Hi..New to the forum and glad to be here. I did some searches but couldn't find anything close to my problem. Also I hope I've placed it in the correct category. My 1997 V6 3.0 has 151k miles and has been trouble free all it's life. A few months ago it started having a check engine light that when investigated turned out to be P0305 or cyl 5 misfire. To date I have replaced the plugs, wires, and the igniter module. The coil pack has been swapped from cylinders 2/5 to cylinders 3/6 with no change in problem. I haven't performed a compression test because # 5 is hard to get to and the strange part of this problem is that the car runs perfectly most of the time when it's started cold. It only misses and posts p0305 after it is driven for 15 to 20 minutes or so. Almost always (but not always) runs fine when cold. I'm leaning toward being an injector problem on #5 but the only way I can figure to test for that is to swap it and unless I missed something that would be really tough to do. Are injectors thermally sensitive when they have problems? Anyone have any ideas?

 

There is a long list of items that could cause these code.

Spark plug, coil, coil wire. loose connector to coil, injector,

low compression, burnt valve, valve clearance off,

MAF sensor, coolant sensor, ECU.

The engine has a cold start system the provides more fuel, perhaps once this system turns off the cylinder is running lean.

Or maybe a intake manifold leak, something happens with engine expands. You can check this by using an unlite propane torch in the area to determine if the RPM pickups.

Don't think the injectors are thermo sensitive, there may be a gasket between the injector and engine acting as a heat insulator.

Might try injector cleaner, run the fuel down in the tank before putting the cleaner in to maximize the effects. Toyota splices into the fuel rail intake hose off and runs cleaner directly into the lines.

 

Yes, I saw that stuff in the book and I pretty much ruled out the things I did (and re-did) such as plugs,wires, and coils. I discounted the low compression and burned valve as how could it run great cold with those? I did clean the MAF sensor and I ran a can of SeaFoam through the brake booster vacuum line and poured another can in the tank with no change (other than a ton of smoke and fumes with the SeaFoam). I suppose the MAF sensor or the Coolant sensor could be at fault but It always picks on cylinder 5. I have seen one other code for random misfire multi cylinder but that was only one time. I suppose it could be a leaking intake somehow this engine has never been run hot or had any thing other than oil changes and coolant flush and replace.

 

It is not uncommon for an engine to get multipule cylinder codes such as P0300, 01, 02, 04. 05 all at once. P0300 is mulitpule cylinder misfire. Or all the codes in one cylinder bank at once. This would be an indicator of a fault effecting all cylinders.

Only one code should in theory narrow down the problem area to that cylinder. Camry injectors rarely plug up but it has happened. If you had not changed the coil would have suspected this as a cause.

A bad coolant sensor can cause all kinds of running problem, surprising how many. But strangely codes are rarely tripped for this problem.

If you have the service info you can test coolant sensor.

 

My book is a Haynes and it doesn't have a test for the coolant sensor. Just says unplug it and if temp gauge doesn't change replace it. I suspect they're may be more than 1 sensor. 1 for the gauge and 1 for the ECM?

 

perhaps im wrong...if you unplug the sensor fans should kick on and if they dont it means its bad...if they do it should be fine.??

 

Ok, I finally had a great weekend with warm temps and blue sky. The task I undertook was to try to "move" the P0305 to somewhere else. After all I had moved I felt my next logical step was to move the injector from cyl 5 (really hard to get to) to the front bank. I had to pull the air plenum to get to that rear fuel rail. I made the swap from cyl 5 to cyl 6 and afterward I had fuel leaks from both fuel rails. Had to make a trip to procure the o rings for all 6 injectors and after a more careful and deliberate rework had it all back together. I drove it for 45 minutes Saturday afternoon with no misfires. This morning on the way to work it failed again......with the new code of P0306!! Yea... So today I'm off to injector city to get myself a replacement. Should be an easy replacement this time as the plenum doesn't have to come off this time. Many thanks to Toyomoho for the assist!!

 

Glad you found the problem!

 

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