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98 Suburban K2500 problems

First off don't panic about checking the timing on all 3. People here take the timing way too seriously when it shouldn't be...OK what I mean by that is everyone strives for -1.94 because Bill Heath determined it's the best place to be and it was discussed vs the Optic Bump yada yada yada...In real life for the average Joe just using his truck for work commute etc there is a fairly wide range of where the TDCO is considered acceptable by GM and it will run fine so don't panic. Of course if it's out of that range, then yes it should be adjusted however it would probably code if it was horribly off. Fishbiting is genrally PMD. Never assume that..we did this and it can't be that. Shit like that happens to me EVERY frickin time. I would clear all the codes and then if the SES comes back on post what new codes you have and we can go from there. You know I have said this many times if you own one of these trucks you should own a spare PMD cause I don't give a hoot nanny what you do or where you mount it or what brand it is, these things fail at random. I have owned enough of them now to know that..If I am reading your sig correctly you own 6 of these so you should definetly have a spare PMD. Now in your first post you said you switched PMDs. What is the status of the "spare one" you used. Was it new ? a "good used one" from Edam etc etc. Fix the boost problem as well but also have you cleaned all the electrical connections ? They can cause really weird stuff to happen...
 
We've cleared codes twice and it was boost sensor both times.
I'm going to install that and I have a new PMD in the shed I will install at the same time as well. Might be this weekend before I see the 98 Suburban again.

Thanks
Jeff
 
There you go. Do all that and check grounds as well. PMD replacement (if remote) and boost sol replacement is about 20 mins worth of work tops. That includes a minor beer break...:D
 
What's got my noodle baking is what he describes is what happended to me and we never did figure out why. It was not the relearn or off timing. That might cuase knocking or a little rough running but my motor was shaking so bad I thought it was going to rip the motor mouns out and spin the motor upside down in the engine bay. I have never seen anything like it. Neither had the other guys and it started as soon as Tim hooked up the scanner and tried a relearn. He thought I bumped the IP too far but I was sure I did not move it at all cause I had forgotten to loosen one of the bolts.
 
JRS, Out of curiousity what PMD were you using whent he engine started shaking violently ? Was it a Standyne or a flight systems (aka D tech,wap,dipaco etc etc)?
 
If youre getting an SES light on statup since this happened I would venture to guess its the TDCO timing fault, the IP needs to be turned and the TDCO learn initiated again. If you have just an OBDII code reader it would tell you the DTC values, even if it doesn't interpret the meaning of the fault correctly. One thing you can do is get a reader, if its the TDCO timing code, then move IP towards drivers side a bit, start truck up, warm it up, shut down, clear the code and run the KOKO procedure. If it finishes the learn and no code then you're fine unless youre picky.

Like Aces said people take the timing seriously, I do in the sense that it needs to be a negative number that doesnt set the PCM DTC, but I dont care so much about the actual value as long as its acceptable. There is a difference between in PCM tolerance, within factory tolerance, and what people set it for "performance". There is a noticeable pedal feel and seat of the pants performance difference between the retarded end of PCM tolerance, the bottom end of factory tolerance and what people set it to for performance.
 
Acesneights1 said:
What's got my noodle baking is what he describes is what happended to me and we never did figure out why. It was not the relearn or off timing. That might cuase knocking or a little rough running but my motor was shaking so bad I thought it was going to rip the motor mouns out and spin the motor upside down in the engine bay. I have never seen anything like it. Neither had the other guys and it started as soon as Tim hooked up the scanner and tried a relearn. He thought I bumped the IP too far but I was sure I did not move it at all cause I had forgotten to loosen one of the bolts.
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And in our case my buddy was the only one touching the Suburban. My cousin and I were dutifully supervising, beers in hands.
I still think he was reaching for the plug to unhook it when it went berserk. Exact same description as Aces.

We never touched anything under the hood til after the the engine was trying to flop out of the Burb.
 
Acesneights1 said:
What's got my noodle baking is what he describes is what happended to me and we never did figure out why. It was not the relearn or off timing. That might cuase knocking or a little rough running but my motor was shaking so bad I thought it was going to rip the motor mouns out and spin the motor upside down in the engine bay. I have never seen anything like it. Neither had the other guys and it started as soon as Tim hooked up the scanner and tried a relearn. He thought I bumped the IP too far but I was sure I did not move it at all cause I had forgotten to loosen one of the bolts.
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That is how mine sounded when I did a TDCO learn as I mentioned in an earlier post. I thought I really F'ed things up for about 30 seconds then all was good.
 
jrsavoie said:
It was a Flight System's. I'm not sure of the origin. I've swapped them around from vehicle to vehicle to use for known good PMD's.
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Hmmmmmmmm...............Coincidence.....
There is no coincidence....only the illusion of Coincidence...
I had the same. I think these PMDs are causing problems that are uncharted and suspect the brand had something to do with it. JMHO. I would never use another one. I have them in both my trucks as well as 2 dead ones on the bench. The working ones are glitchy touchy and do weird things in the cold weather. I get momentary stumbles from it when very cold. Anyway my point being I wonder if somehow(this elec stuff is beyond me)These DTechs are having some sort of reaction to certain scan tools....Possible that the scan tool damaged it ??? I have no facts, only a theory that fits the circumstances. I'll let the elec wizards ponder it from here. Me personally...I'm ready to convert them all to DB2's.
IN the meantime, fix your boost code, and if no other codes are present and your remaining symptom is the fishbite, I just realized you have a few of these that you cans swap the PMD's around on. If that's not working I really have no idea. That is what traditionally causes it. Did you try using yours in a another one of your trucks to see if it makes that truck do it ?
 
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I haven't tried anything yet. The Suburban won't be home again til Friday night.

I agree 100% on changing them all to DB2's. My 89 went for 800.000 mostly problem free miles.

All of the problems I have had with these vehicles has been electronics related. The use of aftermarket parts Or driver related
 
Their not so bad when you have the service manuals and the scanner and get to know them. I havent had any issues with the injection system for 3 years other than the FSO which is common to the DB2. And if anything was going to fail I have pulled my PCM out time and time again, swapping EPROMs a hundred times the last couple years, hooking all kinds of funky stuff to it.
 
I find the whole scanner shit very irritating. I don't have a scanner. Wouldn't know what to do with it if I did. And there obviously isn't anybody within 4 hours or so that I can trust to hire to work on a 6.5 that you need a scanner for.
 
jrsavoie said:
I find the whole scanner shit very irritating. I don't have a scanner. Wouldn't know what to do with it if I did. And there obviously isn't anybody within 4 hours or so that I can trust to hire to work on a 6.5 that you need a scanner for.
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That is why these trucks have such a bad reputation for mechanics and why they go so cheap. They dont understand it either. In reality it is simplistic compared to many even earlier gas computer controlled vehicles. It just isnt understood because its different, especially since diesels and their mechanics lagged in technology implementation of EFI.
 
If you can run a computer to get to this site you can run scanning software on a laptop to scan your trucks.:agreed: It is fairly simple actually. Yes, frustrating at first,:mad2::mad2::WTF: but really cool once you have the hang of it.:thumbsup::thumbsup: Besides , you have many members here to help you through the learning process:D:grouphug: I had done nothing on computers untill 4 years ago when I bought my 1st computer. It took a few days, some cussing and frustration but it was all worth it for the ability to see what is happening with the trucks electronics. Without it everything is guesswork. I wasted way more than $1000 on unneeded parts before I bought GMTDscantech. It's not really much different than it was in the mid 70's learning how to deal with electronic ignition.
 
bk95td said:
If you can run a computer to get to this site you can run scanning software on a laptop to scan your trucks.:agreed: It is fairly simple actually. Yes, frustrating at first,:mad2::mad2::WTF: but really cool once you have the hang of it.:thumbsup::thumbsup: Besides , you have many members here to help you through the learning process:D:grouphug: I had done nothing on computers untill 4 years ago when I bought my 1st computer. It took a few days, some cussing and frustration but it was all worth it for the ability to see what is happening with the trucks electronics. Without it everything is guesswork. I wasted way more than $1000 on unneeded parts before I bought GMTDscantech. It's not really much different than it was in the mid 70's learning how to deal with electronic ignition.
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I have only had a computer for 4 years as well, I understand completely. I was lucky however that I bought my GMTDScan first, before spending money on it as the dealer would have liked.

FWIW, I always shut the vehicle off before disconnecting the scanner, it may not be necessary if the scanner is shut down. I treat it like the obd1 paper clip method, the vehicle ign is supposed to be off when the paper clip is inserted or removed.
 
So nobody "Keys off" before connecting to the ALDL data port?......It's the first thing the manual says.

Except Leo?........and no one thinks that could cause some "kind" of issue?
 
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