Luismond

Hi guys
I have a 99 RX300. State inspection already expired.
Got the CEL (check engine light) on, went to Autozone to get the code and was the P0171.

Definition:System to lean - bank 1 (Cyl. #1 denotes bank 1)
Probable cause:
Lean air/fuel ratio-fuel injector or vacuum leak
MAF sensor concern
ECT sensor fault
Faulty HO2 (heated oxygen sensor)

I checked for vacuum leaks, didn't find any.
Cleaned MAF sensor
And disconnected battery to reset CEL.

Two days later I went to get the stated inspection done and passed.
Only one system was not ready which is OK to pass the inspection in Texas.
"Evap" was not ready.

Question 1 is:

What does Evap refer to?

Then, a week later CEL came back on in the morning, I drove it like regularly and the same day in the evening CEL went off.
The engine always performed OK, no malfunction at all.

Question 2 is:

Can anybody tell me what it could be going on?

Question 3 is:

Should I expect CEL to come back on or that's it, problem solved?

Thank you all very much in advance.

Luis

Luismond

Hi guys
I've seen that many people saw my questions but nobody has answered.
No idea???
Well... I've had CEL coming back on 2 more times, in the same way, come on in the morning, and off in the evening.
So I went to Autozone to check the code and I got P0505

Definition:
Idle air control system
Probable cause:
Large vacuum leak
Engine mechanical condition
Failed IAC valve

I've been checking for vacuum leaks and I can't find any

Can anybody guide me to where I should look?

Then I don't think there is any engine mechanical condition because it runs just perfect

And last. what and where is the IAC valve?

Any inputs are welcome.

Thank you all very much in advance.

Luis

salimshah

There has been plenty of discussion on IACV ... all you need is search.

How are you testing for vacuum leaks? This is not an easy task I would like to learn too.

Salim

Luismond

OK I got it
Thank you Salim
Luis

Aprazur

Change the PCV valve (Positive Crankcase Ventilation) and the rubber grommet it fits in. Its leaking vacuum. Cheap fix ($5 to $10) including the grommet.

The PCV valve is at the right/rear (passenger side). It sits under the edge of the fire wall on top of the front corner of the rear valve cover. It has a black vacuum hose connected to it.

JS

TCAL

I have been checking the threads about this issue and this seems to be a slippery slope. I have a 99 RX300 that I recently changed the MAF, an A/F sensor (Denso) and the PCV valve. (I changed the OCV valve earlier in the year). I reset the codes and the CEL stayed off for about 50 miles, then back on. I notice that it idles differently and I can smell fuel, but I am attributing that to the lean condition that the system reads. I did not change the grommet on the pcv valve . . . I am assuming the grommet is the hose connecting to the pcv? The car has 185K on it, it rides nice but seems to be getting worse at times. My gas mileage also went in the tank prior to the AF change and I am unclear how much (if at all) better it is today. Any suggestions?