Emissions part II

[Oldsmobuick]

Oh so close to passing emissions, but failed again!

Help!

Anyone know what fuel pressure setting the 237 regulator should be at? (vacuum line off?) stock injectors

I am searching for a fuel pressure to pass emissions, and my latest adjustments (to 42psi) are ohhh soooo close! I fixed 3 vacuum leaks, and thought I had it.

I am 10/100ths off on NOX.

Also, I now get a code 44 (exhaust lean) after running on the highway for a while and coming to idle at a long red light!

Oxygen sensor?

Anyone have the p/n for GNX Oxygen sensor AC Delco?
I hear the bosch (I have now) is not the way to go!

Opinions?

 

[WarpSpeed]

AFS-20(GM#25162693) is the normal GN one. I think you're right, O2 sensor, my car didn't like the Bosch unit.
Also, make sure your EGR is working.

 

[sam87]

I have the Bosch 237 & stock injectors. For emissions testing, I turn it down as low as it will go and still run ok to drive me to the test facility. Lower than 40psi - maybe 37-39 range. I run 43psi normally.

 

[TurboJim]

Changing the fuel pressire where the BLM's arent at min or max does NOTHING! The ECM will bring the mixture back to 14.8

If you failed NOx, changing mixture wont do much unless you can get it past 16.9:1 where the car becomes over lean and the chamber is cooled from not hot enuf of an explosion. Do you have functioning EGR? Do you have alky injection? Can you set it up to dribble alky in the engine? You need something to cool the chamber, this is the only way to reduce NOx, get the chamber UNDER 2500*.

Maybe try some gauranteed to pass (I think thats alcohol) might lower temps enuf you get you thru. Using higher octane fuel might help, but HC will suffer. Or, have your favorite chip burner try to add more EGR. Maybe that will help.

 

[UNGN]

A stock 237 regulator is non adjustable and will give 45psi line off. If you are adjusting yours it has been modified by someone.

 

[Oldsmobuick]

I have decreased NOX by 17% from my 1st to second test by adjusting fuel pressure up 7psi ???????

However, I brought HC up 91% with the same adjustment.
(Still some room to go!)

Without software, how do I test EGR function and operation?

I bench tested the EGR valve with an EGR tester, and it checks out ok?????

I also installed a new EGR solenoid.

I guess I need a vacuum gauge?

 

[spining 6]

trick?

the old 3 cans of dry gas trick? if your that close.

 

[WarpSpeed]

You know, there's 15 levels/cells of BLMs, and adjusting the fuel pressure requires time for the ecm to adjust through all those levels,, load vs rpm, etc. It may be a coincidence that emissions changed temperarily, however, turning FP down and driving it, then adjusting it up on the test rack may help.
I would check the vac lines to the egr very carefully as they often wear through on the bottom.
Plus, make sure the little check valve in that line is in right,, I think dark side to engine vac.

 

[Oldsmobuick]

Allright folks.....the latest.....

I pull up the EGR plunger and the motor near dies.

Both at idle and accelerator depressed.

Does this mean EGR passages in motor are ok?
I think it does, and that is a good thing, yes?

Also, I carefully removed and checked all vacuum hoses to egr.
Everything is ok, and the check valve is in the right position.

My next step is road test with vacuum gauge on output of EGR solenoid!

When should this thing begin to pull vacuum, and does it steadily increase with throttle acceleration?

Should I include PCV in my testing?