, you may have bent a valve, or damaged something else.
    If you have mega miles on the engine, you might think about a replacement.
     
  9. Ignato

    Ignato Registered Member

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    Jeez, I sure hope I didn't bend something. I sure don't have the money for major engine work. The engine iteslf only has 117000 miles on it. I was hoping on hitting 200000 before a rebuild. Jeez, I might end up having to sell it and cut my losses. /forums/images/graemlins/frown.gif I'm gonna go ahead and give my boss a chance with the distributor thing I was talking about earlier. If not that...then I guess I'll have to see about doing the timing chain and such.
     
  10. Ignato

    Ignato Registered Member

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    UPDATE!!!

    Check out the first post for the fix!!! WOO HOO!!! /forums/images/graemlins/thumb.gif
     

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