Perplexing engine issue…

[njtaco]

What plugs did you last use? IIRC, the 3.4 runs best on a mix of spark plugs, one brand on the left, another brand on the right. Sounds odd, as it is odd, but it makes a difference.

 

[Grim Reaper]

Guess: Toyota V6 3.0 Blown Head Gasket issue.

I belive that all Tacomas came with the 3.4 not the 3.0...

Did the Taco get it in 95? I thought 96 was the first year for the 3.4 in the trucks.

I know 4Runners still had the 3slo in 95. 96 was a new body for them.

 

[toy_tek]

I too am uncertain if you have a 3.4 or a 3.0. I'm guessing since its a Taco you have a 95.5 with a 3.4... correct?

You could swap the fuel injector to a different location and see if the code follows the injector or stays with the cylinder.

Here is some info from the 97 3.4 FSM: (I'll delete if you have a 3.0)

DTC P030x: RANDOM MISFIRE DETECTED
Circuit Description
A misfire is determined by the ECM. The ECM uses signals
provided by the crankshaft and camshaft position sensors. If the
engine speed rate has changed enough to equal a preset number, a
misfire is detected and the MIL is illuminated. If the misfire rate is
high enough, and driving conditions will cause catalytic converter
damage or overheating, the MIL blinks when a misfire is occurring.
DTC is set when misfiring of random cylinders is detected
during any particular 200 or 1000 revolutions. Possible causes are:
* Ignition system.
* Injector(s).
* Fuel pressure.
* EGR system.
* Engine compression.
* Valve clearance.
* Valve timing.
* Mass Airflow (MAF) sensor.
* Engine Coolant Temperature (ECT) sensor.
Diagnosis & Repair
1) Inspect spark plug and check for spark at misfiring
cylinder. See F - BASIC TESTING - 3.4L article. Repair as necessary.
If spark plug is okay and spark is present, go to next step.
2) Access ECM behind glove box. Turn ignition on. Using DVOM,
backprobe ECM connector. Measure voltage between ground and injector
terminals at ECM E9 connector (A/T models) or E5 connector (M/T
models). See IDENTIFYING INJECTOR TERMINALS table. See Fig. 3 or 4. If
voltage is 9-14 volts for each circuit, go to step 4). If voltage is
not 9-14 volts, go to next step.

IDENTIFYING INJECTOR TERMINALS TABLE
A/T Models
1 ...................... 10 ...................... Red
2 ....................... 9 .................... White
3 ....................... 8 .................... Green
4 ....................... 7 ................ Red/Black
5 ....................... 6 ..................... Blue
6 ....................... 5 ................... Yellow
M/T Models
1 ...................... 12 ...................... Red
2 ...................... 11 .................... White
3 ...................... 25 .................... Green
4 ...................... 10 ................ Red/Black
5 ....................... 9 ..................... Blue
6 ....................... 8 ................... Yellow
(1) - Terminals are located in ECM E9 connector (A/T models)
or E5 connector (M/T models).

3) Disconnect injector of misfiring cylinder. Using ohmmeter,
measure resistance between injector terminals. If resistance is about
13.8 ohms, check for open or short circuit in wiring harness between
ECM and injector. See appropriate wiring diagram in
L - WIRING DIAGRAMS - 3.4L article. Repair wiring as necessary. If
resistance is not about 13.8 ohms, replace injector.
4) Check fuel pressure. See F - BASIC TESTING - 3.4L article.
Repair fuel pressure as necessary. If fuel pressure is okay, check
fuel injector performance. See I - SYSTEM/COMPONENT TESTS - 3.4L
article. Replace fuel injectors as necessary.
5) If all injectors are okay, check MAF sensor and ECT
sensor. See I - SYSTEM/COMPONENT TESTS - 3.4L article. Replace MAF
and/or sensor as necessary. If both components are okay, also check
engine compression, valve clearance and valve timing.​

 

[WhereTheHellIsJames?]

Thanks for the responses everyone!

Grim Reaper- to answer your question, it is a 3.4 V6, not a 3.0.

111db- Thanks for posting that! I'll start moving forward with it, and see what comes up.