clswhitegs

I spent the past few days reading through the whole 19 pages of this thread, definitely some great info in here. It seems that az-dave is the go to here, so hopefully he can shed some light on my situation. Here it is:

- The VSC, VSC off and CEL lights all came on and my '98 GS300 went into limp mode.
- Pulled the P1121 code, but not the P1120
- After reading the original thread by az-Dave, decided to change out both the TPS and the Idle Valve Motor, since I had the TB off, I cleaned it out too.
- Reinstalled, fired up the car, Lights cleared, ran great, but just for a day.
- Back into limp mode, so I double checked my install, then tried to pull codes
- My reader now cant connect to the ECU, my idle is running super high (1.25k), and the Lights are all up again
- Turned off the car, it was late by this time, the next morning fired it up to bring to my mechanic to see if his reader could see anything
- All Light were up, idle was high while in park, put into Drive and the car ran fine but all the Lights were still up.
- Got to my mechanic and his reader couldn't connect either.
- On my drive back home, car went back into limp mode.
- My mechanic said its probably a module issue and that I will more than likely have to bring it into the dealership

After reading through the thread, I am trying to stay away from the dealer since it sounds like they will just change out items that I can do on my own. My next step is to change out the cable side of the TB from the sounds of it and then see whats up.

If anyone can shed some light on my issue so I don't have to change out parts that aren't needed, that would be awesome.

Also, I had read that someone had changed out their CAT system and that fixed the issue for them. I know one of my CATs is toast, and once I had this issue taken care of I was going to do a pre-cat back overhaul, was wondering if that would kill two birds with one stone.

Cheers!

CBREZZIE1

im new member as of today i have the same problem ive done a 3 stage fuel treatment maf sensor new plugs and wires disconnented batt and ecu b fuse not a winner here so do you think that the lever assembly will solve the problem . sick of this crap . 03 gs300

clswhitegs

On page 17 of the thread az-dave gives a list of possible fixes from easiest/cheapest to hardest/expensive. I suggest going through that. I just went out and re-calibrated the TPS and then reset the ECU, got it up to temp. and took it out for a 15 minute test and couldn't get it to fault again, so I am thinking it was just needing an ECU reset after I changed out the TPS and the Idle Motor.

Next up is o2 sensor replacement along with pre-cat back exhaust overhaul.

az-dave

CLSWHITE - I hope the TPS was your issue. For me, I did mine I think a month or 2 before it went into Limp mode daily. So just beware the Accel pedal sensor (called Lever Assy) may still go bad)

As for the throttle being high and ECU reset, I agree the new TPS probably needed to be re-adjusted and the ECU allowed to reset to it.

Thanks for the input. And glad this thread was able to help another person!

LayLowLexo

Anyone know what the THROTTLE BODY ASSBLY part no. is for a 2005 Lexus LS430 ? I am having same issues as most are. My TRAC OFF/ CHECK VSC/ CHECK ENGINE LIGHT all popped up at the same time. My issue before these lights appeared was that at times when I would hit the gas pedal my engine would rev. but my car would not accelerate. Yesterday the issue started happening more and once I knew it, the lights came on.

Anyone have any suggestions??? Any help or advice would be highly appreciated

az-dave

reving engine with no acceleration means engine is getting gas (which means VSC isnt cutting power to throttle body), so for some reason engine power is not going thru the transmission.

you cant have limp mode and a reving engine.

There are forums and threads for LS models you may like to start a new topic, since its a different model, newer (I think by 05 newer models were out with different total engine designs).

Martin321

Lexus GS 1998 here with 174,587 miles.
VCS, VCS Off and Engine Light went on yesterday. Had to push the gas pedal down, all the way down, to drive 20 miles per hour home and the car was in limp mode for sure. First time it has ever happened. I thought that the tranny has gone for sure but I found this great thread yesterday evening which made me feel much more optimistic. I have been driving over last 6 months and have been noticing this motor hesitation at very low speeds, last week at a stop sign the car was even shaking a bit, i thought it was an earthquake as i never had this experienced. This morning i was going to work in in about 7 miles in my trip i had the same thing happen. I knew i had to restart my engine, but the lights stayed on, I was able to get to my local shop.

After about an 30 minutes, mechanic detected P1120 and P1121 and reported that it was related to bad acceleration pedal sensor. I told him if it was the Lever assembly and he confirmed. After reading this post, i told him that maybe it might be the other 2 electronic mechanisms on this mechanical throttle body. I waited until he got a TPS delivered, he put it in and in 2 min told me that my TPS is fine 5.0V on Ohm or something. I also told him that it might be Throttle control motor to the left and he tested it and said that it was fine also.
I have ruled out 2 things, and only one remain on which we both agreed upon that i needed a new Level Assembly. which comes with that accelerator pedal sensor.

Martin321

Mechanic also told me that it happens very rare, when a Mass Air Filter Sensor, YAW Sensor fail. and was laughing at me when i mentioned bad ECU or wires loose. Maybe according to diagnostic codes it rarely happens. I will post again tomorrow to report the results. He took $55 bucks for diagnosing problem, i guess he has to send back the TPS that he had tested and ruled out.

http://www.lexuspartsnow.com/parts/l...060-46010.html

but i called my Lexus dealer part store and will pick it up for $360 tomorrow AM ($90 bucks more), but I am planning to attend a few parties this weekend so i cant wait for USPS to deliver in 4-5days.
I called Queens, Brooklyn, Staten Island Toyota dealers and non had this part number in stock. I just thought it would be a bit cheaper. TPS senor, out of ceriousity I asked, Lexus Bay Ridge said $280. What a rip offs as online it only cost $ 50.

Martin321

Last time i had any major repairs done to my car was at 120,000...timing belt, water pump, and all tune up, including filters. I then changed my battery and generator at around 130,000 and brake pads and rotors. Then at around 150K i hit the potholes a few times and had my control arms and bolt joints changed and i go change my oil every 3-4K miles. My mechanic said, Thanks God, if everyone would be driving a Lexus then i would go out of business

az-dave

You got both an Honest and a GOOD Mechanic my friend...something VERY hard to find in Phoenix.

The fact he mentioned YAW and MAF and laughed at Wires and ECU is amazing because the Dealers always suggest an entire Throttle Body assembly ($1200-$1500) and then the ECU If/When the entire TB doesnt work...time and again. (complete voodoo car work in my opinion)

Hope your new Lever assy fixes the prob...Id give it a 95-99% chance of that being the issue.

I agree about wires...unless theres been fire, or some other damage, the wires can rarely be the problem. ECU also very rare. But that doesnt make money for Sdealers does it?

Martin321

I went to dealership parts Dept, got the Lever Assy part and went to my local mechanic to install it. All previously mentioned lights came back on as i approached my local shop and the limp mode was on. Mechanic took out air intake tube and other parts around it in order to unscrew Lever Assy. Looking from outside - in, throttle body looked almost clean, considering it's a 96GS. He put the Lever Assy in and connected some kind of device next to driver side pedals and had a laptop computer on the other end. Installed the software or something, told me to start the car, adjust the steering wheel straight and push the gas.
After about 40 min the problem was solved, then i went out to test for good 4 hours straight. First on highway i noticed a very small difference when i took my foot off the gas pedal, it seemed not to autobrake as much and was a little more fluent. Also when i did step on the gas, the gas pedal for sure was responding even if i just pressed it a little. My cars hesitation symptom when going on small speeds when it sometimes jerked as soon i pressed on a gas pedal also disappeared.
I am just glad that this nightmare is over with.

az-dave

That is Awesome!

Crumvoc

Just an update. I think I've figured out the problem.. sort of. The dealer had the car for several days, don't know how much time the tech spent with it but it was a lot... they only charged me for 3 hours which I appreciated. They had a computer in it to record events, a mechanical fuel pressure guage, drove fast, slow. The tech took it home with him a couple of nights... and it never did the behavior while they had it! In discussing the possibilities with the tech, he told me that he has seen cases where a hyperactive knock sensor would cause similar behavior for various reasons, including using low octane gas.

I got to thinking, trying to remember when I last fueled before the behaviors started, and I'm pretty sure I put a tank of regular in the car not too long before. Just before I took it to the dealer, I fueled it with mid-grade or premium.

So... the car is behaving itself. I think it does not like regular gas! I'll let you know if the problem recurs.

getindavan

i got P1128 P1120 with the limp mode. i changed everything on the throttle body, and the code disappeared and now have i have P1139 now still in limp mode. im about to pull the trigger on a used ECU. can someone throw me a bone before i do this? what could it be???

Crumvoc

The problem really was the low octane gas, maybe in conjunction with the ethanol they put in gas around here. Not one more issue since I keep using either mid-grade or premium gas. Glad it was something simple, and weird....