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1998 5.7 GMC Van P1351, PO171, PO174


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Discretesignals
Veteran / Moderator


Apr 1, 2012, 10:51 PM

Post #51 of 72 (1161 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

LOL...your too much.

I caught on just at the last minute you probably kicked your post out. I am sure you got HT though.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


b_oneself
User

Apr 1, 2012, 11:59 PM

Post #52 of 72 (1151 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

 


Tom Greenleaf
Ultimate Carjunky / Moderator


Apr 2, 2012, 5:53 AM

Post #53 of 72 (1143 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

b_oneself - did you hit "post reply" before writing anything or was that part of April Fools Day antics?

If by mistake you can change in your settings to see what you posted right after and edit your own from there if a mistake.

BTW, I think this thread has set a site record for # of posts! No problem. The regulars and certainly all mods know how to deal with it,

The one you can Google with kitty as an avatar just to prove I'm not wrapped real tight!

TomCrazy





PS: Go ahead and swat that bug - I almost did first time I saw that one..........

(This post was edited by Tom Greenleaf on Apr 2, 2012, 6:00 AM)


b_oneself
User

Apr 2, 2012, 1:22 PM

Post #54 of 72 (1128 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Tom,
Alas, I did write a lengthy report last night (2:00 AM EDT) and when I went to post it I must have hit the wrong "button". (Maybe because it was a new day -April 2 ???) Rats, I wish I knew how to "check my settings" and see if I can pull it back up. No, that wasn't part of the April Fool's gag. I guess the joke's on me. I suppose I'm just going to have to re-type everything -and there was a lot to mention!


(This post was edited by b_oneself on Apr 2, 2012, 1:40 PM)


b_oneself
User

Apr 2, 2012, 3:36 PM

Post #55 of 72 (1113 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Double rats!,
I just re-typed and re-posted my lengthy report and it was wiped out again! I know I was logged on like I was last night but when I pushed "post reply" it went back to the log-in page. When I logged in again my response was gone (an hour and half of typing). This time my computer followed with the message A fatal error has occurred: unable to post with a GET method at /home/carjunky............................................/post/write.pm line 915.


Tom Greenleaf
Ultimate Carjunky / Moderator


Apr 2, 2012, 3:38 PM

Post #56 of 72 (1113 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Look up top where it says "edit profile" and you can make changes there. Site's software can screw up itself also. I didn't check yours but suggest leaving your email address hidden as about anyone could click on your user name and get it then who knows.

Nobody, even moderators can dig out your registered email address and spammers do get in here but we remove them asap so if you ever search around some may say that it doesn't exist so one of us took it out and sorry if you get a notice of a reply made and nothing there but it just meant it was a junk post not welcomed.

You have a lot of posts on this thread and if annoying can click on "stop watching" on the notice you get. I don't control anything here but will try to make old threads automatically be just locked as archived to stop notices on a done thread,

Carry on,

Tom


Hammer Time
Ultimate Carjunky / Moderator


Apr 2, 2012, 3:50 PM

Post #57 of 72 (1105 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Reboot your computer and try again. Copy the answer before hitting post.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



b_oneself
User

Apr 2, 2012, 4:08 PM

Post #58 of 72 (1100 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Thanks, you guys,
I will re-boot, and re-post, and attempt to save. (my problem is I don't know how to paste it back in later if it does get lost) So I would like to send it via several separate, consecutive posts. Please be patient with me. -I am so lame in the digital world. But I really do need help with the present roadblock.


b_oneself
User

Apr 2, 2012, 6:30 PM

Post #59 of 72 (1089 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Okay, here is part I of a 4 part report. It was supposed to follow DS post #51.
************************************************************************
Part I (of 4)


Masters,
I confess, I was hoping I could pull somebody's leg. I didn't want to go too far out on a limb for fear HT would pound me out of cyber-space. Seriously, before I get to the new problem, I thought it would be valuable to disclose some of the following background leading up to the discovery of what kept the engine from firing.
I traced all pertinent wires to the VCM (the IC trigger wire (B)- the signal wire #9, and the CKP signal wire -#31 & ground wire -#28) None of these wires had any continuity to ground or to any other wire in the 4/ plug connectors going into the VCM (WHITE,BLUE,RED,BLACK).
I began, one at a time, disconnecting the various sensors, plugs, etc. in the FI system to check for spark at the secondary coil wire while cranking the engine ---to no avail. I noticed during the process a series of tiny "clicking" noises inside that plastic intake manifold every time I turn the key on or off (even with the injector harness plug disconnected) Normal?


...................................to be continued...............................................................


(This post was edited by b_oneself on Apr 2, 2012, 7:18 PM)


b_oneself
User

Apr 2, 2012, 6:52 PM

Post #60 of 72 (1087 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

                         Part II (of 4)

I returned to what I believe to be the crux of the problem and it couldn't be put better than this, -(I wish I knew how to utilize the quote function in this forum) "What is triggering the ICM to be on all the time? With the transistor on all the time when the ignition is on or while cranking, the coil is going to be on all the time too. This theory would also explain why the PCM keeps setting the P1351 high volt circuit code" Discretesignals post #40 (And the waveform did verify this theory -one, continuous signal pattern, up to 4 volts, but never "breaking".)
I did re-check the disconnected plug at the ICM (A,B,C,D) and got the proper readings following the diagnostic chart previously posted by DS. (12 volts at (A and D) when key is in run position, good ground at (C), and 1-4 AC volts at (B) during cranking. The only remaining question concerns my reading of DC volts on (B) with the key off - .002 volts and with key on -- .004 volts. According to DS , "there should be no volts whatsoever". Is it possible that reading is just my volt/ohm meter goofing up?
Next I was lead to the clue that cornered the culprit in this nasty drama.

.....................................to be continued....................................................................


(This post was edited by b_oneself on Apr 5, 2012, 12:16 AM)


b_oneself
User

Apr 2, 2012, 7:15 PM

Post #61 of 72 (1086 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

                                      
Part III (of 4)


I decided to check the voltage on the ICM by back-probing (with my volt meter on 12 volts DC) to see if I could observe a break in the signal. I started with the IC trigger wire (B) that comes from the VCM (A double mistake- First, I didn't disconnect the plug at the ICM, and second, I had it on the DC scale while testing an AC signal. Cf: DS post #10.) My friend's assertion is that that circuit is an AC signal to or from the VCM and the ICM and the CKP. So guess what happens during this improper test? It fires! I turned the engine off in two seconds and it got me to thinking. I just grounded the coil signal through the volt/ohm meter, so it could finally break the voltage and produce spark...which made me conclude that just because the connector on the ICM checks out when it is unplugged, it doesn't mean it is communicating with the terminals inside the ICM. Then, remembering the advice of Tom Greenleaf, Cf: post #29 and #30, I improvised a better connection to the ICM and...what do you know? It fires up immediately, every time, but now there is a new, different problem. It only runs about 10 seconds and then shuts down, -every time. What I am worried about is my jamming 12 volts DC down a 2 volt AC circuit and maybe I fried something.

.......................................to be continued........................................................


(This post was edited by b_oneself on Apr 2, 2012, 10:12 PM)


b_oneself
User

Apr 2, 2012, 7:50 PM

Post #62 of 72 (1077 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

                      Part IV (of 4)

Now, sheesh, I have a different challenge, - what fun. It seemed to me that the fuel pump was working in the crank and run position -which makes me ponder why it immediately cuts out, (fuel or spark?) It sounds like I have solved one issue only to have created another one. What did I forget to do? I still haven't bolted the computer back in yet in case I need to retrieve it. And there was a procedure I was suppose to go through with the VCM once I get the engine running consistently. I suppose I will have to borrow my friend's scanner tool again to see if I am getting any new trouble codes. (Right, not the Vantage diagnostic tool, -thank you HT, I am a glutton when it comes to correction.) After following this sorry saga anyone have any ideas?, poignant comments?, wild guesses?,...............revelations?..............jokes?


(This post was edited by b_oneself on Apr 2, 2012, 10:14 PM)


Discretesignals
Veteran / Moderator


Apr 2, 2012, 9:32 PM

Post #63 of 72 (1070 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Do you have a fuel pressure gauge attached to see if the pressure drops out before it dies. Does it restart after it dies?

You still have that oscilloscope? Does your buddy know how to use it? That scope can find out what is dropping out to make the engine quit. You just have to know how to use it and where to hook it.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Apr 2, 2012, 9:56 PM)


b_oneself
User

Apr 2, 2012, 10:36 PM

Post #64 of 72 (1057 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

I'm on it tomorrow! My buddy does have said tools and know-how and will be willing to look into this. That would be the scanner tool now, or the Vantage tool? He suggested I just hot wire the fuel pump to be on all the time, after the relay, to determine the fuel/spark question. It does restart immediately -each time after it dies. Thanks again for all your support. (I'll check back as soon as I've got more info.) B-1


b_oneself
User

Apr 4, 2012, 5:27 PM

Post #65 of 72 (1016 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

  

**************VICTORY!************** Well, almost. I believe I am close to the end of this unsolicited puzzle. I am delighted to report that for the first time since I my initial post on March 13, my engine is up and running -though I am not completely out of the woods yet. The present status is as following:

1) I did discover a vacuum leak, repaired it, and when the engine finally started I encountered no trouble code P0171 or P0174 on the scanner. Problem solved. Thanks once more for getting me past this hurdle.

2) As per my condition yesterday, it turns out there was a GM PASSLOCK relearn procedure necessary as a precondition when replacing the VCM. Once I accomplished this, the engine started right up and continued to run and idle nicely.

3) However, I have two remaining new codes that popped up (P0340 and P1336) - but, I think I can deal with both of these. The P1336 refers to the GM Crankshaft Variation relearn procedure that one must do if the VCM has been reprogrammed or replaced the CKP has been replaced. (I actually don't have that function in this Scat scanner tool but my buddy says that's all gobbily-gook and that if you just drive it 40 miles it will automatically reset the CKP sensor variation.
The P0340 describes a problem with camshaft position sensor (CMP), and when I touched the connector for the CMP on the distributor I noticed a drop in the RPM -and then again a rise when I wiggled the connector. I am confident I can strengthen that connector (Cf: post #29 and #30) and make that trouble code P0340 disappear. *Update*-I have just confirmed that I was correct on this point. I subsequently "re-enforced" the connectors in all three problem areas.

4) As a footnote, or maybe an appendix: I am reflecting on all the many steps in this journey to get this vehicle on the road, including the detours, the mistakes, the purchases, the lessons and, of course, the top-notch help we get from the moderators (and everyone else) on this wonderful, professional forum, and for all of it, (except the wasted money), I am most grateful. I cannot help but look over the entire adventure and ask, Why?. I don't mean this in the most profound philosophical sense, but rather, why did I get stuck? Consider this: the P1351, P0340 codes came down to a bad connection at the ICM and the CMP. The other thing that through us for a loop was another bad connection at the coil. Weird, (or maybe not so weird) - I'm trying to connect the dots. I don't really believe the coincidence of 3 connectors going bad at once. On the other hand each of the corresponding parts to be plugged into (ie., the ICM, the CMP in the distributor, and the coil) are all aftermarket parts recently replaced! It's my theory that these aftermarket manufacturers are outside the specs that make for a good snug fit. Anyway I'm off to complete this mission, test my theories, and hopefully get the van through the CA smog test by the end of the month. If I don't pass or get stumped again I'll check back in. Otherwise,.....................Adios, and a most sincere THANK YOU


(This post was edited by b_oneself on Apr 4, 2012, 11:30 PM)


Hammer Time
Ultimate Carjunky / Moderator


Apr 4, 2012, 6:44 PM

Post #66 of 72 (1011 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

I guess we were ignoring the security warning on the dash all this time.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
Veteran / Moderator


Apr 4, 2012, 9:00 PM

Post #67 of 72 (1006 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Passlock shouldn't kill the ignition, just the injectors. Passlock also won't kill the engine while it is running. Only disables the engine from starting.

You have all sorts of goofy things going on with those connectors. I honestly still don't understand the P1351 code showing up because of a connector problem, but that looks to be resolved.

Crankshaft variation doesn't learn by driving it around. You have to use a high end scan tool to do a crank learn. If you don't do the crank learn, the PCM will disable the misfire monitor or give you the wrong cylinders that are missing if it does end up missing.

Glad to see you got it going and good luck with your inspection. Smile





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Apr 4, 2012, 9:04 PM)


chickenhouse
Enthusiast / Moderator

Apr 4, 2012, 10:02 PM

Post #68 of 72 (997 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Might also want to stop the leaking on the pcm.


nickwarner
Veteran / Moderator


Apr 4, 2012, 10:26 PM

Post #69 of 72 (989 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

this is the longest damn post I have ever seen. Glad to see you followed instructions and have a running engine. I'm sure we will see you back.


Tom Greenleaf
Ultimate Carjunky / Moderator


Apr 5, 2012, 5:32 PM

Post #70 of 72 (973 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Yep - site record I'm near sure. Glad thru all this there was such positive results. Thanks for the kind words for the techs and the site. I just did the heavy looking on. These guys are sharp no question.

Best of luck with the emissions test,

Tom


supra200
New User

Dec 9, 2012, 11:25 PM

Post #71 of 72 (740 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

im sorry after reading this thread "what was the exact problem"? vac leak? security issue? coil ground? bad wire? what?


Sidom
Veteran / Moderator


Dec 10, 2012, 12:01 AM

Post #72 of 72 (737 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Unfortunately this is one of the biggest problem here.....Poster will not comeback & close a thread with either the fix or I give up....

If you are having a problem go ahead a start a new thread & we see if we can help you out......We don't add new problems to old threads, it gets too confusing....






__________________________________________________________________________________________





1998 5.7 GMC Van P1351, PO171, PO174


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