Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Go Back   Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum > General > Tech Talk > S Chassis

S Chassis Technical discussion related to the S Chassis such as the S12, S13, S14, and S15.


Reply
 
Thread Tools Display Modes
Old 03-07-2019, 04:01 AM   #1
Lehr98
 
Join Date: Apr 2018
Location: CA
Age: 26
Posts: 19
Trader Rating: (0)
Lehr98 is a well-known jackass
Feedback Score: 0 reviews
KA Cali smog help

I’m trying to make my s13 coupe pass smog. Here are my results. https://imgur.com/gallery/PISIBhy I am planning on using seafoam, replacing cat and charcoal cannister, try to clean the egr and bpt. Is there anything else you guys recommend?
Lehr98 is offline   Reply With Quote
Sponsored Links
Old 03-07-2019, 07:31 AM   #2
jedi03
Nissanaholic!
 
Join Date: Jul 2008
Location: albuquerque
Posts: 1,836
Trader Rating: (8)
jedi03 is on a distinguished road
Feedback Score: 8 reviews
fresh fuel, run it for at least 15 min before testing, fresh oil change, new spark plugs/wires, that's all i can think of for now...
jedi03 is offline   Reply With Quote
Old 03-07-2019, 08:01 PM   #3
240sxTuck
 
240sxTuck's Avatar
 
Join Date: Sep 2016
Location: Sonoma County, CA
Age: 29
Posts: 18
Trader Rating: (0)
240sxTuck is an unknown quantity at this point
Feedback Score: 0 reviews
Not as bad as mine, lol. Gross Polluter all across the board! I just got mine done hot, which is pricey, but easy to do. I plan on passing legit next time i need to smog it.

Cat should be the last thing you replace. I would start small. Go ahead and seafoam it (probably gonna wanna change your spark plugs afterwards). Check for vacuum leaks. Make sure all your solenoids are hooked up right, and working (EGR, SCV, AIV). Make sure it's timed and idling correctly (20 degrees BTDC, 700 +/- 50 RPM). Make sure there are no exhaust leaks. Check for EGR, BPT, AIV, and SCV function. If all that checks out, replace the cannister.

I'm no expert at all, but your results makes me think there's something wrong with your valves or timing (assuming everything else i mentioned is working). Check valve lash, and make sure they're all seating properly. I would also do a compression test on all 4 cylinders. It can tell you if you have a bent valve, or if they're opening early. It might also be a good idea to check your injectors, make sure they're not staying on too long. It's bizarre to me that your HC and CO are fine on the low speed test, but GP on the high speed test, and your NOx is the opposite. What was your CO2% for each test? High amounts of HC and CO means there's not enough heat to burn off all the fuel in the cylinder, and won't produce a lot of CO2. High NOx can mean there's too much heat in the cylinder.

It would also help to know how well the engine runs. is it smooth or rough? are their any RPM ranges where it starts performing poorly?
240sxTuck is offline   Reply With Quote
Old 03-08-2019, 12:43 PM   #4
banandana
 
Join Date: Oct 2017
Location: CA
Posts: 9
Trader Rating: (0)
banandana is on a distinguished road
Feedback Score: 0 reviews
Quote:
Originally Posted by 240sxTuck View Post
Not as bad as mine, lol. Gross Polluter all across the board! I just got mine done hot, which is pricey, but easy to do. I plan on passing legit next time i need to smog it.

Cat should be the last thing you replace. I would start small. Go ahead and seafoam it (probably gonna wanna change your spark plugs afterwards). Check for vacuum leaks. Make sure all your solenoids are hooked up right, and working (EGR, SCV, AIV). Make sure it's timed and idling correctly (20 degrees BTDC, 700 +/- 50 RPM). Make sure there are no exhaust leaks. Check for EGR, BPT, AIV, and SCV function. If all that checks out, replace the cannister.

I'm no expert at all, but your results makes me think there's something wrong with your valves or timing (assuming everything else i mentioned is working). Check valve lash, and make sure they're all seating properly. I would also do a compression test on all 4 cylinders. It can tell you if you have a bent valve, or if they're opening early. It might also be a good idea to check your injectors, make sure they're not staying on too long. It's bizarre to me that your HC and CO are fine on the low speed test, but GP on the high speed test, and your NOx is the opposite. What was your CO2% for each test? High amounts of HC and CO means there's not enough heat to burn off all the fuel in the cylinder, and won't produce a lot of CO2. High NOx can mean there's too much heat in the cylinder.

It would also help to know how well the engine runs. is it smooth or rough? are their any RPM ranges where it starts performing poorly?
PS california allows +/- 3 degrees of ignition timing from factory spec or you will fail smog.

I've heard adjusting the idle to just below 1000rpm will help in some cases with emissions when testing. Something around 1100 is the limit afaik

Check the ECU diagnostics mode to see if the o2 sensor is reading rich or lean; it'll tell you if the ECU is trying to trim fuel up or down. Replace the o2 sensor if it's old. Check for unmetered air.
banandana is offline   Reply With Quote
Old 03-09-2019, 11:57 PM   #5
240sxTuck
 
240sxTuck's Avatar
 
Join Date: Sep 2016
Location: Sonoma County, CA
Age: 29
Posts: 18
Trader Rating: (0)
240sxTuck is an unknown quantity at this point
Feedback Score: 0 reviews
Quote:
Originally Posted by banandana View Post
PS california allows +/- 3 degrees of ignition timing from factory spec or you will fail smog.

I've heard adjusting the idle to just below 1000rpm will help in some cases with emissions when testing. Something around 1100 is the limit afaik

Check the ECU diagnostics mode to see if the o2 sensor is reading rich or lean; it'll tell you if the ECU is trying to trim fuel up or down. Replace the o2 sensor if it's old. Check for unmetered air.
TBH, the O2 sensor won't tell you much unless you're looking at a oscilloscope. Gotta see it in the graph to really get a decent understanding of what's going on, otherwise it's just a bunch of meaningless flashes on the dash
240sxTuck is offline   Reply With Quote
Old 03-10-2019, 04:35 PM   #6
banandana
 
Join Date: Oct 2017
Location: CA
Posts: 9
Trader Rating: (0)
banandana is on a distinguished road
Feedback Score: 0 reviews
Quote:
Originally Posted by 240sxTuck View Post
TBH, the O2 sensor won't tell you much unless you're looking at a oscilloscope. Gotta see it in the graph to really get a decent understanding of what's going on, otherwise it's just a bunch of meaningless flashes on the dash
The information in the full service manual will show you how to put the car into a diagnostics mode which flashes 2 LEDs on the ECU depending on it running 5%+ rich or lean, or within spec. Just using the dash light won't get you anywhere
banandana is offline   Reply With Quote
Reply

Bookmarks


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 11:22 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
vB.Sponsors
Copyright ? 1998 - 2022, Zilvia.net