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2003 gmc envoy_slt_xl
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Discussion Starter #1 (Edited)
Hi, my name is David and this is my first post on the forums. I wish it wasn't because of this problem. I know there is a wealth of experienced owners here so I hope you can help me figure out my issue.

A little background. I own a 2003 GMC Envoy XL with the 4.2L 6 cylinder at about 148,000 miles. Here is what started the whole thing. I started to notice that the truck was getting horrible gas milage along with a strong, rich gas smell from the exhaust. Then we started getting the SES light along with it running rough at idle, mostly while at stop signs and red lights. Well, a trip to Advance Auto told us we had a P1345 code. Speaking to a local mechanic, he said that there have been problems with the coils on these vehicles. After much research, I decided to do all the cheap easy fixes first. I changed the plugs but it was no better. I then read on here, how to clean the throttle body which I did including disconnecting the battery for 30+ minutes. At the same time I replaced the #4 coil that looked corroded when I changed the plugs even though I didn't have a code for that. A quick test drive, and I thought all was well. Exhaust was not rich smelling and everything seemed to run really smooth. Needless to say, it quickly returned to it's original state. Rich exhaust smell, rough idling and all. Now another problem began to raise it's head. Now it would skip or bump or something when going up a hill or under some load. This began my research once again. The SES light was coming on again and it was the same code, P1345. After all my reading on here, I was convinced I had a bad camshaft position actuator solenoid (CPAS). I order the part from RockAuto and installed it last night. Now here is where I am totally at a loss. After cranking up for a spin around the block, it runs like crap! It literally sounds like its running on 3 or 4 cylinders. It's making a horrible chugging sound and even the lights dim somewhat when idling. The SES is now flashing at me. I panicked and put the old CPAS back in trying to get it back running at least the way it was before. No go! It's acting the same way. I left it sitting last night because I just don't know what else to do. Any ideas? I do most all of my own maintenance and repairs but this one is running me into the ground. Thanks beforehand for any advice.
 

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2002 gmc envoy_slt
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91 Posts
How about disconnecting the battery again for more than 30 mins. Let the computer relearn the tune up. Good luck.:m2:
 

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2003 gmc envoy_slt_xl
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12 Posts
Discussion Starter #5
How about disconnecting the battery again for more than 30 mins. Let the computer relearn the tune up. Good luck.:m2:
I can give that a try but I disconnected the battery for 30+ again last night while changing the CPAS and then again when putting the old one back in. It never hurts to try again though. Maybe I'll leave it off a little longer.
 

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2004 gmc envoy_slt_xuv
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691 Posts
Yes, well documented, If you want to read, do a search, non-iridium plugs cause many members driveability issues.
 

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2003 gmc envoy_slt_xl
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12 Posts
Discussion Starter #9
Yes, well documented, If you want to read, do a search, non-iridium plugs cause many members driveability issues.
Ok, that's enough for me, I'll give it a shot. Should I change the plugs and hope everything pans out or should I buy a cheap code reader while I'm at it? That flashing SES light really bothers me. I obviously don't want to drive it to the store to have it read since you shouldn't drive it while it's flashing like that. It's really not drivable anyway. Advance Auto has one for sale for about 50 bucks. It looks like it only give you the code number and thats it. I don't want to waste money on it though if it's not necessary.
 

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Northwest Chapter
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11,824 Posts
Whoa there, flashing SES light means misfire. Use a code reader and pull the stored history codes, it might point you to a specific cylinder misfire.

Drop the AC Delcos in and see if it makes a difference.

Also, did you play with the CPAS before you installed it? I think they need to be set a certain way when installing.
 

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2003 gmc envoy_slt_xl
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Discussion Starter #11
Whoa there, flashing SES light means misfire. Use a code reader and pull the stored history codes, it might point you to a specific cylinder misfire.

Drop the AC Delcos in and see if it makes a difference.

Also, did you play with the CPAS before you installed it? I think they need to be set a certain way when installing.
I'll pick up a code reader when I get the ac delco plugs. All I really did was pull the old one out and pop the new one in all while having the battery unhooked. Should I have done something different?
 

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2003 gmc envoy_sle_xl
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59 Posts
Disconnect, then REconnect ALL of the coil wires...there may be a loose wire or bad connection at the terminal. Could have happened while you were moving stuff around.

New plugs, even non-AC's won't really cause the problem you're having. Unless the specific plug is bad...other brands will at least start the engine and fire.

You didn't dump any oil additives in did you?

Oh...and the CPAS?...Looking directly at it from the passenger side, the terminal should be rotated to an approximately 11o'clock position.
 

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Discussion Starter #13
Disconnect, then REconnect ALL of the coil wires...there may be a loose wire or bad connection at the terminal. Could have happened while you were moving stuff around.

New plugs, even non-AC's won't really cause the problem you're having. Unless the specific plug is bad...other brands will at least start the engine and fire.

You didn't dump any oil additives in did you?

Oh...and the CPAS?...Looking directly at it from the passenger side, the terminal should be rotated to an approximately 11o'clock position.
I'll check the coil connections while I'm already putting in the AC Delco plugs. I've already ordered the AC Delco 41-103's from Advance Auto and am about to leave to pick up the order. I got 15% off because I ordered online today :D. So I am going to change them anyway just to eliminate any possible issues.

No I did not add any additives to the oil. I used Valvoline 5W-30 oil and that's it.

When I put in the new CPAS the connector is about at the 10-11 position which is where the old one was. I will recheck this though.

Thanks everyone for the advice. I will report back later to let you all know how it went.:worried:
 

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2003 gmc envoy_slt_xl
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Discussion Starter #14
P0300

Ok, so now I've got the code reader on it and it says P0300 which is a random misfire code I believe. Now on to replacing the spark plugs with the AC Delco Iridiums.
 

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2002 chevy trailblazer_ltz
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3,250 Posts
I had the flashing SES light about 4 yrs ago, and had the P0300 code.....since I didn't know what cylinder it was, I ended up replacing all the coil packs. Problem gone.
 

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2003 gmc envoy_slt_xl
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Discussion Starter #16
From Bad to Worse

Boy, I'm ready to push this thing off a cliff. Okay, I put in the AC Delco Iridium plugs. I noticed that two of the other plugs I pulled out were wet and smelled strong of gasoline. Indication that those two are not firing, right? Well, I still had the old coil from when I changed it out a couple of weeks ago. I figured it wouldn't hurt to put it in place of one of the coils with the wet plug just to try and narrow down to a single coil maybe. To make a long story short, I put it all back together with new AC Delco plugs, checked all connectors going to the coils, etc. and I put the new CPAS back in, all the while the battery is unhooked. After that I crossed my fingers and fired her up. Still sounded like an old junker :suicide:! SES light is still flashing and all. I put the code reader back on it and still has the P0300 multiple misfire code. Frustrated, I though I would pull off the cover off that covers the coils, start the engine and mess with the wires and connectors on the coils to see if I had a problem at the connector. Well, right in the middle of that it all chokes down and dies on me. I figure maybe the PCM doesn't like the breather cover off, so I put it back on. Now the dad blame thing won't even crank. It spits and sputters but will not crank. :hopeless: I check for codes again and now there is a P1345 code along with the P0300 code. So as I type this, I one again have the battery unhooked hoping that whatever I screwed up by running the engine without the breather cover will fix itself (PCM?). Regardless of that, I am no closer to solving my problem. What next? Replace all the coils? That can get pricey. Overall, I'm beyond frustrated. Is there any more advise to be had? I'm afraid now I can't avoid the mechanic. :sadcry:
 

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2003 gmc envoy_slt_xl
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Discussion Starter #17
A new day

Well, after all I did last night I have a non running Envoy with a dead battery. I am hopeful today will bring some new insight. The only thing I can go back to is how much worse things got after changing the CPAS. I know that this adjusts the timing from 0 - 25 degrees, correct? Could I have a severe timing problem? Should I also replace the cam sensor? Is there any type of relearn procedure I need to follow? Any type of PCM update requires a trip to the dealership, right?

Sorry for all the questions, I'm just spitting them out as they come to me.
 

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Discussion Starter #18
It's time to hand it over to the professionals

Well, I gave it my best shot, but my Envoy now sits at the mechanics shop. I will update this thread when I know what the problem was. Thanks to those who offered advice and suggestions. :thx:
 

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2003 gmc envoy_sle_xl
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Well, I gave it my best shot, but my Envoy now sits at the mechanics shop. I will update this thread when I know what the problem was. Thanks to those who offered advice and suggestions. :thx:
Please do let us know...My 1345 issues as just re appeared. I'm talking to a GM Master Mechanic on another site. I also will keep touch when my issue is resolved...sounds like a REAL frustrating problem for many.
 
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