My 99 Rx300 has 150K miles, last week it started running bad and was throwing a p0171 code, I read these forums for about 3 days and checked all the hoses, replaced the PCV, Gas cap, cleaned the MAF and reset the computer by disconnecting the batter over night. I know some of this was not the problem but I had the parts so I did it anyways, now its running ruff again and now I get P0302, I moved the coil packs around and the code stays the same, i checked the plug and the one from cylinders #2 does look different (all black, others have white on the tip)

also I have checked the resistance on the fuel injectors and they all read 13.3

i have read many post, there are allot of info in them, but I see many with out resolution posted

Please help, I have to get to work on Wednesday and need to fix this.

 

Did you try changing the spark plug over to another cylinder, too?

 

Certainly appears that #2 is not firing and you have ruled out the coil pack. Next you need to check sparkplug as has already been suggested and then the ignition wire. Guess it is possible that your injector is stuck open but I would think you would get a DTC for Bank 2 rich.

 

well i changed the spark plug it ran great, drove it around and now its running ruff again and I am getting code p0171. I am about to pull my hair out.

should I just change out the sensors and maf?

 

i just changed the plug in Cylinder #2

 

current codes are p0171 & P1153

 

The p0171 is usually just a result of having the p1153. It should go away once you replace the oxygen sensor.

Is it still running rough? Because a bad o2 sensor, won't make it run rough.

 

maybe i am wrong by saying its running ruff, its acts like its staring for gas or air. i just took off both o2 sensors, I am going to replace them soon as I have no idea what the try next

 

also as I have not able to find any post with out an end result I promise to post the resolution

 

as i was trying to remove the o2 sensor under the (i think its bank 1) i somehow stripped the threads.

so now I need need to replace the exhaust manifold. anyone know an easy way to do this?

 

Unfortunately it does not get any easier (imho). I would discuss it with an exhaust shop or a machinist and see if they can put helicoil or sleeve or just weld and tap new threads in. Reason I suggested exhaust shop is that they may be the only ones who would do this without removing the exhaust manifold.

Due to elevated temperature, jb-weld etc would not work (there may be a product that I do not know of) and once again an exhaust shop is your best bet.

A bit too late, but if you had read the posts here in CL, we recommend 1/2 turn out and 1/4 turn back in. But things do happened and even the back and forth procedure is not guaranteed.

Keep us posted on the progress and hopefully a solution.

Salim

 

It is at a muffler shop, I will let you know

 

well, they re tapped the manifold, $350 (labor and new sensor) and i am back in business. the new MAF i ordered came today too. so we will see that did the trick. I will update tomorrow with details.

 

So far, so good, and the check engine light went off on it's own, It feels like it has way more power too

 

ok so far so good.

in the end result it looks like my car flagged p0171 code i repaired it by changing the o2 sensor on the exhaust manifold facing the rear of the car.

my disclaimer is to be careful when changing this.