Hello Everybody. I have a 2000 Rx300 AWD with 164,000 miles. It was well maintained with all of the service records from the previous owner.

I am at wits end.

Had been dealing with a p0440 and p0446 for awhile.

Then, recently, it began to run rough and have random misfires.
Codes: p0300, p0302, p1300, p1305, p1310, p1315, p1320, p1325. When the car is actively misfiring, I have a flashing CEL and it goes into safe mode and won't shift into overdrive. Also, the misfiring happens at 2300RPM's.

The p0440 and p0446 are gone. I changed out some dry rotted vacuum lines. Maybe that is why it is gone. Still don't hear the SWOOOOOSH when I take off my gas cap though.......

So i followed the trail to the OCV's. I changed out both, cleaned the filters. Still happening with codes. Changed both cam shaft sensors. No effect.

Is there anything I'm missing? The timing belt has been changed.

Or do I just need to suck it up and go t a mechanic. I've always done my own work, but I can't get any further in this diagnosis than I have.

I have done the IAC cleaning in the past. Checked and cleaned the MAF.

Possible vacuum leak? Did letting the p0440 and p044 go for 6 months cause another problem? If so, why are those codes gone now?

I appreciate any advice. Especially since it is Memorial day weekend. I am waiting for a call back from a recommended mechanic on Tuesday when they get back into the shop.

Thanks!
Dorian

 

Your P0440,P0446 are most likely unrelated to the other trouble codes. Since they went away, I wouldn't worry about them. The P1300-1325 codes are indicating coil malfunctions on all 6 cylinders. It is extremely unlikely that all 6 coils failed at once. The manual suggests looking for a harness problem in the IGF circuit. If you don't know what the IGF circuit is then, yes, its time to contact a good mechanic.

 

Did the misfire codes come after timing belt change?
Or any other specific action/repair that was done?

Salim

 

Salim-
The timing belt was changed several years age.

The only other repairs before this issue was the changing of the rotted vacuum lines trying to solve the 0440 code.

Baetke-
If I knew where to look for the harness in the igf system, I would check that. Could you offer more info?

Thanks
Dorian

 

How about connecting a timing gun to verify?

Salim

 

Here is a link to a ton of helpful articles on how Toyotas work. Check out the articles on ignition for an explanation on how the IGT/IGF signals work.

http://www.autoshop101.com/

PM me if you need a copy of the electrical wiring diagram.

Baetke

 

I Just picked it up from the Lexus Specialist.
The mechanic I had it with yesterday saw the whole system drop out at once. All 6 cylinders. Could not diagnose any further. Thought it might be electrical or in the ECM.
So I took it to Clear Choice Lexus here in Houston this morning. They said they only saw the p0302 code which was the #2 coil pack. I had already changed that with an Oreilly part. So they only charged me $50 for the diagnosis and I just went and exchanged it.

Lesson learned. Only buy Lexus Parts. The time I have invested in this was way more than the price difference I would have paid by using Lexus Parts.

Thanks for your Help!
Dorian

 

So, just to be clear, did replacing the #2 coil with an OEM coil solve all of your problems?

This would be valuable information since all of the coils share a common IGF wire it would indicate that an aftermarket coil could interfere with the IGF signal for all cylinders.

 

I've lost count of the number times I've seen people buying crappy electronic components from crappy aftermarket manufacturers and ended up spending more money replacing more parts and chasing their tails trying to figure out why the part(s) did not fix their issue. I've seen in BMW forums, Jeep forums, Volvo forums and now Lexus forum. Its hit or miss with more misses. When it comes to electronics, especially sensors, always buy OEM. No substitutes..

 

Amen to that!
For those that are hesitant to spend the high prices Lexus charges, if you do your homework you, you can often find the same parts from Toyota for a lot less. Toyota and Lexus often use the identical part with just different part numbers.

 

Yes. Replacing the coil solved all of the codes and the problems I was having.

Dorian