4.7 V8 misfire condition

[NCrunner2012]

Hey guys and gals,

I rarely post for help but I'm having trouble with a new to me 05 V8.

Had it about a month. I noticed the occasional hesitation/misfire (no cel) so I decided to do a tune up. Truck has 212k miles so I figured it was do. Timing belt done at 190k. I went to the parts store and bout the NGK iridiums that the guy said I needed and installed those. As I'm swapping them I see 6 out of 8 coils are cracks and just plain toasted. So I bought 8 new denso coils from camelback Toyota.

I use this truck to tow my boat on the weekends as I drive my 98 daily. All was running good, but this weekend I towed the boat about 100 miles round trip and as I was almost home the light came on after idling for a minute or two. When I got home I had the following codes:
P0308
P0300
P0301
P0302
P0303
P0306
C1201

there seems to be no reason. Injectors seem unlikely as they would all be malfunctioning at one time. I'm stumped.

99% of the time it runs fine and smooth. Just the occasional hiccup normally when it's in 4th or 5th gear and I get on it some or I'm towing.

What should I check next? Maintenance is sketchy as I don't know the history.

Thanks for the suggestions!


SOLVED: fuel pump, ended up testing fuel pressure and for 22psi with surges up to 29-30. From my research I found it was supposed to be 44-48. So new pump fixed my issues.

 

[TrueBlue]

Have you cleaned the MAF, TB, and replaced the air filter?


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[wmflyfisher]

I have a similar condition in my new to me 05 V8 with 175k. It runs perfect at anything over idle speed. At idle I can just barely let off the brake and it has a constant jump or surge. It's driving me nuts. No CEL and a reputable mechanic said all sensors are operating within the proper perameters. Wonder if our issues are something related. I just changed the plugs as well to Denso iridiums too. The ones I pulled out were in great shape. The exact same plugs. I'm thinking about letting Toyota look at it soon.

 

[Phils4th]

How does it idle? Where you confident in setting the plug gaps? All coil wires and connections were in good shape? Check all wiring to ecu for coorosion and connection.

 

[NCrunner2012]

Have you cleaned the MAF, TB, and replaced the air filter?


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Ok sorry for the delay here. I pulled the plugs and checked the gap. New air filter, 8 new coils. I have not cleaned the MAF. I fee the problem is bigger then the MAF.

When it's hot, on startup it does not run well. After a while it will clear up and run fine.

I'm leaning toward something fuel related or it doesn't like the plugs I put in...

They are NGK iridium IFR6T11 plugs.

The problem is it's not consistent. It will drive fine for 3 days then have a meltdown.

 

[NCrunner2012]

P0174
P0300
P0302
P0304
P0306
P0171
C1201

I had cleared the codes to see what codes would come back trying to narrow down what cylinders are acting up. The light came back (as I knew it would) and these are the codes that came up.

 

[NCrunner2012]

Another update here so I can go into more detail.

the problem is a hesitation when driving, typically when I reach 5th gear and the rps drop to their lowest point while driving is when I feel it the most.

Occasionally, I will start it (engine is warm) and it will not idle. It will fall on its face. I will have to baby the throttle until i get it up to speed then it will clear out and run fine. Normally this is what makes the light come on.

I am going to have the fuel pressure checked since I dont have a tool, and see if that tells me anything.

 

[jfry008]

-Timing may be off on your even number cylinder bank, since all of your even number cylinders are throwing codes.


http://www.toyota-4runner.org/4th-g...8-rough-idle-misfiring-p0300-p0301-p0308.html

RANDOM MISFIRES

 

[NCrunner2012]

-Timing may be off on your even number cylinder bank, since all of your even number cylinders are throwing codes.


http://www.toyota-4runner.org/4th-g...8-rough-idle-misfiring-p0300-p0301-p0308.html

RANDOM MISFIRES

I saw this when I was searching. But it doesn't happen all the time. This is an intermittent problem.

I hooked up a fuel pressure gauge and it read 22 PSI at idle. The highest it went was 29psi when I would rev it up some.

Isn't it supposed to be 40 or 45psi??

Leaning toward the pump starting to give out

 

[jfry008]

Yea, I think the fuel pressure should be in the 40s

 

[toyo]

Idle FP needs to be between 38-44 PSI.

 

[toyo]

How are you checking the FP? I would recheck it just to confirm. If the FP comes back good I would 1st look at your air induction syste. All connections from the air cleaner box to the TB are tight with no cracks in the hose. Get a can of carb cleaner and spray all around the intake manifold sealing surface while the engine is idling. If you notice any change in the idle re-spray it again to verify. If it changes then you have an intake leak and more than likely a bad intake gasket.

The P301 thru P308 are misfire codes. It does not mean the coil or coils are bad. Many other problems can throw these codes.

Let me know how things happen.

 

[NCrunner2012]

How are you checking the FP? I would recheck it just to confirm. If the FP comes back good I would 1st look at your air induction syste. All connections from the air cleaner box to the TB are tight with no cracks in the hose. Get a can of carb cleaner and spray all around the intake manifold sealing surface while the engine is idling. If you notice any change in the idle re-spray it again to verify. If it changes then you have an intake leak and more than likely a bad intake gasket.

The P301 thru P308 are misfire codes. It does not mean the coil or coils are bad. Many other problems can throw these codes.

Let me know how things happen.

Checked via the banjo on the ds fuel rail. I ran the gauge up to the windshield and drove. Idle was 21-22psi. Even high rpms only saw 29psi of fuel pressure. I'll check for intake leaks today before I jump to the pump.

Those numbers are low right?

 

[skott]

I don't know exactly what the fuel pressure is supposed to be, but yours certainly seem low (as a previous poster stated).
Does your scan tool show fuel trims? If it does, I bet it'll show you're running lean (ECU is adding extra fuel). You're probably right on the verge of it not been lean enough to set a lean code, but lean enough for it to misfire when you really smash the go pedal and need extra fuel.

 

[Streetfighter]

I had the same random misfire...thought it was fuel, until.....

http://www.toyota-4runner.org/4th-g...-fe-timing-belt-failure-aftermath-repair.html

 

[nevada]

as with the others above, im unsure of what the desired fuel pressure is for this engine, but im pretty sure in the 20's is much too low.

even the older 4runners(and many other vehicles) were in the low 40's. I would expect the same for this one.

in fact, if it indeed is supposed to be 38-42, im surprised it will even start with the pressures you are seeing. I know my old 22RE wouldn't start until it hit 40psi.

 

[NCrunner2012]

I wanted to post the results of the new fuel pump. The truck runs absolutely amazing!! Definitely low fuel pressure causing the occasional fall on its face. I actually used it to tow my boat about 3 1/2 hours to Va from NC and it performed great.

Thanks everyone for the comments and replies!