BRAKATK

Hey all,
Its been a while since I was here last, but I have a real problem with my beloved 93 GS300. It only has 107k miles and all major service work at the proper mileage, but for the past few days its been running like its missing, has bad gas or clogged fuel injectors. The crazy thing is it'll run smooth for a few minutes, then run real rough, then fine again...etc. Its worse in the morning/after sitting. At hwy speed, it seems fine. I added some injector cleaner, but that hasn't had any effect over the past 150+miles driven.

I did some searching on this and there was nothing specific enough for our cars. I changed the plug wires as they needed it bad anyhow, but that did not solve it. Any ideas?

Leo

Kaiser

iTrader: (1)

Running lean at idle is a possibility. Check the O2.

BRAKATK

Thanks! I am not a sensor guy-mostly cause I've never had a problem with my motor before. Could you be more specific on the O2? I had my mechanic look it over-there were no codes in the system, he checked plugs, (there is no engine light on). He thought that if a sensor was going, there would be a check engine light on or codes. He was the one who suspected a clogged/faulting injector.

Tammy

Suggest to have you vehicle placed on a good diagnostic machine the can analyze your combustion on all cylinders. It can determine if the problem is lean or rich evenly across all cylinders. If so, I would suspect the O2 sensors in the exhaust manifolds. They can be on the verge of failure, without triggering an error in the "on board diagnostics".

BRAKATK

Tammy-Are the sensors in the engine compartment or are they further in the exhaust system, like under the car? The reason I ask is that I ran over a plastic bag a few weeks back and discovered that it stuck under my car and melted on my catalytic converter and other parts of the exhaust. COuld that have damaged my O2 sensors? Just worth asking.

Are the diagnostic machines you mention only at Lexus Dealers? Will any dyno shop do?

Thanks!

Tammy

There is an emission sensor just before the catalytic converter, mounted in the down pipe. Insure the bag didn't break it's wire leading into the passenger compartment.

Additionally, there are two total O2 (fuel-air mixture) sensors, located in each of the exhaust manifolds.

The machines that come to mind are the large Sun or Snap-On analysis machines. The better repair shops have them. You might call around your area.

BRAKATK

Had another import mechanic take a closer look. Turned out the #6 cylinder was not firing correctly as the spark plug "cone" near the gap was cracked! Replaced the plug and she is purring like new again!

Told first mechanic I went to he has been replaced.