engine running a bit erratic

flyweed

Original poster
Member
Apr 20, 2012
47
Hey guys

hope you can help me solve a problem I'm having the started about a day ago on my 2004 Envoy XL (IL6)

in stop and go/city traffic when I am sitting at idle at a stop light (AC on) the idle drops occassionally about 100rpm, and I can "feel it" happen sort of a small shake of the engine...and then at about 2000 rpm, if I maintain 2000rpm my engine will sort of "chug" and I'll get rpms that go from 2000 and then drop to about 1800 and then jump to 2200 and then back down to 2000rpm...and again you can feel it, almost a chugging, hesitation, type of feel.

I haven't cleaned my throttle body for probably 2 years....the spark plugs are OE. Is there anything else that I should check or look at that would cause this??

Thanks for any help.

Dan
 

CaptainXL

Member
Dec 4, 2011
2,445
flyweed said:
Hey guys

hope you can help me solve a problem I'm having the started about a day ago on my 2004 Envoy XL (IL6)

in stop and go/city traffic when I am sitting at idle at a stop light (AC on) the idle drops occassionally about 100rpm, and I can "feel it" happen sort of a small shake of the engine...and then at about 2000 rpm, if I maintain 2000rpm my engine will sort of "chug" and I'll get rpms that go from 2000 and then drop to about 1800 and then jump to 2200 and then back down to 2000rpm...and again you can feel it, almost a chugging, hesitation, type of feel.

I haven't cleaned my throttle body for pobably 2 years....the spark plugs are OE. Is there anything else thatI should check or look at that would cause this??
Hi
Thanks for any
Dan

Honestly. The truck is 8 years old. Put new plugs in first. Start with the simple stuff first. Especially if you are overdue for maintenance which it most definitely appears to be the case.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
And I wish you'd thought to share the mileage. Many members see benefit in cleaning the throttle body every 30K. Especially if the erratic idle clears up if you turn the AC compressor off.
 

flyweed

Original poster
Member
Apr 20, 2012
47
Well, I am going to do some routine maintenance on it this next week...yeah, I'll admit I've kind of just ignored her for a while. Anyway, I am going to replace the plugs, take the Throttle body off and clean it up again, and seafoam the engine through the vacuum line as well. So where we sit after those things are done.

Dan
 

MacMan

Member
Mar 3, 2012
194
As mentioned above, disconnect battery, replace plugs (AC Delco Iridiums or NGK only), and then remove & clean throttle body). I think this will solve your issues.
 

flyweed

Original poster
Member
Apr 20, 2012
47
View attachment 21655

Ok Guys...I can't believe I did it...todays weather was 96 frickin' degrees out..but I wanted my 04 Voy back in good running condition during this hot weather....I pull the Throttle body off and it was in serious need of a good cleaning. Got it all shiney and new looking. While I had that off, I pulled ALL 6 coil packs and bought new AC Delco Iridium replacement plugs, and replaced all 6 plugs with new.

NOW.....cylinders 1-4 (starting with 1 at firewall) old plugs looked pretty much fried, but dry. Plugs 5 and 6 also looked pretty well shot, but had OIL on them. Does this mean the coil packs are shot, and not working? OR???????????

Any help would be great. Thanks for your time

Dan
 

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Sparky

Member
Dec 4, 2011
12,927
Was the oil on the end of the plugs or on the threads and boot area? It isn't uncommon for the donut gaskets to seep a little oil into the plug wells and get the tops of the plugs a little oily.
 

Mooseman

Moderator
Dec 4, 2011
25,487
Ottawa, ON
Oil on the outside of the plugs just means oil is leaking past the valve cover gasket. Not a serious issue unless the plug well is full of oil. If the coil pack(s) were failing and misfiring, you would have gotten a CEL and code set for it. Could have been poorly firing plugs due to age/wear if the firing side of the plug is dirty or wet. The new plugs should fix that. Did you disconnect the battery while you were cleaning the TB and replacing the plugs? Very important step.
 

flyweed

Original poster
Member
Apr 20, 2012
47
the oil looked fresh, and golden (not black and burned) and was kinda oozing down the threads of the plug and onto the firing end..there was NO oil sitting in the wells at all. I did INDEED disconnect the battery when I changed the plugs and cleaned the TB..it is actually still disconnected, and now I gotta go out reconnect, and then FOG the engine with seafoam yet..and then I am done for today!!

Dan
 

Sparky

Member
Dec 4, 2011
12,927
Sounds like there was a tad bit of oil down the well around the plug where you can't really see it. If it is fresh there is no way it came from inside the combustion chamber. The only other possibility is for it to come from a seeping valve cover gasket.

Since it is so little I wouldn't worry about it. Like I mentioned it isn't that uncommon of a thing to happen to this type of valve cover (I've seen Hondas do it too). You could check the valve cover bolts for proper torque, just in case.
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
flyweed said:
View attachment 7831



NOW.....cylinders 1-4 (starting with 1 at firewall) old plugs looked pretty much fried, but dry. Plugs 5 and 6 also looked pretty well shot, but had OIL on them. Does this mean the coil packs are shot, and not working? OR???????????

Any help would be great. Thanks for your time

Dan

I may be miss-reading this, but if you ever get a P030x code, plug #1 is closest to the radiator.
 

flyweed

Original poster
Member
Apr 20, 2012
47
Hey Guys...Ok, update now that I got my engine all buttoned back up, and battery reconnected and then took it for a 6 mile drive into town and back. Anyway....the erratic rpm's are GONE, and the engine has smoothed out in that aspect...but it seems like there is no "low end" get up and go upon take off..and it sounds kind of "stuttery"...ALSO, my SES light is came on Solid as I was driving, and then once I hit 30MPH it would start blinking..and then when I'd coast or drop below 30MPH it would go solid again. Any thoughts?????

Also..something else weird upon start up...now when I put the key in and start the Envoy up.....for about 2 minutes there is this "clicking" sound coming from the rear passenger side of the vehicle. It did this when I started it up at my house..then I drove into town..and went into the grocery store, and got some stuff..came back out, started it up again and it did the same thing....clicking sound in the rear passenger side for approx. 2 minutes immediately following start up..then it stops.

Thanks
Dan
 

Sparky

Member
Dec 4, 2011
12,927
Stuttery and blinking SES means a misfire. First make sure you got the coils seated right, particularly the front (#1). It is easy to get that one next to the plug not on the plug. Ask me how I know :tongue: If all the packs are seated right, get the code scanned to determine which cylinder is acting up.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
flyweed said:
Also..something else weird upon start up...now when I put the key in and start the Envoy up.....for about 2 minutes there is this "clicking" sound coming from the rear passenger side of the vehicle. It did this when I started it up at my house..then I drove into town..and went into the grocery store, and got some stuff..came back out, started it up again and it did the same thing....clicking sound in the rear passenger side for approx. 2 minutes immediately following start up..then it stops.
On a long wheelbase truck, right after a battery disconnection, clicking that stops after two minutes is always a failing rear HVAC actuator. Either the temp or the airflow mode control is not working for you. You can try another recalibration by pulling the HVAC-B fuse (rear fuse #36) for ten seconds with the ignition off, putting it back in, then turning the ignition on but don't start the engine for 90 seconds. You should hear the front and rear actuators going through their paces, but your rear might have a clicking again if the actuator is skipping or broken a plastic gear tooth. GM misdesigned them and they fail sometimes when they're old when you pull or swap batteries.

Location is behind the passenger side trim panel - far rear:

rearactuators-orig.jpg
 

navigator

Member
Dec 3, 2011
504
you also mentioned sea-foaming after the new plugs, I might have done it before the new plugs. It is possible you fouled out the new plugs with the seafoam.
 

CaptainXL

Member
Dec 4, 2011
2,445
flyweed said:
Hey Guys...Ok, update now that I got my engine all buttoned back up, and battery reconnected and then took it for a 6 mile drive into town and back. Anyway....the erratic rpm's are GONE, and the engine has smoothed out in that aspect...but it seems like there is no "low end" get up and go upon take off..and it sounds kind of "stuttery"...ALSO, my SES light is came on Solid as I was driving, and then once I hit 30MPH it would start blinking..and then when I'd coast or drop below 30MPH it would go solid again. Any thoughts?????

Also..something else weird upon start up...now when I put the key in and start the Envoy up.....for about 2 minutes there is this "clicking" sound coming from the rear passenger side of the vehicle. It did this when I started it up at my house..then I drove into town..and went into the grocery store, and got some stuff..came back out, started it up again and it did the same thing....clicking sound in the rear passenger side for approx. 2 minutes immediately following start up..then it stops.

Thanks
Dan

You need to get a scan tool on it. You probably have a P0300. Looks like you decided to work on your vehicle yourself. I would invest in a Haynes manual.
 

flyweed

Original poster
Member
Apr 20, 2012
47
I don't have a scan tool, but I do have a good friend who owns a little repair shop here in town...He's going to do my radiator flush and fill for the cost of a couple gallons of Dex Cool and he said he'd scan my codes, and see what the misfire situation is..and he'd figure it out. So that's this Thursday morning I take it in to him.

I do appreciate ALL of your guys' help and input, but I'm about as far as I can go on this problem, but I will fix the rear HVAC actuator if need be.

Dan
 

Mooseman

Moderator
Dec 4, 2011
25,487
Ottawa, ON
Don't run the truck too long if it's misfiring as this will kill your catalytic converter. For the rear ticking, definitely the rear actuators. Both of mine started ticking after one of my alternators replacements. It's at a point now that they wore down the gears and hardly hear them anymore. I don't care about the rear HVAC so :raspberry:.
 

flyweed

Original poster
Member
Apr 20, 2012
47
Mooseman said:
Don't run the truck too long if it's misfiring as this will kill your catalytic converter. For the rear ticking, definitely the rear actuators. Both of mine started ticking after one of my alternators replacements. It's at a point now that they wore down the gears and hardly hear them anymore. I don't care about the rear HVAC so :raspberry:.

Just another udpated: I pulled the fuse for the rear HVAC and low and behold reset it and now there's NO clicking noise. So I can check that one off my list!

Now..another question..and this has been happening for a long time, I just have always ignored it, but thought I'd ask now anyway....when I am running the AC I have cold water that drips onto my foot when I have it near the gas peddle...also, it drips on the passenger side as well, and gets my carpet all wet. I know it's condensation from the AC, but why is it dropping in my truck??

Thanks
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
flyweed said:
I know it's condensation from the AC, but why is it dropping in my truck??
You don't need to be confused; it's the classic clogged drain syndrome. You should have noticed it wasn't running onto the ground. Just wiggle or poke a wire into the drain tube and step back quickly as about a quart of moldy water is about to gush out.

acdrain3-orig.jpg
 

flyweed

Original poster
Member
Apr 20, 2012
47
the roadie said:
You don't need to be confused; it's the classic clogged drain syndrome. You should have noticed it wasn't running onto the ground. Just wiggle or poke a wire into the drain tube and step back quickly as about a quart of moldy water is about to gush out.

acdrain3-orig.jpg

THANKS! I just went out and pulled the hose, and low and behold about a quart of water ran out..I cleaned out the hoses and connector and reinstalled them..should be good to go.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
flyweed said:
....should be good to go.
...except for this little matter of toxic mildew growing in the padding under your carpet, especially on the passenger side. I'd take the carpet and pad out for an inspection, disinfecting, and drying in the sun. Really - it never goes away, especially if you don't fix the dripping after the first incident or so. Glad you mentioned it, though, and most of us here know the fix.
 

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