99 3.4L coil packs and 02 sensors???

[wdhigh]

Got a 99 limited 3.4 4wd. Pretty sure it's a california emission setup due to the fiasco changing the previous 02 sensors. Changed out for the Bosch before I found out not to. Anyway, got a little misfire action going on along with bad 02 sensors again.

Was going to replace all 3 coil packs since it has 270k on it and both 02 sensors. Do the coil packs need to the denso also? They are $102 at dealer and he only has 1. Are any aftermarket ones an acceptable replacement? Are the Cali emissions models like mine able to use standard coil packs?

Ok, how bout the 02 sensors? Is there a less expensive place to get the Cali emission densos?

Thanks in advance!

 

[TheDurk]

1. Personally, I wouldn't replace a coil until it goes. Most of these coils will outlive the truck they came in.

2. That said, Cali. trucks use the same coil packs. I would think it a very dubious move to substitute an aftermarket coil for a good factory Denso.

3. If you have to, just like the A/F and O2 sensors, you can get OEM Denso sensor from Amazon for much less than dealer($58):

Amazon.com: Denso 673-1201 Ignition Coil: Automotive

4. To get the best deal on OEM sensors, get your Denso part number here:

Find My Part | DENSO Auto Parts

then order from Amazon or wherever you can find the best price.

 

[wdhigh]

First code was misfire on random cylinders.
Second was misfire on cylinder 1 and 3

Cleared them and waiting on them to show back up.

Any idea which coil pack controls 1 and 3? Are they on the same one?

Thanks!

 

[TheDurk]

First code was misfire on random cylinders.
Second was misfire on cylinder 1 and 3

Cleared them and waiting on them to show back up.

Any idea which coil pack controls 1 and 3? Are they on the same one?

Thanks!

No. Coils feed pairs separated by 3.

1-4
2-5
3-6.

The coils sit on top of the odd coils, which are on the passenger side, with number one in the front. So the coils firing 1 and 3 are the front two on the passenger side.

 

[wdhigh]

Thanks!

 

[wdhigh]

Well I give up, guess it's time to pay up! After 61 miles of driving waiting on another CEL it came. The same old p0420 and now cylinder 2 misfire.

Thanks for trying to help. Will turn it over to someone that knows what they are looking for.

 

[Doc2012]

Well I give up, guess it's time to pay up! After 61 miles of driving waiting on another CEL it came. The same old p0420 and now cylinder 2 misfire.

Thanks for trying to help. Will turn it over to someone that knows what they are looking for.

Ok. Stop.

You've got random misfires happening, and a 420 code.

When was the last time the Plugs/wires were replaced?

Did you use factory Denso or NGK plugs?

Are all your injectors working correctly? Any chance they can be clogged?

Get a mechanics stethoscope, and listen to the injectors.

For future reference, here's some other things that can cause a 420 code.

Go through these, and see. Search for the ohm/volt readings, and eliminate them as the possibilities.

 

[wdhigh]

Bad injector on #2 after having it hooked up at a shop.

Also tech says po420 is bad cat, not sensor. Claims he would not pay price for new cat, but new sensors will not cure the cel.

 

[TheDurk]

Bad injector on #2 after having it hooked up at a shop.

Also tech says po420 is bad cat, not sensor. Claims he would not pay price for new cat, but new sensors will not cure the cel.

Techs usually say that. Sometimes it's true, if cat is damaged, or honeycomb is broken or plugged, it's toast. But the 4Runner ECU is so picky, that a slightly degraded rear sensor can provoke P0420's. If it's been in there for 80k+, it's worth a try as you need to replace it anyway.

I had a P0420 three years ago, and a new sensor cured it. YMMV. My factory cat is in good shape.