I've noticed for the last few months, my 2001 LS430 with 107,000 miles, can lose power while I'm driving. While I'm driving if I hit the accelerater, instead of an instant repsonse, there is a dead spot where the car does nothing and feels sluggish until it kicks in. A second later, the car will respond as usual, with instantaneous acceleration when i step on the gas. This problem coincides with another symptom. While I'm driving at a steady spead, i can feel the car losing power (almost as if it is slowing down). Both conditions are sporadic, and there are no messages lighting up on my dash. I will experience this a few times each time I take my car out. Anyone have a clue??? I wouldn't know where to begin. Thanks all.

 

Do you think adding a bottle of Techron concentrate might help?

 

You might want to try resetting your ECU. Disconnect your battery for 5-10 minutes then reconnect it. You will loose your radio station settings. IIRC, the car "learns your driving patterns" and will shift accordingly. You may also consider cleaning your MAF, but not so sure on this one...

Before trying these though, see what other members have to say.

 

I had a very similar problem on my 2003 LS430 a few years ago. After asking the dealer to investigate a couple of times, a new air filter appeared to fix the problem. I haven't had the problem since.

 

There you go - some standard diy stuff to try first and good routine maintenance anyway -

1. Run a can of Techron concentrate fuel system cleaner thru one or two tanks of gas
2. Clean the MAF - use MAF spray cleaner available at parts store
3. Clean the Throttle body - use clean rags and TB spray cleaner avail at parts store.
4. Make sure you have clean air filter
5. Disconnect the negative lead on the battery for 5-10 minutes to reset ECU

IF you do all that and it stills lags and its not throwing codes I would consider changing out MAF - get one from a place that will allows easy returns with no restock fee - the MAF can be changed out in 3-5 minutes or less with only a screw driver and if it doesn't fix the problem you should be able to easily return it.

 

Thanks everyone for all your imput. I will begin with the techron and go from there.

 

Update: Took my car to Lexus for the $99 diagnostic. I use the same tech whenever I go there. He cleaned the MAF and checked the throttle body and fuel flow. Found no detectable issues other than some slight debris on the MAF. I will be running a second tank mixed with Techron in a few days. So far, no issues. If the problem returns, I'll probably replace the MAF with an aftermarket, and next the TPS. Both parts are relatively inexpensive. To be continued.

 

Boca - I had perhaps a similar problem with my GS430 - it would happen sporadically and left no codes - it felt like I would lose power for a split second or two, almost as if I had removed my foot from the accelerator but I hadn't - turned out to be a TPS - had it replaced and never had the issue again - hope that helps a bit.

 

Im having the same problem with my 108k '01 ls. It generally only occours durning its first warm-up of the day but will have the odd late day hiccup as well. It seems to only happen under a very slight acceleration or even at lower speeds with the cruise on. Also the motor seems to fall on its face after shifting from first to second and even worse second to third. I test drove a 52k '05 model a few days ago and experienced none of these issues. The car pulled well through all the gears and actually seemed to pin me back in the seat after the shift points rather than me moving forward due to a slight stall such as i have in my car.

 

Bcorey....You described it perfectly! When I'm driving and it happens, it's as if I had taken my foot off the accelerator. Othertimes, when I try to accelerate, I feel a "dead spot" with the accelerator until it kicks in. I guess, if it returns, I will change the TPS first. The MSRP from the Lexus dealer is $102.00 which is not terrible. Do you know if it's a big deal to change? Thanks.

 

Its the drive by wire effect.

 

Boca - I paid an Indy shop to replace mine but I read several posts afterwards stating that it was a pretty straight forward procedure - I found this link and after reading it, I can't recall if I replaced my TPS or the Accelerator pedal position sensor - I'm starting to think it might have been that later - I sold the cars years ago and no longer have my records for it. Give this link a read and I'll see if I can dig up some more on what I actually did to my old GS.

https://www.clublexus.com/forums/per...on-sensor.html

 

Boca - according to this thread I found, I replaced my pedal assembly... give this thread a read as well as it details many similarities

https://www.clublexus.com/forums/gs-...tting-out.html

 

Thanks bcorey. Now I'm really confused! I thought it would be any easy fix. In the mean time, I haven't had any symptoms for a few days since my MAF was cleaned. I'm crossing my fingers but as electronics go......I can only be cautiously optimistic.

 

The "Drive by Wire sysem" actually consists of the APP (accelerator Pedal Position Sensor), The ETC (electronic throttle control) which has an electric motor, and the TPS (Throttle position sensor). It could be any one of these 3 parts that could be causing our symptoms, not to mention the MAF. Before changing any parts I will need to speak with my local Lexus service manager who also happens to be a Guru with many issues on our older cars. Threre are quite a few threads on this very topic, but mostly with the 2nd generation GS. Bcorey......not sure if the GS has the exact same setup as the LS430 but it might. Now that I know that it can be any one of 3 or even for electronic parts, I will need to research further before changing them out. Thanks for your help.