Hi,

I know this is the LS forum, but i guess this engine is more common in the LS than the GS.
Car is a 2010 Lexus GS460 180k miles.
My engine keeps stalling when engine is hot. No warning lights, reading errors says running lean. Sometimes it has trouble starting only with the accelarator pushed the engine stays on.
The car trys to keep the engine running but at idle speed the car stalls,
Revving the hell out of it solves the problem for a short time.
Errors are bad cats, running lean.
Maf changed
Temp sensor changed
fuel pump changed
throttle body changed
spark plugs changed

Christian
Any hints?

Thanks Chris

 

Have you inspected the catalysts?

 

Carbon build up problem maybe...have you done a fuel system cleaning

 

My wife's Jag had this problem at around 165K miles. My mechanic did a smoke test and it turned out the gasket(s) to the intake manifold was shot.

 

Sounds like a vacuum leak that only occurs when the engine is hot, so something is expanding when it's hot and revealing a leak and then contracts when it's cold and closes the leak...cracked intake? Intake gaskets? Exhaust manifold?

 

If the errors are bad cats thats the first thing u you should of done

 

Hi the cats look perfect. Since the engine is running lean, couldnt the cats error be an issue caused by running lean?

Christian

 

Well to be honest you can't really tell if cats are good just by looking at them. Bad cats won't cause driveability issues unless they are clogged, and if they are clogged you'd have a massive loss of power and probably wouldn't be able to get the car to go over 20-30 mph.

If the cats are bad - in the sense that they aren't functioning - then the post o2 sensors/sensor, wouldn't fluctuate, it would stay a little too steady. You'd need a scan tool to know if that's happening. I suppose you could you use an infrared thermometer to measure the temps of the exhaust pre and post cats, that would help you determine if they are "working", but it wouldn't be as accurate.

A lean condition could cause problems with your o2 sensors, then again bad 02 sensors could cause a lean condition. And an exhaust leak could also cause your o2 sensors to interpret your engine as lean, when it's really just your exhaust (causing driveability issues).

I'd have someone hook a scan tool up to it and see what's going on. Then I'd like to have them smoke test my exhaust and intake to check for leaks.

 

Hi,
but sometimes the car runs fine. No power loss at all.
Topspeed 260km/h on the autobahn.

Christian

 

Have you seen the price of replacement cats? That's the last thing to change until you've eliminated everything upstream first. Sounds like a trip to the stealer is in order.

 

you can get aftermarket cats for like $100.00

 

Both pre-cat O2 sensors should be replaced by now based on mileage as well as the engine temp sensor. Pre-detonation / and or pinging is more common with carbon issues. All 3 of these sensors can be sending bad readings to the ECU without a CEL. As others mentioned, double check for for vacuum and exhaust leaks.

 

Hi,

the car already went to the dealer twice!
First thought temp sensor,
second thought MAF
Both were not solving the problem.
How could the cats be clogged when the visual inspection looks fine and the car runs perfect in between?
Thinking about deleting the back cats.
Dealer was reading the o2 sensors they work perfectly.

Christian

 

Fuel filter? Not enough fuel equals lean. But I would think the engine would experience knock and get that error code too. <----- All of this is speculation.

 

True, but an LS460 cat is $1300 plus installation.