P0300, P0302, etc.

[sdb999]

I've searched previous posts but nothing current so here goes.

Vehicle:
99' 5spd, 3.4L, 250k, running fine until...

Condition:
Stumbling and hunting idle with CEL.
(5) Codes in order:
P0300, Random Misfire.
P0302, #2 Misfire
P0304, #4 Misfire
P1300, Igniter Circuit
P0304, #4 Misfire.

Related (possibly) Recent Maintenance:
228k Plugs, Wires, Air Filter
231k Fuel Filter
245k Coolant System, Radiator, Tstat, hoses, Coolant.
139k MAF Sensor

Thus Far:
Pulled all coils and Resistance is in spec for all.
Cleared Codes and on Restart same stumbling idle, no code yet but waiting.

I'm going to start pulling plugs for inspection and check for Vacuum leaks. Not opposed to throwing parts at it like plugs/wires but after that I'd like to have a better idea before we get into real money.

Looking for recent diagnosis experience but specifically wanting a way to test crank and cam sensors. That's the first thing that comes to my mind anyway.
Thanks All, S.

 

[TheDurk]

I'd focus on the P1300. A fault in the igniter circuit or the igniter itself can easily be the source of the other codes.

Why would you ignore that and go after the cam and crank sensors for which you are NOT getting codes?

P.S. Checking those requires an oscilloscope.

 

[sdb999]

That was my first stop, but on this truck it appears that the igniter is integral with the coil pack(s). Would love to be wrong if you can point me in the right direction.

 

[TheDurk]

That was my first stop, but on this truck it appears that the igniter is integral with the coil pack(s). Would love to be wrong if you can point me in the right direction.

Igniter is separate and is mounted just behind the air filter box on top of the passenger side front wheel well. It looks like this:

The wiring diagram (on a 2002) looks like this:

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/ewdtmc2/ewdtmpdf/ewdsourc/2002/024runne/systemci/013sis.pdf

FSM troubleshooting on a 2002 looks like this:

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/02toyrm/02toypdf/02rmsour/2002/024runne/di/eg5vzfe/cip1300.pdf

You can't find the '99 on-line. The setup is the same, but the ECM connections are different. If you get that far, I could scan them for you, if asked nicely . Easier is to swap in another igniter if one is available.

 

[sdb999]

Yep, there it is...my service manual is mistaken as it clearly describes the igniter/coil as one unit and not serviceable separately. It happens and I've seen much more grievous errors. Anyway all good now it turned out to by BOTH #2 and #4 plug wires. This engine makes a lousy V4. Thanks for the help, I'll keep those links for future reference.
S.