Neophyte2b

I have a 2013 GS350 AWD F-Sport that I purchased several months ago. On two or three separate occasions, the vehicle would shudder for a few seconds while I was at a traffic light. What might be causing that? I tried using some Techron Fuel Injection Cleaner after the first occurrence, but it still occurred once or twice more. It doesn't do it all of the time, but only occasionally. Any thoughts on what's going on and what I can do about it? Thanks.

TAURUSSLVR

You know I noticed that as well ! After awhile I came to a realization. I figured out that it was just my car waiting in anticipation for the green light.

TAURUSSLVR

But seriously, have you tried cleaning out your throttle body and /or the MAF sensor? Do you have your AC running?

Neophyte2b

The A/C is running. I have not tried cleaning those two items out. How would you go about doing that?

gs350lex

I had the same symptom a few months ago but it would rarely happen so it was hard to pinpoint it. I initially assumed it was nothing but fast forward a month later and i started getting a check engine light which i assumed was attributed to bad gas(since the CEL came on after filling up my gas tank). Turns out it was a bad 02 sensor and I no longer have any of those symptoms and car runs great now. I can't say for sure if that's your problem because in my previous cars it was due to a dirty throttle body so my advice to you would be just to wait it out.

Eventually you will know if the CEL shows up and if not you can always clean out the throttle body as others have suggested.

I wish you luck please keep us posted!

bclexus

Since the engine shudder you're experiencing only happens sporadically when stopped and in gear it suggests the problem is not a leaky or disconnected vacuum hose or a damaged engine mount, which are two common reasons if the engine shudder happens each time the car idles while in gear. Another cause for shuddering is a defective spark plug, but there is practically a zero chance that is the problem. Bad fuel - almost certainly not. Two other causes that could be the problem are a oxygen sensor in the exhaust system going bad or in need of being cleaned...or the MAF (mass air flow) sensor needs to be cleaned. Then, there is one more likelihood - the ECU (engine computer unit) is reevaluating conditions (e.g. air, fuel, temperature, etc.) and is electronically adjusting itself, which happens on an ongoing basis.

If you have disconnected or replaced the battery recently, that can cause the ECU to electronically readjust itself which can cause a brief shuddering from time-to-time. Also, a disconnected or replaced battery can oftentimes play havoc with the ECU because of a dirty MAF sensor that worked fine until the ECU was reset due to the battery being disconnected, which suddenly requires the dirty MAF sensor needs to be cleaned to satisfy the reset ECU.

So, depending on whether the battery has been disconnected or replaced recently (which resets the ECU) and may require the MAF sensor be cleaned, you might just need to make a few WOT runs through 2nd gear to blow the soot and condensation buildup out of your exhaust system and engine cylinders - something your engine will be very thankful for you to do every so often! Short trips, lots of idling with the engine rarely ever being taken to redline is not good for the engine or its many sensors (e.g. MAF, O2) that can cause the engine to shudder randomly...

TAURUSSLVR

Here's a good place to start.
https://www.clublexus.com/how-tos/a/...itating-365739

Can find a wealth of info in the DIY section just gotta search. Also I've seen some YouTube videos on older models with a little variation.
I mentioned the AC because if it's blowing warm or hot air it might well be the AC condenser struggling. I'd start with the throtte body and MAF sensor first.
You can pick up throttle body cleaner and MAF cleaner at your local auto parts store.

Not sure if this will solve your issue but it's a good place to start problem solving it.

Neophyte2b

Thanks for the advice! I'll keep you posted.

Neophyte2b

Thanks! I'll look into that.

fuddyduddy

It happens to me once in a great while. I assumed it was the ECU going through a battery of emission related tests.