cylinder 3 misfire questions and what I've done so far

On my way up to work this morning, my truck started running poorly and vibrating from the motor....like it was missing. Problem was occuring mainly at idle and acceleration up to about 2100 rpm. After 2100 rpm the problem seemed to get better. When I was going down the freeway and let off the gas, the problem went away.

Got to work, did some research on the interwebs and narrowed it to a misfire of some sort and decided to start small and change out the plugs. All the plugs were worn and needing replacement...but all came out the same (wet but not fouled), except for cylinder 3 which came out pretty much dry and tan. Replaced all the plugs, hoped for the best.....didn't solve the problem. Great

Borrowed a friends code reader and it in fact read misfire on cylinder 3. My next plan of action is to replace the ignition coil for that cylinder. I checked the MAF sensor and it was dirty..so I q-tipped it clean (going to get some MAF cleaner tomorrow). Is the ignition coil being bad a possible culprit? The one thing that has me thinking is the fact that that plug came out different.

Oh yeah....2007 tacoma, 4.0, 340,000 miles on the ticker .

Besides minor replacement of wear items, this truck has been great to me

Any input is appreciated!

 

Could be a coil or injector?
Can you unplug coil #3 and hear a sound difference?
Do you have a Misfire Code or Check Engine Light.
If so, and it reports #3 as misfire, then swap the coil and see if you get a misfire on the the cylinder you swapped the coil to.
If the misfire remains on #3, check the injector.
The injector is not as easy to diagnose as the coil.
I’d start at the coil first.

 

Move coils, don't change it. Throwing parts at a problem makes it more expensive and frustrating.

Cylinder #3 and #4 often indicate headgasket failures, I would still start by moving coils and possibly injector. But it may need a leakdown test.

 

Thanks for the replies very much fellas. Yes, there is a check engine light on (was blinking) and a misfire code to accompany it. I'll swap coil like you guys suggested and see if I can the code to change cylinders. Therehasn't been any noticeable coolant loss or milky oil to speak of. I have had an oil leak from that side of the engine for some time though. The fact that the plug I pulled from cylinder 3 was dry, give any indication to what might be going on?


Also, my work is 120 miles away from my mechanic at home. Do you think I could limp my truck home to get it to my mechanic without causing catastrophic damage?

 

Flashing check engine light means converter damage, usually means the cat is overheating due to overfuelling, which may mean the injector is failing in one form or another.

 

flashing is just telling you you have an active bad misfire. not that the cats dieing a painful death (but prolonged driving with a nasty misfire will kill the cat

if you said the plug was fairly dry and based off your mileage i wouldnt doubt the injector has failed.

 

Num 3 might not be getting fuel

 

Kind of what I'm figuring.

Do you think 120 miles is too far to limp home?

 

if its actively misfiring i wouldn't honestly. you'll likely cause more damage as you drive it. last thing you want is to cook a catalytic or worse the engine

 

I would NOT drive it that far, if I did NOT have to.
If I HAD to, I would Unhook the Injector at the plug on the harness.
As that should keep it from dumping fuel in the cylinder.

Again, I would NOT drive it if that were an option.

 

even unhooking the injector will continue to misfire (obviosuly) in turn the longer you drive on it adjacent cylinders will start to randomly miss too, when my avalons ignition coil failed it started as a cylinder 3 misfire half way to work. by the time i got to work (10 miles) i had multiple random misfires and it as across all 6 cylinders... Ideally you shouldnt drive it.

 

I will agree.
You should not drive it.

But if you have to for example ,“stuck somewhere a tow isn’t possible”, then you should try to prevent
further damage while doing “what is not always best”

Again I agree with you. It is not advised to drive on a misfire.

 

This has happened to me once before. If you haven’t done it already check the electrical connector to the injector. Trace the wire to the injector and give it a push back onto the terminal. I heard a noticeable click and problem solved.

 

What was the code(s) you pulled ?

 

Wouldn’t a bad injector throw a code too?

‘07 w 340,000 miles is awesome!! Congrats!!!

What did you clean the MAF with? You might have just added to your problems sorry to say.

If you ARE going to be replacing parts, consider sticking to OEM (coils, sensors...) as aftermarket can can just compound/confuse the situation.

I too wouldn’t drive it as far as you want with it misfiring.

Good luck.

 

Where are the connectors for the injectors? That's my last hope of what it could be. I think its the injector though. Gobba pull the plug soon and see if its even wet in cylinder 3

 

Try the link in post #2 below.

https://www.tacomaworld.com/threads/how-to-change-fuel-injectors-2010-4-0-litre-engine.356015/

 

At 340K I would go straight for the throat. Rule out engine head gasket issues and perform a cylinder leakage test.

Don't play around with other stuff because you are wasting time.

My money is on head gasket failure. The mileage and year is a huge indication to me.

 

What would be symptoms of head gasket failure besides white tailpipe smoke, loss of coolant, and milky oil?

Just pulled cylinder 3's spark plug......dry again. Changed out the ignition coils from a cylinder I know was good. Zero change

 

have you tried swapping injectors?