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05-21-2013, 08:34 AM #1
- Join Date
- Feb 2009
changing spark plugs with problems
I just replaced all the wires and 7 (yes 7 plugs). The back left passenger side was a bear and I ran out of time. My problem is, when I start the truck it chugs. After driving for a little bit it seems fine. But every time I start out it chugs for a while. When it is chugging the check engine light flashes when I accelerate, then it just stays on constant. I won't have time to do the last plug until this weekend. Could leaving one old plug in cause this condition. I thought I had a loose wire, but then the idle is fine after running for a little bit so I don't see how that could be the problem. It is a 2004 suburban with the 5.3 not flex engine. Any ideas? thanx
05-21-2013, 09:49 AM #2
I would get it to a auto parts store and have them check the codes ASAP. A flashing engine light is an indication of a misfire. This can damage your cats quickly. I would not be driving it. Not changing one of the plugs should not cause the light to come on. I guess that it could if you put some crazy performance plug in all the other places. But, I doubt it. How many miles are on it? how bad where the old plugs? What kind of plugs did you put in it? The back passenger side plug is not that hard to change if you use the correct extension.
1995 Silverado 4x4
6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge
2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system http://www.gmtruckclub.com/forum/sho...5-GMC-Yukon-XL
2002 Silverado ext cab 2wd (Sold)
2003 Yukon XL (Totaled)
05-21-2013, 10:12 AM #3
- Join Date
- Feb 2009
I put in delco 41-110 iridium plugs. It has 160,000 miles on it and the plugs didn't look that bad, worn but not that bad. I bought the truck with 90,000 miles on it and it's the first time I've changed plugs, not sure if they were original. What kind of extension works on that back one? I fought with it for a half hour before I ran out of time.
05-21-2013, 10:36 AM #4
I think that I just use a little short 1" extension. Just long enough that I can get swing the ratchet without rubbing the exhaust manifold. After you break it loose and loosen it a little, you should be able to get your ratchet to engage into the socket without an extension. Yes, you will have very limited movement and it will take a while to get out, but it works. You need to be careful, if you use too long of an extension you will end up with your ratchet tight against the fender wall when you loosen the plug. Then you risk cross threading it attempting to screw the plug back in enough to get your ratchet out. I think that it takes me about 1/2 hour to change all 8. I have also done 20-30 times on multiple 5.3L. That is the hardest plug to get to. But, in the whole scheme of things it is not that hard. It could be worse. I think that @ TRPLXL2 here said that she basically had to pull the motor out of her trans am to change the plugs. That would suck.
Last edited by Pikey; 05-21-2013 at 01:32 PM.
05-21-2013, 10:43 AM #5
- Join Date
- Feb 2009
Do you put the metal covers back on the new spark plug wires?
05-21-2013, 12:18 PM #6
Did you replace the cap and rotor? I always do cap, rotor and plugs. Either you are not getting a good connection with the new wires... or there could be an issue with cap and rotor. That's where I'd check first.2009 Chevy Silverado 2500HDLT 6.0L w/ Towing Package, Dick Cepek GM8 Rims, Dick Cepek FC II 33X11.50R17,RKSport Ram-Air Hood(Functional), Lazer Lite Aluminum Tonneau Cover, Road Armor Stealth Bumper, PIAA Lighting, Diablo Trinity Tuner, Diablew Custom Tune, BullyDog Cold Air Intake, American Racing Headers w/highflow cats, Corsa Performance Sport Exhaust, Custom Striping, Black Bowties front and rear, Fuel Grille Inserts, Recon Headlights, Readylift Shocks, Readylift Upper Contol Arms, 2" Blocks in the Rear..
Future Plans: HD Tie Rods, Under hood upgrades, Crower Camshaft and possibly electric fans.
05-21-2013, 12:52 PM #7
There is no cap and rotor on a 2004 suburban 5.3L, it uses a coil pack above each cylinder. I do agree that you might want to check wire connections, although it is odd that it only does it at start up. Did you use dielectric grease on the plugs and wire ends that connect to the coil packs?
05-21-2013, 01:02 PM #8
It didn't click in my head that it had the coil packs... if it ran fine before you changed the wires then my guess is its the wires. I know in the older engines if the spark plug gap was off you would get similar results to what you are seeing... but I believe... someone else will chime in that plugs come pre-gapped now.
05-21-2013, 01:17 PM #9
The iridium plugs come pregapped. You should check the gap when you get them. It is not correct you should not attempt to correct it, you will damage the plug. I would say that maybe he got dirt on a plug or messed up a gap on the plug while installing it. But, if that was the case I would think that it would run poorly all the time not just on warmup. Another thing to check would be the MAF connection, connectors at the front O2 sensors and the throttle position sensor connection (if equipped with a separate TPS, some are integrated into the TB) . You could have a bad connection at the MAF. I would get the code read, to help point you in the proper direction. This little explanation that I found may help with what I am trying to say. I always thought that it ran closed loop first, guess that I was wrong.
The RUN Mode has two CONDITIONS called Open Loop and Closed Loop. When the engine is first started and engine speed is above 725 RPM, the system is in Open Loop operation. In Open Loop the PCM ignores the signal from the Heated Oxygen Sensor (HO2S), and calculates the air/fuel ratio based on inputs from the TP, ECT, MAF sensors. The system remains in Open Loop until the following conditions are met:
1. The HO2S has a varying voltage output showing that it is hot enough to operate properly (this depends on temperature).
2. The ECT has reached a specific temperature (reported to be 170 degrees).
3. A specific amount of time has passed since starting the engine.
When these conditions are met, the system enters Closed Loop. In Closed Loop the PCM changes fuel injector on-time based on the signal from the HO2S. This allows the air/fuel ratio to stay very close to 14.7:1.
Last edited by Pikey; 05-21-2013 at 01:27 PM.
05-21-2013, 01:34 PM #10
Again... if it ran fine before... my guess it is a direct relation to what you had changed. If not then I'd look into what Pikey says.
Also, when we used to hang with my hotrod buddies and I built my own engines... of course this was way before all the new computer controlled crap... we'd always purposely gap the plus a little wider to try and get a little hotter spark and play with the timing to squeeze as many ponies out as possible. I distinctly recall it running rougher until all was up to temp.
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