My engine is now misfiring P0306 (1 Viewer)

[HomersCanyonero]

I've been ignoring/resetting the P0420 for a long time. I recentely got the P0402 code and I was resetting it as well.

Well, this weekend the 80 starting driving very sluggish and I thought I had a problem with my muffler (replaced two years ago with a generic one from muffler shop) or catalytic converters (originals since 1996).

The 80 started sputtering, so I went to two muffler shops and one said that my cats looked burned out and needed replacement based on the color of the cats. Also mentioned that my muffler looked like it was buring based on the color of the muffler.

Another muffler shop took temperature readings of the cats. Showed me the gauge reading over 500 degrees in between the two cats, but only in the mid 200s on the front and back of the cats.

Both shops said they thought they were hearing a misfire. I hadn't checked the codes because I had just reset the P0402 a day go. I checked the codes again and now I see a P0306 and P0401.

I went straight to a repair shop to get the misire looked at and I won't know until tomorrow.

I'm trying to figure out if a constant misfire can be caused by EGR blocked ports? I'm guessing I have to fix the misfire first prior to addressing any issue with the cats/muffler.

 

[HomersCanyonero]

It's not the wire nor the plug. Plug is only 5k miles old and wires were replaced in 2004, so less than 100k miles. Checking compression. If compression is good, then checking fuel injectors next.

 

[HomersCanyonero]

I know, I know. I'm just talking to myself, so here it goes. Compression test was good and engine is running strong.

It looks like coolant has been leaking from the coolant heater valve above the fuel injector #6. So, need to replace the heater valve (all coolant hoses and PHH were replaced last year, so these are good) to prevent further leaking. Replacing with new OEM heater valve.

In hindsight, I should have replaced the heater valve when I replaced all the coolant hoses including the PHH. Make a mental note to add this to the PHH preventive maintenance program.

Need to replace fuel injector #6 which seems to have been corroded by the leaking coolant. Replacing with new OEM fuel injector and cleaning the other 5 fuel injectors which look to be in okay shape.

Also, going to clean the EGR ports while in that area to see if it helps with the P0401 and P0402 that I was getting recently.

I'll report when done just to keep it in this knowledge base -- even though I'm the only one posting. I'm getting parts from local Toyota dealer since I need this rig up and running asap.

 

[SiRaDuDe]

Read this https://forum.ih8mud.com/80-series-tech/122621-code-p0305-help.html

Seems to be a common problem with the harness melting agains the EGR and causing injector problems.

 

[robertaleon]

X2 on the engine harness wrap. One suggestion if you go with a rewrap of the harness or spend time back there with the EGR - take the hood off.

 

[HomersCanyonero]

I had the wire harness checked and it looks to be in good condition. I was considering a new wire to the fuel injector #6, but didn't have to.

Old injector was brittle, so it got replaced with a new Toyota OEM one. The rest of the injectors were cleaned and re-installed with new injector seals. EGR ports were cleaned.

Heater control valve was replaced with OEM one, so no more coolant leak in that area.

I had the valve cover gasket and the intake hoses replaced. Oil had been leaking up in that area for a while.

It's running smooth now. Let's see if I get any codes now. I've only driven for 10 miles and everything sounds and looks great.

 

[LandCruiserPhil]

I had the wire harness checked and it looks to be in good condition. I was considering a new wire to the fuel injector #6, but didn't have to.

Old injector was brittle, so it got replaced with a new Toyota OEM one. The rest of the injectors were cleaned and re-installed with new injector seals. EGR ports were cleaned.

Heater control valve was replaced with OEM one, so no more coolant leak in that area.

I had the valve cover gasket and the intake hoses replaced. Oil had been leaking up in that area for a while.

It's running smooth now. Let's see if I get any codes now. I've only driven for 10 miles and everything sounds and looks great.

Good to see you have it running right again. Are you still in need of new cats?

 

[HomersCanyonero]

Re: Are you still in need of new cats?

Not sure. I still haven't gotten the P0420 code, but I've only driven about 75 miles since replacing the fuel injector. The cats are 15 years old and almost 200k miles, but I'm going to wait until I get the code again.