Soft Pedal Surge - '98 Es300

[Fast Eddy]

My ES300 with 130K mi has stumped a Toyota master diagnostic tech who spent 1.5 hr and couldn't id the problem. Any help?

The problem:

There is a surging at 1500 RPM in all gears (inluding locking the trans in low) with/without A/C, with a soft touch to the gas pedal. The problem is intermittant and only after the engine is fully warmed at full temperature. There are no error codes and no check engine light.

I have changed:

Spark Plugs

Coil Packs

Plug Wires

Throtle Position Sensor - TPS

Mass Air Flow Sensor - MAF

Direct Clutch Speed Sensor

The Throttle body has been serviced. The problem remains unchanged and intermittant. I have run two tanks of fuel system cleaner, no help.

Every tech tells me it is something different. I've been told:

Clean fuel tank & lines - $350

Fuel filter - most think not

Service Fuel Injectors

It is a vacuum leak, do a smoke test (Techs have told me that leaks always set an error code)

It is the transmission

It is the torque converter

O2 Sensor problem - I've been told doesn't need to set an error code

ECM or PCM computer problem

I could run out of money before I fix this. Any help??

[Fast Eddy]

Problem Found - It was the EGR valve. I removed the vacuum input and plugged it with a "golf T" and the surging stopped.

The good news is that it should be fixed by the dealer for free. I have a letter that Lexus sent to customers with 1996 through 1998 models announcing an enhanced (extended) warranty for 1996 through 1998 models covering the emission control system for 150K mi and 14 yr.

[beach109]

That was quick--glad you found it. Knowing it with other vehicles (such as my current), a bad EGR can cause quite a bit of things. And, at least, no just throwing parts and money at it as best guesses.

Any idea what all is covered or how with that extra emissions extension on '96-98s? Only curious, as I've randomly started looking at a '97 and some other ES's.

[mburnickas]

Bad EGR;s are very common on these years. I had mine go at 70K and I need to remove mine and clean it..

Since you have 139K you are lucky and I would clean TB, Ivac and intake soon; if you have not. I suggest Amsoil Power foam since it blows the doors off of the beloved seafoam, distilled water, B12 chemtool etc.

[Fast Eddy]

Problem Found - It was the EGR valve. I removed the vacuum input and plugged it with a "golf T" and the surging stopped.

The good news is that it should be fixed by the dealer for free. I have a letter that Lexus sent to customers with 1996 through 1998 models announcing an enhanced (extended) warranty for 1996 through 1998 models covering the emission control system for 150K mi and 14 yr.

It covers the evaporative storge canister, evaporative system pressure sensor, fuel cap, fuel tank, fuel tank filler neck, purge valve, tank vapor vent line, three-way valve, and any other part or component, excluding any maintenance parts, between the fuel tank and the intake manifold (but not including the intake manifold) designed to contain or conduct fuel vapor from the fuel system.