Driving my 4Runner home the other night and it started riding rough. I had a CEL on before this of P0171 (I think). Never fixed it. After it to started riding rough, I have P0302 plus P0171. It "shimmies" at idle and power is gone. I've also had the dreaded FLASHING CEL when driving.

I've checks coil packs, sparks, and fuel injectors. Checking the fuel injectors with a supercharger was a lot of fun by the way. All checked out fine, I'm stumped for now. Any ideas?

List your year, milage, and mods. What parts did you actually replace? Are they OEM replacements?

Have you moved coils around and injectors to see if misfire moves to another cylinder?

1997, SR5, V6 - 5VFZE, Supercharger, 270,000 miles

I swapped coil packs and changed spark plugs with no change. I checked the resistance on the #2 fuel injector and it was 11 ohms. I replaced it with a rebuilt injector that I had anyway.

Could it be something as simple as the MAF? I haven't checked it yet.

When I had a misfire code I had to replace the coil packs with new ones. I also put new wires and plugs.

Compression and block test for a blown HG.

That's my plan for the weekend.

If those come up good, I would swap injectors with another cylinder. Known good>>>rebuilt injector out of the box.

What does #2 spark plug LOOK like? (First thing I do on a single cyl miss is eyeball the plug.)

If your coil packs tested good & you changed your spark plugs, I would go ahead and do the rest of the basic tune up stuff if it hasn't been done already. This way you can get caught up on maintenance & troubleshoot at the same time.

1. Spark plug wires if the current ones are old
2. Dual ground spark plugs
3. Clean MAF
4. Clean throttle body & replace the TB gasket
5. PCV valve/hose/grommet
6. Check the the air intake hose for cracks (especially where it attaches to the throttle body)


After I completed the above list a few weeks ago it resolved a few issues I was noticing:
-a faint whistling sound that seemed like it was coming from the engine bay
-occasional tap sound during hard acceleration which was usually noticed on the highway. The best way I can describe the sound is a bolt gently tapping against a skid plate. Sounded like it was coming from the front passenger seat area or passenger side of the engine bay.
-occasional "bucking" sensation which was also usually noticed on the highway
-a very mild delay accelerating from a dead stop (this only happened once & was just as I was pulling into my neighborhood to start the maintenance work).

It never fails to surprise me how a basic tune up can give a little more pep to how a car runs and add a few extra mpg.

Following your suggestions: I replaced my spark plugs and all wires with NKG double grounds spark plugs. I also cleaned the MAF and TB.

While I had the plugs out I did a compression test but not sure what to make of it. I've never done this test before so I'm NOT confident with the accuracy.

1 - 195
3- 200
5 - 190

2 - 190
4 - 180
6 - 190

I attached a pic of the old plugs too for any spark plug readers.

And after all that the 4Runner seems to be running better than before but i haven't been on the road yet.

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