03 gmc gremlin problems- flashing engine light, reduced power

Discussion in 'GM Electrical Tech' started by 620nova, Jan 27, 2013.

  1. zigger215

    zigger215 Member 2 Years 500 Posts

    When is the last time you changed your O2 sensors?
  2. 620nova

    620nova New Member

    o2 sensors are orignal. Ok put truck on lift, reworked a couple grounds. removed water pump , broke my puller trying to get balancer off, it was my smaller puller, couldnt get large one in there. I will pick up a larger 3 leg one tomorrow. looking at book the oil pan has to come off to change timing gear set and oil pump. looking at the pan, does the fornt carrier have to come out ? looks like a lot of room around it. might be a good time to put a new fornt actuator in it anyways. plan to change timing set, oil pump, water pump, crank sensor, dealer relearn, new cats and exhaust next monday.
  3. shibby2oo8

    shibby2oo8 Member 2 Years 100 Posts

    Ouch been there before, you can rent tool from az, advance etc in a pinch. I really feel eventually your gonna find the green monster in a connector or in a wire loom and it will fix all of your problems. The oil pan has a rear pickup tube and even then just take the bolts out of the motor mounts and jack up the motor some. I would take the pan off before the crank pulley.
  4. TRPLXL2

    TRPLXL2 Epic Member 5+ Years 1000 Posts

    I'm sure you know this already, but make sure you buy a new balancer bolt. They are one time use bolts, If you reuse it you can end up with the "death wobble" on the balancer. Since your doing the oil pump, look into an LS6 high volume Melling pump. They are ported for better flow, I am running one on my LS1 no problem. Take note of the rubber o-ring on your water pump shaft as well, the new pump will come with 3 different colored o-rings. Red, green, and black, It is very important that you replace with the correct color o-ring.

    I would tell you what we had happen with our balancer, but I don't want to jinx you lol!! We had it on the engine stand too, let's just say the factory puts lots of loctite on that bolt!
  5. 620nova

    620nova New Member

    Almost finshed with timing chain replacmement, just to confirm the tech's comment it is indeed a roller motor. But now i got to go back to auto parts store the crank sensro they gave me is about 3-4 inches long, I could make two fo mine out of the one they gave me. old chain was deflecting about 1.2-5/8" new on more like 3/8" i dont think its a smoking gun. Here is another thought the metal tap that holds the crnak sensor in is it required to be a good ground ?? or just mounting tab, my block is very rusty, almost zero oil leaks anywhere, just a seep around engine oil cooler. but alot of flaky rust under and around crank sensor.
  6. shibby2oo8

    shibby2oo8 Member 2 Years 100 Posts

    Generally they act more like a switch sending digital signals so i dont think it needs a ground. In some very rare cases the reluctor wheel that is pressed onto the crank can move causing probs but it is very seldom seen and i would check it as a very last option. Im still in the camp of wiring/ ground issue.
  7. TRPLXL2

    TRPLXL2 Epic Member 5+ Years 1000 Posts

    Well I learned something new today!!! I wish mine would have been a roller to begin with, It could have saved me some money. Good luck with your truck, I am out of advice now lol!
  8. 620nova

    620nova New Member

    all is back together, below is the list 0f changes

    1). reworked grounds, none appeared bad
    2). cleaned throttle body housing and blade
    3). cleaned mass air flow
    4). also cleaned throttle body anodization where rubber goes around outside. oxidaztion around the bottom was really bad maybe leaking there ?? I took emery cloth and polished up the outside of the trottle body and cleaned rubber boot.
    5). replaced timing chain/gear set
    6). replace oil pump
    7). replace crank shaft sensor
    8). replace temp sensor
    9). new thermostat new water pump new belt tensioner

    Started right up, clean and crisp, before when i would unhook battery thruck wouldnt idle just right until i ran it a little ways, this time it didnt do that. as soon as rpm come off and idle the flashing light, which was expected.
    Tomorrow at 8am new flowmaster cats and duals, then gm dealer for crank relearn at 3pm. wish me luck ???? Thanks for your help guys.

    Yes I bought a new crank bolt 5.70 at gm dealer.

    - - - Updated - - -

    ok new cat and flowmasters, went to dealer they did the crank relearn and amazinly didnt come back with anything on thier 32 point check. tech said all sensor feedbacks looked good. thought it was all good, pulled out, exhaust a little louder than i wanted but a good deep tone, just then blinky , blinky , blinky. ses light blinks from just off idle to 3k. i called the dealer back and its going back wend. put it in the garage for the last 6 hours tonight, going back thru grounds, added grounds to each head,firewall,battery. fuel pressure 48psi at idle, give a little gas and it runs up to 55. put a timing light on each plug wire and watched it fire form idel to 3k. checked computer connectors. also new mass air flow tonight also
  9. TRPLXL2

    TRPLXL2 Epic Member 5+ Years 1000 Posts

    I learned from experience, and other peoples problems with grounding off of the heads. Not a good idea. All the engine swaps I have read with LS engines warn of using the heads for a grounding point, I relocated mine to a different location after I had some freaky issues with sensor inputs and outputs. I could take a test light while the motor was running, and hold it on the bolt on the back of the head and you could see it blinking or fading. My heads were brand new too, so you would think they would be a good ground??
  10. a.graham52

    a.graham52 Rockstar 100 Posts

    not to sounds like a jerk but i feel from the beginning you should have gotten your hands on a scan tool that would show you cylinder missfires. that way you could see if it is a single cylinder that its seeing or if you have random, multiple cylinder missfire.

    just to make my idea more concrete... i had an 05 silverado yesterday that came in for as SES light. had a p0420 cat low inefficiency code turning the light on. ALSO had a p0300 that had set but had yet to command the light on. you wouldnt know it was missing but it had skips on cylinders 1,3,4,5,6,8. i found out the customer had been in a other place to have some work done and that place had installed some ngk plugs and most of them were loose and plug wires loose on the plugs themselves. hell cylinder 6 i never even took the wire off, just in screwed it from the block :0. but to be honest i would never had known it was skipping if i hadnt looked that deep with a scan tool.

    all im saying is if you check it with a scan tool and find out the ecm believes only one cylinder is skipping then that drastically reduces your possibliltys of what the problem could be. not only that but when you have problems like this its a lot cheaper to recheck things like ignition componants then it is to throw parts at it.

    3 years ago i refused to recheck spark plugs i had recently installed in my truck when it ran like crap. went as far as putting a brand new carburetor on it and did sure as hell didnt fix my problem. ended up damaging number one plug when i dropped it on the steering shaft when i installed it. a $500 repair when a free check and $6 plug would have fixed it.

    if you check missfires and find them all on one bank you could possibly be looking at plugged cats. seen it happen with my roomates truck. you could have a cylinder balance test done at a dealer or repair shop to verify the ejectors are all flowing properly. jsut some more ideas.

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