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Thread: Greenhorn

  1. #41
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    No MAF on the P10 LL8s, SD only. No PCV valve, exhaust VVT takes care of that (ok there is one but no one has reported any problems with them even after a few hundred K).
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

  2. #42
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    Thank you very much guys!

    Okay, after about 60k miles, it's probably well past time to change the plugs. I haven't pulled them yet, so I don't know the condition, just yet. (What do you think, wires too? Any recommendations on plugs or wires for Trailblazers? I use Magnacore wires on my Merkur...)

    I've also been experimenting with better gas and think there's been some improvement there as well.

    If that doesn't solve it I can dig down into the PCV option.

    As far as ECT, it 'seems' to be okay and has always indicated as I would expect. The engine runs mid range, and I'm thinking the likelihood of having a faulty thermostat and a perfectly wrongly calibrated ECT sensor is probably very slim.

    It seems like it's detecting knock when the engine up-shifts and here as I drove on flat freeway and then up a bit of a grade. Most trends aren't quite this bad, but, I don't think it would be a good idea to start tweaking until I get to a good and safe starting point.

    Thanks again, I really appreciate your help!

    - bret

  3. #43
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    No wires on the LL8, coil on plug. Plugs are good for 100K, I made the mistake replacing them at 50k with Bosch Platinum +4s for ~25K and then yanked em for the stock iridium AC Delcos. Dont waste the $$ on plugs, just pull them out, check them, then use anti-seize otherwise it can be a pain later down the road to pull them.

    Thats where Im seeing KR, Im running 0TM and hear a ping every once in a while when upshifting, but more often in 4th on the freeway at ~65-75, it will ping then kick the TCC off lockup.
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

  4. #44
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    Alright, thank you! I guess I should look under my own hood a little more often. I'll go ahead and do just as you say and post back to ya.

    Yup, that's where I'm seeing KR most too. Thanks!

  5. #45
    New Member bpayne_69's Avatar
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    Quote Originally Posted by joecar
    Bret/Whodunnit,

    That's too much knock too often...

    Try these things:
    - 91 octane gas (you live in CA);
    - clean the MAF sensor (use only CRC "MAF Cleaner" or CRC "QD Electronic Cleaner"... do not use "Electrical" cleaner or "Brake" clean);
    - check to see if oil is being pulled into intake via PCV valve;
    - are your spark plugs in good condition;
    - is engine coolant temp. overheating (is ECT sensor reading right);

    Joe
    Joecar, I noticed that the inside of my intake (behind throttle body) has a good bit of oil on it. It looks pretty wet and seems to be comeing from the vacuum hose that comes into the intake just below the brake booster vacuum hose. I don't think it's the PCV hose, but it does look like it is comeing out of the block. What causes this or what else should I check? Thanks.

  6. #46
    Joe (Moderator) joecar's Avatar
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    Oil and oil vapour reduce the "octane number" and may induce/allow ping...

    On F-body cars, the PCV hoses come off the rear of both valve covers, merge into one tube that runs to the front, thru PCV valve and into the intake manifold (just downstream of the throttle blade)... when accelerating, oil is pumped up the pushrods and floods the valve cover area, and the g-force pushes the oil rearward and into the said hoses and gets sucked right into the manifold... brilliant design, gets all your oil changed every 3K miles by virtue of you having to add 1 qt every 500 miles...


    I am not familiar with your car, are you sure that the hose you mention is not feeding the MAP sensor...?

    If it is coming from the block, then it may well have to do with crankcase ventilation, and you could be getting oil thru it;
    if can you splice in a clear tube you will be able to see if that's where oil is coming from.

    There are also other means that oil can enter the intake manifold.
    Last edited by joecar; September 8th, 2007 at 04:36 PM.

  7. #47
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    Default injector flow rate adjusts afr?

    i was getting a bank to rich error and adjusted the injector flow rate up and it went away...if i adjust it down it comes on more often...i thought it would be the opposite...i was thinking since my I-6 has 156,000 maybe the ejectors are worn
    2003 TB EXT I-6 210,000 miles... Volant CAI.. NO CAT with magnaflow ..efans ...pcmforless tune and hotchkiss swaybar and air bags in back springs...new alt, pwr steering pump and water pump at 200,000 shooting for 300K or more

  8. #48
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    Hi folks!

    As suggested, I've been running with 91octane for a while now, but I'm still not quite seeing the MPG I was hoping for and it seems like the idle is a little rough at times; sometimes stumbling when I first give it gas. Though I've never "heard" a knock with this car, I was seeing KR's of around 5-8 before (89octane) and now its more like 2.5. Is this consistent with what you would expect from normal commute driving or should I keep searching until I get down to 0 KR?

    (attempting to attach a couple .log files for your reference)

    Also perhaps worth noting is that I had found some oily residue present around the airfilter box and intake ducting (post-filter), but I used to think that K&N would make sure their filter oil couldn't cause other problems with the car. Perhaps I was wrong and should try to prevent any loose oil in there as well...I'll work on that side of things, but if anyone wouldn't mind taking the time to offer additional advice, I'd really appreciate your help!

    Thanks for your advice!

    - bret

  9. #49
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    Can you post up your current tune so I can check it out? or email it to the email addy I have in my profile. If you want me to help you with the trans or some minor engine tweaking let me know.
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

  10. #50
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    My current tune should be bone stock. '03

    I do have slightly larger tires (+2.4") and a K&N air filter. Other than that... hmm....

    Thank you so much for being willing to take a look!!! I really appreciate any help I can get.

    - bret

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