Rough Idle multiple Cylinder Misfire

Hi,

 

I have an 05 Legacy GT, earlier in the week I noticed that my car was idling rough when I would stop or start the car. The check engine light eventually came on and i checked the codes and it was P302 and P303 which were Misfires in cylinder 2 and 3. I cleared the codes and they came back in a few hours..

 

Do anyone have any suggestions on what it might be? I find it hard to think I'd have two bad coil packs at the same time. I've checked/cleaned the ECU connectors. Has anyone see this before or know what i should check?

id check the coil packs and plugs. move them to different cylinders and see if the mis fire follows.

figure this out?

 

I got the same two codes with a PO171, system too lean, bank 1. I cleared the codes and only the PO171 keeps coming back. Still idles like a bastard and stalls.

Mine ended up being a vacumn line that came off, it was located under the intercooler, I found it by using a smoke machine and seeing where it was leaking.

Hi,

 

I have an 05 Legacy GT, earlier in the week I noticed that my car was idling rough when I would stop or start the car. The check engine light eventually came on and i checked the codes and it was P302 and P303 which were Misfires in cylinder 2 and 3. I cleared the codes and they came back in a few hours..

 

Do anyone have any suggestions on what it might be? I find it hard to think I'd have two bad coil packs at the same time. I've checked/cleaned the ECU connectors. Has anyone see this before or know what i should check?

 

Our stock OEM injectors are known to go bad, replacing them would surely fix the problem if you don't have a leaky vacuum line.

I am experiencing similar conditions with my 2005 Legacy GT. As I have then aggravated beyond belief in the past few months with the car's performance and issues regarding missfires check engine lights and idling ...the love that I once had for this car is slowly deteriorating , so if anyone could help or offer a suggestion it would be terrific and greatly appreciated ...the following codes have been detected and scanned on my vehicle within the past 60 days... P0304,p1153,P1152, p 0172, p 301, p 302, pf f fe ( whatever the hell that means?.).. The following parts have been changed within the past 60 days ....mass air flow sensor, 4 NGK Iridium plugs .30 GAP, upstream o2 sensor, thorough cleaning of all fuel injectors, throttle body manual cleaning..the current typical scenario is start the car after it warms up the idle will bounce from close to 0 to about 1400 rpm and back again up and down up and down while I am at an idle sitting still. When I Drive the car during deceleration lots and lots of Popping backfire comes through the exhaust. Most of the time when I come to a stop sign the idle goes so low, it will shut the car off most times, but it will start right back up... I've parked it for the past 3 weeks, I can't stand to drive it it makes me nuts, I want to dump it off a bridge... as I mentioned any input will be greatly appreciated ...please no sarcasm as I'm simply to my breaking point with this problem. I wanted to add a bit of information concerning the replacement of the upstream o2 sensor.. it was replaced because the voltage reading was 2.5 volts ,and it is supposed to be less than 1 volt . However after the purchase and install of the new one the voltage stays the same at 2.5 volts? so I probably threw away a perfectly good o2 sensor and replaced it with a Bosch brand. I really don't understand why the upstream o2 sensors, regardles the brand, they are all reading 2.5 volts & that is awfully strange... my email address is..... generaljoe67@verizon.net in the event an email is preferred

I am experiencing similar conditions with my 2005 Legacy GT. As I have then aggravated beyond belief in the past few months with the car's performance and issues regarding missfires check engine lights and idling the love that I once had for this car is slowly deteriorating so if anyone could help or offer a suggestion it would be terrific and greatly appreciated the following codes have been detected and scanned on my vehicle within the past 60 days... P 030 4,p 1153,P 1152, p 0172, p 301, p 302, p f f fE... The following parts have been changed within the past 60 days mass air flow sensor, 4 nGK Iridium plugs, upstream o2 sensor, thorough cleaning of all fuel injectors, throttle body manual cleaning..the current typical scenario is start the car after it warms up the idle will bounce from close to 0 to about 1400 rpm and back again up and down up and down while I am at an idle sitting still. When I Drive the car during deceleration lots and lots of topping backfire comes through the exhaust. Most of the time when I come to a stop sign the idol as it is going lo it will shut the car off most times I've parked it for the past 3 weeks I can't stand to drive it it makes me so angry I want to dump it off a bridge. as I mentioned any input will be greatly appreciated ...please no sarcasm as I'm simply to my breaking point with this problem. my email address is .... generaljoe67@verizon.net in the event an email is preferred

Sounds like you need a leak down and compression test...

Sounds like you need a new shortblock. And a lesson in how to use punctuation.

 

And before you start on about how angry you already are, remember, this is the internet, there are only printed words; how they're presented is not only important, but is also a representation of you and whatever intelligence you may (or, as I suspect, may not) possess. This is clearly indicated by your addition of an email address, as if your post were some kind of Craigslist ad. (Hint: this isn't CL!)

 

 

Your host of issues leads me to believe that you should indeed run the car off an elevated precipice. Don't forget to wear your seatbelt!

http://legacygt.com/forums/showthread.php/diy-rough-idle-cold-start-cold-temps-lgt-07-09-155325.html

 

This just solved my rough idle and misfire issue... maybe check into it