Tripletsix

Ok guys I have been continuosly trying to improve my emission due to CA smog. I have done almost everything I can think of what to bring the NoX down. My HC and CO are fine. My car runs smooth, idles smooth, and idles at the right RPM. It's a 5 speed manual, 259K miles there is no EGR on this engine. No CEL also.

As you see I'm failing at 15mph but passing 25mph in NoX I don't understand why its running lean.


I've checked my ignition timing 12 BTDC, Throttle body sensor(functioning/backprobed), fuel pressure from fuel line is 60psi(before the fuel filter and with engine off) the fuel filter has been replaced two years ago; fuel injectors are 12.5 ohms as they should be; Checked for outside vacuum leaks with carb cleaner spray(haven't ran vacuum gauge to it yet...) Not too sure about my map sensor since it's reading at 4.83V(while the engine off) also to note that this is tested through two wires from the connector and also the power from connector to the battery.

Things I've done/replaced for the last two months...
Intake manifold gasket
Throttle Body gasket
PCV (even old one was still clicking)
2 O2 sensors (Bosch)
Catalytic converter(CA legal)
Battery (since it was 4 years old)
Cleaned the ground wires and put copper shields on the grounds(little overkill but securing my peace of mind)
New (NGK)sparkplugs and wires
New cap and rotor
Seafoamed it 1 time
Lucas fuel treatment injector cleaner 5 times(injectors looks clean from the tip POV)
Been running Chevron 91 octane fuel
*********

I have an OBD2 hookup to laptop but don't really understand much of anything besides O2 sensors voltage. If you'd like to see my overall data I'll post that if it helps to understand.

First time I got it smogged two months ago failed by visual but after that its been failing on emissions I've been taking it to the smog place atleast 10 times now.

DieMaster

iTrader: (1)

things that catch my eye are:

60 psi fuel pressure seems a bit high. shouldn't it be around 40 (rob?)

5.05 v at the map sensor isnt right. one wire should read that constantly, one ground or 0v constantly, and the last one should fluctuate when you quickly tap the gas. that last wire is the actual signal. the other 2 are power to the sensor.

91 octane fuel is kinda high for a stock motor. use what the user manual recommends. (i think it's no lower than 86.)

hope this helps.

Tripletsix

The 60 psi before fuel filter, I haven't tested it after the fuel filter. I wasn't sure if that'd be the same after the filter. The Del sol manual from dealership says, it is 40-47 psi after fuel filter. I was skeptical seeing it being so high... however could that mess up the regulator to cause a drop in fuel pressure drastically basically leaning the engine?

The map sensor is actually at 4.83V with engine off.

And I wasn't sure if octane ratings really do affect combustion temperature

famous323

iTrader: (9)

Had the same problem my fan was intermittently working , also air in coolant system , I replaced faulty fan switch and bleed the air out passed with flying colors

Tripletsix

How long does the fan have stay running? I notice my fan runs for like 5 seconds then it shuts off and does it again in another minute or two it doesn't stay running more than 5 seconds.... It's at operating temperature idling (220° through OBD2 via laptop). The radiator is topped off with 50/50 coolant should be no air in it left.

famous323

iTrader: (9)

Not really a matter of how long but how quickly it kicks on , mines wouldn't even kick on when the engine is warmed up, it comes on about 45minutes later , your fan sounds like it's running good. Car idles fine ? No vaccum leaks ?

Former User

The engine is running lean, which is causing the high NOx. Fill tank with 87 octane fuel. Replace the fuel filter and then go from there.

Tripletsix

My time is limited I will do the correct pressure check and new fuel filter I will be getting back to you guys by saturday after I smog it. Thanks for everyone posting and taking your time for me.

Tripletsix

Okay guys and for you Ron as well. I passed the emissions! There could be 4 different variables of why it was running high on NOx...




I've replaced the fuel filter from Wix(2 years old) to a Duralast. I've did the correct methodical testing procedure with a banjo adapter too pressure gauge and this time it's after fuel filter got readings of 44-45 psi without regulator vacuum line attached; 33-34 psi reading while vacuum line is connected.

Coolant reservoir was basically empty however the radiator was topped off anyhow stupid as I was it could have possibly made my NOx go up. But it strikes me and now it makes total sense that the coolant temperature sensor is only there to tell me the average cooling temperature from temperature gauge not if there are any hot spots.

Third, of the nit picking was my very recent(3 weeks old) O2 sensors were Bosch. I've replaced it with a new set of two NTK O2 sensors after researching they're more sensitive in readings (and OEM equivalent).

Last of all my ignition coil died and had replaced it with Accel coil. Because I was cranking the engine for dry and wet compression to see how well my rings and cylinder bore walls are doing. I've been cranking the engine too many times since my sparkplugs were getting excessively soaked with engine oil. Took me almost five times to get them dried up. I've only used a tablespoon of oil as the book says 1 tablespoon of oil. And I was very particular with measuring it with a measuring tool like making homemade food measuring ingredients.

What could be the culprit I ask???
Thank you all for your time.

DieMaster

iTrader: (1)

glad you got it passed. i never use Bosch anymore unless im not going to drive it very much or going to sell it. my moneys on the O2 sensors.