tizfun Posted March 6, 2009 Report Share Posted March 6, 2009 (edited) Help !!!! Hey everyone... You all remember my tranny went a few weeks ago. Got that fixed.. while I was there they had my truck on the scanner and told me my #1 cylinder was misfiring.. They asked me how long since I changeD my plugs with 280,000 kms and I told them I hadn't yet.. So off I go and get me some AC DELCO plugs and attempt to change them myself.. no problem, all went out/in and when I started up the truck, the service engine light came on.. I went to take it out for a spin and it shakes alot when you get moving.. Once up to speed, it goes away... Any mechanics out there that can PLEASE send some advice my way.. I'm about to put the old ones back in... Tiz Edited March 7, 2009 by tizfun Link to comment Share on other sites More sharing options...
Raf Posted March 6, 2009 Report Share Posted March 6, 2009 when's the last time you changed your plug wires? next step in the chain after that cap & rotor if equipped Link to comment Share on other sites More sharing options...
dannyboy Posted March 6, 2009 Report Share Posted March 6, 2009 Make sure you used the correct plugs Check the plug leads aren't mixed and are secure Check the distributer lead is secure. Dan Link to comment Share on other sites More sharing options...
Sinker Posted March 6, 2009 Report Share Posted March 6, 2009 What dannyboy said. Link to comment Share on other sites More sharing options...
tizfun Posted March 6, 2009 Author Report Share Posted March 6, 2009 This is the newer Trailblazer with the 4.2 ltr.. The plugs are located just underneath the airbox... I loosened the screws to remove the plug cover and put it back in place... Seemed like a simple job, but I created a mess... Tiz Link to comment Share on other sites More sharing options...
tizfun Posted March 6, 2009 Author Report Share Posted March 6, 2009 Got the correct plugs too Part # 41-103... Straight from the dealer... Tiz Link to comment Share on other sites More sharing options...
bigredfisher Posted March 6, 2009 Report Share Posted March 6, 2009 (edited) did you put the plug wires in right (firing order) you can find the firing order on the internet, what year is your vechicle???? Edited March 6, 2009 by bigredfisher Link to comment Share on other sites More sharing options...
Maverick Posted March 6, 2009 Report Share Posted March 6, 2009 Yeah change your wires, you might have put the wires on the wrong spark plugs though if it's running rougher than it did before. Check your wires to make sure they are all on but I would replace the wires and distributor cap and rotor (if equipped) as stated above, it will be more efficient and run a lot better in the end. Link to comment Share on other sites More sharing options...
Tybo Posted March 6, 2009 Report Share Posted March 6, 2009 Did you gap the plugs? Link to comment Share on other sites More sharing options...
tizfun Posted March 6, 2009 Author Report Share Posted March 6, 2009 It's a 2003 .... There is no distributor cap.. There are no wires... Each plug has it's own wire for each cylinder... there's no way to mix them up as I changed one at a time... Tiz Link to comment Share on other sites More sharing options...
irishfield Posted March 6, 2009 Report Share Posted March 6, 2009 What Tybo said and did you drop any plugs before install? Link to comment Share on other sites More sharing options...
Bernie Posted March 6, 2009 Report Share Posted March 6, 2009 (edited) There are a few things that can happen to create a misfire when replacing spark plugs. First thing is when removing the boot from the spark plug is to be firm but gentle with them. Twist the boot until it loosens it's grip on the porcelain on the plug, then twist and pull on the boot only-never the wire. If you damaged the boots it will misfire. You got the old spark plugs out OK so we wont go there. Remove the spark plugs from the boxes and inspect them to make sure they are not cracked and the electrodes are all in properly. I do see a few defective ones. Look up the proper gap, best to make sure on line or your parts supplier as the specifications can change from the sticker on your vehicle. I add a little touch of anti sieze compound but not too much as the anti sieze can interfere with the heat transfer from the spark plug. Keep the porcelain clean! Anything on there can act as a conductor and will follow that instead of jumping the gap and misfire. I add a touch of di-electric grease to the inside of the plug boot to help prevent arcing down the porcelain and allow for easy removal of the boots the next time plugs are removed. If all is good it may be a bad ignition coil or two. This is where a scan tool makes it easy as it will identify which cylinder is misfiring. PS. One of the biggest problems I see with guys doing their own plugs is poor tools. If the socket you use isn't proper it is easy to crack the plug going in. Edited March 6, 2009 by Bernie Link to comment Share on other sites More sharing options...
SlowPoke Posted March 6, 2009 Report Share Posted March 6, 2009 I'd be inclined to say weak coil but I don't know enough about that vehicle. Single or seperate coils? Also could be a bad injector spraying the plug or weak fuel pressure. Sometimes it's best to get diagnosed professionally than throwing parts at a problem. Link to comment Share on other sites More sharing options...
danbouck Posted March 7, 2009 Report Share Posted March 7, 2009 I'm guessing the boots were damaged or the plugs were not gaped. Link to comment Share on other sites More sharing options...
BUSTER Posted March 7, 2009 Report Share Posted March 7, 2009 Take it ice fishing already! Link to comment Share on other sites More sharing options...
tizfun Posted March 7, 2009 Author Report Share Posted March 7, 2009 Well you guys have been a great help... I went back and looked the first plug nearest the fan.. This one, when putting the boot back on gave me some trouble getting back on as there are wiring harnesses in the way.. I took it off and put it back on so it sealed properly.. Secured the bolt back on which hold the boot and started it up... Can you believe it.. smooth running... Took it out for a spin and no hesitation and when stepping on the gas, it moved really nice.. I went out this evening and took a drive on the Hwy 401 doing a 120-130 kms.... No more bucking and it drove really well... Thanks to all of you for all your help... I've been in jams many a times and when looking for help and tips, I know to come here as you all are very helpful... I appreciate all the advice and help.. Tiz Link to comment Share on other sites More sharing options...
ohhenrygsr Posted March 7, 2009 Report Share Posted March 7, 2009 your name says it all lol glad you got it fixed Link to comment Share on other sites More sharing options...
OhioFisherman Posted March 7, 2009 Report Share Posted March 7, 2009 Glad to hear you got it worked out, my first thought was also the plug wires. My Astro and Safari vans with the 4.3 engine started having problems in wet weather around 125,000, it was time to change plug wires.It looks like the coils are separate for each cylinder? The thing that goes over the plug? Computer controlled distribution of spark signal? If you got the plug from the dealer I would assume it is the proper plug, a wrong heat range on them can also cause bucking, mis- firing. Link to comment Share on other sites More sharing options...
Radnine Posted March 7, 2009 Report Share Posted March 7, 2009 I went out this evening and took a drive on the Hwy 401 doing a 120-130 kms.... Tiz Here is another tip....SLOW DOWN Link to comment Share on other sites More sharing options...
Cudz Posted March 7, 2009 Report Share Posted March 7, 2009 Here is another tip....SLOW DOWN Let's give him the benefit of the doubt. He stated 120-130 kms. This is distance, not distance over time. Link to comment Share on other sites More sharing options...
ecmilley Posted March 7, 2009 Report Share Posted March 7, 2009 sounds like you cracked a plug, If yyou want drive it to my shop in scarborough I'll give iit a look for a large tim's Link to comment Share on other sites More sharing options...
Markystang Posted March 9, 2009 Report Share Posted March 9, 2009 I know you got it fixed, BUT: There is a TSB on the Trailblazer if you ever happen to have problems with missing again. Apparently, when parked with the nose of the vehicle downhill in the rain, the rubber at the back of the hood leaks and water runs onto the top of the engine, and it gets in beneath the coil packs causing an electrical short and in turn a miss. There is an updated hood rubber that will prevent this from happening again. It was around $40 if i rememeber. I can look up the TSB# and part# for you if you're interested.... Link to comment Share on other sites More sharing options...
BillM Posted March 9, 2009 Report Share Posted March 9, 2009 Here is another tip....SLOW DOWN That is slow for the 401 Link to comment Share on other sites More sharing options...
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