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Thread: Stock 2002 silverado problems

  1. #1

    Stock 2002 silverado problems

    Alright so here is the rundown, I've read many of these posts trying to see if I can solve the issue from somebody else's issue. So far no luck. I've put probably close to 50 hrs into just sitting down going over everything and trying stuff. This is what I have so far. Stock 2002 silverado other than valve springs are changed, the harness has been made standalone, and the O2's are in the collector of my headers, stacks that go through a hood, not your normal style of header. I'm using the stock Delphi MAF sensor, it has the numbers 25168491 in the plastic, the sticker is no longer readable. I recently replaced the cam sensor and that solved the issue of it being hard starting, but only on the day I installed it. The next day after letting it sit, it went back to hard starting. I guess I should also state that this motor is backed by a th350 so all the trans has been deleted, and also it doesn't have A/C. The harness has the bare minimum needed to run. This thing has me stumped and another person who has done dozens of these swaps stumped even more. I have pulled the harness off about 5 times and checked it and everything goes where it is supposed to and also when it is hooked up everything appears to have the correct voltage.

    Also the throttle response is not there. You sort of have to pedal it to get anything out of it. If you try to slowly get the rpm's up it will fall flat on its face at around 3k, or if you hold the throttle almost any position. Just recently it coded low voltage on the knock sensors, and also sometimes it will code random misfire, but not always. If you can get it past 3k it will run to rev limiter, wouldn't do that before I changed the cam sensor. Also when it comes down from 3k or anything above that, it seems to like to stop reading from the O2's whether it is in force closed loop or not.

    When it does this, the rpm's drop from the high rpm to 1500, but then the 02's stop reading and the computer starts throwing fuel at it, and the idle will jump up to somewhere between 1800 and 2200 for a few seconds and then the O2's start reading again and the idle will drop back down to 800. I'm at a loss for what needs to be done. I was able to get it to rev sort of consistently once by turning off the EGR stuff.


    Here is my current tune, and a couple of the lastest data logs. Right now I'm leaning toward a bad coil pack(s) and/or knock sensor(s), but I also think this issue goes deeper. Any help is much appreciated, I would really love to let this thing sing and not just sit on a trailer or parked in the yard.

    test aug 29 15.hpl
    stock tune egr off.hpt

  2. #2
    Advanced Tuner
    Join Date
    Apr 2015
    Posts
    302
    I can't check your tune right now, but can you set it up to run as open loop? Maybe also use the scanner to absolute spark control and set it to around 10 degrees. Basically anything to get it to run in a static mode, then go from there.

  3. #3
    Senior Tuner
    Join Date
    Feb 2009
    Posts
    1,931
    Running a v8 off a v6 os and having 2 dead holes?