Misfire codes again P0300, P0301, and P0302

[Bob98SR5]

Alrighty, after getting some alligator clip extensions for my multimeter and using it on the the ground side of the plug, I was able to obtain readings on the plugs. Using a cut off of 5,000 ohms, all the plugs need to be replaced. Most mfgs spec somewhere between 4k to 6k, fyi:

Plug___RES___Cut off___Var (out of range)
1*____6.3_____5.0_____1.3
2*____6.5_____5.0_____1.5
3_____6.7_____5.0_____1.7
4_____5.8_____5.0_____0.8
5_____5.9_____5.0_____0.9
6_____6.3_____5.0_____1.3

* Cylinder w/ the misfire reading

Time to go run errands w/ the lady. Next up: resistance testing the coil pack and wires.

[Bob98SR5]

Coil packs out of spec on 1 test. See below

Test #1: Primary test
Pull off the wires off the coil packs by levering the tab outwards (small screwdriver helps) and gently pry and pull off the head off the coil pack. Don't pull by the wires (just a gentle reminder). The two pronged harness leads is what you want to probe.

CP #_____Res_____Cold range_____Var (out of range)
1_______1.10_____0.67 - 1.05_____0.05
2_______1.13_____0.67 - 1.05_____0.08
3_______1.13_____0.67 - 1.05_____0.08

You can do this test hot too. I didn't hot test because all the parts are off. Perhaps the next time I'll hot test first.

Test #2: secondary test
Place negative probe on coil pack contact (top end) and then positive contact inside the business end of the coil pack. You should see the coils if you peer inside the end of the rubber end

CP #_____Res_____Cold range_____Var (out of range)
1________12.9_____9.3 - 16.0_____OK
2________13.1_____9.3 - 16.0_____OK
3________13.0_____9.3 - 16.0_____OK

I believe these coil packs are on the cusp of going out. Since the spark plugs are going to be replaced, I'm going to play it safe and get a new set of coil packs too.

[Bob98SR5]

Spark plug wire (manual calls them High tension wires) resistance test

CP #_____Res____Max Res___Var (out of range)
1________17.0____25.0_____OK
2________16.2____25.0_____OK
3________16.0____25.0_____OK

SP wires are ok; keeping these.

[4x4mike]

I think I'll print out your testing procedure and slip in the glove box as it might come in handy one day. I carry a spare coil pack and DMM but having a procedure would be very helpful.

Without a dead CP, do you think you've gotten any closer to finding the problem?

[Bob98SR5]

Mike,

For the most part, I'm covering the procedure from the manual with some exceptions. Since I pulled out the parts, I can't do the tests to check the results with the parts hot. But I'll put this all in a write up when all done.

So coil packs and spark plugs so far are out of spec. I checked the MAF sensor and Camshaft position sensor and both are ok (will post pics n results). I didn't check the crankshaft because I ran out of time and needed to pull off the cover.

There's some other things to check, namely the ECM (behind glove) which I'll check once everything's back in. But I'm hoping its just the coils and plugs.

[toyotech]

If you swapped plugs and coils around and no change. The problem isn't pkugs or coil.
I'm leaning at injectors as this is a common problem

[Bob98SR5]

Toyotech,

I didn't swap plugs or coils this time around. I wanted (for learning purposes) to just pull them as is and follow the Toyota manual procedure.

Yeah, I'm hoping you're NOT right I do have this sinking feeling you're right, but I'm going through the diagnostic and testing procedure to make sure other things aren't affecting the misfires. I have seen this misfire issue plaguing the 3rd gen community for quite some time and none of the threads I've seen have followed the factory procedures. I have a fuel filter on the way (since I haven't replaced that thing since '04 (yeah that long---probably 100K miles), new plugs, new coils, and on a side note a new PCV and hose since it's very worn.

I'll have to do some research on remfg'd injectors. The cost of new OEM injectors made me spit out my coffee this morning. Maybe Denso has a better price.

[toyotech]

When i was a Toyota tech. We never tested the parts if we have known good parts to swap aeound. It's the best true way to test. Being .05 of from spec isnt something I would be alarmed about and say it's a bad part. Temperature and testers can show that margin of error.

[Bob98SR5]

Toyo,

Yeah I can understand not testing. It's tedious for sure. As this is my second go around though, I want to make 100% sure of the cause. Aside from the somewhat laborious and time consuming task of removing parts to get to the injectors (remember I don't have a garage now---all the work I'm doing is with the truck on the street!), I can't believe that my Witchhunter-rebuilt injectors failed after only 41 months of VERY light use. I bought my Golf in early 2013 and my commute was only 10 miles round trip. The 4runner was only driven sparingly on the weekends just to keep the battery fresh and the fluids circulated. So if I had to guess, those rebuilt injectors probably only have about 10k miles maximum on them.

That said, I've started to research prices for OEM and off-brand injectors. Getting a new set of OEM injectors are about $170 x 6. I may just get 2 of the 4, but I don't like replacing things like this and not getting the full set.

[toyotech]

just replace the three under the manifold. You can also test the injectors by measuring the resistance if you wanna be sure. I would test them before replacing them.