mk4r34

iTrader: (1)

93 Sc300 factory
Manual
138XX miles.

Code 25(running lean) came up and doing searches it seems to be the 02 sensors?I've done a lot of maintenance on this car but,have not replaced them yet.I have noticed a heavy fuel/exhaust smell upon start-up for the past year+ and today before the cel came on the car was idling at 4-500 which it usually idles at around 800.Any ideas?or does it sound like the 02's need attention?

Thank You

1JZPWRD

iTrader: (59)

Is this the only code that came on now? Just 25?

If so, I would say the 02's do need attention. Don't cheap out on them... Also make sure your cats are closed up.

SC400slide

iTrader: (11)

When I had that well known smell of "running lean", I replaced the bank 1 o2 sensors. The smell left, and so did my entire list of issues.

Zinik

iTrader: (1)

fuel pump and or filter?

mk4r34

iTrader: (1)

Yeah that was the only code I did it a couple times to be sure.Cheap out ?Wouldn't just bout any universal o2's be fine?OBD1 runs a 4 wire right?

Bertman

iTrader: (1)

I agree with 1JZPWRD about not being cheap with the O2 sensors. I'd get DENSO O2s if I were you. You must remember than oxygen sensors are a big part of your Engine Management set up and must read as accurate as possible to achieve maximum efficiency. Look up RockAuto.com for a set at a good price (that's where I purchased my Denso O2 sensors).

93twintrbo

iTrader: (1)

Check your upstream o2 voltage. There is a diagnostic box under the hood. Take a dvom (digital voltmeter) and with the negative lead on chassis ground, put the red lead on "ox1". Voltage should fluctuating from .1 to .9volts. What you are looking for is that the Ecu is trying to shoot for .45v (stoich). My guess is that the o2 sensor is reporting lean (.1-.3v). You may want to check the response time by inducing a lean condition. And looking for an rpm drop as well as the o2 sensor reporting low voltage. Hope his helps.

mk4r34

iTrader: (1)

So the day after I cranked my car the check engine light came on for about 30 sec and turned off.I have been driving the car for a week with no light coming on maybe something was stuck in the injector?but,I am still skeptical if I should replace the upstream 02's??The exhaust smell is getting to me on start ups in the parking decks.My Lexus tech said "well it's an old car they all do that"...riiiight....so would it be the cat,02's,injectors,dirty something?what?

SC400slide

iTrader: (11)

The smell could be caused by clogged catalytic converters, upstream o2 sensors, or even MAF, (fuel to air ratio a bit off?...) If you haven't already, I'd definitely replace the upstream o2 sensors. They could use a change even if they aren't the cure for the problem, knowing that Lexus's eat through o2's like candy. Your mechanic is correct, old car's do exactly that, with something wrong with it. Your cat's could be in need of replacing if they are clogged. For instance, the fuel to air ratio isn't correct and the raw fuel burns through the honeycomb on the cat causing to melt the metal into a wall, then no exhaust can get through the system and will find a leak somewhere or make it's own. You can replace the catalytic converters or just remove all of the honeycomb and run it with a cat delete...
Keep this thread updated

mk4r34

iTrader: (1)

Still waiting on the o2's to arrive anytime now.Car has been progressively running rough like a misfire of just fuel being dumped and very rich smell with lots of smoke until engine warms up.Im hoping the o2's fix it but,having doubts after reading some posts.

SC400slide

iTrader: (11)

I think the o2's could very well be the fix. It's amazing what a difference in idle new o2's make...

mk4r34

iTrader: (1)

UPDATE:

So it was the o2 sensors(upstream) For future reference the symptom I had(besides a heavy fuel/exhaust smell for months)was a very rough idle/shaking out of no where during x-mas traffic.You have about or under 1000 miles before the sensor just quits and the car rides very rich,idles about 1200+ rpm,lots of hiccups,and lots of white smoke upon start -up.Even though I had a "lean"code show up I lost 40-50 miles on my last tank.Hope this helps other out

ScWift92

I Was just driving home and My Car Was misfiring And very hesitant. it would go from non misfire to misfiring and running like crap then i smelled a lean smell when i pulled over checked all my plugs to the dizzy and yet nothing no code? It suddenly stopped misfiring once the CEL came on and ran fine but only with a raw gas smell ?? has any one else had the missfire???

mk4r34

iTrader: (1)

I've had that problem a couple times.
Once when I had oil in my plugs which fixed it.Another when the cap blew in my ecu which seems to be common.That was real bad though on the hwy going 70mph it would stutter down to like 65mh on/off.Also if you haven't yet check and clean your egr valve and IACV.

ScWift92

Is It Prob The O2?