06 Tacoma random stalls in park.

I have a 06 Tacoma 4.0L V6, i am having trouble trying to trouble shoot this issue. My Tacoma will randomly stall when in park, my RPMs will spike and then drop below my normal idle and it will die. As well it smells rich in fuel as if computer is commanding more fuel than needed. Any and all advise would be great need. thank you in advance.

 

Idle Control Valve?
Mass Air Flow sensor?
Throttlebody?

 

Not to sure, our diagnostic senor had codes for CAT efficiency bank 1 and bank 2, and the engine load was in the high 30s when normal idle for it is -15 load

 

Clogged cats?

 

not to sure im pulling my truck into the shop next Friday when its open i have to change out my control arms. i can drop them then. and see if that is my issue

 

There is no Idle Control Valve on 4.0

 

Clean the throttle body and maf sensor. Use their appropriate cleaners and a Qtip to get into the nooks of the TB. The butterfly is motor driven. I don't move it when I clean mine. I'm afraid I'll strip the gears that move it. Gotta luv throttle by wire.

 

I concure MAF and TB Cleaning are in order before spending any money...

 

especially if you offroad the throttle body can get very dirty. Took me 3 rags to clean all the junk out then blasted the sensor clean. Worse comes to worse it gets a new throttle body first.

 

P0420 and P0430 mean the cats are worn and the exhaust will smell like fuel, this is normal for those codes.

They generally don't affect driveability.

Starting with MAF and throttle clean is best. Spark plugs have short intervals on these trucks, so check them if not done in the last 30000miles.

 

The P0420 code I dealt with was nothing more than a bad gasket at the Y pipe. Took a bit to find the leak as it was tiny.

 

Some are used to working with Tiny things...

 

Really...?


Was that the voice of experience typing?


Hehehe. I love these emojis.

Here's some salt if you don't have any..................

 

This isn't normally symptomatic of a clogged cat in my experience; choking and loss of power under load? Yes, but at idle? Not normally. Check your fuel trims... I'll bet they're pegged hard on rich, which could account for both codes and the fuel smell.

 

Are you referring to the spring-loaded flange near the muffler?

 

No, cat to Y pipe.

 

My wild, crazy theory that will likely have detractors - bad injector(s). One or more injector could be dumping too much fuel periodically (leaky). It would cause the rpm to suddenly spike, then die at idle. The periodic rich condition may not be enough to notice when driving at speed because of the higher constant rpms, but may be enough to have blown out the cats over time.

 

Appreciate the clarity.

Just check mine and both are leaking ever so slightly, but probably enough to trip the 420/430 DTCs.

Thanks for the tip!

 

My indicator was less than 1/8" wide soot mark.

 

No soot on mine.
Did the reverse-shop-vac-up-the-tail-pipe-soapy-water trick and both flanges were generating small amounts of bubbles.

So......replaced the two gaskets (Bosal #256-214) $3.19 ea. @ AutoZone today and my Short Term Fuel Trims are now
hovering around zero. They were around -8 or -7%. Before I replaced the spark plugs & cleaned the MAF and TB my numbers
were -13 or -12%. Need to do a few more drive cycles to see if things are back to normal.
Although TorquePro is still indicating a low voltage O2 catalyst monitor reading on one bank.
I'm sure the 420 will come back, which case I'll replace the downstream sensor on that bank and see where that leads.
The other side is in spec, but is low as well.

The 420 started after running out of gas in AZ and AAA dumped in a few gallons of gas.
Filled up with what I recall on the pump as "At least 12% ethanol". CEL came on about 30 miles later.
Timing was suspicious.

Checked for vacuum leaks....nada.

Truck runs GREAT and gets 21-22 MPG average.

I haven't checked my fuel pressure as of yet, but that might be something to do before the sensor replace.
Clogged fuel draw in the tank??? That might have explained the lean condition before, but now I'm good.

Fortunately I didn't need to smog this year!!!!