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Thread: 1999 Chevy Silverado 4x4 5.3 w/4L60 bogging down and code P0353

  1. #1
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    1999 Chevy Silverado 4x4 5.3 w/4L60 bogging down and code P0353

    Hello, I am new to HP Tuners. My daughter bought this 1999 Chevy Silverado 4x4 about a month ago for $500. The reason it was so cheap is because someone had tried to steal it by popping the steering column which in turn set the security vats off. The owner had someone try to fix it which he didn't know what he was doing so she gave up and sold the truck to my daughter. Yea my daughter thought hey dad can fix it for me! Well after finding out what version OS it had which is not a popular one(OS9379910) I was able to flash it to OS12208322 using PCMHAMMER and was able to disable the Vats in Tunerpro. After messing with that for a week I finally got the truck started but cannot get it to run right. I ended up breaking down and bought HpTuners which has helped a lot with it running better but not all the way. It starts up and idles perfect but when you put it in gear to take of it bogs down really bad. It was throwing a code of P0355 coil pack. I replaced #5 coil pack and now it is throwing P0353 which is odd and it doesnt run any different. If anyone has any ideas I would sure appreciate it. My son in laws truck broke down last week and he is using my truck until I get it fixed. SO now I have 2 trucks down. Any help would be appreciated. I am including the scanner log if anyone can look at it and help me out.

    Also I have changed all the values to the 1999 Chevy in the new os I flashed to it.

    7stfiule.hpl

    Larry

  2. #2
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    Basics first. Restricted exhaust, clogged injector inlet screens, fuel pressure, etc.

    Those trucks have regular fails on all those issues. Check for melted/overheated wiring/connectors at the top of the fuel tank. I have seen some that grow a weird film/coating inside the fuel tank and lines, when the growth builds up thick enough it begins to slough off and clog injectors, filters, and burn up fuel pumps. If somebody actually "drove it like they stole it" melted catalyst bricks wouldn't be a huge surprise.

    What are you doing in that log - rev in neutral, driving, loading it against the brake...? Hard to picture what's going on with so many channels missing. It goes way lean and tries (and fails) to add fuel when you did whatever you did that wasn't idling.

    P0351-358 will only set if there is an open, ground, or short to voltage on the ign coil control wire, cavity 'C' at each coil, the not-black/not-brown/not-pink wire. This should be an easy fault to nail down without putting on a blindfold and throwing parts at it.
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  3. #3
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    Thank you for the lead. I dcid what you said about the C wire at each coil. I checked all of them put dielectric grease on all connections. Not getting the code now and it is running better. I did mess with the tune some also. Here is the scanner file. I watched a youtube video on how to add certain channels for the basic tune.

    Again Thank you so much especially the diagrams! The tune is still not perfect but it is better than before. I will play with it again tomorrow. If you have any suggestions on what I need to look for I would appreciate it also.

    Larry
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  4. #4
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    It's still trying to add up to 30% more fuel at times, that's not a tune issue, that's the PCM trying to react to some other mechanical/electrical problem. The stock tune won't be that far off if it still has stock parts. You need to stop trying to fix this by diddling the PCM and go back to basic diagnostics.

    What's the fuel pressure at key-on, pressure at idle, pressure under load? Drop the exhaust at the manifolds to check for restricted converters. Drain off some fuel and see if it seems 'normal' - color? smell? water?

    Log shows a bunch of misfires on #1 too. A few on #3 that I'd normally ignore if there were no other problems, but not in this case.

  5. #5
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    And please add a channel to show either PRNDL position or trans current gear. Or both. Or hell, everything. Anything not needed can be ignored, but if you don't have a channel in the list that data is gone forever.

    Fuel trims this far off on a stock vehicle are not a tune issue:
    screenshot.17-12-2019 18.42.49.png

  6. #6
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    Thank you for all the info!!!! First the misfires were my fault. I didnt get the spark plug boot on good enough and it came off and that was wehat caused the misfires. . Second I added the PRNDL to the channels. I am going to take your advice about possible water in the fuel. I mentioned this to my buddy and he said it would bog down even while idling if there was water in the tank. Well when we picked up the truck it had sat outside with no gas cap on it and to mention it has a flatbed so the gas inlet tube was exposed to the elements with no gas cap. I am going to dr4ain the tank tonight and do another test. I will update with new scanner log when I get this done.

    Thank you for all your help!!!!!!!!! I really appreciate it

  7. #7
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    Thank you so much for pointing out the converters! When you said this I thought to myself that one side of the exhaust sounded really funny but never put 2 and 2 together. So after I drained the gas tank and didn't find any water I decided to check out that one side on the exhaust. Well low and behold I was able to get it unclogged and now it runs really good!!!!!!! I will be doing a new scan today and will upload it in a bit. Again thank you very much!!! Now the only thing mechanically I need to get fixed is the battery light keeps coming on. Going to switch out altenators on it to see if I can get that to quit coming on.


    Quote Originally Posted by blindsquirrel View Post
    It's still trying to add up to 30% more fuel at times, that's not a tune issue, that's the PCM trying to react to some other mechanical/electrical problem. The stock tune won't be that far off if it still has stock parts. You need to stop trying to fix this by diddling the PCM and go back to basic diagnostics.

    What's the fuel pressure at key-on, pressure at idle, pressure under load? Drop the exhaust at the manifolds to check for restricted converters. Drain off some fuel and see if it seems 'normal' - color? smell? water?

    Log shows a bunch of misfires on #1 too. A few on #3 that I'd normally ignore if there were no other problems, but not in this case.