speltier

Howdy friends! I'm so glad to make the shift to Lexus and I'm glad too see such a robust community following my favorite model, the RX300. I just got my first (and hopefully last) RX a few days ago. Screaming deal on a 2002 in very frosty shape.

I had an exhaust leak fixed today. The hanger between the cat and resonator had torn a bit, so my muffler guys welded it up. On my way there, I was cruising along at 65, and my mpg computer was reporting about 22, or 23 mpg. This was the same mileage I was getting on my way from Chicago, where I bought the car, to Ann Arbor.

After I had the leak fixed, I hopped right back on the highway, and even at 60 the computer was telling me around 13 MPG. Whoa.

So, having scoured these stacks of info, I pulled my ecu-b (7.5) and efi (20) fuses, leaving them out for a little while… 20 minutes.

I haven't had her back on the highway yet, but I'm wondering if anyone has any ideas about this… I had a thought that the welding might have fried the O2 sensor which is adjacent to the area. No CEL, yet, though.

It seems to sound, smell and perform the same as before the repair, so I'm wondering if my mpg computer is just confused.

I hate seeing that 6 or 7 mpg figure, around town. It's very distracting.,

Anyway, thanks in advance, and I look forward to joining in many discussions to come.

Best,
Ash

speltier

Additional info…

Yesterday I cleaned my MAF sensor and IACV valve, and replaced the air filter.

Baetke

Start by resetting the mpg meter and do a manual calculation of your mileage on your next tank of fuel to see if the meter is reporting accurately.

speltier

good idea. That test is underway presently. Also, I feel like I'm smelling gas rich exhaust in the cabin, but no check engine light. Will air /fuel ratio sensors always report if they are malfunctioning?

Baetke

If you are smelling gas fumes, something is really wrong. Are you sure your check engine light is functioning? Turn the key to the ON position but don't start the engine. All of the "idiot lights" including the check engine light should turn on so you can verify that a bulb isn't burned out or hasn't been removed (a favorite trick of used car salesmen). If the car is running rich you run the risk of burning up your catalytic converter in pretty short order.
Do you have a OBD2 code reader and know how to use it? If so, check your short and long term fuel trim values. They will tell you for sure if you are running rich or lean.

speltier

Thanks! Im on it.

speltier

in fact it appears that my check engine light is not working. Charming.

Baetke

Given your prior description of symptoms I would recommend not driving the car if at all possible. Driving a car that is running rich will eventually melt the catalytic converter and they are expensive to replace. Fixing the check engine light isn't terribly difficult but that won't tell you whats wrong. The next step is to get a code reader/scan tool and pull the trouble codes and freeze frame data. If none of that makes sense to you its time to find a mechanic. Of course you can always take it to the shop that last worked on it and see if they will help you out.

speltier

Thanks again. Yes, codes more important than a bulb, for sure. I'm envisioning B1S1 solving all my problems. Cross the fingers.

speltier

Codes!
P0125, P0171, P0174
Ive got af sensors on the way, and an o2 sensor. I just cleaned my maf, but will replace it if the a/f sensors arent the culprit. I just cleaned my MAF, but...

I got so data off the scanner...

speltier

can't figure out how to post the photos, so here it is. on both banks the short term fuel trim is 19.5%, the long term fuel trim 53%. Certainly out of spec, I think. also on the i/m readiness screen 'evap' and 'o2s' have red X's next to them.

I also noticed a torn CV boot, which I will probably not do myself. Too cold around here for that at the moment.

Also, the bolt holding the oxygen sensor is sheared off flush with the mating surface. Drill and tap?

Baetke

P0125 code is odd; indicates coolant temp too low to go into closed loop operation. You might need a thermostat.
P0171/174 are the same thing. I think you may have an exhaust leak upstream of the O2 sensor. This would cause the sensor to think the exhaust gasses are lean and it will tell the ECU to make the mixture richer, thus the smell you noted earlier.

Baetke

If you're referring to the downstream sensor (the one under the drivers seat) that one has nothing to do with the fuel trim. It is just there to measure catalytic converter efficiency. Good idea to fix it though. If you can drill and tap, great. I think Hillman makes a replacement stud that fits.

speltier

I just discovered an exhaust leak in the flex pipe at the front of the car. Most of the metal fabric is shredded, and there's a half inch crack or so underneath it. Could an exhaust leak like this cause my problem? On another note, I noticed what I thought was a torn CV boot, but it appears that the power steering pump above it is leaking., and dripping onto the boot. Opinion on OE vs amazon on those?

Baetke

Hard to say if a leak there is far enough downstream of the A/F sensor to not make a difference. A better question might be... Why is it damaged and is there any other damage upstream? A leak at the exhaust manifold gasket or manifold to cat flange or a crack in the manifold would definitely be a problem. Give it a good visual and audible check when running to see if you can hear any leaks. The flex pipe could explain the smell of fumes in the cabin.

I always use OE parts because I don't want to take a chance on having to do the job twice. That being said, I've saved a lot of money by buying Toyota parts instead of Lexus. The trick is to figure out the cross referenced part number. Toyota/Lexus won't help you.