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    TBI Surging/Hunting for Idle When Warm in Park

    Sntrym, yes I have actually replaced both of these in the last couple years I've owned the truck. Looking at the graph in my earlier post, the CTS output is constant while this is going on. I don't see anything in the sensor input to the PCM that would indicate a problem there. I have also...
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    TBI Surging/Hunting for Idle When Warm in Park

    Thanks sntrym. I've replaced the distributor with no change, so I don't think this is the issue, unfortunately. I've had the truck in a local reputable shop for four days in a row now, but no diagnosis yet.
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    TBI Surging/Hunting for Idle When Warm in Park

    Tech, thanks for following up. Here's a more recent pic showing the engine speed vs desired speed--it's definitely unable to get the speed where it seems to want to. Looking at it closely, the IAC movements lag the drops in rpm by a little bit, leading me to believe that something is trying to...
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    TBI Surging/Hunting for Idle When Warm in Park

    Update for anyone following: I did find some cracks in the distributor magnet, as was pointed out by a couple people here (thanks guys!). So I swapped that and the coil while I was at it over the weekend. It does run smoother now than before, but still has the same problem. Here's a pic of...
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    TBI Surging/Hunting for Idle When Warm in Park

    Here's some more data from the Malfunction Codes file. Anyone know what "Air Fuel Mode Word" means?
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    TBI Surging/Hunting for Idle When Warm in Park

    All, I was able to get the app and bluetooth adapter up and communicating this morning. Thanks for this great suggestion! Here's a pic of some data showing about 16 surges until it finds its groove around the 157sec mark. It makes sense to me that the MAP follows the IAC position. There are a...
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    TBI Surging/Hunting for Idle When Warm in Park

    Matt, You and Michael are thinking along the same lines as far as a bad distributor. I wonder though, why would this only happen in Park/Neutral? Got some more data to share in the next post.
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    TBI Surging/Hunting for Idle When Warm in Park

    Howdy Tech, I didn't swap the alternator, just the battery. The problem persists with no change over the last couple weeks, I just haven't had much time to spend on it. I purchased that OBD1 bluetooth adapter and am working with the developer (huge help) to get it working with my tablet. I...
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    TBI Surging/Hunting for Idle When Warm in Park

    Michael, Thanks for the link, I see what you're talking about now and I'll take a look when I have a chance. Question though: if this were a mechanical problem such as a bad magnet why would the problem go away when I unplug the base timing connector?
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    TBI Surging/Hunting for Idle When Warm in Park

    Tech, Thanks again for the link to the device. After researching this some more I've gone ahead and ordered that ALDL bluetooth box as well as a cheap Android tablet. It's cheaper than buying a fancy code reader, and I'm sure my kids will love the tablet too. I'll post up an update with what I...
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    TBI Surging/Hunting for Idle When Warm in Park

    EGR is a new Delco unit, and the problem persists even if I plug the vac line going to it and/or disconnect that EGR valve/switch. Can you tell me more about the distributor magnet test? Where can I find it, and how do I test?
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    TBI Surging/Hunting for Idle When Warm in Park

    Thanks Tech. Unfortunately I don't have an Android device to work with this or a laptop at home. I've been poring through the shop manuals and there are a few tests I can do at the PCM connectors, but nothing like what this software can do. I've tried some of your suggestions already--tweaking...
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    TBI Surging/Hunting for Idle When Warm in Park

    All, Lots of quality time spent under the hood this weekend, but still haven't solved it unfortunately. Here are some updates and new data points: Noticed that if I deny the computer the opportunity to surge/hunt 'til it finds its groove (by putting it into R or D right after starting), it will...
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    TBI Surging/Hunting for Idle When Warm in Park

    Thanks grampadirt, I've been reading up on this a little bit and may have to dive into it. Unfortunately I don't have a laptop to use at home but may be able to take one home from work. Anyone got any other ideas for handheld tools that could take sensor readings from the OBDI ALDL real-time...
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    TBI Surging/Hunting for Idle When Warm in Park

    Haven't tried disconnecting. Since they're so cheap I did go ahead and throw a Delco one in there the other day, made no change. My thinking is now that it may be unable to decide whether it's cold (open loop) or warm (closed loop), and it's bouncing back and forth between the two until it's...
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    Howdy to all, need help with a problem

    Thanks, me too! Had an Olympic White 96 S10 a while back and always loved this color.
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    Howdy to all, need help with a problem

    Thanks guys. I went ahead and posted my problem here in the engine performance section: http://www.gmt400.com/threads/tbi-surging-hunting-for-idle-when-warm-in-park.33400/
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    TBI Surging/Hunting for Idle When Warm in Park

    Howdy all, Long time lurker and fan of the site. I'm having a problem that's driving me crazy and am hoping the community can help. I've searched for this exact issue with no luck yet. Here goes: The truck: 1995 Silverado K1500 ECSB Z71, 5.7, auto, 82k miles I bought a year and a half ago from...
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    Howdy to all, need help with a problem

    Howdy, Long time lurker and fan of this site, finally decided to start posting, as I'm having an issue with the 95 that's driving me crazy. Can someone point me in the right direction as far as where to ask the community? By way of introduction, here's some info on my truck: 95 Silverado ECSB...

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