I have a 2006 her with 64700 miles on it. I keep getting miss fire code on #4. new plugs all new coil packs just put in a new air filter and mass air flow sensor. what else maybe a fix.

Asked by Nov 04, 2017 at 02:39 PM about the Chevrolet HHR

Question type: Maintenance & Repair

don't want to get rid of this car in such nice shape but tired of issue

4 Answers


Vacuum leaks can cause a misfire, poor injector pattern can cause a misfire, low compression can cause a misfire. So easiest first, when was it's last professional injector cleaning? Not a pour in the tank stuff, that's good for maintenance but not a badly restricted injector, might need a new injector on number 4, vacuum leaks really need a smoke machine to find them properly any more, usually compression is still good at this mileage unless something in the basic engine has went south like a valve or cam lobe, piston, etc. HTH

3 people found this helpful.

Thank u I will pass this on to my mechanic. We put a new mass air flow sensor earlier today and cleared the misfire #4 code. When he checked air filter it was pretty dirty he cleaned the air flow sensor when he unplugged the sensor it popped up a miss fire code. So I bought a new one and he replaced today. So far I have drove about 60 miles today so far no code. If it was a internal issue would code be so random


No it would not be random, you could clear it and after it went into closed loop the code would return if there was an internal vacuum leak. Are you running top tier fuel in it? If not I would start using it and add a bottle of Techron every other tankful.

1 people found this helpful.

I use shell fuel most of the time I will put there best in with some Techron. I purchased a new fuel injector off amazon last evening. I drove it yesterday 4 separate times and put about 65 miles on it. Without the engine light coming on we will see today I’ll drive it again it rained last night could moisture play a role into the miss fire code after I washed it yesterday I took it around the block and that’s when the miss fire #4 came back on. Thank u for your responses. I really appreciate them. This is for my daughter she is 15 1/2. and a straight A student and a great kid I’m just trying to give her a nice car to drive. Again thank u.

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