2008 Toyota Camry V6 P0303

[The Critic]

My father-in-law's 2008 Camry V6 has a misfire on cyl #3. This is the middle cylinder on the rear bank.

The misfire can ONLY be duplicated under full-throttle acceleration while climbing a steep hill. You can do full-throttle acceleration from a stoplight all day and the issue will never occur.

Under normal driving conditions the vehicle drives perfectly fine. I drove it normally for over 400 miles and it did not develop any misfires.

Fuel trims are normal, +/- 5%.

So far, the following troubleshooting has been done:
- Inspected spark plugs. Plugs are OE, in good condition and gap is correct.
- Installed new Denso Ignition Coils on the Rear Bank (1/3/5). This vehicle still has the "problematic" early style coils. No change.
- Swapped injector #3 with injector #4. No change.
- Relative compression test is normal.

At this point, my plan is to remove the rear valve cover and inspect the valve springs with a boroscope. I have been advised that valve spring failure on the early 2GR-FE engines is a rare but known issue.

Note: this car has recently displayed P0301, P2237 and P2240 faults but at this time, I can only duplicate the P0303 fault.

Any assistance or direction is appreciated. Thanks.

 

[CharBaby]

Just shooting from the hip...

Knock sensor(s)?

 

[bbhero]

What about the spark plug wire itself ?
Or is that a complete part of the coil/wire?

I bet it is the valve spring that's causing the issue.

 

[gathermewool]

WOT at what RPM?

 

[Trav]

My father-in-law's 2008 Camry V6 has a misfire on cyl #3. This is the middle cylinder on the rear bank.

The misfire can ONLY be duplicated under full-throttle acceleration while climbing a steep hill. You can do full-throttle acceleration from a stoplight all day and the issue will never occur.

Under normal driving conditions the vehicle drives perfectly fine. I drove it normally for over 400 miles and it did not develop any misfires.

Fuel trims are normal, +/- 5%.

So far, the following troubleshooting has been done:
- Inspected spark plugs. Plugs are OE, in good condition and gap is correct.
- Installed new Denso Ignition Coils on the Rear Bank (1/3/5). This vehicle still has the "problematic" early style coils. No change.
- Swapped injector #3 with injector #4. No change.
- Relative compression test is normal.

At this point, my plan is to remove the rear valve cover and inspect the valve springs with a boroscope. I have been advised that valve spring failure on the early 2GR-FE engines is a rare but known issue.

Note: this car has recently displayed P0301, P2237 and P2240 faults but at this time, I can only duplicate the P0303 fault.

Any assistance or direction is appreciated. Thanks.

Change the plugs, you cannot inspect spark plugs internally and because it is intermittent there will probably be no visual sign of an issue, for the sake of testing move it to another cylinder if you want. Misfire under load like you are experiencing is usually a sign of an ignition issue of some sort.
Consider buying one of these for future ignition diagnosis, good Canadian made tool.

GTC GTC505 Engine Ignition Analyzer

GTC GTC505 Engine Ignition Analyzer on sale at a great price with free shipping! JB Tools

www.jbtools.com

 

[LazyDog]

In some cases, it could also be a bad valve not sitting properly. Leak down test will help here!

 

[The Critic]

WOT at what RPM?

~5K ish.

Change the plugs, you cannot inspect spark plugs internally and because it is intermittent there will probably be no visual sign of an issue, for the sake of testing move it to another cylinder if you want. Misfire under load like you are experiencing is usually a sign of an ignition issue of some sort.
Consider buying one of these for future ignition diagnosis, good Canadian made tool.

GTC GTC505 Engine Ignition Analyzer

GTC GTC505 Engine Ignition Analyzer on sale at a great price with free shipping! JB Tools

www.jbtools.com

Plugs are 15k old, but I can swap to another cyl for testing. I am a bit skeptical of an ignition issue that occurs this sporadically though.

 

[bbhero]

I think Trav possibly may well be on to something here.

I changed plugs, rotor, and distributor cap on a 95 Sentra... Ran better but not totally right. Changed plug wires and it ran perfect. Same thing happened to my ladys Pontiac Sunfire.

Being that this is isolated to one particular plug leads to something being wrong in that particular ignition or fuel or mechanical cylinders location.

 

[mattd]

You either have an ignition issue or a valve hanging open whether that be from a bad guide or a weak spring. JMO

 

[The Critic]

Here is the freeze frame data.

 

[mattd]

I would pull the valve cover and have a look.

 

[Trav]

~5K ish.


Plugs are 15k old, but I can swap to another cyl for testing. I am a bit skeptical of an ignition issue that occurs this sporadically though.

View attachment 74498

Sure you can pull the cover and have a look see but you wont know the spring tension unless you remove it and test it. Why would a valve hang or spring not have enough tension only under certain conditions?
I have seen very few failed plugs but it does happen, when under load combustion and plug temps rise these high temps can have an effect on the plugs internal resistor. Always go with the cheapest thing first, the scan tool may not give you the info you are looking for when nothing is out of order, it is intermittent as you said 400 miles.
You do as you see fit but If it were me there would have been a new plug in there the first time I saw the higher misfire count for that cyl. It would suck big time to pull the cover and go through the mechanical inspection business only to find out it needed a $7 plug.
JM2C

 

[mattd]

Sure you can pull the cover and have a look see but you wont know the spring tension unless you remove it and test it. Why would a valve hang or spring not have enough tension only under certain conditions?
I have seen very few failed plugs but it does happen, when under load combustion and plug temps rise these high temps can have an effect on the plugs internal resistor. Always go with the cheapest thing first, the scan tool may not give you the info you are looking for when nothing is out of order, it is intermittent as you said 400 miles.
You do as you see fit but If it were me there would have been a new plug in there the first time I saw the higher misfire count for that cyl. It would suck big time to pull the cover and go through the mechanical inspection business only to find out it needed a $7 plug.
JM2C

I have had several GM 4.3s and some others only exhibit a misfire under very high load/and moderate to high RPM. Every single one of them had tight valve guides. When I suggested pulling the valve cover, I mean to check for any broken springs. Obviously you cannot check spring tension this way..
I also suggested checking ignition components even though he said they were recently changed..

 

[Luftmasse]

All of this is just a guessing game until you scope out the ignition system.

 

[Trav]

I have had several GM 4.3s and some others only exhibit a misfire under very high load/and moderate to high RPM. Every single one of them had tight valve guides. When I suggested pulling the valve cover, I mean to check for any broken springs. Obviously you cannot check spring tension this way..
I also suggested checking ignition components even though he said they were recently changed..

I didn't mean he should not pull the cover, sure there could be something wrong under there, there sure could be. I was only saying not to put the cart before the horse.
Tight guides that I have seen (I have no idea about the GM 4.3) have been a manufacturing defect or from improper sizing when being replaced but this is an 08 Toyota V6. I can see a broken spring but why would it only show itself under these circumstances? This is what is interesting.

The misfire can ONLY be duplicated under full-throttle acceleration while climbing a steep hill. You can do full-throttle acceleration from a stoplight all day and the issue will never occur.

The only real difference I can see is full throttle from a stoplight and full throttle going uphill is the combustion chamber temperature and pressure difference is raised in both cases but is not sustained in the stoplight scenario. He also said..

Note: this car has recently displayed P0301, P2237 and P2240 faults but at this time, I can only duplicate the P0303 fault.

Added to the mix a possible A/F monitor short issue who knows where it could end up. I am only verbalizing my diagnostic thought process not trying to say this or that poster is wrong or what I think it might be is correct. I have no idea I don't have the car here.

 

[HangFire]

This is a VVT-i system, so a possible reason the code only shows up under certain conditions, is that a certain amount of valve advance only occurs under those conditions. If so, that could point at a weak valve spring or sticky valve.

But yes, it could still be anything at this point.

 

[The Critic]

Performed a leakdown test on a cold engine:

Cyl 1: 5%
Cyl 2: 17%
Cyl 3: 5%
Cyl 4: 4%
Cyl 5: 4%
Cyl 6: 6%

I tested #2 twice. First time I got 27% leakdown, second time was 17%. In both situations, I could feel the air coming out of the dipstick tube.

Also moved #3 coil to #4.
#3 spark plug was moved to #2.

Re-tested the vehicle under the same conditions and misfire remains on #3.

 

[Trav]

Time for a look see.

 

[meep]

swap coil pack and see if the misfire follows it.

 

[mattd]

No air at all out intake or exhaust? Interesting it’s out of the crankcase. Especially with a 10% variation in leakage. Also interesting your diagnostics tell a problem with cylinder 2 but the ECM is blaming #3. What’s the firing order? Definitely got a mechanical issue.