Cylinder misfires or bad injectors, please post here.

Add another P0304 Cylinder 4 Misfire to the list. STOCK 2006 spec.B

**WHEN CEL TURNS ON**

- Always at cold start

- Very rough at idle, but not dying

- Smoothes out at higher RPM and not even noticeable at boost

- Rough at idle even when warm

- Fluctuates based on temperature and air and humidity

- Always steady CEL accompanied by flashing cruise control light

- Accompanied with low fuel economy

WHEN CEL IS OFF

- Idles fairly smoothly (at first), and gets progressively worse before CEL turns on

- Boost and higher RPMs are good

- STILL low fuel economy (even when CEL was off for 5 months) <--- WHY?

Here's my breakdown:

- Several months ago, CEL came on, but it was /very/ temperamental. Everytime I wanted to take it to get checked out, the CEL would turn itself off (NOT RESET) and stay off for a couple weeks.

- This went on for a few times

- Then, CEL was gone for 5 solid months - never showed. Though, the car did seem like it was running in "safe" mode because I felt less power and definitely a drop in mileage

Recently:

- CEL finally came back on a couple weeks ago, and I took it to my shop. I had the plugs changed recently so they did the coil. Ran nicely with more power and better fuel economy for about 25 miles and then CEL came back on the next day.

- Swapped the injectors and still got the same code, but I still suspect that the injector is bad.

- Did a compression test and got about 135, which is a little low, but not horrible.

- Finally took it to dealer because I wanted to see what they would know. They said that I was /barely/ getting a misfire in cylinder 4. WHAT?! (THOUGHTS ON THIS?) This surprised me. They showed me the 'roughness' or whatever meter and cylinder 4 was at like "1" roughness. They asked me if I was using synthetic. Please.

- I put in some Techron fuel cleaner when I filled up recently just to see if that might clean up the injectors too. Didn't prevent CEL from coming back on after they cleared it on Thursday.

- The dealer is doing something with the intake parts on Monday. I am not sure what that's going to do. Based on the forums, it seems that if it's not a burnt valve (which it's not) then it's fixed by the coil (which is replaced) or the injectors - which has not been done... I haven't seen anyone on here or other forums say anything about the intake with my symptoms (very rough idle and smoothes out at higher rpm with decreased fuel economy). Why are they doing stuff with the intake? Does that make sense for what's happening?

Other:

- My MechE friend who's been taking apart cars since he was a kid said that I should clean the MAF sensor (also suggested to the dealership), but doesn't another code come up for the MAF sensor?

- He also said that it might be the NOx sensor too and it's feeding "lies" to the ECU. But, wouldn't another code pop up for a faulty sensor?

- He said to check if the rattling at idle is rhythmic or erratic. I forgot why... It seems rhythmic though. Thoughts?

Unfortunately, I'm driving cross-country in about a week and need this done ASAP so I was forced to go to the Subaru dealership in Wakefield instead of Cityside in Belmont (because they were very booked).

I have Subaru extended warranty Gold Plus plan or whatever so I have most everything covered.

Any idea what I should tell these Subaru guys to check out next or replace next or clean next?

You have already changed coil pack so that is eliminated. I would change injector first, if that doesn't fix it check the intake manifold seal which could be checked by spraying something around it with car running when cold. Some have had rubber gaskets not seal there.

I would also do a compression test on cylinder 4.

I went round and round with this recently and mine ended up being 30 psi cylinder 4. Its going to either be ringland or burnt valve but motor not tore down yet.

If its not running at low RPM but OK at high it could be valve. Some have seen this with a ringland.

Anyway good luck but injector is where I would go first.

Add another P0304 Cylinder 4 Misfire to the list. STOCK 2006 spec.B

 

 

Recently:

 

........

- Did a compression test and got about 135, which is a little low, but not horrible.

 

- Finally took it to dealer because I wanted to see what they would know. They said that I was /barely/ getting a misfire in cylinder 4. WHAT?! (THOUGHTS ON THIS?) This surprised me. They showed me the 'roughness' or whatever meter and cylinder 4 was at like "1" roughness. They asked me if I was using synthetic. Please.

- I put in some Techron fuel cleaner when I filled up recently just to see if that might clean up the injectors too. Didn't prevent CEL from coming back on after they cleared it on Thursday.

- The dealer is doing something with the intake parts on Monday. I am not sure what that's going to do. Based on the forums, it seems that if it's not a burnt valve (which it's not) then it's fixed by the coil (which is replaced) or the injectors - which has not been done... I haven't seen anyone on here or other forums say anything about the intake with my symptoms (very rough idle and smoothes out at higher rpm with decreased fuel economy). Why are they doing stuff with the intake? Does that make sense for what's happening?

 

Any idea what I should tell these Subaru guys to check out next or replace next or clean next?

I have an '05 GT with 169,000 miles. I went through the injector issue a LONG time back - probably 3 years and 85,000 miles ago. Replaced two injectors with factory replacements from subarupartswarehouse.com, sent those to deatchwerks for rebuilding and have been ready for another to go, but they never have. At ~168,000 miles, the turbo finally went (I know, I am lucky to go that far.) Local ASE mechanics (not dealer - dealer here is not good option) tried to replace the turbo with aftermarket brand to save some $$ and gain some power. Did not go well, that turbo came apart in the first 200 miles. After the repair of the bad replacement turbo, I started getting the rough idle issues like you describe - would often choke out at stop lights, but ran pretty well at higher RPMs. Cleaned MAF, ran the codes and shop said it needed a "tumble generator valve position sensor" - problem is, you cannot buy that sensor, you must buy the intake manifold assembly, which has that sensor pre-installed. If your shop is relating this issue to the intake, it might be this sensor.

I called SOA and complained about requiring people to buy an intake manifold assy just to get a $50 sensor which attaches with two machine screws to the outside of the manifold. No response to date.

By the way, my 2005 with 169,000 miles has ~150 on the compression test.... I think I lucked out with the durability of the powertrain I got on this one...

You have already changed coil pack so that is eliminated. I would change injector first, if that doesn't fix it check the intake manifold seal which could be checked by spraying something around it with car running when cold. Some have had rubber gaskets not seal there.

 

I would also do a compression test on cylinder 4.

 

I went round and round with this recently and mine ended up being 30 psi cylinder 4. Its going to either be ringland or burnt valve but motor not tore down yet.

 

If its not running at low RPM but OK at high it could be valve. Some have seen this with a ringland.

 

Anyway good luck but injector is where I would go first.

Compression test was done and got around 135.

Subaru dealership just replaced the intake gaskets and that didn't do anything. The light came on a few hours after I got home during a cold/warm start.

I took it to Autozone and it read both P0304 and P0302 aka Misfire in Cylinder #4 and #2.

This is new...

I bought some MAF Cleaner to try that.. Here are some pictures below..

BEFORE

http://i1114.photobucket.com/albums/k534/hlefbad/maf%20sensor/P1000214.jpg

http://i1114.photobucket.com/albums/k534/hlefbad/maf%20sensor/P1000215.jpg

http://i1114.photobucket.com/albums/k534/hlefbad/maf%20sensor/P1000216.jpg

http://i1114.photobucket.com/albums/k534/hlefbad/maf%20sensor/P1000217.jpg

AFTER CLEANING

http://i1114.photobucket.com/albums/k534/hlefbad/maf%20sensor/P1000219.jpg

http://i1114.photobucket.com/albums/k534/hlefbad/maf%20sensor/P1000220.jpg

Does anything look odd with the MAF sensor? I really don't know much so I'm not sure. It /looks/ like other pictures online, but I can't be certain.

I cleaned the connectors as well, but just forgot to take pictures..

Anyway, so now the dealership has ordered an injector, but if both #2 and #4 cylinder misfires came up, can it be the injector?

I'm starting to run out of ideas of what to try next...

P0302 and P0000. swapped coil packs and the cel came back. pretty sure its the injector. the car drives fine, no abnormal hesitation, idles like normal. tried injector cleaner but the cel cams back.

ill swap injectors for #2 and #4.

it seems as though ppl are replacing the bad injector, shouldnt all the injectors be replaced?

hiefbad:

Yes it could be 2 injectors acting up. I had to replace 2 of mine before motor went

what i meant was should all 4 injectors be changed, or is it ok to do only 1?

i need to swap the current injectors to see if the cel follows the injector.

kingJ:

You can change just one.

Id just take it into the dealer and have them change out the injectors in the cylinders that are misfiring.

installed new plugs and a new injector in cylinder 2, the cel came back. P0302, and P000.

what to change now?

Use the AP and log roughness cylinder and see which cylinder is causing the CEL.

Change that plug and injector as it may not be number 2 or you have more than one.

If that doesn't fix it time to do compression and or leak down test.

installed new plugs and a new injector in cylinder 2, the cel came back. P0302, and P000.

 

what to change now?

Try swapping the coil packs and see if the code follows to the other cylinder. if it does, then get a new coil.

If it doesn't, then do a compression test and pray.

hiefbad:

see post number 155

swapped injector 2 (newely installed) with injector 4 and cel came back on. at this point im thinking its a valve issue. do these cars have a fuel preassure regulator or something similar?

i need to get this diagnosed but im out of the powertrain warranty. the car is a 05 with 55k miles. should i take it tot the dealer and see is SOA will help, or take it to a independent shop. I would hate to take it to the dealer and SOA doesnt help, then im stuck with a large bill.

edit, wanted to add that the car does not fire right up anymore. needs a few cranks to get it going.

could this be oxygen sensor related?

yes its on the fender on drivers side near the fuse box with all the fuel lines and hoses running to it.

Could be fuel pressure causing the crank issue, but i would do a compression and leak down test.

had the dealer check the problem, they pulled the valve cover and said the valves had 0 clearance. definatley a valve issue, but it could be a burnt valve, or a dropped guide, not sure. they claim they need to remove the heads to find out.

car has 55,000 miles and this should not happen to such a young engine.

anyways, dealer quoted thousands to fix this, trying to get quotes from independant shops that know subarus.

any input would be appreciated.

I had the same issue at ~64K miles on our 2006 OBXT Ltd. Burnt valves on 2 and 4 - attributed to bad gasoline (the SOA field engineer singled out Exxon - which we used in the car very often (93 Octane)).

Thankfully after some conversation - SOA covered the repair (which entailed removing both heads and cleaning/resurfacing the exhaust valve seats). It's been running beautifully ever since (now at 75K).

i took it to the dealer because of SOA. SOA wants me to pay the bill for the teardown and depending on what caused the problem (bad gas, hard driving, etc...) they will then decide if they will help. dont really want to take that chance. dealer quoted something like $7K for a "worst case" deal.

other independent shops have quoted $2500 ish for the work.

car has 55k on it and the powertrain warranty ended nov. 2010.

i purchased the car in oct. 2009 with 40k miles on it. i have my records, but no records from the previous owner.

shitty deal, what to do?

Has anyone noted any of these problems getting worse while running the A/C? I got a CEL this past weekend, haven't checked the code yet, but I'm almost positive its a cylinder misfire, based on the shuddering idle and the ecu hunting the tach for a smooth idle.

CEL cleared itself the next day.

Plan of action (and this seems to be the process for everyone in this thread):

-Check for vacuum leaks, including hoses and IC cracks, etc.

-Clean your MAF

-Try injector cleaner, swap injectors to see if misfire moves

-Inspect plug wires

-Swap coils, see if misfire moves

Has anyone tried the rebuilt injectors from Rock Auto? for ~$25 apiece I'd be much more interested than buying all new ones.

jsmith-what was the cause of the valve problem?

brock-1st check the code. I have tried the injector from rockauto, its a beck arnley unit. seems to work fine. ebay has some as well.

jsmith-what was the cause of the valve problem?

 

brock-1st check the code. I have tried the injector from rockauto, its a beck arnley unit. seems to work fine. ebay has some as well.

They attributed my valve issues to not running premium fuel, but were astounded that I had all my gas receipts and could prove that i was using premium. Then they changed their story and said exxon specifically. I filled up for a year at hess (had a gas card) and then Wawa after that almost religiously, not sure if either of them are subs of exxon.

They attributed my valve issues to not running premium fuel, but were astounded that I had all my gas receipts and could prove that i was using premium. Then they changed their story and said exxon specifically. I filled up for a year at hess (had a gas card) and then Wawa after that almost religiously, not sure if either of them are subs of exxon.

Translation: they're trying to snow you, and you're shooting them down.

Good for you.

(In addition, what's all this about Exxon selling bad gas? I know a retired executive who would beg to differ.)

the same story was going around WA about Arco (BP sub) years ago. Was dis proven.

I believe their are only 2 substantial differences to any gasoline: 1. where it comes from (AK, Indonesia, Saudi Arabia, Iran, Venezuela) and 2. what detergent additives the company uses.

I used Exxon/Mobile exclusively in my M3 because of the Techron, and when the engine was torn down the mechanic said it looks like it made a difference. but it is ridiculously subjective. I use Shell in my Leggy mostly, but I'm not nearly as anal about the gas as I was in the bimmer.