02 Tacoma misfire issue

[ccpalmer]

I have a 2002 Tacoma 4cyl. 2.4l, 190,000 miles. It has been giving me a strange issue for some time now. I get a misfire on one cylinder but only under a certain condition. It's always when I restart the truck after having been used earlier that day. It will then flash the check engine light and run on three cylinders for about 5 minutes. Then it runs fine. It won't do the problem for a few weeks then it will happen a lot for a few days, then nothing for a week to a month.

This has been happening for about a year. I had it looked at by Toyota a year ago and they tried switching coil packs but the problem stayed on the same cylinder. I just took it to the dealer again because for the first time ever it started misfiring almost all the time, even on the first start of the day. They now say it is the injector at fault.

I'm wondering if bad injectors act that way. I find it very strange that the problem would only occur on restart, and also that it would almost always last for about 5 minutes. Anyone with experience with injector problems know if this is a common issue? Anything else I should be looking at? I suspect more of an electrical issue?

Thanks for any help - I have an appt. Wednesday to get the injectors replaced but they want $200 a piece for Toyota injectors. I'd hate to shell out all that and have the same problem. I'd replace them myself but it's cold out and their labor charge is pretty low.
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'71 Westy

[VOLKSWAGNUT]

If an injector dribbles when the engine is off (or cools down) it can basically flood the cylinder and cause that cylinder to misfire on the next start up. The misfire can occur until it clears out the extra fuel (or the injector heats and reseals) and the plug that was fuel fouled clears and dries off and begins to spark again.. Heat does help that.
So yes.. it's plausible.

Easy and cheap diagnosis without any parts required.
Swap the injector to another cylinder and see if it follows the injector.

Techron fuel additive is one of the best to help clear up injector issues.

Other possibilities, oil leaking down an open intake valve or even coolant entering a cylinder can can cause nearly the same symptoms.

Pulling the known cylinders spark plug that is misfiring during the misfire event can indicate a lot.
Fuel, Oil, Coolant on plugs are fairly easy to detect.


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[ccpalmer]

I just pulled the plug on the bad cylinder after it was misfiring and the spark plug looked fine and was completely dry. I pulled another spark plug to compare and they looked identical. So it does seem the injector isn't firing. Question is whether it is the injector or electronic signal...

I'm going to try Techron fuel additive next.
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'71 Westy

[sb001]

AS VWNut suggested a great test is simply to swap injectors between two cylinders and see if the problem follows the injector. That will also tell you whether it's the injector itself or an electrical issue. Free and fairly simple.
Did you ever get the code read? On a 2002 Tacoma, there is a "random misfire" code p0300, but then there are also cylinder-specific misfire codes (p0301 for cylinder 1, p0302 for cylinder 2, etc.) It would help to know what the error code says.

http://troubleshootmyvehicle.com/toyota/1.8L/how-to-test-misfire-codes-1
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[ccpalmer]

Codes are p0300 and p0304
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'71 Westy

[skills@eurocarsplus]

you need to get live data and watch it. pay attention to fuel trims.

or shotgun a bunch of parts at it. seems to be the way of the world these days.

got a Mercedes here now. guy just put 2,500 clamz in it doing all sorts of neat fuel related stuff. all junk from the interwebs.

found his problem in short order. needs a 90.00 TPS. but somehow I'm a crook for charging for diag, yet the other place took his money and never fixed a thing.

it is not uncommon to swap parts from cylinder to cylinder to see if a miss follows that injector/coil/plug etc...

be careful just going all rock star with a DVOM. ECM injector drivers are sensitive and may not like what your meter will do with them.

also if it has VVTi that will cause issues as well with misfires as the ECM is looking for advance/retard of the cam

use genuine parts.

you can pull the fuel rail and watch for drips, but it may be inconclusive if it fails to act up.

also, it eats time, you need to watch them like a hawk. a slight dribble may evaporate before it hits the rag
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[Ian]

My friend has the same issue with the same truck. A mouse ate some of his engine wiring harness.
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[VOLKSWAGNUT]

[skills@eurocarsplus]

[VOLKSWAGNUT]

[ccpalmer]