loud3nergy

This has been happening to me lately. I have a 99 GS400 w/125k miles. Ill be driving and then the CEL and VSC lights come on and have no throttle response for the first 80-90% of the gas pedal range and then it goes to the back-up cable response. I have done many searchers on ClubLexus and most have pointed towards the TPS and PPS sensors. So to narrow it down I took it to the local toyota dealer (closest Lexus dealer is 1.5 hrs away) and ran a diagnostics test on it. It was showing that it needed a Catalytic converter and they quoted me a price of approx $1300. My question is, would the catalytic converter really cause these symptoms if it was faulty? I have owned the car for 6 months and have only used Shell or BP premium gas. Any insight would be priceless right now.

--UPDATE 1--
Well replaced some parts and have done some more research with out any progress... replaced the TPS sensor on the throttle body along with the Throttle Body Lever Sensor (what the actual cable wraps around) Still having the same issues. Also took the CATs on the headers off to inspect them and they are both fine. Car does it all the time now, it never acts right.. symptoms include:

-No throttle response except for last 25% of throttle
-Ideling high, around 1100 RPM
-When shifting it will shift late and very hard jerking the car and most times chirping the tires going from 1st to second.
-CEL, VSC and VSC OFF lights are always on

****anyone else having the problem please help me as with what resolved the issue for you.****

--UPDATE 2--
Replaced the Mass Air Flow sensor and still having the same issue.. Replaced the Electric motor that controls the butterfly and still the same issue.. Took a test light to all the plugs connected to the APPS, TPS, and Electric Motor and none are hot. I am out of Ideas!!!!

Items Replaced:
APPS, TPS, Butterfly Motor, MAF
Items Checked:
CATs on both headers. Check pigtails for all sensors with car turned on and with car running and none are getting power. Checked all fuses in all fuse box locations (under hood, Drivers floor and Pass Floor)

PLEASE any help or ideas at this point would be GREATLY appreciated!

Mr Jokster

iTrader: (8)

nevermind... i didnt read it all...

but did you check the fuse to the MAF sensor? I found that mine was the fuse and not the actual sensor.

dung0981

iTrader: (1)

CAT wont give you that problem, Since you have replaced the TPS sensor(The one on Throttle Body) and TB motor. Did you check the gas pedal sensor. i think the ECU might not work right, so its giving u shifting problem.
Dont worry about the VSC light because its associated with the CEL.
Remember reset the ECU after you replaced those sensors. every time reset the ECU, idling at 1100 RPM is normal.
If you have access to scanner, check for Butterfly Motor position ( 11-13% are normal)
Hope this help

loud3nergy

I have replaced the Gas Pedal Sensor (Accelerator Pedal Position Sensor - APPS), with every install we reset the ECU. What scanner are you speaking of? Code Scanner? And THANK YOU so very much for your guys help!

loud3nergy

any ideas?!

99SC42

iTrader: (44)

I have a gs3 and mine would not even move sometimes lexus replace the tranny but it end being the TB it was clogged up ,they told me that i need to replace the TB $1600.I took the TB apart and cleaned i with some gu cuter problem fix i hope you have the same issue caause it's easy fix

loud3nergy

well, We took the intake hose off the throttle body and wiped down the inside with the butterfly open. wasn't too bad dirty.

sleeper408

iTrader: (6)

That is weird. I had the problem before with the car running in "safe" mode. I think I may need a new TPS and/or APPS. What code did you get? I pulled codes P1120/1121.

paradox

Any progress with this? I'm interested in what the solution was, if you had it fixed. Thanks.

loud3nergy

none at all.. Still trying to think of what it could be.. Only thing I can think of is MAYBE its an O2 sensor (big maybe) or at worst the ECU?

YOO

At the back of my mind i was thinking the ECU is the problem. but most of the time, Scanners will pick that up and tell you its the ECU failing.

I had a CEL and VSC come on and off on its own. but i never had any throttle reponse issues. So i drove the car like that for over 6 months and never seen any other issues.

So one day, i was bored and decided i'd work on my car. I did a small tune up job on the car: replaced filters, filled fluids, and replaced SPARK PLUGS. AND of course resetting the ecu.

AMAZINGLY! the CEL and VSC lights turned off!!! and the car ran smoooother then ever!

So my conclusion for my issues where the spark plugs???

I knew all my spark plugs were toasted once i took the first one out. I was running Denso Iridium plugs and replaced them with NGK-R premium plugs.

I cant seem to make a connection in my mind on how spark plugs will cuase the alert of VSC and the CEL gave me a MAF sensor code... WEIRDDD...


i sure hope this helps a tad-bit!

keep us posted!

2JZuL8r

I am having the same symptoms as the first post except my CEL light has never came on. Also my throttle will pulse during acceleration and sometimes hiccup when I am cruising. I am not having the last 25% throttle response problem. I am looking forward to the solution to this thread.

Evil Twin

CEL light is on and the code # is??????????

WVGS4

My bet it is the ecu. The battery had died on mine before all the problems started, my wife - wanting to go the mall - had hooked up the trickle charger to get it started. Well it never started for her and when I returned I found the charger was hooked up backward. I soon after had similar sporadic -what I thought was a fuel delivery problems. This continued for several days until it finally quit running. It would turn over strong but no fire. NO codes were thrown , I was stumped. After repalcing fuel pump, cleaning MAF, relays ect.. No luck. When the car was almost out of battery from cranking it would actually fire and sputter a bit. It seemed like it had to be an ecu issue. The price of a new ecu and key is a little scary dealer estimates range from $400 - $1400. I found several locksmiths online. They will re-flash an ecu for anywhere from $200 - $400 this includes 2 new keys, but they don't have FOB capablities. Since I had tried everything else I could think of what I did was get another ECU of Ebay, you should be able to find one between $100 - $200. The catch was the only ecu I could find was a 99, I own a 98. I also wasn't sure my was bad, I had heard that it might have been immobilized since the plastice upper had seperated from the metal lower part of the key. Since the ecu you get probably won't have the key with it, you send the working key you currently use and have both ecu's reflashed to your key. It only took about a week round trip. When I got them back I had two ecu's flashed and four spare keys. I put the original ecu first and it started right up. (ahhhhh sweet success). I wasn't sure the 99 ecu would've worked but now I have an extra, along with extra relays and a fuel pump. I'll sell you the ecu and keys I have for $450 if you want to give it a shot.

loud3nergy

at this point I have given up on it completely.. I currently have the car for sale on some local forms for 8k obo.