AdEvod

I have a 1994 Lexus LS400. I've been having performance issues with an engine remanufactured last summer due to a blown rod bearing at 137k miles. The car's performance is suffering greatly as it can't accelerate. I thought it was the cats, according to web research. Both catalytic converters have been replaced but the problem persists. Yesterday, the service advisor stated that codes 41,25,26,71, and 55 were stored in the diagnostic computer.

The codes were cleared however codes 41 and 55 came back. I called the Lexus dealership to inquire about the TPS and the shop foreman recommended cleaning the throttle (plate) body first. I was told by the engine builder today that they do not always clean an engine's throttle body, thus it "may" be dirty. I'm reluctant to pay for more services that may not work however I need to get this car up and running ASAP.

Should I move forward with purchasing the TPS & replacement knock sensors in addition to having the throttle body cleaned or clean the throttle body first and go from there?

Yamae

Before you purchasing the TPS & the knock sensor, I suggest you to check the ECU simply measuring the ripple voltage at the diag connector.

AdEvod

Thanks Yamae. I'll have a friend of mine check it.

python

iTrader: (4)

when u replace ur knock sensors(both of them)..and u will
make sure to get the connectors from the dealer and replace the starter as well...and get a denso starter,assuming it hasn't been replaced.

AdEvod

Thanks Python. The starter was replaced a few weeks ago with an original Denso. To the original question, should the cleaning be completed before buying more parts, which is what the Lexus shop foreman suggested?

This is where I'm stuck. The induction cleaning may solve the issue and it may not....

python

iTrader: (4)

it wont solve the knock sensor issue...u should have replaced the knock sensors when u did the starter

AdEvod

Should have? How would one have known to do that? I'm an insurance advisor, not a mechanic. The issues in the thread were not apparent to the degree that they are now, at the time the starter was replaced. It was presumed that the performance issues were catalytic converter related, and turned out to be something different or in addition to as previously stated.

python

iTrader: (4)

ur knock sensors are about 12 inches from the starter..now ur doing it twice

LScowboyLS

what python means is that these two jobs (knock sensor and pigtails, as well as starter), are a royal pain to replace, a huge labor job, so many people just replace all of it while they are in there.