P0100 Problems

[D_Bomb17]

Hello all, 

 

Recently, my '00 Qx4 has been having a few issues. SES light came on, so I checked it with my Amazon OBD2 scanner. "P0300 random misfire". It's been randomly stalling on me at low speed, usually when I switch from forward to reverse or vice versa. At times it has a hard start. There is sometimes a hesitation if I come off the accelerator. It idles decent. 

 

Then, yesterday I was driving with a heavier load than normal (3 extra people and some luggage), outside temperature in the 30s C, the vehicle stalled twice within 10 minutes. It felt like I had lost all power and couldn't accelerate, and the engine ran until I pulled over and came to a stop, where it would then stall. It threw another code, this time P0100, to go along with the misfire code. MAF sensor or circuit.

 

Did some digging, turns out this could also be caused by a vacuum leak. Where should I start with this issue? 

[D_Bomb17]

Little update. 

 

Idle was really rough yesterday, sitting at 500rpm, then bogging down to a stall. Decided to unplug the MAF sensor and the idle went back to normal!

Guess I'll start with replacing the sensor and go from there. 

[Slartibartfast]

While you're replacing the MAF, have a good look at the rubber tube connecting it to the throttle body. If that cracks, the engine gets air that the MAF doesn't know about.

[D_Bomb17]

On 7/14/2024 at 8:53 AM, Slartibartfast said:

While you're replacing the MAF, have a good look at the rubber tube connecting it to the throttle body. If that cracks, the engine gets air that the MAF doesn't know about.

This was the first thing I replaced! Previous owner had it duct taped, but did a horrible job. 

I replaced the MAF this past weekend. The hesitation, hard start, and stalling seems to be gone! It seems to have more pep as well!  That pesky misfire code disappeared, but it still idles a little rough.

 

I'll keep this thread posted on what I find.