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2004 chevy trailblazer_lt
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Discussion Starter · #1 ·
I need help! I changed my spark plugs in my '04 TV about three weeks ago. Ever since I've had really inconsistent throttle response. Immediately after the plug change, my TV was running GREAT! It was like having a brand new car!!! A couple of days later I noticed the engine could "cough" (that's the best way I can describe it, or slightly cut out. Now the throttle response and acceleration are the worst they've ever been.

It seemed like maybe there was some obstruction or other problem with the air intake or that I had failed to reconnect one of the vacuum hoses, so I took everything apart and it was fine. Then I thought there was maybe water in the fuel, so I cycled through some SeaFoam to see if that would help... nothing. I've never changed the fuel filter, so that was going to be my next plan of attack. Any ideas???

:thx
 

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2003 chevy trailblazer_ls
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please dont say u put in bocsh spark plugs:nono:
If so u might want to purchase ac Delco or ngk plugs

Also try cleaning the throttle body and replace or clean ur air filter:thumbsup:

changing the fuel filter is a good idea also if u havnt done it
 

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Discussion Starter · #3 ·
I did use the AC Delcos. I had bought the Bosch at first, but then after consulting this site returned them for the real deal.

The air filter is new and the throttle body looked pretty clean when I changed out the plugs. I didn't give it a really close look, though. That could be the problem?
 

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2003 chevy trailblazer_ls
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unhook the negative terminal post for about 45 min first...clean it or replace it the air filter..change the fuel filter and hook the terminal back up then see what it does:undecided
 

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2003 chevy trailblazer_ls
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no but there will be some in the filter...do a How-to search and theres a relly helpful thread on changing it out:cool:
 

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2002 chevy trailblazer_lt
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I wouldn't think it's the fuel filter. It either works normal or not at all, not really an in-between.

edit: nvm I read it as if you just bought the TB :X
 

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2002 gmc envoy_slt
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The problem started a few days after he changed his spark plugs. Lets start there.

Go thru each coil pack, disconnect them, and push them back down making sure they are fully seated on the spark plug. It is pretty easy to install the coil pack with the cone piece not on the plug.

After you do that, make sure all of the connectors on the top of the coil pack are firmly planted.

How tight did you tighten the spark plugs? did you use a torque wrench?

Im wondering if your problem lies in that area....
 

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2003 chevy trailblazer_lt
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:cry:Is there an easy way to test the coil packs? I have a good bit of hesitation and from idle and it almost stalled this morning. I also have a BIG loss of power when I accelerate hard. It seems as if it has a little pause every other second but I can see the tach jump to indicate anything and I can only hear a very faint pause. I have just changed the spark plugs with AC Delco OEM, new BEHR Fan clutch a few weeks ago with new belt and water pump, cleaned the TB several times a month ago and changed the Fuel filter. I am not getting a CEL and have NO idea what to check next. Any ideas? I need help and have no idea what to do from here. This all started months ago which started my long nights of ready TV with symptoms like everyone else, none of the items above have helped resolve the problem.
:sadcry:
 

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2003 chevy trailblazer_lt
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:cry:Is there an easy way to test the coil packs? I have a good bit of hesitation and from idle and it almost stalled this morning. I also have a BIG loss of power when I accelerate hard. It seems as if it has a little pause every other second but I can see the tach jump to indicate anything and I can only hear a very faint pause. I have just changed the spark plugs with AC Delco OEM, new BEHR Fan clutch a few weeks ago with new belt and water pump, cleaned the TB several times a month ago and changed the Fuel filter. I am not getting a CEL and have NO idea what to check next. Any ideas? I need help and have no idea what to do from here. This all started months ago which started my long nights of ready TV with symptoms like everyone else, none of the items above have helped resolve the problem.
:sadcry:
an easy way to check coil packs is to start the truck. with it running, start disconnecting the coil packs one at a time if the idle changes, that coil pack is working. so reconnect and move on to the next one. if you disconnect one and the idle does not change that means that, that pack is bad.
 

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did u check both sides of the throttle body? back side of the flap was clean.. cause that is where the gunk forms...

if ur not getting any mis fire codes being thrown i would doubt the pack aint on the plug... but mite not be all the way on... did u check the gap before putting them in? i know they come pre gapped but u cant rule out them being dropped in transport...
 

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2003 chevy trailblazer_lt_ext
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I would say clean the throttle body for that you'll have to remove it from the intake assy. you may need to get the torque specs to re-install.
it won't hurt your ride to try..
 

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2003 chevy trailblazer_lt
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I did clean both sides of the TB. I did not double check the gapping of the AC Delso plugs though. I did check the first set I put in about 25K ago and this problem started way before last night when I put the replacement AC Delcos in.
I tested the coil packs by running the engine and disconnecting each of the coil packs 1 at a time and the engine did respond to each one being remove (1 at a time obviously) Is it possible that the coild pack boot is not on the spark plug even if it is clear that the idle responds when disconnecting the coil pack?
I am also now, as of last week idling at like 1,000 rpm instead of my normal 6-800. Not sure if that helps.
I just replaced the MAP sensor and no dice their either.
:cry: I need help, AND my TRUCK too.
 

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2003 chevy trailblazer_lt
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since it responded to each one that you disconnected that means all packs are good and the boots are on the sparkplug.
 

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I also have this ticking noise when I am driving and accelerating. I can only hear it when I have a car/truck next to me or a cement wall etc... IT is only when I am accelerating above 10mph in "Drive" I do not get the noise at any speed when I pop into neutral and rev (No noise) Not sure if this helps or is part of the problem. I did change the MAP/MAS and still have the problem. I did get an error for Bank 1 running rich and and low voltage to MAP/MAS. I do have a K&N filter, I cleaned it 2 weeks ago and did not put to much oil on as I did not put any oil on it yet becaause I did not have the oil refill kit.
Any thoughts or ideas?
 

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2004 chevy trailblazer_lt
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Discussion Starter · #20 ·
My plan for the weekend is to re-seat all of the coil packs. Is there a good way to make sure they are seated well? The front one and two rear ones don't allow a lot of room to maneuver.

My idle is good (about 600 rpm) and it doesn't seem to be missing, though a couple of times I stopped at a light and could feel the truck rocking a bit.

I didn't use a torque wrench to tighten the spark plugs, just tightened them to about where they felt when I took the old ones off.

I'll also be changing the fuel filter and cleaning the TB this weekend. I'm really at a loss for what's going on!!! :worried: It ran great at first when I changed the plugs!
 
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