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    '93 454 TBI in California...

    That's the one I keep looking at. It make a distinction of -1990 and 1990+, I guess on the basis of vacuum vs electronic EGR. I actually don't know which I have... being a P30-based motorhome, the chassis could be much older than 1993. Obviously I need to look, but I wonder if there's any way...
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    '93 454 TBI in California...

    To reply to my own post, I just remembered that intake manifolds are exempt from CARB requirements so long as they preserve original function... So the question becomes any recommendations for a good intake that maintains EGR, etc.
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    '93 454 TBI in California...

    Hi guys - I am wondering if anyone has any recommendations for California legal bolt-ons for a '93 454. This is not in a GMT400, it's in a P30, but this always seems like the best resource when it comes to TBI truck motors. I'm looking for improvements in the mid-range ... Freeway RPMs hover...
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    P30 454 TBI - Code 44

    I did a little more digging around, and here's where it is now - I found both grommets in the valve covers were a bit worn, so I replaced them both. I had no history on the PCV valve itself, so I replaced it too. I used factory GM parts here, from gmpartsgiant.com (they've always been great) I...
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    P30 454 TBI - Code 44

    The light remains on for perhaps 30-45 seconds at a time. Nothing happens before, during or after as far as I can tell - the vehicle behaves totally normally at all times. Nothing I do seems to cause the light nor cause it to go away - playing with throttle and road speed neither prevents the...
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    P30 454 TBI - Code 44

    I've got a '93 P30 motorhome that has started lighting the CEL periodically while cruising at freeways speeds. There didn't seem to be any rhyme or reason - and no drivability issues seem to go with. On a recent trip, I brought along my Tech 2 to see if it could help pinpoint the issue...
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    Possible misfire, or battery issue, or gremlins.

    File this under no explanation: I replaced the NGK iridiums with Delco coppers last week. I have not put a large number of miles on the truck, but in several test drives the misfire has not returned, and neither has the AIRBAG light. I cannot explain that interaction at all, but apparently there...
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    Possible misfire, or battery issue, or gremlins.

    Test drive this evening: Same crap startup, fading with just a little heat. But, the misfire shifted from #3 to #1 - it was not as dramatic, with single-digit misfire counts vs double-digit but still only affecting the one cylinder. Fuel trims were slightly less negative - At idle, LTFT is...
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    Possible misfire, or battery issue, or gremlins.

    The #3 plug is pretty brown, and when stone cold there may have been some dampness on it - nothing I could smell, but a little shimmery. #1 still looks pretty new. The plugs are NGK Iridiums. I have no idea why I went with Iridiums - I typically only use them on very modern cars as they are...
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    Possible misfire, or battery issue, or gremlins.

    Okay, let's discuss cylinder #3.... :) At idle, LTFT creeps up to -12%, and STFT up to -2% At 40-50mph cruise, LTFT is -8% and STFT between 0% and +3% At 65mph cruise, LTFT is -4% and STFT -1% or 0% Injector pulse is between 3.6ms and 4.1 on both banks at idle But, telling: At idle or *very*...
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    Possible misfire, or battery issue, or gremlins.

    I am going to take it for a drive here in a sec to generate that data, but here is some other information: It looks like the CMP value is dynamic - so I have 4 degrees when cold, but it zeroes out once warmed up... like, within 3-4 minutes of idling. I realized Tech 2 has a misfire logging...
  12. T

    Possible misfire, or battery issue, or gremlins.

    Some more information: This morning I noticed the PCV grommets in the valve covers were in poor shape, so I replaced them. I cleaned the valve itself, but didn't have a replacement on hand - I will probably do that just because. Edit: I also inspected the air filter (good) and cleaned the MAF...
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    Possible misfire, or battery issue, or gremlins.

    No worries - I appreciate the effort. I will definitely follow up if/when I cure the issue - I hate when you find threads that don't have resolutions! I am liking the idea of a failing VR on the alternator - it would explain everything. The dash gauge registers no fluctuations - but I have no...
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    Possible misfire, or battery issue, or gremlins.

    Checked for the ground strap last night - I don't know how I never noticed it, but it's there and in excellent shape. Dusty but not damaged, oily, or corroded. After 24 hours battery voltage was at 12.4v - I'm going to come back to it tomorrow. I still don't know why it read 12.7 in the first...
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    Possible misfire, or battery issue, or gremlins.

    I don't recall ever seen a passenger side engine ground - maybe that's a component here... rough description of where it is? I'm in California - typically rust and corrosion aren't problems... but total failure still is! :)
  16. T

    Possible misfire, or battery issue, or gremlins.

    Hi all - This is my first post here, but I've been reading these forums for years and years... but in 20 years of owning Suburbans I've just never had a problem I couldn't get through. This one, though, has be baffled. Sorry for the long post, but I figure I'll get all the details out - I've...

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