[decipha]

i did a tune for a gent that can't pass tx emissions


they do 2 speeds for emissions testing in his county

15mph and 25mph

results

25mph (2354 rpm) std / current
hc 120 / 70
co .67 / .5
co2 10.8
o2 5.2
nox 850 / 382
dilution >6 / 11.3

passed all


15mph (1373 rpm)
hc 124 / 158 FAILED
co .69 / .43
co2 11.2
o2 4.8
nox 937 / 475
dilution >6 / 11.6

just barely failed hc



i did some research as emissions testing is all new to me, gotta love new orleans


anyway hc is a measurement of unburnt fuel in the exhaust

possible causes:
over advanced ignition timing :duh:

:coffeespray:


im thinking it may have something to do with the injector timing too as i have it spraying a tad earlier at 1300


anywho, first time it failed because the wrong tune was loaded :headbang: , second time was my fault :sorry: , 3rd time a charm?

don't need history to repeat on this one, looking for advice on how to get it to pass definitely with no hiccups

im thinking about yanking 6 degrees of timing and baising lean a tad while cranking up the injector timing down there

any/all thoughts/tips/suggestions greatly appreciated

thanks in advance

[EDS50]

http://shop.advanceautoparts.com/webapp ... ku=7070191

[FinnCobra]

Is this low emission vehicle with cats, catalysator efficience or temp maybe low? Do they measure lambda ? Apparently vehicle is with smog pump because of big o2. I had large racing catalysator too far from headers in my previous car, and it cooled too much when load was low.

[decipha]

whats up brethren finn !!!

yep it has the smog pump still functional
im not 100% but im pretty sure it must have cats
it was warmed before getting smogged just hopped off the interstate

i did the above in my OP and we shall see

[fkloss]

Yeah we have emissions here in ole Texas .
I did a tune by playing with the maf and changed the curve at the low rpm scale from 800 to around 1800 rpm, leaned it way out and that passed the car and than drove out and switched tune back. I just love the Tweecer for that. LOL!!

[FinnCobra]

In Finland we have emission tests and inspection every year since... I can't remember. It's very common reason for disqualifying inspection.

[DonMaximo]

The tester who tested my Texas car (w/ cats) could not tell me if a Lean condition would have any influence on the tests.

With that said, I'm almost inclined to use this suggestion of getting in there with a LEAN tune... and then switching to my "motor" friendly tune afterwards. Of course, if this works, I keep the tune for the annual inspection.

Yeah we have emissions here in ole Texas .
I did a tune by playing with the maf and changed the curve at the low rpm scale from 800 to around 1800 rpm, leaned it way out and that passed the car and than drove out and switched tune back. I just love the Tweecer for that. LOL!!

[cgrey8]

He couldn't tell you because he didn't know or he couldn't tell you because he couldn't discuss details that would allow you to tune around the test?

[Chucko]

Here's a hare-brained theory for you decipha. Where's the injector timing at the low speed test RPM? Maybe it's just plain unburnt fuel sneaking through during overlap?

[decipha]

inj timing is 380 down there and 440 for the higher revs

[Chucko]

380 would seem to be in the overlap zone for most reasonable cams. Worth a shot anyway.

[DonMaximo]

He didn't know...

I asked a guy at another shop... and the same response.. They did not know.

Here is my Cam Spec

He couldn't tell you because he didn't know or he couldn't tell you because he couldn't discuss details that would allow you to tune around the test?

[Chucko]

That cam spec has 11º of overlap at .050", more at .006" - too bad Comp didn't see fit to document the .006" events.

[cgrey8]

They did...the duration@.006 is 273/282. All the info is there.

All-n-all, that's a very radical cam. It's wide duration and a very narrow LSA which together produces all that overlap and very little manners on the lower RPM range. It would be far more tolerable if the LSA was 112 or 114. But with that wide of a duration combined with a narrow LSA, this is clearly not a low RPM cam at all. I'd be surprised if it would idle smoothly at 800RPMs. The only engines I'd expect this to be installed on are large CIDs (347s or greater) and engines designed for high RPMs.

[DonMaximo]

I continue to appreciate all the feedback being afforded this subject and to Mike for getting it started.

While the cam profile may seem aggressive on paper, I don't know that I'd call it a high RPM cam. This motor dyno'd with a dual-plane intake and carb... and lost steam around 5600 RPM. Even now, on the road, I can feel a sharp decline in power as I cross 6K.

I'm sharing the dyno figures to convey what this motor (with the cam) have produced on a motor dyno.

Another consideration I was making is that this darn Emissions facility enters in the specs for my "stock" 92 5.0L, with stock gears into the testing equipment/computer.

What I really have is a 5.7L motor w/ 373 gears, and to reach the speeds they require on the emissions chassis dyno, in second gear, is resulting in this motor exhaling a larger volumn of exhaust gases than stock. When on the dyno...my LC-1 dash gauge is reporting an almost constant 14.5 AFR...again, kudo's to Mike for dialing me in while I simulated these Slow/High speed tests on the road.

As I mentioned earlier, I am leaning toward going in with a LEAN calibration...because I have failed this test twice so far for higher than allowed HC's.

Any thoughts, ideas, or suggestions are all welcome.

They did...the duration@.006 is 273/282. All the info is there.

All-n-all, that's a very radical cam. It's wide duration and a very narrow LSA which together produces all that overlap and very little manners on the lower RPM range. It would be far more tolerable if the LSA was 112 or 114. But with that wide of a duration combined with a narrow LSA, this is clearly not a low RPM cam at all. I'd be surprised if it would idle smoothly at 800RPMs. The only engines I'd expect this to be installed on are large CIDs (347s or greater) and engines designed for high RPMs.

[decipha]

i say we go in lean 16:1 AFR about 1.09 lamda, kick the injector timing to 500 across the board and run with it

[cgrey8]

If the engine was loosing steam around 5600RPMs with that cam, my knee-jerk thinking is the intake, heads, and/or exhaust were holding you back. The cam wanted the engine to flow more, but if the parts can't do more, that's all you get. All parts have to be sized to work together. A radical cam with undersized heads and/or intake is not going to work as well as those same components with a milder cam.

I can't count otherwise stock 302s that were built back in the day that had a big cam and a Holley 750 cfm double pumper. And every one, the results were less than stellar. BTW, I'm not saying your build is near stock. But there is something limiting the engine's RPMs, and I don't believe it is the cam.

[Chucko]

They did...the duration@.006 is 273/282. All the info is there.

Yeah, the duration is there, but not the open and close events at .006".

But maybe I'm being too picky. :soapbox:

[Chucko]

What I really have is a 5.7L motor w/ 373 gears, and to reach the speeds they require on the emissions chassis dyno, in second gear, is resulting in this motor exhaling a larger volumn of exhaust gases than stock.

That doesn't matter. Their sniffer only reads parts per million, not grams/mile. Which fact is to your benefit.

I suggest bumping up the injector timing so the exhaust valve is closed before you start spraying under test conditions. Hence the importance of those .006" events — not just duration.

[Chucko]

i say we go in lean 16:1 AFR about 1.09 lamda, kick the injector timing to 500 across the board and run with it

A bit radical, but it might get the job done - if it doesn't fail due to high NOx. And if it does, put some fuel back in it.

[cgrey8]

They did...the duration@.006 is 273/282. All the info is there.

Yeah, the duration is there, but not the open and close events at .006".

But maybe I'm being too picky. :soapbox:

I still say all the info you need is given. With the info given, you can calculate the .006" events. But why bother with all that? Let EEC Analyzer do it for you:

CompFW273HR108.jpg

I didn't enter any of the event values, that was all EA. I entered the .006 and .050" duration, valve lift, and Intake/Exhaust centers. But since the Exhaust center wasn't given, I had to trial-n-error the exhaust center value until EA calculated an LSA equal to the cam card.

BTW, the off the seat durations are not unreasonable for a performance cam (for comparison, the E303 is 280/280). Those same lobe lift and durations would make a great cam for any engine that can handle those lifts if the LSA was something closer to 112. If I were putting this in a truck, I'd prefer an LSA of 114. Wider LSA will flatten out the torque curve, but it does limit how high the torque will go. Looking at the cam profile in EA, they've added what looks like about 4° advance to the cam to help recoupe some low end torque the LSA is killing. The only thing I can say negative about the cam is I think the LSA is too narrow for my taste. If it were me recommending an off-the-shelf cam, I'd have suggested this one:

CompFWXE274HR12.jpg

This is a very popular street cam with 347 and 351w engine builders with aftermarket heads. Notice the similarity in both lifts and durations. The only difference is less "built-in" advance and that 112 LSA.

[fkloss]

He ever pass emissions?
Just took mine down today and past better than the old motor with the 5.0.
264 hr comp cam 331.
The 274 is more aggressive but should not lay down until 6200...
The 264 I'm running just keeps going past 6000 but we do not go past that,
So I would check spark,fuel not getting enough? Usually when the rpm slow down possible fuel issues!!

[DonMaximo]

Yes I did pass.

3rd time was a charm ---

Here in Texas there is a Low & High Speed test. For these Fords up and and including 1995 models, they must be put on a Dyno-like machine and a gas probe inserted into tailpipe.

Tests are suppose to be performed while the car is in 2nd gear.

Low Speed: Maintain a speed between 10 & 15 MPH.
If you fall outside of these limits for too long (seconds), test is aborted, must start again

High Speed: Maintain speed between 20 & 25 MPH and keep RPM's < 2500.
This one can be a bitch if you have alot of gear in your rearend.

It's been rumored that using a different gear could help with some setups.

Decipha-Mike is responsible for helping me pass ! So my Thanks goes out to Mike once again !!