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Thread: Heres a challenge for you guys...DBW 5.3l dies randomly and wont restart until sits

  1. #1
    Tuner in Training
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    Heres a challenge for you guys...DBW 5.3l dies randomly and wont restart until sits

    I have a 01 5.3l DBW with a z06 cam. Motor has been running fine except for recently it decided it would like to die at random times. Once it does this it will crank over and not restart. I tried many combinations of tricks and things to try and get it to start again but it seems like walking away for about 15 minutes does the trick. I tried to take my boy to school the other day and as I was turning left across an intersection in morning traffic it dies in the middle of the intersection.
    I tried cleaning the air filter, MAF, Throttle Body, 02 Sensors, and checked all of my fuses and electrical connections to make sure they were making contact. I tried to get a log of it happening tonight.....lol I got about half a block from the house before it died and would not restart for about 15 minutes. I did find that if I pump the pedal in a fit of anger that it helps it fire up. I don't know how that works. but it makes me think that when I push the pedal it must open the throttle blades some and allow it to get more air to fire off. Maybe I have the air set to low in the tune somewhere. im still new to tuning and have my tune set up to tune the ve table I think. I will attach the tune and the config file if anyone wants to take a look. It died at about 1:15 or so in the log and the config is Default Imperial.

    MAF disabled tune for tuning.hptDied on decel.hpl

  2. #2
    Tuning Addict 5FDP's Avatar
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    You didnt fail the maf completely, if thats what you tried to do.

    You didnt set the DTC's correctly yet, it likely looking for a MAF reading and not seeing what it should.
    Last edited by 5FDP; 06-19-2015 at 10:47 PM.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
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    I just ran out and flashed the original tune to the truck and tried to start it and no dice. Same thing.
    Attached Files Attached Files

  4. #4
    Tuning Addict 5FDP's Avatar
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    Without it in front of me I can't say exactly what is wrong.

    I guess you could check to see if it starts and runs with the MAF unplugged, you might have a pedal it to get it run a little. You could check fuel pressure aswell and make sure it's not fuel related. I've only dealt with the 2003+ drive by wire throttle bodys, all the other 99-02 trucks have been cable TB's so I dont know if the throttle body is causing the problem.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  5. #5
    Tuner smokestack's Avatar
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    Sounds like fuel pump is going out.

  6. #6
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    That wasy first thought as well. Ive had this pump for a while. In fact i had a similar condition in the past and found that the hose between pump and the pickup split open. But with that i had reduced pressure. Here i have 58psi with key on and it holds steady after key off. And it stay around 60 while driving. Could it be the pump if it has pressure like that.

  7. #7
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    Yes, it depends whether or not you have that when the problem is present or not. If you have correct pressure then. It's not the pump...

    Could be something like battery voltage dropping out due to a terminal over heating and loosing connection too. You might be able to datalog batt v to clarify that, atleast to the ecm. Still wouldn't rule out lost voltage elsewhere... If at all possible would try to duplicate as close to the house as possible away from traffic Then have laptop and tools on hand to check pressure and so on...

    Just a thought.
    2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
    2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80

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  8. #8
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    Challenge accepted.... Crank Position Sensor. The housing of the crank position sensor is made of plastic, that's right, friggin' plastic. Over time the plastic becomes very brittle from exposure to heat. Once that happens the plastic can no longer expand and contract from driving cycles and will develop tiny hairline cracks. This sends the sensor into a frenzy and 9 outta 10 times there is no code to find! So, Give it a try, cheap part and just might be it.
    Check the twisted pair going to the sensor as well. If that pair has "fused together" in any part of it replace it. If the shielding breaks down the signal will cross and make this happen as well. The lead is more money than the sensor so I'd go there first. Hope this fixes it man!!
    Edit: the reason it starts after 15mins from ones I've seen go bad, is that the sensor cools enough those cracks tighten to stop the interference. These cracks may not even be visible to the naked eye they can be so small
    Last edited by MMGT1; 06-27-2015 at 09:07 AM.

  9. #9
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    Replaced the crank sensor and ran new wires from the pcm to the snensor and it cranks and fires right up every time now......except if it is vacked down the driveway. Once it hits the curb it shuts off and just cranks. I shake the wire harness behind the manifold and it fires up. Pulled the harness and no loose or frayed wires. What besides the crank sensor would cause a no start?

  10. #10
    Advanced Tuner Road's Avatar
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    Ground wire on back of cyl head

  11. #11
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    Not sure what fixed it. I pulled the harness and went through every wire. Retaped everything and checked resistance from each wire from the sensor to the pcm. Everything checked out and i retaped it and hooked it back up. All has been fine the last few days now. Now i just need to figure out my p0300 code. Hopefully just the long tubes.