04 LS V6 only got 60 000kms anyway my engine shakes or misfires only in idle i feel it more when i put the car in reverse and in drive i feel it less when its in park or neutral but is present at all times except when the rpm is over 1000 when i accelerate from 0 it feels like the car is hesitating I changed the spark plugs with OEM ones coil packs all in pretty good condition....So any ideas on what might be causing this? oh also when the car is in drive and i put in park the rpm goes from 500(normal idle ) up 1000 then back to 500
engine shaking/misfiring not sure which one
- Thread starter lking
- Start date
joegr
Dedicated LVC Member
You can not tell the condition of the COPs (Coil-On-Plug, they're not coil packs) by looking. You can only tell by stress testing. Since most can't stress test them, most people just replace them. The PCV valve and elbow are also a problem on the V6.
thanks...whats an elbow?
joegr
Dedicated LVC Member
tireman
Dedicated LVC Member
vacuum leak
check all vacuum hoses carefully for leaks, if the 04 has the PCV valve? then the vacuum hose from the throttle body to the PCV is probably split, or the PCV hose elbow, I found the rubber hoses crack from the heat near the rear of the engine compartment. My PCV elbow split around 60K miles, the hose to the TB at about 112K miles. Somewhere you have a leak. Oh! Pull off the PCV hose at the throttle body if the idle does not change then the hose is split somewhere.
check all vacuum hoses carefully for leaks, if the 04 has the PCV valve? then the vacuum hose from the throttle body to the PCV is probably split, or the PCV hose elbow, I found the rubber hoses crack from the heat near the rear of the engine compartment. My PCV elbow split around 60K miles, the hose to the TB at about 112K miles. Somewhere you have a leak. Oh! Pull off the PCV hose at the throttle body if the idle does not change then the hose is split somewhere.
okay i checked all hoses except for the ones at the rear of the engine which is hard to see because its being blocked by the bar thats there could anyone confirm that the 2004 V6 has an "elbow" hose also a picture of where this hose is located would be nice thank u
*UPDATE*
i'm still not sure what the problem is BUT i believe i'm getting closer to it i tried to listen for any hissing noises coming from the vacuum lines thats when i noticed a strong smell of fuel coming from the passengers side of the engine also i put my hand on different parts of the engine and it seems like the engine is misfiring from the passengers side which leads me to believe that this may be be a coil pack problem after all if a coil pack is not working that means theres no spark if theres no spark then theres raw fuel going though the engine and out of the exhaust this could also explain the nasty smell i'm getting from the exhaust when i drive my car correct me if i'm wrong
I did not gap my spark plugs do they have to be gapped? they are OEM spark plugs
i'm still not sure what the problem is BUT i believe i'm getting closer to it i tried to listen for any hissing noises coming from the vacuum lines thats when i noticed a strong smell of fuel coming from the passengers side of the engine also i put my hand on different parts of the engine and it seems like the engine is misfiring from the passengers side which leads me to believe that this may be be a coil pack problem after all if a coil pack is not working that means theres no spark if theres no spark then theres raw fuel going though the engine and out of the exhaust this could also explain the nasty smell i'm getting from the exhaust when i drive my car correct me if i'm wrong
I did not gap my spark plugs do they have to be gapped? they are OEM spark plugs
joegr
Dedicated LVC Member
You always should check/set the gap on plugs. Even if they were set correctly at the factory, they may have been bent in some during shipment.
BTW, they are not coil packs, they are COPs (Coil On Plug).
Coil pack = two or three coils in one pack that fire four or six cylinders, and sparkplug wires are used.
COP = one coil connected to the top of the sparkplug. A rubber boot and spring are used to make contact, instead of a sparkplug wire.*
*: Exception: some GM applications use a single coil like a COP, but mount it remotely from the plug, so a sparkplug wire is used in those cases.
*UPDATE*
i unplugged each COP while the engine was running one of the COPS didnt make a difference in idle the engine was shaking the same way with the COP plugged and unplugged i took out the COP looks just like the other ones so i took out the spark plug doesnt look like a spark ever occurred since i put it in looks brand new i took the other two spark plugs out of the same side the tips are black they smell like fuel i'm thinking this is because of too much fuel and of course thats because of the COP that is not working correct me if i'm wrong i'm going to go ahead and order a COP from the dealer ship i'm hoping that the COP is the problem rather then a stuck open injector
i unplugged each COP while the engine was running one of the COPS didnt make a difference in idle the engine was shaking the same way with the COP plugged and unplugged i took out the COP looks just like the other ones so i took out the spark plug doesnt look like a spark ever occurred since i put it in looks brand new i took the other two spark plugs out of the same side the tips are black they smell like fuel i'm thinking this is because of too much fuel and of course thats because of the COP that is not working correct me if i'm wrong i'm going to go ahead and order a COP from the dealer ship i'm hoping that the COP is the problem rather then a stuck open injector
*UPDATE*
changed the COP car is running a lot better no fuel smell no misfiring like before BUT i'm still getting little burps its not like the misfiring i was getting before where it was constant misfiring now it comes and goes for example lets say - means no misfire and + means misfire
--------+------------+++-------++------++++++--------+-------+-----+++ and so on Any ideas of what might cause this kind of misfire?
changed the COP car is running a lot better no fuel smell no misfiring like before BUT i'm still getting little burps its not like the misfiring i was getting before where it was constant misfiring now it comes and goes for example lets say - means no misfire and + means misfire
--------+------------+++-------++------++++++--------+-------+-----+++ and so on Any ideas of what might cause this kind of misfire?
joegr
Dedicated LVC Member
It could be many things, but the most likely is that it's another coil. (The one you replaced failed completely, those are easy to find. Most LS coils just become marginal instead of complete failure. Those are hard to find. That's why most LS owners just replace all the COPs when this starts happening.)
yeah i think ur right its probably another coil i'm going to buy one coil replace the coils one at a time with the new coil c if i could find the one that misfiring i cant afford to spend $600.00 on 6 COPS they go for $94.00 each at my dealer
joegr
Dedicated LVC Member
I'll bet that Max (look to the right) can sell you the same coils for less, even including the shipping.
joegr
Dedicated LVC Member
The misfiring was another coil. Cars running smooth now...finally
does the engine light turn off once it can no longer detect a problem OR does it have to be reset?
It'll turn off by itself after a few driving cycles with no misfires.
If you had a check engine light, why didnt' you just scan the codes? It would of told you which cylinder was misfiring.. I scanned mine without a light, and it still told me which ones were misfiring. Also, with a scan tool you can turn the CEL off..