skeletor

iTrader: (1)

well just bought a 93 ls400 to daily and it failed emission with flying colors. I already seafoamed the intake and cleaned the egr. thought about retarding timing a bit as well( for the test only) i still have to measure the temps before and after the cats to see if those are acting correctly. thing is i dont have any cel however with just the key in the accessory position the cel is on and doesnt turn off. only when i start the car does it turn off. is it supposed to cycle and shut off with key on engine off? any ways any tips would help this situation thanks cl

test
hydrocarbon read at 2.12 standard is .80
carbon monoxide read at 7.30 standard is 15.00
oxiides of nitrogen read at 4.06 standard is 2.50

PureDrifter

iTrader: (10)

cats are possibly toasted from the way the readings are coming up. But to confirm I would do a full tuneup with plugs, wires, caps, rotors, and confirm all 8 cylinders are firing.


you can't adjust timing like that on a 1UZ.

yes it's supposed to cycle once you actually start the engine. www.lexls.com has a codereading tutorial.

skeletor

iTrader: (1)

Would reading the temp before and after cats confirm a bad one? And with the key on engine off the cel should come on then off correct?

LScowboyLS

you can adjust the timing on a 1UZ, but it is not the simple distributor rotation the OP is probably thinking of in his mind, of course!


No, only a back pressure test can in some cases, but I wouldn't worry about the cats they very rarely go bad in an LS400, it is extremely likely to be something else, such as:

vacuum leak(s) (likely)
manifold leak
leak after MAF in main air tube
EGR malfunction (likely)
ignition or fuel injection systems issue
O2 sensor(s)
failing ECU capacitors
charcoal canister or a leaky purge valve
knock sensor
PCV valve (cheap)
MAF (AFM) sensor

and a few other causes (I got tired of typing - lol)

the CEL should go off after you start the car up for sure!

I would disconnect the negative battery cable for a few hours or overnight, then drive the car for a hour of mixed city. highway, etc., and then download the codes following this easy procedure

post the codes you come up with here in this thread, and we will advise ya from there!

skeletor

iTrader: (1)

http://www.youtube.com/watch?v=tzVe4...ature=youtu.be
i see code 71, egr system malfunction? now what lol?

LScowboyLS

following the troubleshooting steps listed in the service manual here


that code and the resulting bad emissions can be caused by a bad EGR valve, a bad EGR gas temp sensor or a bad engine control module, aka ECM aka ECU

if, after going through the troubleshooting chart step by step, the chart points you to "Check and replace engine control module" (aka ECM or ECU) - then you will need to follow my guide concerning failing ECU capacitors

python

iTrader: (4)

check your vacuum hoses associated with the egr..then check to see if ur getting the proper amount of vacuum with the car running and in gear so u will need a vacuum gauge hooked up while ur driving...I highly doubt its ur ecm

skeletor

iTrader: (1)

Ok still no luck guys egr and vsv check out per fsm. Can't find the egr temp sensor no it isn't under the egr and if it is I'm blind. Is it common to only have a code 71 with the car running. With the accessory position forward I have nothing. The cel isn't even on while driving only when I pin the data plug and turn the vehicle on it reads 71.

skeletor

iTrader: (1)

And isn't the egr electronic? Am I missing a vac source? I see coolant lines going to it but no vac

LScowboyLS

did you miss the post where I sent you the pages of the factory shop manual? - there are pics! (no great ones, but they are there), it shows the EGR temp sensor!

remember, my guide concerning failing ECU capacitors
definitely apples to a 93, one of the more common years for this common issue!

skeletor

iTrader: (1)

There is no temp sensor under the egr I have looked also my egr modulator is on the passenger side I'm assuming 1uz has went thru changes thru out the years

LScowboyLS

I linked you to the 1993 LS400 factory service manual, in post #6 above, do you think Lexus is confused as to whether or not you have an EGR temp sensor??

TRUST ME - you have one!

go reread the manual!

ok, here is a BIG DIAGRAM of your EGR gas temp sensor on 1993 LS400!

skeletor

iTrader: (1)

im assuming its supposed to be here. i also wanted to say thanks for all the help so far lscowboy

LScowboyLS

I cannot tell by your photos, but if the EGR gas temp sensor is missing, that would explain why you are failing the emissions test!

skeletor

iTrader: (1)

You can also click the photo. I did get a chance do break up n clean out the intake passages fully as well