az-dave

Oh yeah...DONT use Bosch plugs...use OEM...Im pretty sure they are NGK or Denso...

The bosches just dont last, and they are so difficuly to access especially the #5 & 6 that you dont want to be replacing them.

I would also suggest replacing the spark plug wires if youve got over 150K on the car...helps with spark.

FrankT

Yea NGK or Denso...

I don't believe in the shotgun approaches to diagnosing, it gets very expensive, money that can be put some where else...

I will post a factory diagnostic procedure for a misfire code when I get home tonight.

ballin

I had that issue also, and the Stealership told me it was the ABS system. They said that I would have to replace the ABS pump because it controls the VSC. I guess I could see that b possible.

BTW. Anyone knows where to buy MAS/MAF sensor for our GS besides the Stealership?

FrankT

P Rock- what code did you get when you went to autozone?

P0306 Misfire Detected Cylinder 6, (I would check spark plug, injector and do a compression test)

P1325 Igniter Circuit Malfunction No. 6 (I would check the igniter and the wire harness)

P Rock

Thanks!! I got P0306 (misfire detected cylinder 6). I'm doing sparkplug first since it's the cheapest. I looked up the DIY and it doesn't look like something fun in 20 degree weather here in Cleveland. I might have to suck it up though....

az-dave

OK guys....I installed the new $125 Throttle Position Sensor (TPS). I installed it while I was at work...the car went into Limp mode on the way to work yesterday.

It Ran great up to the store...about 1/2 mile...came back, fine. Parked it for 2 hours and

BAM..Limp mode and all 3 lights again.

In Other words....its not the TPS Sensor....Now, after driving home 15 miles in Limp mode (got up to 70MPH on the freeway Very slowly) I diagnosed some things:

I can replicate the problem by unplugging ANY of the 3 cables plugged into the Throttle Body....If I unplug the TPS plug, the Butterfly motor plug, or the plug next to the throttle spring/cable, it does the exatc same thing:

The Throttle doesnt respond until the last 25%
The RPM at Idle goes up to about 1000-1100 RPM
The VSC, VSC OFF and Engine Lights come on.

This leads me to believe its 1 of 2 more problems:

1) The Butterfly Valve motor control is malfunctioning/not detecting where the butterfly valve is - OR -
2) The ECU is shot.

I do not believe this is a misfire, or an O2 Sensor...having worked on car a long time I think they would produce very different problems, and would be less random.

My car isnt misfiring, and the chug-a-chug happening just before the ligths kick on and car into Limp mode is the butterfly valve freaking out...

If anyone has any suggesting please let me know...Im at the point where Im gunna be forced to take it to the Dealership and risk buying an ECU I might not need.

FrankT

That sucks, buying parts just in the hope that it fixes the problem...just make sure you adjust the TPS as per factory specs or you will have more problems...


Pull the codes and post them... there is no other way to help you.

az-dave

Hey P Rock...

Did you finally get a solution to the problem?

Just to be sure...your car is going into the "Limp Mode" correct? Where it only responds to the last 25% of throttle?

Mine started monday night...fine tuesday, then started again wed, and today its staying in Limp mode full time.

Ive disconnected the battery for more than 30 mins 2 times....that way when I take it to the dealer I get the proper codes.

Im curious to know if you got yours fixed yet?

I know for 100% sure its NOT the TPS sensor...but it could be the throttle body or throttle controller motor....or...the ECU (ouch)

P Rock

Sounds like you and I have different problems. My diagnostic came back misfire in cylinder #6. It's intermittent so it can't be a coilpack. I'm thinking it's the plug. It's running fine once again without me touching a thing yet... Lights are still on though.

sockfocks

iTrader: (1)

Possible leaking injector? You probably need to pull the plug and read it. See what color it is. If its the injector, the plug may be carbon fouled from the cylinder running too rich IE leaking injector.

dallison

my co-worker now has 0300 0305 and 0306 and hesitation also

FrankT

It would help if you post what vehicle you were talking about...
Or are you just posting a comment?

Maybe you should start a new thread with a thought out question, if help is what you are needing...

az-dave

Ok..well Im going to Post this in this Thread, and start a new thread also.

I replaced the Idle valve Motor, which is the larger electrical object next to the TPS on my 98 GS300. Problem is solved.

The Codes I got were P1120 and P1121 - Accelerator Sensor problem. However it wasnt really the Accelerator Sensor, it was indeed to actual electrical Motor that controls the opening of the Butterfly valve inside the Throttle body.

My symptons were:
VSC, VSC OFF, and ENGINE Lights would come on, followed shortly by my car going into Limp Mode, where only that last 25% (if that) of the throttle would respond (basically have to floor the pedal to even move at all).

The first part I tried was the Throttle Position sensor, which is on the front side of the throttle body, and the easiest thing to replace...this didnt help at all.

Next, with some trouble shooting, and using an ohm meter to see if the throttle electric motor was getting elev, I found that the elec motor just to the left of the TPS was basically freaking out and shutting down. The Accelerator Pedal Sensor is on the Back-side of the throttle body where the throttle cable connects to, and has a spring on it. It was fine.

GS300's are indeed "drive by wire" concerning the throttle...the cable triggers the Accel Pedal Sensor, which sends a signal to the ECU, the ECU then sends power to the Idel Valve Elec Motor (next to the TPS), which opens and closes the mechanical butterfly valve, then the TPS sensor detects how far the elec motor is actually opening the butterfly valve...its a closed-loop feed-back system, meaning any failure in any sensor will cause the entire systm to fail.

The throttle cable apparently is ONLY there to allow the fail-safe of having that last 10-25% throttle when the electronic system fails...there is a gearbox inside the throtle body which allows the tail end of the throttle to manually engage the butterfly valve...the rest of the time, the butterfly valve is 100% opened and closed via the idle control motor.

burma

Sorry to bring this old thread back to life....

Today i had the same problem as what many people have already diagnoised.
Was on the freeway and then my VSC, check engine lights, came on and lost power when i press the throttle except for the last 95% and even then it jerked. Lucky there was a traffic jam so i just cruized at about 5km/hr.
So i turned off the engine and started it again and then everything seemed fine, all dash warning lights were gone and it drove normal. Weird

Anyway i go the a Lexus dealer and there are 2 errors, one the Accleration cable error (common problem), the other one was an error regarding the VVTi.
some thing with my cams or the VVTi seems wrong. he said my car's engine was sounding louder than normal.

Anyone know if this is going to be a major problem? Im going back to get it checked in a few days. Im so scared about the cost that im likely to receive from them!

P Rock

I just wanted to let everyone know and for search purposes that I've solved the problem earlier this year and have never had a problem again.

This thread is probably leading to me not being able to sell my car on this forum either LOL. (...since I never provided closure to my problem until now)

Anyhow... the problem was the #6 sparkplug. Coils tested out fine so I decided to replace the plug. Instead of replacing just the #6, I decided to replace them all since they're cheapest and you'd have to replace them eventually anyways.

Car has been running perfect ever since so for everyone with the same symptoms, check the plugs first since they're cheapest option.

Hope this helps