07 fit misfire at idle with AC on.
#1
06-22-2018, 12:40 AM
07 fit misfire at idle with AC on.
I almost hate to do this since there are so many threads posted about misfires but, here we go anyways.
CEL came on P0301 error. Cleared code and has yet to reappear but still acting the same.
Plugs changed
coils changed in the indicated cylinder with a new one from Napa (cheapest one they had $80) all other systematically swapped with other old plugs from a car at a wrecker with no difference with each plug.
valve clearance checked.
Car has had a very slight sporadic misfire when idling without the AC on. Runs great when driving.
Turn on ac and the misfire becomes much more noticeable and is still sporadic. Car again seems to run fine when driving.
Any suggestions?
CEL came on P0301 error. Cleared code and has yet to reappear but still acting the same.
Plugs changed
coils changed in the indicated cylinder with a new one from Napa (cheapest one they had $80) all other systematically swapped with other old plugs from a car at a wrecker with no difference with each plug.
valve clearance checked.
Car has had a very slight sporadic misfire when idling without the AC on. Runs great when driving.
Turn on ac and the misfire becomes much more noticeable and is still sporadic. Car again seems to run fine when driving.
Any suggestions?
Last edited by Lucas1976; 06-22-2018 at 10:57 AM.
#2
06-22-2018, 09:57 AM
What brand of coils? Where did you buy them?
Type , source and installation detail for the plugs.
Who did the valve clearance adjustment?
Below are the common items to recheck:
Coils are off brand or counterfeit (bought of Amazon or e-bay from private party)
Plugs, same as above, plus
- dirt on the plug gasket surface
- anti seize was used (I know manual recommends it but it makes matters worse!
- the new plugs were tightened to specks, which may be not enough to compress the plug gasket (I only using torque wrench when doing taper plugs).
For valve adjustment:
-engine was too warm
-the adjustment screw moved when jam nut was tightened
The aluminum rocker arm rollers may be worn out (uncommon)
There is variety of reasons engine may miss with a/c on including:
bad wiring connectors (harness problem)
EGR valve is not fully closing
One of the EGR jet ports in intake is plugged up
Blown head gasket
and so on
PS I don't post this to show how smart I am
, but to keep this in mind while doing even simple operations such as spark plug change !
Type , source and installation detail for the plugs.
Who did the valve clearance adjustment?
Below are the common items to recheck:
Coils are off brand or counterfeit (bought of Amazon or e-bay from private party)
Plugs, same as above, plus
- dirt on the plug gasket surface
- anti seize was used (I know manual recommends it but it makes matters worse!
- the new plugs were tightened to specks, which may be not enough to compress the plug gasket (I only using torque wrench when doing taper plugs).
For valve adjustment:
-engine was too warm
-the adjustment screw moved when jam nut was tightened
The aluminum rocker arm rollers may be worn out (uncommon)
There is variety of reasons engine may miss with a/c on including:
bad wiring connectors (harness problem)
EGR valve is not fully closing
One of the EGR jet ports in intake is plugged up
Blown head gasket
and so on
PS I don't post this to show how smart I am
, but to keep this in mind while doing even simple operations such as spark plug change !
#3
06-22-2018, 10:15 AM
Spark plugs were ngk. I just went finger tight then 1/4 turn. I’ll see if perhaps I can tighten them a bit more also read about regapping them to make it .030 - .040
Valve adjustment done when cold adjusted to .006, and .011 and rechecked after each one adjusted and then again at the end to be sure.
coils cheapest ones from Napa. $80. Others were all systematically swapped with older ones from a car at a wrecker with no change and even tried swapping the new one with no change.
Valve adjustment done when cold adjusted to .006, and .011 and rechecked after each one adjusted and then again at the end to be sure.
coils cheapest ones from Napa. $80. Others were all systematically swapped with older ones from a car at a wrecker with no change and even tried swapping the new one with no change.
Last edited by Lucas1976; 06-22-2018 at 11:00 AM.
#5
06-22-2018, 07:14 PM
O
Went back to the store and bought the recommended NGK plug. Car seems to be running great now.
Picture shows tge plugs lugs I bought last week. Wish I would have noticed the discolouration before
#6
06-22-2018, 07:33 PM
Scratch my previous post. Which hasn’t shown up yet. Wife took it for a spin and it’s still doing the same thing. Replaced the Bosch plugs (could have sworn I bought NGK) with NGK and Ordering hitachi coils off amazon now fingers crossed that’ll fix it
coil from Napa is a ultra8
coil from Napa is a ultra8
Last edited by Lucas1976; 06-22-2018 at 07:36 PM.
#9
06-22-2018, 10:41 PM
Thanks for the help. I’ll keep you posted.
Wife says it does run better with the NGK plugs in it so that’s a bonus and the misfire doesn’t seem as bad when it happens but I’m wondering if it’s because it’s a lot cooler outside... seemed a lot better to me as well
Wife says it does run better with the NGK plugs in it so that’s a bonus and the misfire doesn’t seem as bad when it happens but I’m wondering if it’s because it’s a lot cooler outside... seemed a lot better to me as well
#12
06-24-2018, 10:51 AM
RockAuto had the Hitachi coils cheaper than anyone when I did mone a coupla months ago. full set of coils and full set of NGK irids one step colder to my door for $180....
#14
07-04-2018, 01:28 PM
So I've been having a problem with my engine misfiring when i have my AC on.
i have an 08.
the RPM's dip but the car stays alive.
I was hoping to find someone with a similar issue on here but i see a lot of posts on misfires that dont include having AC on .
Question:
Did your missfire go away when you turn on your AC?
I was hoping i could find an answer before i start ordering parts but i guess my issue is not super common?
i might be able to provide a video if i get some help on this.
also, my CEL does not turn on and has not turned since i've owned the car for the past 2 years.
i have an 08.
the RPM's dip but the car stays alive.
I was hoping to find someone with a similar issue on here but i see a lot of posts on misfires that dont include having AC on .
Question:
Did your missfire go away when you turn on your AC?
I was hoping i could find an answer before i start ordering parts but i guess my issue is not super common?
i might be able to provide a video if i get some help on this.
also, my CEL does not turn on and has not turned since i've owned the car for the past 2 years.
#15
07-05-2018, 12:01 AM
My misfires did not completely go away when I turned the AC off. They were still there but much less significant.
As an update to my original post my hitachi coils just arrived today. Took ten minutes out of my day and slapped all four into my little beast and voila! Problem seems to be fixed!
My wife will drive the car tomorrow and I’ll know for certain but I sat in the driveway for a good 15 minutes with no misfires with the ac on and car in drive (when the misfires were at their worst).
Fingers crossed.
So to review;
replaced my spark plugs with ngk things got a bit better but misfire was still there.
Did a valve adjustment. No change in the misfires but, the exhaust ones were all tight so I’m thinking it was a good thing to do. (Easy job for even a very novice do it yourselfer. Good videos on YouTube to follow).
Finally replaced all four ignition coils with hitachi. Problem resolved.
As an update to my original post my hitachi coils just arrived today. Took ten minutes out of my day and slapped all four into my little beast and voila! Problem seems to be fixed!
My wife will drive the car tomorrow and I’ll know for certain but I sat in the driveway for a good 15 minutes with no misfires with the ac on and car in drive (when the misfires were at their worst).
Fingers crossed.
So to review;
replaced my spark plugs with ngk things got a bit better but misfire was still there.
Did a valve adjustment. No change in the misfires but, the exhaust ones were all tight so I’m thinking it was a good thing to do. (Easy job for even a very novice do it yourselfer. Good videos on YouTube to follow).
Finally replaced all four ignition coils with hitachi. Problem resolved.
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