93 sc400 smog please help !!!!
09-04-12, 12:07 AM
#1
Rookie
Thread Starter
93 sc400 smog please help !!!!
Hi Forums...
I know this topic if off topic.... But I'm seriously in need for answers before smog. I recently complete my 4.0 V8 swap on a SC400.... I failed on 15mph with extemely high HC and CO with real low NOx and at 25mph I failed HC by just a tad.... Just wondering, if I reverse the vacuum line on a purge valve, will it give me the numbers as stated or numbers on the bottom image... I double check the line from canister to purge and seem like it was reverse. After I switch the line around, I don't have the hesitation from complete stop to acceleration..... Please help...
Recent done:
1) Complete tune up with NGK Spark Plugs, Cap and rotors, PCV, waterpump, tensioner, and timing belt. Timing is on point and ignition system is good. No fuel leak or intake leak. Don't believe it's the catalytic converter because low NOx. I'm going to clean the throttle body tomorrow and replace the air filter
Uploaded with ImageShack.us
I know this topic if off topic.... But I'm seriously in need for answers before smog. I recently complete my 4.0 V8 swap on a SC400.... I failed on 15mph with extemely high HC and CO with real low NOx and at 25mph I failed HC by just a tad.... Just wondering, if I reverse the vacuum line on a purge valve, will it give me the numbers as stated or numbers on the bottom image... I double check the line from canister to purge and seem like it was reverse. After I switch the line around, I don't have the hesitation from complete stop to acceleration..... Please help...
Recent done:
1) Complete tune up with NGK Spark Plugs, Cap and rotors, PCV, waterpump, tensioner, and timing belt. Timing is on point and ignition system is good. No fuel leak or intake leak. Don't believe it's the catalytic converter because low NOx. I'm going to clean the throttle body tomorrow and replace the air filter
Uploaded with ImageShack.us
09-04-12, 02:09 PM
#2
I would have to go with catalytic converters or your o2 sensors are completely shot.
What makes you think its still good at 190,000 miles? have you replaced it before?
Did you use the exhaust manifold and cats from your new engine or your old engine?
just cause you have low nox doesn't mean your cat is good.
nox is related to combustion temps and usually varies with ignition timing.
seeing as the ignition timing is not adjustable on an sc400 I would say you are probably ok there, and the numbers reflect that.
from that chart, I would have to say it runs good, but nothing is getting converted at all or it is simply running way too rich.
For your 15mph test, your cat may have not been warmed up enough, but even when it was at the 25mph it wasn't up to par.
What makes you think its still good at 190,000 miles? have you replaced it before?
Did you use the exhaust manifold and cats from your new engine or your old engine?
just cause you have low nox doesn't mean your cat is good.
nox is related to combustion temps and usually varies with ignition timing.
seeing as the ignition timing is not adjustable on an sc400 I would say you are probably ok there, and the numbers reflect that.
from that chart, I would have to say it runs good, but nothing is getting converted at all or it is simply running way too rich.
For your 15mph test, your cat may have not been warmed up enough, but even when it was at the 25mph it wasn't up to par.
Last edited by Ali SC3; 09-04-12 at 02:13 PM.
09-05-12, 02:03 PM
#3
Rookie
Thread Starter
"I would have to go with catalytic converters or your o2 sensors are completely shot.
What makes you think its still good at 190,000 miles? have you replaced it before?
Did you use the exhaust manifold and cats from your new engine or your old engine?
just cause you have low nox doesn't mean your cat is good.
nox is related to combustion temps and usually varies with ignition timing.
seeing as the ignition timing is not adjustable on an sc400 I would say you are probably ok there, and the numbers reflect that.
from that chart, I would have to say it runs good, but nothing is getting converted at all or it is simply running way too rich.
For your 15mph test, your cat may have not been warmed up enough, but even when it was at the 25mph it wasn't up to par.
__________________
ALI SC3: I recently just put in a used JDM motor (unknown mileage) even though they say below 40k. Checked compression and leak down test.. Everything came out ok. I think I just might need to save up some money for some new cats. Any advice where I can get it for cheap (California Legal)
I spend couple hours on the car yesterday.... Finally felt a misfire, therefore I rechecked all the spark plug wires and finding out that L/S Bank spark plug wire from distributor cap to coil pack was shorting out to the head. Therefore, I replaced the wires set with new one cleaned throttle body, air filter, rechecked timing, test 02 sensors (ok). Brought it to the SMOG today.. Here's my result: Any advice will be great
Uploaded with ImageShack.us
What makes you think its still good at 190,000 miles? have you replaced it before?
Did you use the exhaust manifold and cats from your new engine or your old engine?
just cause you have low nox doesn't mean your cat is good.
nox is related to combustion temps and usually varies with ignition timing.
seeing as the ignition timing is not adjustable on an sc400 I would say you are probably ok there, and the numbers reflect that.
from that chart, I would have to say it runs good, but nothing is getting converted at all or it is simply running way too rich.
For your 15mph test, your cat may have not been warmed up enough, but even when it was at the 25mph it wasn't up to par.
__________________
ALI SC3: I recently just put in a used JDM motor (unknown mileage) even though they say below 40k. Checked compression and leak down test.. Everything came out ok. I think I just might need to save up some money for some new cats. Any advice where I can get it for cheap (California Legal)
I spend couple hours on the car yesterday.... Finally felt a misfire, therefore I rechecked all the spark plug wires and finding out that L/S Bank spark plug wire from distributor cap to coil pack was shorting out to the head. Therefore, I replaced the wires set with new one cleaned throttle body, air filter, rechecked timing, test 02 sensors (ok). Brought it to the SMOG today.. Here's my result: Any advice will be great
Uploaded with ImageShack.us
Last edited by MikesLexo; 09-05-12 at 02:12 PM.
09-07-12, 12:52 AM
#4
Rookie
Thread Starter
Okay, today i jack up the car and retest 02 sensors upstream. It fluctuate between .100 to .600 at idle.... At 2500rpm it will fluctuate between .200-.800..... I unplug one of the vacuum to see how's the 02 sensor will respond which it went to 50mv-100mv and when I plug it back in. It will go right back up to 800-900mv for 1-2 seconds and will fluctuate between 200mv-800mv Meaning it's reacting like it should for both upstream... Down streams stays about 500mv
Almost seems like something making my 02s to run rich. Checked fuel injectors: Reading about 13.8-14.0 ohms (Specs:13.8 ohms).. Therefore, I checked the ECTS finding out that there's no ohms across the pin. Removed the ects and found out it was crack between the plug to the unit.
Questions:
1) Even though it's obd1, shouldn't it have thrown a code for open circuit at ECTS or something
2) Since open circuit ECTS will keep system in Open Loop (Extremely rich & longer than normal injector pulse): Will it gives me the reading above?
3) On OBD1 system: How can I find out is it in closed loop system?
Almost seems like something making my 02s to run rich. Checked fuel injectors: Reading about 13.8-14.0 ohms (Specs:13.8 ohms).. Therefore, I checked the ECTS finding out that there's no ohms across the pin. Removed the ects and found out it was crack between the plug to the unit.
Questions:
1) Even though it's obd1, shouldn't it have thrown a code for open circuit at ECTS or something
2) Since open circuit ECTS will keep system in Open Loop (Extremely rich & longer than normal injector pulse): Will it gives me the reading above?
3) On OBD1 system: How can I find out is it in closed loop system?
12-30-12, 06:12 PM
#5
Driver School Candidate
Join Date: Sep 2007
Location: MA
Posts: 20
Likes: 0
Received 0 Likes
on
0 Posts
If you do the self diagnostic for transmission and engine do you see error codes ?
I'm at +300k on original Cal-spec 94 Sc400, passed smog on original cats. car gets regular tube ups...
I'm at +300k on original Cal-spec 94 Sc400, passed smog on original cats. car gets regular tube ups...
Thread
Thread Starter
Forum
Replies
Last Post
