failed emission help
#1
failed emission help
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
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
#2
BahHumBug
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.
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.
#4
Lexus Champion
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!
Would reading the temp before and after cats confirm a bad one?
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)
And with the key on engine off the cel should come on then off correct?
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!
#6
Lexus Champion
http://www.youtube.com/watch?v=tzVe4...ature=youtu.be
i see code 71, egr system malfunction? now what lol?
i see code 71, egr system malfunction? now what lol?
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
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#8
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.
#10
Lexus Champion
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!
remember, my guide concerning failing ECU capacitors
definitely apples to a 93, one of the more common years for this common issue!
#12
Lexus Champion
TRUST ME - you have one!
go reread the manual!
ok, here is a BIG DIAGRAM of your EGR gas temp sensor on 1993 LS400!
Last edited by LScowboyLS; 09-10-13 at 09:48 PM.