Help ASAP, emissions testing underway and only a partial pas

[Tim240z]

Ross,

Are they not checking for NOx? If not, richen up the idle a bit. That should do it.

Tim

[jt1]

With about 1/4 tank of gas, dump a gallon of methanol in it. Drive like a maniac on the way to the test and fill it up after the test. Methanol is the active ingredient in the "guaranted to pass" stuff.

 

John

[Mudge]

Denatured alcohol can help, but it will be rough on the fuel system, so use with caution. Never go beyond 10%, at least as a recommendation. Make sure the car is good and hot as well.

 

These are just general guidelines, here is some stuff on emissions:

 

http://www.carprogrammer.com/Z28/PCM/emissions/

 

One or more of the documents will tell you what each item means, and how to change the values by changing either your fuel/timing/running temp or etc

 

Where I live idle RPM is no more than 1250 RPM, so if your truly unlimited bump that sucker up a bit!

[Sumo]

Hey Ross,

Try RXP, it's an emissions reducer and negates oxygenated gas so you have complete burn of the gas. Im not affiliated with them but i have used their product.. A LOT! You can buy these at Autozone or O'Reilly/HI/LO. Although i dont know if they have it there in Canada. Here's the link

 

RXP

[Modern Motorsports Ltd]

I hope all of your and yours had a fine New Years! I'm working to pass my required emissions testing so I can renew my insurance.......your input is most welcome!!

 

OK, it's now time for me to pass our local 'sniffer' emissions tests……based solely on tailpipe emissions: at idle (~30 second test) and at cruise (~30 seconds at 40 km/h (24 mph)).

 

It's my first time running thru with my new Edelbrock Proflo EFI (all notes relative to my typical 'base' program that my car runs fine with). Here's what I reprogrammed prior to my first test today:

 

-retarded overall (global) timing 10 degrees (in the past this gave me far cleaner burn with crap power/but good burn for the test)

-reduced fuel at 12 and 18" of vacuum from 1000-3000rpm by 6% (should cover off cruise test range)

-reduced idle fuel to -6 or -8% (don't recall which)

-left idle target speed at 725rpm (my error, I forgot to raise it for cleaner burn)

 

I then tested and aced the cruise test and miserably failed the idle test. The car was lumpy on idle and rpm was fluctuating +/- 100 or so of target.

 

I then kept most of the above settings but revised idle fuel and rpm upward (thinking this would help as HC was high and CO relatively low), to -2% (above was -6-8%) and rpm to 1000 (but it would only rise to 800 with present physical setting). I then tested again and cruise was same, idle results now in ~1/2 but I still need more and CO is rising….the proflo is harder to set for a very smooth and leaner idle IMO (I could be out on some other setting/idle air control for ie.) and it’s running hot as it goes thru with the proflo sensor locations reading 200degrees for coolant and 120 for air (false positive on air as I know, due to sensor location).

 

For background info, it’s a chevy 350 bottom bottom end/roller top end with ZZ4 camshaft that I’ve passed via carbeuratur tweaking previously. At present I have many header leaks at the header/head interface which should be in my favour……all sniffers are based on ppm or %......so the more ‘non-emissions’ gases I can introduce without triggering their alarms the lower my % of emissions gases they’re sniffing (ie. a per cent balance, not a mass balance). Only HC and CO are monitored for a pass or fail on the idle test.

 

Here’s a summary of my test results: (I’ll include cruise for others reference in their experiences post and future).

 

Driving Pass (1st and 2nd test similar)

HC (ppm) ave. passing reading 63

Vehicle reading 13

Maximum allowable 217

 

CO (%) ave. passing reading 0.48

Vehicle reading 0.36

max. allowable 217

 

IDLE Fail, test1, and test 2

HC (ppm) ave. passing reading n/a

Vehicle reading 1264(test1) 673 (test2)

Maximum allowable 342, 342

 

CO ave. passing reading n/a

Vehicle reading 1.73 3.52

max. allowable 3.90 3.90

 

CO2 and O2 are monitored and results given, but not part of pass or fail (I’ve heard they will fail you if O2 is too high as it’s likely an illegal leak if all else is well)

 

CO2 7.7 to 8.9% during idle test 1

8.5 to 9.7% during idle test 2

 

O2 7.2 to 8.4% during idle test 1

4.5 to 5.3% during idle test 2

 

During the 2nd run I wrote down these parameters from my proflo sensors: idle rpm was 790-860, and fuel input (milliseconds injectors are open) was 4.7-5.4), and vacuum was 16.0-18.0 varying with 10 degrees timing. (in the past I've passed with about 0 degrees to -2 timing at idle….yes -2, seems to give a cleaner burn. With the proflo my base timing is locked in at 10 (ie. I can’t drop it below 10 BTDC without physically moving the dizzy, I can only raise it above 10 which suits all other uses…..it's typically at 25 BTDC with my 'normal' idle with this setup) and I'd rather not physically alter that if I can avoid it.

 

OK, so what’s suggested here??

 

Between 1st and 2nd run I did increase the idle fuel mixture and that seemed to reduce HC but CO has now increased near my upper pass limit. I don't 'think' I altered timing b/t run 1 and 2, but don’t recall as I was running short on gas and it was running quite hot with the settings but A/F wasn't reading 'lean' (but exhaust leaks are obviously affecting O2 sensor). I have to say it's nice to play with buttons rather than screwdrivers/timing gun etc.

 

Items I have done in the past but didn't get to doing today prior to testing are:

-oil change (filters HC's correct?)

-fill up with high octane Mohawk with additives (has less fuel, therefore less emissions to generate per given shot of gas)

-add some methyl hydrate to my tank (not great for the motor, thought I’d see if I can avoid using it now that I have the EFI

 

ALL inputs welcome……..I’m looking fwd to having a combo now nailed down for future testing! (I can save up to 3 different programs in my ECU in addition to the edelbrock base program).

 

I'd like to go thru again this afternoon or tomorrow morning so quick input is most welcome. I'm sure physically raising the rpm will help (screwdriver setting on throttle body to get you in the ballpark and then you use the ECU control to fine tune) to 1000rpm (I believe 1200 rpm is their maximum limit).

 

Thanks! And hail to those who can aid in this repeating situation

 

Hopefully the data reads OK on your screen, I previewed it hear and it seems legible......

___________________

small update, in my 2nd idle test (and first) rpm was only ~800, and I just found out they now have no limit on idle rpm for their tests......so maybe I'll target 1000 or 1050 for my next shot, and perhaps add some 'CRC Guaranteed to Pass' additive?