emissions help- how to lean out

[davs5.0]

trying to get my new combo dialed in for emissions. Ran it through and passed 2 of the 3 gases we test up here.

The problem was my HC (hydrocarbon). the thing is running pig rich right now and I need some ideas on how to lean this thing out for the test.

The new motor is a 331, AFR 185's Emission Legal, AFPR set at 40 lbs (vaccuum off), Autolite 3924's, 30 lb injectors, Edelbrock Performer RPM, no air pump, smog from back of heads run into exhaust, 76 MM C&L with 30 lb sample tube, 65 MM FMS TB, EGR block off plate.

I ran it with the Mac Prochamber just for fun to see what it did. I've got the stock h-pipe with cats and that will go back on for the next test.

How can I take some fuel out of the motor for testing and what kind of timing should I be running for the best emissions? Timing is set at 14 right now.

 

[Swarzkopf]

Turn you fuel pressure down. Run it lean and it'll put out less emissions.

 

[ninety15.0]

Well i dont think its just that easy. turning the FP down might work, but i have heard that the computer just compensates for the decrease in pressure by a longer injector pulse width....and visa versa fir turning the pressure up. I would say that if you throw the stock h pipe back on there it will take care of your hydrocarbon count. also when you take the car to get it tested make sure its nice and warm....your hydrocarbon count will be much higher if the motor is cold. also im not sure but dropping the timing back down to 10* and putting cheaper gas in might also help you out a little bit. good luck man....tell us how it comes out.

 

[davs5.0]

Sounds good so far, will keep you guys informed

 

[Michael Yount]

The lack of air pump is hurting you also -- that supplies excess O2 to the cats, which supports further oxidation of the HC into CO2 and H2O. You might get by by leaning it out - but as you lean it, combustion temps go up and that INCREASES NOx production. Careful.

 

[Swarzkopf]

!!

The computer only compensates so much. You need to have the fuel pressure set in the correct range for the computer to calibrate injector pulse to where it should be.

If you don't believe me, turn your adjustable regulator all the way down and take it for a spin around the block.

 

[ninety15.0]

obviously if there is no FP the car wont run....it will just idle....i have been there too...but i didnt say to turn it down to 0..and i dont think he would ever do that either. if the fp is anywhere within 5-10% of the stock settings...then the computer should be able to adjust for that..good luck man

 

[davs5.0]

Would running a hotter plug help out? Someone suggested that. I'm running autolite 3924's right now.

 

[Michael Yount]

A 'hotter' plug allows the chamber to be hotter; colder plug transfers more heat out of the chamber ultimately into the cooling system. If you run hotter that could help with unburned HC's and CO, but higher chamber temps could increase NOx production. How far under the NOx spec were you?

 

[Michael Yount]

You're seeing the challenge that the designers face - generally the things you do to help with HC and CO hurt you with NOx, and vice-versa. It's takes a balanced approach. Do you still have your air pump that you could put back on and just plumb it up to the cats?

 

[autoXr1]

trying to get my new combo dialed in for emissions. Ran it through and passed 2 of the 3 gases we test up here.

The problem was my HC (hydrocarbon). the thing is running pig rich right now and I need some ideas on how to lean this thing out for the test.

The new motor is a 331, AFR 185's Emission Legal, AFPR set at 40 lbs (vaccuum off), Autolite 3924's, 30 lb injectors, Edelbrock Performer RPM, no air pump, smog from back of heads run into exhaust, 76 MM C&L with 30 lb sample tube, 65 MM FMS TB, EGR block off plate.

I ran it with the Mac Prochamber just for fun to see what it did. I've got the stock h-pipe with cats and that will go back on for the next test.

How can I take some fuel out of the motor for testing and what kind of timing should I be running for the best emissions? Timing is set at 14 right now.

This may explain part of your problem. http://www.mustangworks.com/articles/electronics/InductionBlues.html Timing changes often have insignificant changes in AFR and emissions. It's likely you just need to have the ECU recalibrated for your mods.

 

[davs5.0]

whats involved with recalibrating the ECu. What kind of money are we looking at for something like this.