Hey guys,

My GS450h has been through a lot over the past years, and now the dealership and I are both stumped. During a cold start, the engine idles rough until it is 'warmed up' . After that, no problems; lots of power, no change in fuel economy etc.

Notes about my car's history;

-93,000miles/150000kms
-Valve recall complete (but done incorrectly, which lead to a whole engine rebuild....yay)
-New plugs, wires, injectors, ign. coils----post rebuild
-The rebuild was done by a high-performance shop, so if there's any initializations that have to be done, then they haven't been done as of yet
-Misfire CEL on all cylinders that I keep erasing; from idling or hard acceleration then letting off the gas...ie, going back to "idle"

The RX-h owners and many others talk about the ISC LEARNING PROCEDURE. Could this be the cause? I got my hands on an RX400h service manual the other day and asked my dealer to look into the ISC procedure. They said that the GS450h doesn't need it and that all control system parameters check out.

This is dealer #3. The engine shop also had a look at it and deemed that nothing mechanical was flopping around. Regardless, once the engine is in closed loop, it goes away, which leads me to believe that it's control related.

Any help would be awesome!!! Thanks!!

 

Update - I took it to the dealer again, and they scanned/freeze frame and they can't determine why it won't idle when cold.

It's crude, but I figure that I'll swap out these sensors:

Coolant temp
MAF
Crank Angle
Cam Angle

 

can you show a video of the problem? strange problem when there are no warning lights illuminated

 

Oh, wait. Just looked again today and the computer has given general misfire (P0300) and multiple misfire on basically every cylinder + flashing CEL while driving sometimes. I'm going to focus of the MAF since there seems to be many issues with sealing, gaskets etc.

Let me know!

 

Well, have you left the vehicle overnight for them so they can start it up in the morning and try and see what the problem could be.

Edit: oh see you said it was a misfire.

 

Yes, I did, and of course "we found nothing."

In terms of the noise I hear, I've narrowed it down to the fact that the engine is misfiring, while the hybrid generator/motor is trying to keep it's desired pace at idle. As soon as I even touch the throttle, it all goes away. My goal is to solve this idle problem first.

Could I ask a BIG favor of someone???

Could you run your car at idle (hot/cold, doesn't matter) and disconnect your MAF sensor so that your car dies? As it's stumbling before death, could you report to me if the engine clunks a lot? You will probably get a Check Hybrid Light (do a 12V battery pull for 30 mins).

I've noticed a slight noise when the engine turns off automatically (since day one) that has always worried me a little. I'd like to benchmark it versus someone else's.

Thanks guys!

 

Point of interest: The CEL and misfire/idle symptoms sound IDENTICAL to the GS300/350 letters that people started receiving from Lexus yesterday. Spread the word, maybe the 450h's are next

 

update! what happened to the car?

 

Mine is doing the same! Did you figure it out?

 

Hey guys, go look at my thread about "FYI: Direct Injector Seals," it explains the solution.

I saw my independent Lexus Master/Hybrid mechanic and he said that these cars sound like s*** when they don't idle properly (ie, the tranny clunking). The noises are normal (if it runs poorly). I'm having the Direct Injector seals done as we speak.

 

^ covered under warranty? only in extreme cold temps your able to replicate the problem?

 

It's being replaced under the engine rebuilder's warranty (and if they don't feel comfortable doing it, I'll have Lexus do it and simply charge the shop). It has been happening ever since it came back from its rebuild, which was July. The engine block itself has to be 'cold' for this to happen. Once it warms up to operating temperature, everything is perfect.

I should have a definitive answer in about 2 weeks.