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2003 GMC Sonoma Misfire


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JerryAL
Novice

Apr 20, 2014, 4:13 AM

Post #1 of 11 (6104 views)
2003 GMC Sonoma Misfire Sign In

Hello,

So I have a 2003 Sonoma SLS 4.3L V6 with 166,000 miles and about a week ago it started idling really rough and then started throwing me a P0301 error code which I know means a cylinder 1 misfire, and I started smelling burning gas coming out of the tailpipe. So the first thing I did was change out all my spark plugs since it was about time to do so anyway.

The spark plug in cylinder 1 was black and burnt, but all of the other spark plugs looked fine. However, after I changed out all of the spark plugs now I get a P0300 multiple random misfire code instead of just the original P0301 code, and the original rough idling still exists.

I then replaced the cap and rotor and the cap did look pretty corroded, but the problem still remains. Also, I did check out all the spark plug wires with an inline spark plug tester and a volt meter for continuity and they were all fine and producing a consistent spark.

Now I am at the point where things get more difficult and more expensive and quite frankly I do not want to be just guessing and replacing items that are not the problem.

So any thoughts, or do you think it is probably a spider fuel injector problem?

One last thing, the truck seems to run fine when it is up to speed. I do not notice any lack of power at speed, it is only rough when idling.

Thanks,

Jerry


(This post was edited by JerryAL on Apr 20, 2014, 4:26 AM)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 20, 2014, 4:35 AM

Post #2 of 11 (6094 views)
Re: 2003 GMC Sonoma Misfire Sign In


Quote
Also, I did check out all the spark plug wires with an inline spark plug tester and a volt meter for continuity and they were all fine and producing a consistent spark.


Those tests really don't prove anything as far as the wires are concerned. I would definitely replace the ignition wires as these days they deteriorate faster than the plugs.

DO NOT, under any circumstances turn the distributor at all. The ignition timing is not adjustable.Turning the distributor can mess things up bad.



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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.



JerryAL
Novice

Apr 20, 2014, 6:49 AM

Post #3 of 11 (6080 views)
Re: 2003 GMC Sonoma Misfire Sign In


In Reply To

Quote
Also, I did check out all the spark plug wires with an inline spark plug tester and a volt meter for continuity and they were all fine and producing a consistent spark.


Those tests really don't prove anything as far as the wires are concerned. I would definitely replace the ignition wires as these days they deteriorate faster than the plugs.


Ugh... so I have to ask does anyone have a simple way to remove those little black clips holding the spark plug wires?

I was able to get one of them off using pliers to pinch the ends, but I can not even reach the other ones with pliers. There has to be a trick to it that I am just not seeing I hope???

Thanks...


(This post was edited by JerryAL on Apr 20, 2014, 6:50 AM)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 20, 2014, 7:15 AM

Post #4 of 11 (6076 views)
Re: 2003 GMC Sonoma Misfire Sign In

I don't know what black clips you are referring to. The only thing that may be difficult is the boots sticking to the cap tower or the spark plugs. The way you break that free is by twisting the boot to break the seal and then they will come off much easier after that.



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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.



JerryAL
Novice

Apr 20, 2014, 7:46 AM

Post #5 of 11 (6072 views)
Re: 2003 GMC Sonoma Misfire Sign In


In Reply To
I don't know what black clips you are referring to. The only thing that may be difficult is the boots sticking to the cap tower or the spark plugs. The way you break that free is by twisting the boot to break the seal and then they will come off much easier after that.


They are the little black clips that and route the wires from the distributor cap to the plugs. Some of them are just impossible to reach, and after some research I have found many other complaints online about them.

About to just give up and just pay a mechanic...


kev2
Veteran
kev2 profile image

Apr 20, 2014, 7:55 AM

Post #6 of 11 (6067 views)
Re: 2003 GMC Sonoma Misfire Sign In

currently you have a p0300? nothing else? and everrything works ?

I see mention of a new plug just #1 cylinder?
ALSO you did use a AC Delco plug? anything else would be a suspect in the P0300.

clear up that confusion Im having and we can try some tests.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 20, 2014, 8:15 AM

Post #7 of 11 (6066 views)
Re: 2003 GMC Sonoma Misfire Sign In

Let's not detour here yet. You have 155K on this thing and the wires need to be changed before going on a treasure hunt.



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

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.



JerryAL
Novice

Apr 20, 2014, 10:14 AM

Post #8 of 11 (6058 views)
Re: 2003 GMC Sonoma Misfire Sign In


In Reply To
currently you have a p0300? nothing else? and everrything works ?

I see mention of a new plug just #1 cylinder?
ALSO you did use a AC Delco plug? anything else would be a suspect in the P0300.

clear up that confusion Im having and we can try some tests.


I put in all new NGK G-Power Spark Plugs in all 6 cylinders. I also did just change the spark plug wires as suggested, but I am still having the same really rough idling issue.

However, now it is just back to giving me the single P0301 misfire error code in cylinder #1 instead of the P0300 random misfire code, and yes those are the only 2 error codes that I have received.

In addition, I tried adding some B-12 Chemtool to the fuel to see if I had a clogged fuel injector, but it also has not changed anything.

The gas smell coming from the exhaust is really strong now as well.


(This post was edited by JerryAL on Apr 20, 2014, 10:17 AM)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 20, 2014, 12:13 PM

Post #9 of 11 (6049 views)
Re: 2003 GMC Sonoma Misfire Sign In

I would put a fuel pressure gauge on it and not only check the running pressure but see if the rest pressure holds when the key is shut off to see if the injector is leaking down.
You might also want to take a compression test on #1



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

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.



(This post was edited by Hammer Time on Apr 20, 2014, 12:13 PM)


JerryAL
Novice

Apr 20, 2014, 7:19 PM

Post #10 of 11 (6035 views)
Re: 2003 GMC Sonoma Misfire Sign In

I was searching through some videos on YouTube and found a video about a vacuum hose leak on a 2003 S10 the same as my truck.

So then I decided to really go and take a good look at all of my hoses and discovered a huge crack and leak in the very same place that the guy in the YouTube video below found:

link deleted .................. not allowed

My question is what does the hose in the video really do because I have not had a chance to replace mine yet.

Do you think that particular hose in the video could be causing my misfire problem or is it unrelated?

The other end of the hose does run into the engine itself.


(This post was edited by Hammer Time on Apr 21, 2014, 2:27 AM)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 21, 2014, 2:28 AM

Post #11 of 11 (6026 views)
Re: 2003 GMC Sonoma Misfire Sign In

That guy was repairing his air conditioner mode controls. That's not what youre are trying to fix here.



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

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.







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