pigneguy Posted October 17, 2021 Share Posted October 17, 2021 Having trouble passing Smog. Replaced rotor, cap, wires, plug, o2 sensor, cleaned injectors , new cat etc, figures are way down but mechanic says probably need EGR to get it to pass, except this is a federal car so never had an EGR. only fail is : NO (PPM) 25 mph MAX 609 AVE 265 MEAS 893 Link to comment Share on other sites More sharing options...
jdog Posted October 17, 2021 Share Posted October 17, 2021 Location? 4 or 6 cyl Nox? 2 more posts and the classifieds will open up for you. You can always put your Vin in the registry Link to comment Share on other sites More sharing options...
pigneguy Posted October 18, 2021 Author Share Posted October 18, 2021 Los Angeles, and its a '91 4l straight 6. HO. Link to comment Share on other sites More sharing options...
jdog Posted October 18, 2021 Share Posted October 18, 2021 I didn’t think the ho had a egr any ho guys wanna correct me? Link to comment Share on other sites More sharing options...
fiatslug87 Posted October 18, 2021 Share Posted October 18, 2021 jdog is corrrct, no EGRs in 91 & 92 MJs. Why are you asking for a 90 EGR valve for a 91 HO? Link to comment Share on other sites More sharing options...
jdog Posted October 18, 2021 Share Posted October 18, 2021 Can you post a picture of the smog report? Link to comment Share on other sites More sharing options...
87MJTIM Posted October 18, 2021 Share Posted October 18, 2021 If the vehicle didn’t come from the factory with an EGR, how can DMV require one be installed? Just asking. Link to comment Share on other sites More sharing options...
gogmorgo Posted October 18, 2021 Share Posted October 18, 2021 What did the old spark plugs look like when you pulled them? Badly carbonned up, evidence of running lean maybe? Link to comment Share on other sites More sharing options...
pigneguy Posted October 19, 2021 Author Share Posted October 19, 2021 youre right ,no egr on a '91 here's smog reports: initial gross polluter and last one with new cat. wires, plugs, rotor, cap etc swapped out O2 sensor but purchased a bosch ny mistake, will swap in an NTK this week IMG_1554.HEIC Link to comment Share on other sites More sharing options...
Eagle Posted October 19, 2021 Share Posted October 19, 2021 NOX is related to temperature, isn't it? What thermostat are you running -- and does it work? What spark plugs are you using? Link to comment Share on other sites More sharing options...
pigneguy Posted October 19, 2021 Author Share Posted October 19, 2021 champion plugs RC12LYC Link to comment Share on other sites More sharing options...
Eagle Posted October 19, 2021 Share Posted October 19, 2021 https://janaktech.wordpress.com/2016/02/19/particulate-matter-and-nox-emissions-phenomena-in-engines/ https://www.alentecinc.com/papers/NOx/The formation of NOx_files/The formation of NOx.htm Link to comment Share on other sites More sharing options...
zomeizter Posted October 19, 2021 Share Posted October 19, 2021 change the oil and take it in again... Link to comment Share on other sites More sharing options...
oldmanche Posted October 23, 2021 Share Posted October 23, 2021 Any luck getting it to pass? I'm having the same problem with my '91 - high NO. We had a bad vacuum leak (bent injector rail) but that is fixed along with a bunch of other clean up to vacuum lines and grounds. I can't even remember what we have done at this point. With everything we have done to it to try and pass it runs amazing, especially after we just installed 4 hole injectors these week and taking in in. Link to comment Share on other sites More sharing options...
Inadaze Posted October 24, 2021 Share Posted October 24, 2021 Switch to a 185 thermostat With a spray nozzle on your garden hose clean out the fins on your radiator Make sure your mechanical fan clutch is working fine or just replace it Run 91 octane (can be debated if 91 creates a cooler combustion chamber temperature) Smog it with a 1/4 tank keep the weight down Sea foam your engine and do an oil change Run some fuel injector cleaner through your fuel system Change out your fuel filter Check or change out your fuel injector pressure regulator on the injector rail By your numbers look like you could afford to create a richer A/F ratio Trying to get your computer to create a richer burn, same air, more fuel, lower combustion temps, lower NOx Also Check for a cracked exhaust manifold down at the collector Check the exhaust manifold gasket especially around the #5 and #6 cylinders Any pre cat leak could cause a High NOx situation To check for leaks just pressurize your exhaust system and with a spray bottle with some soapy water spray the gasket and collector areas and look for bubbles (small shop vac works well) Link to comment Share on other sites More sharing options...
oldmanche Posted October 24, 2021 Share Posted October 24, 2021 Well except for the vacuum we have done all of that. We've checked for leaks but not as thorough as that method - will need to give it a try. Link to comment Share on other sites More sharing options...
pigneguy Posted October 26, 2021 Author Share Posted October 26, 2021 On 10/23/2021 at 3:02 PM, oldmanche said: Any luck getting it to pass? I'm having the same problem with my '91 - high NO. We had a bad vacuum leak (bent injector rail) but that is fixed along with a bunch of other clean up to vacuum lines and grounds. I can't even remember what we have done at this point. With everything we have done to it to try and pass it runs amazing, especially after we just installed 4 hole injectors these week and taking in in. no luck, no vacuum leaks, swapped out the bosch O2 sensor for an NTK.....figures barely changed it's frustrating. Link to comment Share on other sites More sharing options...
pigneguy Posted October 26, 2021 Author Share Posted October 26, 2021 On 10/24/2021 at 8:53 AM, Inadaze said: Trying to get your computer to create a richer burn, same air, more fuel, lower combustion temps, lower NOx Mechanic says he can't adjust the timing etc as the computer justs re-adjusts..... how does one "hget the computer to create a richer burn..." under these circumstances ? Link to comment Share on other sites More sharing options...
jdog Posted October 26, 2021 Share Posted October 26, 2021 Does the mechanic have a scan tool to see live data? Link to comment Share on other sites More sharing options...
Inadaze Posted October 26, 2021 Share Posted October 26, 2021 Yes, you are correct, it has no adjustment, that's were the -- Cleaning out your radiator Going to a colder thermostat Cleaning out your injectors or maybe bigger injectors Maybe A colder spark plug 91 octane Make sure the clutch on your fan is working --Comes into play. High combustion temperatures leads to High NOx Ask me how I know. The cooler it runs the richer the computer will try and make it run, like starting it up on a cold morning. Also, check for an exhaust leak! Link to comment Share on other sites More sharing options...
Inadaze Posted October 26, 2021 Share Posted October 26, 2021 pigneguy Did pressurize or did you pull a vacuum on you exhaust system? Link to comment Share on other sites More sharing options...
pigneguy Posted October 26, 2021 Author Share Posted October 26, 2021 PASSED!! Link to comment Share on other sites More sharing options...
fiatslug87 Posted October 26, 2021 Share Posted October 26, 2021 Congrats!!! So, what did you do??? Link to comment Share on other sites More sharing options...
Inadaze Posted October 27, 2021 Share Posted October 27, 2021 Awesome, every 2nd year I always sweat bullets. I forgot to to ask if it was Auto or Manual, RPMs on the 25mph 2305 rpm on the Fail vs 1478 on the pass the lower RPM also could of played a roll in the Pass also. I Love to see these on the road, I have a goal to have as many or more as Fiatslug !!! Hopefully we get one in over at Fairfield PnP, meetup, and tag team it and save a little bit of history Link to comment Share on other sites More sharing options...
pigneguy Posted October 27, 2021 Author Share Posted October 27, 2021 16 hours ago, fiatslug87 said: Congrats!!! So, what did you do??? Smogged cold and kept shop fans on the front. Lower rpms seem to have helped also. Link to comment Share on other sites More sharing options...
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