Check Engine Help: P0303
Thread Starter
Joined: 07-07-2010
Posts: 8
From: MD
Check Engine Help: P0303
Problem:
Wife's HHR is a 2009 with the 2.4L engine, 90k miles. Started getting a P0303 - Cylinder 3 Misfire Detected error. No change in drive-ability. If I clear the code, sometimes it goes away for a week, sometimes for a day. It's intermittent but consistent, if that makes sense.
Experience:
Mostly competent shade tree mechanic. I've swapped clutches, done timing belts, I'm decent at troubleshooting. Mechanical engineer by schooling. Plenty of tools.
Research:
https://www.chevyhhr.net/forums/showthread.php?p=674419 - Low gas apparently. Not my issue.
https://www.chevyhhr.net/forums/problems-service-repairs-42/cel-fuel-injector-18749/ - Bulletin #08-06-04-046 - Water in spark plug well (I didn't see any during any work I've done, but that doesn't mean some isn't there. I will be checking this again.)
https://www.chevyhhr.net/forums/problems-service-repairs-42/misfire-cylinder-3-a-32207/ - valve seat issue
Searching TSB Thread, https://www.chevyhhr.net/forums/show...303#post693708 - Valve carbon buildup (possible, any easy way to check?)
and https://www.chevyhhr.net/forums/show...303#post435979 - internal engine crack in the crankcase area that allows engine coolant to enter the engine oil. (No mixed fluids that I've noticed, and I do the oil changes)
Solutions:
I started with swapping plugs in #2 and #3. Still had P0303. Swapped coil packs between #2 and #3. Still had P0303. Bought a new fuel injector and installed in #3. And here we are today with P0303 again.
Sanity check:
Air/Fuel/Spark/Compression.
Air: I can't think of anything obvious that would stop air to just one cylinder without pulling the intake manifold and poking though the runner for #3.
Fuel: obviously the rail has it, and my new injector should be good. I could try swapping injectors.
Spark: Unless it's in the wiring, I've checked plug and coil.
Compression: I haven't checked this, but I do have a gauge. Might as well at this point, but does anyone think I'll find low compression on #3 causing a misfire?
Looking under the hood, left to right we have: Belts, #1, #2, #3, #4. Right? (Man, I'd feel stupid but happy if I replaced the wrong injector, lol)
Thoughts? I can't think of anything cylinder #3 unique except for wiring at this point, and I'm capable of using a multimeter, I just don't know what to start checking. If it's not wiring, it's probably something more major, and hopefully under warranty.
Wife's HHR is a 2009 with the 2.4L engine, 90k miles. Started getting a P0303 - Cylinder 3 Misfire Detected error. No change in drive-ability. If I clear the code, sometimes it goes away for a week, sometimes for a day. It's intermittent but consistent, if that makes sense.
Experience:
Mostly competent shade tree mechanic. I've swapped clutches, done timing belts, I'm decent at troubleshooting. Mechanical engineer by schooling. Plenty of tools.
Research:
https://www.chevyhhr.net/forums/showthread.php?p=674419 - Low gas apparently. Not my issue.
https://www.chevyhhr.net/forums/problems-service-repairs-42/cel-fuel-injector-18749/ - Bulletin #08-06-04-046 - Water in spark plug well (I didn't see any during any work I've done, but that doesn't mean some isn't there. I will be checking this again.)
https://www.chevyhhr.net/forums/problems-service-repairs-42/misfire-cylinder-3-a-32207/ - valve seat issue
Searching TSB Thread, https://www.chevyhhr.net/forums/show...303#post693708 - Valve carbon buildup (possible, any easy way to check?)
and https://www.chevyhhr.net/forums/show...303#post435979 - internal engine crack in the crankcase area that allows engine coolant to enter the engine oil. (No mixed fluids that I've noticed, and I do the oil changes)
Solutions:
I started with swapping plugs in #2 and #3. Still had P0303. Swapped coil packs between #2 and #3. Still had P0303. Bought a new fuel injector and installed in #3. And here we are today with P0303 again.
Sanity check:
Air/Fuel/Spark/Compression.
Air: I can't think of anything obvious that would stop air to just one cylinder without pulling the intake manifold and poking though the runner for #3.
Fuel: obviously the rail has it, and my new injector should be good. I could try swapping injectors.
Spark: Unless it's in the wiring, I've checked plug and coil.
Compression: I haven't checked this, but I do have a gauge. Might as well at this point, but does anyone think I'll find low compression on #3 causing a misfire?
Looking under the hood, left to right we have: Belts, #1, #2, #3, #4. Right? (Man, I'd feel stupid but happy if I replaced the wrong injector, lol)
Thoughts? I can't think of anything cylinder #3 unique except for wiring at this point, and I'm capable of using a multimeter, I just don't know what to start checking. If it's not wiring, it's probably something more major, and hopefully under warranty.
Platinum Member
Joined: 04-09-2006
Posts: 7,043
From: Vancouver, BC, Canada
Wow - you have done your homework for sure!!! Nice job so far, and glad the info here has helped out.
Yeah, I think the compression test is a good next step. Check #3 cyl as well as all the others of course. And Yup, it's belts, cyls 1,2,3 and 4.
Keep us posted on the progress.
Yeah, I think the compression test is a good next step. Check #3 cyl as well as all the others of course. And Yup, it's belts, cyls 1,2,3 and 4.
Keep us posted on the progress.
Thread Starter
Joined: 07-07-2010
Posts: 8
From: MD
Yeah, the engineer in me makes sure I research properly before diving into most things.
I'll do a compression check on all 4 when she gets home later. Hot engine = best case scenario for compression. So I should also probably test it cold at some point just in case that reveals anything.
For testing, the throttle should be open, right? Should I just pull off the throttle body (it's fly by wire as far as I know). Where is the fuel fuse/relay that I need to pull for testing? Anything else I'm missing? Pull the plugs one at a time, thread in gauge, and crank a few times to check compression?
I'll do a compression check on all 4 when she gets home later. Hot engine = best case scenario for compression. So I should also probably test it cold at some point just in case that reveals anything.
For testing, the throttle should be open, right? Should I just pull off the throttle body (it's fly by wire as far as I know). Where is the fuel fuse/relay that I need to pull for testing? Anything else I'm missing? Pull the plugs one at a time, thread in gauge, and crank a few times to check compression?
Platinum Member
Joined: 04-09-2006
Posts: 7,043
From: Vancouver, BC, Canada
I know the procedure was noted somewhere here regarding how to crank it and test, but I can't think where it is. I had a quick look using the Search tool at the top of the page, and didn't see anything quickly.
I am quite sure that the throttle body can be left in place., and the throttle should be fully open. and it should be done with all the plugs removed. I think there is something that needs to be done though to stop the ignition (spark) system - it maybe needed to prevent harming some of the ignition circuit????????
Hopefully someone else can jump in here with more info.
I am quite sure that the throttle body can be left in place., and the throttle should be fully open. and it should be done with all the plugs removed. I think there is something that needs to be done though to stop the ignition (spark) system - it maybe needed to prevent harming some of the ignition circuit????????
Hopefully someone else can jump in here with more info.
Moderator
Joined: 01-23-2009
Posts: 26,483
From: Fredericksburg,VA
It should be a printout with the kit if you are "borrowing" it. Throttle really shouldn't matter with a non-start crank. But I've never done the test, don't take my word. Do a leak down too.
Are you having disappearing coolant? Head gasket, maybe.
I recently became a Sea Foam convert. You might give it a try, It seems to have cured a oil burning issue I had (rings or valves). I did the induction thing and let sit 16 hours, then added 1/3 to the oil.
#1 is the passenger side.
Are you having disappearing coolant? Head gasket, maybe.
I recently became a Sea Foam convert. You might give it a try, It seems to have cured a oil burning issue I had (rings or valves). I did the induction thing and let sit 16 hours, then added 1/3 to the oil.
#1 is the passenger side.
Thread Starter
Joined: 07-07-2010
Posts: 8
From: MD
Wife got in too late last night to do a hot test, so I did a cold one this morning. I didn't bother with the throttle, but I removed all the plugs and coils and fuel fuse/relay.
Results are:
225, 230, 140, 230.
Obvious issue in #3. I have added coolant to it before, but I never really thought much of it, since it wasn't a lot. But head gasket or valve issue moved way up on the list.
Guess it's dealer time? I've never taken a vehicle to a dealer - for anything. I've maintained my truck for the past decade or so on my own. She's never had any major problems that required a dealer. Any tips? Any recommended dealers in the Harford County Maryland area?
I can do a test on it hot if anyone thinks that'll help, but if it's internal to the engine, I think it's going to be something I'd rather have the dealer take care of under warranty.
Results are:
225, 230, 140, 230.
Obvious issue in #3. I have added coolant to it before, but I never really thought much of it, since it wasn't a lot. But head gasket or valve issue moved way up on the list.
Guess it's dealer time? I've never taken a vehicle to a dealer - for anything. I've maintained my truck for the past decade or so on my own. She's never had any major problems that required a dealer. Any tips? Any recommended dealers in the Harford County Maryland area?
I can do a test on it hot if anyone thinks that'll help, but if it's internal to the engine, I think it's going to be something I'd rather have the dealer take care of under warranty.
Last edited by waltjensen; Nov 17, 2013 at 11:10 AM. Reason: More info
Moderator
Joined: 01-23-2009
Posts: 26,483
From: Fredericksburg,VA
You would only be losing $10 with a seafoam treatment, could be rings sticking or junk on a valve.
Theoretically, all dealership service departments are the same. Depending on date of first title, you may be under drive train warranty.
I wonder why it always seems to be #3?
Theoretically, all dealership service departments are the same. Depending on date of first title, you may be under drive train warranty.
I wonder why it always seems to be #3?
Thread Starter
Joined: 07-07-2010
Posts: 8
From: MD
I don't (yet) have a leakdown tester, but I will soon. Looks like that's the thing to pinpoint where I'm losing compression. I think I'm comfortable trying that before I launch into the realm of dealerships.
I guess trying seafoam isn't going to hurt it, but I'd like to know in advance what problem I'm chasing before I accidentally fix something, lol.
I guess trying seafoam isn't going to hurt it, but I'd like to know in advance what problem I'm chasing before I accidentally fix something, lol.
Deceased
Joined: 06-30-2010
Posts: 25,739
From: Kannapolis NC
X2
And I think the problems being centered on cylinder #3 might indicate a "hot spot" in the head, that even under the best circumstances, doesn't quite get an adequate flow of coolant.
It's not just Ecotecs, other engine families are known to have a built in Achilles' Heel.
GM 2.8 V-6's that had cam oiling problems, Chrysler's aluminium block 198cid Slant Six's self destructed with regularity, and then you have the Vega 2300 who's failings are too numerous to even get into.
And I think the problems being centered on cylinder #3 might indicate a "hot spot" in the head, that even under the best circumstances, doesn't quite get an adequate flow of coolant.
It's not just Ecotecs, other engine families are known to have a built in Achilles' Heel.
GM 2.8 V-6's that had cam oiling problems, Chrysler's aluminium block 198cid Slant Six's self destructed with regularity, and then you have the Vega 2300 who's failings are too numerous to even get into.