coldspring

My 98 GS300 is running lean (p0171) and another code Cat below threshold, which I know my CAT is shot. I can not figure out what is causing this lean condition. I have checked for vacuum leaks to no avail. Could the CAT be causing the lean condition. The car runs but the idle is too low approx. 500-600 and the car has no power accelerating (the exhaust makes a gurgling noise at WOT). I know the CAT is shot also because I heard the sound of glass being pushed through my exhaust. Will replacing my CAT clear the lean status and restore power?

Och

iTrader: (3)

You cat is most likely shot because of the lean condition.

Start by replacing your maf.

GS4_Fiend

iTrader: (22)

Sounds like you got a heavy exhaust leak. Have that checked out.

coldspring

Already replaced MAF sensor, the CAT seemed to have went out after sitting for 10 months. Car would not run and think I broke it while trying to get it running.

Choritsu-shi

No.... CATS don't go bad from just sitting and they generally aren't the cause of running lean... damaged cats are the results of running lean.

Although... after more thought, which was first? The lean condition or the damaged CATS?

If your already damaged CATS go unattended, they could continue to worsen by breaking apart and then clog your exhaust system. This would certainly cause the car to lose power.... and also run hotter, which therefore, could then cause a false, lean condition.

So yes, replacing the CATS will restore power... and could possibly clear the lean status. If it continues to run lean after replacing the CATS don't drive it until the lean problem is solved.

Choritsu-shi

EN_VY

Sounds like a cat problem. At one time I noticed loss of power. It gradually increased until my car wouldn't go over 10mph.

ElitistK

iTrader: (4)

it's a maf problem. primary o2 sensors are the ones that helps your ecu tune af ratio, which is before cat. if you run a search, you'll know that p0171 is a maf problem 80% of the time (and i fixed my p0171 with a new maf).

coldspring

I have already replaced the MAF and Choritsu-Shi seems to be tracking because my car was not throwing lean codes until my CAT went out. I have 205,000 miles on this car and while trying to get it to run the engine back fired a few times, which at one point I heard the ceramic glass sound running through my exhaust and a lot of fine rust looking dust was left on my garage floor. I finally got the car running and it started running lean. I will take to Monroe tomorrow and get it replaced, hopefully this will correct the lean status.

gundamwing

hey guys i have a 98 gs300 the car has 297412 miles on it ,now i was going to florida from texas ,once i got into florida and stop to get some gas and after filling up the tank i notice a check light on the dash,going back on the highway i accel the car and the response was very poor it was as if the car was not getting any gas to power the car anyway after 20hrs of driving i got to south florida ,i took the car to a shop and they check code and it gave us p0171 lean condition on bank 1, they check the maf, the reading was correct but they clean it anyway,the code was still there,i had to leave back for texas so i headed out 3hrs into the drive from south fl i was in orlando then the car stall on the highway i pull over and try to start it back it would crank but no turn over i called tripple A and they towed it to the lexus dealer in orlando ,after the car stayed for the night the next day they began to work on it ,they start it and it crank it turn over as if nothing was wrong ,they check what could be causing the lean code but only came up with a possible bad fuel pump so they change it and put in a new one with a new filter and gave the car an induction flush and clean my gas tank after that the code clear by itself so i headed out for texas and got there safe with no check light coming back on ,thinking my problem was solved a week after getting back home it happen again the hard start but now only to follow up with the shaking of the motor, once it start and some slightly poping sounds like misfire then the car would just stall and i would start it again and it would do the samething without stalling the second time and once the car warm up it would idle smooth and rev out good but once i drove it and press for gas it would not respond it would feel as if its not getting any gas ,the check light came back one ,so this time i got i new tune up i change the throttle body gasket and the vaccum hoses along with a new pcv valve thinking that was maybe the problem that didnt solve it either ,now when i check the codes i got the lean code p0171,p0130,p0133,p0150,p0153,man i park the car cause i dont want to damage the cat but i dont know what to do mang,i was thinking it could be the fuel pressure regulator going bad or my injectors or the one which fire up cyclinder one is bad i dont know i have took out alot out of the whole of this sum and now i am a fed up 2jz lover this suck you guys can someone give me some advise on the next step so i can solve this cancer which is eating away at my mind,please you lexus heads out there talk to me mang this lean problem is causing too much problem man i also change the o2 sensors man and the same codes ,man .....just help me help

pricerite

i had similar problem with my 2001 gs300 with 160k
i got the exhaust leak fixed at muffler shop and cleaned the maf with the spray
after that check engine is gone, car runs fine
i also disconnect the battery when i was cleaning the maf
i hope this helps

GS4_Fiend

iTrader: (22)

You got a fuel delivery problem. Even though, you got a new fuel pump, i would still check the fuel pressure AND volume if its within specs. Also make sure power and ground is good on the fuel pump.Then i would check the fuel injectors if they are clogged. Lastly, check the MAF sensor is giving out the correct voltages.

gundamwing

i will bring the car to my homeboy on monday and i will tell him what you said so he can check it out and i will keep you guys updated on what happen ok will post back by tuesday thanks

GS4_Fiend

iTrader: (22)

No offense but plug exhaust/cat doesnt cause lean. Its rich instead.

gundamwing

ok i post last week about the lean condition and the codes that my gs was giving me,well i took the advise of gs4 and i check the fuel pressure regulator and the pressure was not at the right level so saturday i replace it and i clear the codes and my did the car start p like a champ,no hard start or shaking from the motor ,since then i have been driving it and so far so good no codes came back and in the mornings it starts right up ,i hope this it for real and no more lean conditions and crazy codes to come,but for now i can say thanks to all who read my post and look out for me if anything happen i will let you guys know ok thanks

GS4_Fiend

iTrader: (22)

Glad you got it solved. Did you replaced the fuel pump?