RE: The dreaded PO300 CAUTION LONG POST AND GETTIN LONGER
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RE: The dreaded PO300 CAUTION LONG POST AND GETTIN LONGER - 11/3/2007 4:54:44 PM
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thegr81
Posts: 2621
Joined: 1/16/2007
From: PHOENIX,AZ
Status: offline
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Hope that it is finally fixed for you gator!!! If anything else happens let us know, cause then we go to war again. LOL 
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2001 2wd 4.3 vortec v6
"I'm not fat, I'm a minitrucker"
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RE: The dreaded PO300 CAUTION LONG POST AND GETTIN LONGER - 11/4/2007 9:44:45 AM
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swartlkk
Posts: 14308
Joined: 5/1/2005
From: Waterloo, NY
Status: offline
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Wow Tim! I hope this is it!! If it is, it just goes to show you that something as simple as that can cause a world of hurt!!
_____________________________
Kyle-
2004 Rainier
1970 Chevelle - Resto
1974 K5 Blazer - Resto
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RE: The dreaded PO300 CAUTION LONG POST AND GETTIN LONGER - 11/5/2007 9:02:53 PM
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Hanr3
Wheels & Tire Moderator
Posts: 3476
Joined: 5/11/2005
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SO
Your saying it was in your spark circuit. 
Yes, you MUST have dialectric grease between the Ignition Control Modual and the bracket. The bracket acts as a heat sink. As you pointed out, it gets hot there. The grease helps sheild the heat from the IGM. When the modual gets hot, it typically shuts down. The common symptom is a no start when hot condition. Eventually leading to a no start condition if let go.
Glad you found the problem. Sure feesl good doesn't it. 
_____________________________
"Some people spend an entire lifetime wondering if they made a difference.
The Marines don't have that problem."
-President Ronald Reagan
'87 S10-Blazer - SOLD
'93 S10-Blazer 4x4x4 - Sons DD, engine swap is done.
'00 S10-Blazer 4x4x4 - My
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RE: The dreaded PO300 CAUTION LONG POSTas123 - 11/10/2007 1:01:08 PM
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ddolbin@sbcglobal.ne
Posts: 1
Joined: 11/10/2007
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have you thought about your cam position sensor?
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RE: The dreaded PO300 CAUTION LONG POSTas123 - 11/11/2007 9:05:27 AM
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blazeofglory
Posts: 50
Joined: 9/30/2007
From: Navarre Fl
Status: offline
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I replaced the cam position sensor and the effect was minimal, if it made any difference it's so small that it's negligible.
I suppose I should update the situation as of today. It's been about a week,........and so far the PO300 hasn't reared it's ugly head. (no SES light, or DTC)
Fuel mileage has improved slightly,(up approx 1-1.5mpg) so at least I'm headed in the right direction. It's running better than it has in a very long time, which is a plus. I'm SO close, I can see the light at the end of the tunnel.( and it's not a freight train comming toward me )
I still have a slight miss, but it is nowhere as bad as it was before, ( hasn't tripped a DTC ) So I am comming to the conclusion that this whole issue is the result of not just one thing, but many little things adding up.
I found a TSB (03-06-04-041A, clogged distributor vent screens) that I should have performed when I was changing the cam position sensor and had the distributor pulled out  . Will it help,.... I doubt it, but it's easy enough to do, won't take long, and is one of those things that "couldn't hurt".
I did connect a vacuum gauge to the intake and observed a slight fluctuation (1-1.5 in) at the rpm where the miss is most prominate (19-2100 rpm) but so far have not located a leak. Other than that the gauge is steady as a rock, and shows 20 in at idle.
So that's where I'm at. I'll keep you posted,....but as always thanks for the continued support and ideas it really helps.
Thank You All,
Gator
_____________________________
2001 s-10 Blazer LS 4.3 5 spd 2wd
2004 Kawasaki ZRX1200
1986 K-5 Blazer 4x4 420ci 700r4 4in lift 33's
1979 c-35 1 ton dually 505 4L80E
1971 ElCamino SS 496 6 spd 4.56 posi
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RE: The dreaded PO300 CAUTION LONG POSTas123 - 11/11/2007 1:33:32 PM
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blzR
Posts: 131
Joined: 2/8/2007
Status: offline
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"have you thought about your cam position sensor?"
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Where is this sensor thing hiding?
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RE: The dreaded PO300 CAUTION LONG POSTas123 - 11/11/2007 5:36:13 PM
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blazeofglory
Posts: 50
Joined: 9/30/2007
From: Navarre Fl
Status: offline
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Wayne,
The cam position sensor (distributor pick up) is located under the distributor cap and rotor. It's what the wires are connected to inside the distributor. It's one one the (few) parts that I "threw" at the problem.
Thanks,
Gator
_____________________________
2001 s-10 Blazer LS 4.3 5 spd 2wd
2004 Kawasaki ZRX1200
1986 K-5 Blazer 4x4 420ci 700r4 4in lift 33's
1979 c-35 1 ton dually 505 4L80E
1971 ElCamino SS 496 6 spd 4.56 posi
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RE: The dreaded PO300 CAUTION LONG POSTas123 - 11/13/2007 11:20:02 AM
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blzR
Posts: 131
Joined: 2/8/2007
Status: offline
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Excellent Blazeofglory!
Maybe for giggles i too will 'throw' one in for good measure. :)
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RE: The dreaded PO300 CAUTION LONG POSTas123 - 11/13/2007 2:01:51 PM
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blazeofglory
Posts: 50
Joined: 9/30/2007
From: Navarre Fl
Status: offline
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Wayne,
Are you still fighting the misfire issue you had awhile back?
A nickels worth of free advise,.... The sensor is a hall effect type, it either works or it doesn't. But just for giggles you might try cleaning and/or removing the vent screens inside the disributor first. It won't cost you any $$$ and you only have to remove the cap and rotor to access them (there are 2) There is a TSB in effect for it (# 03-06-04-041A) so it's something worth trying .It's like a 5 minute deal. Give it a shot.
Gator
_____________________________
2001 s-10 Blazer LS 4.3 5 spd 2wd
2004 Kawasaki ZRX1200
1986 K-5 Blazer 4x4 420ci 700r4 4in lift 33's
1979 c-35 1 ton dually 505 4L80E
1971 ElCamino SS 496 6 spd 4.56 posi
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RE: The dreaded PO300 CAUTION LONG POSTas123 - 11/19/2007 10:35:59 AM
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havrelm1
Posts: 37
Joined: 6/18/2007
Status: offline
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My friend had a similar issue around 50-55 under slight accelleration he would get misfires like you described. Turns out the wiring for the Air Intake Tempe Sensor was bad and needed an overlay, problem solved, runs great now.
Something to consider, all you really need is new wire and maybe a new connector if you can't replace the pins too. Should be able to get some wire with the pins already attached from the dealership.
_____________________________
1998 Blazer, 4.3L Vortec, 4-door 4WD.
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RE: The dreaded PO300 CAUTION LONG POSTas123 - 11/19/2007 5:21:04 PM
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blazeofglory
Posts: 50
Joined: 9/30/2007
From: Navarre Fl
Status: offline
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Mike,
Thanks for the idea, I'll look into it. (again) I replaced the IAT sensor early on, (The misfire seemed more pronounced when the ambient air temp was lower) I checked the wiring at the same time and I thought it was all good. Thought the same thing about the TPS, until I rechecked it more closely and found a small dead spot in it.
I still have a slight misfire, but as of yet have not had a return of the SES light, and or code(s). I sometimes think it's temp related,(air, not engine) so something in the IAT system would make sense, but sometimes air temp seems to have little or no effect. Still, it's something to revisit.
I'm rechecking for a vacuum leak, as that is something else that would make sense, (given the vacuum gauge fluctuation.) I'm also going to hook up the old leakdown tester as soon as I find it,...( bet it's hiding out with my OTHER fuel pressure gauge! ) to check for a sticking valve.
Again thanks for the idea.
Gator
_____________________________
2001 s-10 Blazer LS 4.3 5 spd 2wd
2004 Kawasaki ZRX1200
1986 K-5 Blazer 4x4 420ci 700r4 4in lift 33's
1979 c-35 1 ton dually 505 4L80E
1971 ElCamino SS 496 6 spd 4.56 posi
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RE: The dreaded PO300 CAUTION LONG POSTas123 - 11/20/2007 12:27:55 AM
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blzR
Posts: 131
Joined: 2/8/2007
Status: offline
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Wayne,
Are you still fighting the misfire issue you had awhile back?
A nickels worth of free advise,.... The sensor is a hall effect type, it either works or it doesn't. But just for giggles you might try cleaning and/or removing the vent screens inside the disributor first. It won't cost you any $$$ and you only have to remove the cap and rotor to access them (there are 2) There is a TSB in effect for it (# 03-06-04-041A) so it's something worth trying .It's like a 5 minute deal. Give it a shot.
Gator
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SorrY for delay, just seen your reponse today!
YUP still fighting my *chitty-chitty-bang-bang* * now that it's getting colder,the problem is really showing it's ugly head.Just 2days ago, while coming out of a intersection the dam thing gave itself gas and spun me right into the oncoming lane!! good thing nobody was there. i so WISH this issue was a past one,and yes off to the stealership for the umpteenth frigg'n time. My guess is the computer is fried..
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RE: The dreaded PO300 CAUTION LONG POST AND GETTIN LONGER - 1/10/2008 9:19:41 AM
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boarder
Posts: 4
Joined: 1/10/2008
Status: offline
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Hello-
This is kind of an old thread but just curious to know because I am having almost the exact same problem with my 1998.
Gator: I was just wondering if just adding dielectric grease to the back side of ICM is what most noticably reduced hesitation. What do you think the logic to this is? Is the grease isolating the module?
Did you replace the module again when you added the grease, or was that the fix?
I must say it sounds like a bizarre fix , but you can't argue with results.
Thanks
Kelly
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RE: The dreaded PO300 CAUTION LONG POST AND GETTIN LONGER - 1/10/2008 9:30:33 AM
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swartlkk
Posts: 14308
Joined: 5/1/2005
From: Waterloo, NY
Status: offline
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The grease does not insulate, but allows for better heat transfer given the gap filling nature of grease. There are more appropriate thermal transfer pastes that can be used, but dielectric grease should suffice.
Without first hearing from Gator, I cannot say for sure whether he replaced it or not, only my take on the situation. If the module was heating up due to poor heat transfer to the bracket/heat sink, this could cause things to not operate properly when hot, but work perfectly fine when cool. I do not believe that he replaced the ICM once he changed the grease, but I could be wrong.
_____________________________
Kyle-
2004 Rainier
1970 Chevelle - Resto
1974 K5 Blazer - Resto
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RE: The dreaded PO300 CAUTION LONG POST AND GETTIN LONGER - 1/10/2008 9:41:46 AM
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boarder
Posts: 4
Joined: 1/10/2008
Status: offline
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Thanks
Sounds like poor placement of a sensitive piece of electronics.
May not be my problem but it sure is interesting.
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RE: The dreaded PO300 CAUTION LONG POST AND GETTIN LONGER - 1/10/2008 9:59:19 AM
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swartlkk
Posts: 14308
Joined: 5/1/2005
From: Waterloo, NY
Status: offline
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I wouldn't consider it poor placement... The old ones were in the base of the distributor and used the distributor housing as their heat sink... They had many more problems than the newer designs do. But I agree with Gator, the new one should have come with a small tube of thermal paste.
_____________________________
Kyle-
2004 Rainier
1970 Chevelle - Resto
1974 K5 Blazer - Resto
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RE: The dreaded PO300 CAUTION LONG POST AND GETTIN LONGER - 1/10/2008 10:56:03 AM
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quinnman105
Posts: 591
Joined: 8/16/2007
Status: offline
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Kyle,
Blazeofglory Changed the TPS and the MAP sensors.Tomorrow I will go through all my grounds again, so far all the wiring and electrical componants have checked out fine or have been replaced. Everything I have done up to this point has helped but not cured the problem, ha has also Checked / cleaned and reinstalled all the grounds.guess i'll throw some more money at it tomorrow ( cap, rotor, and plugs) even though I don't think it will make any difference. Plug wires checked out fine (multimeter) and no signs of arcing to ground by sight or sound (checked last night) As for the distributor I inspected it while it was out during the MFI spider upgrade and it appeared to be fine, nothing worn, cracked, broken etc.standard production tolerences (excessive shaft end play, corrected with a moroso shim and a new roll pin) I haven't checked the ignition pick up yet he also Spent the morning replacing vaccum lines as some were starting to deteteriorate. Replaced the pick-up in the distributor. he has not checked the timing (with a timing light) because he was under the assumption that the computer was responsible for timing and that it was not adjustible.the distributor housing doesn't rotate when the bolt is loosened. That being said I haven't looked to see if there is even a timing tab on the front cover. I'm sure that there is a probe holder for a magnetic pick up type timing light, but all I have is a snap-on inductive style. If there is a timing tab I could check,(if just to rule out any timing issues) I don't believe that it is a timing issue as the miss is during light/ part throttle cruise only.( usually between approx 18-2400? rpm/ 50-65mph) Under idle/ acceleration etc. it doesn't seem to be a factor. In my understanding if it was a timing or valve train event, like a weak spring for example it would start at low rpm and get progressively worse no matter what kind of load was present. I'm still leaning toward an electrical system issue or vaccum leak. Doesn't mean that he won't check to rule them out
I Hope this is what you were looking for Kyle...
Quinnman105
_____________________________
2001 Chevy Blazer
4x4, 4dr
4.3L Vortec V6
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RE: The dreaded PO300 CAUTION LONG POST AND GETTIN LONGER - 1/10/2008 1:13:15 PM
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swartlkk
Posts: 14308
Joined: 5/1/2005
From: Waterloo, NY
Status: offline
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How bad is the stumble? Like barely noticable or pronounced?
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Kyle-
2004 Rainier
1970 Chevelle - Resto
1974 K5 Blazer - Resto
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RE: The dreaded PO300 CAUTION LONG POST AND GETTIN LONGER - 1/11/2008 4:38:52 AM
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boarder
Posts: 4
Joined: 1/10/2008
Status: offline
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Its barely noticeable, and is usually only found if I search for it.(hold in first or second gear at about 3000 rpm) Did most of the typical tune up stuff. Cap, rotor, plugs, wires, PCV, Fuel filter, replaced a couple of rotted vac. lines, cleaned EGR and MAF & fuel pressure test checks out.
Everything I have done has seems to help. I think the MAF sensor cleaning was the most noticeable.
Did it last nite.
MAF sensor was very dirty. Is it possible that the computer will take some time before it will "relearn"
how to run after all these changes. Lets say due to dirty MAF sensor engine is running rich or lean and causing a misfire. After MAF is cleaned, I assume the ECM is still trying to correct for the problem.
Could this take a little while to "relearn" or does this happen very quickly.
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RE: The dreaded PO300 CAUTION LONG POST AND GETTIN LONGER - 1/11/2008 8:31:21 AM
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swartlkk
Posts: 14308
Joined: 5/1/2005
From: Waterloo, NY
Status: offline
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At this point, I suppose it would be best for quinn and boarder to create separate threads to keep track of the diagnosis on each vehicle... Please post a new thread with your symptoms, what you have tried and/or noticed. That'll help keep down the confusion on my part atleast! LOL
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Kyle-
2004 Rainier
1970 Chevelle - Resto
1974 K5 Blazer - Resto
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