98 AWD, AEM EMS

I have it idling at 1000 rpm (272s). I have the a/f ratio around 14.0 and the timing around 6 degrees.

Should this have me covered?

Your going to want to run it leaner, not richer, and a little bump in base timing tends to clean up HC's to a degree.

Assuming you've got a good cat?

And, you won't really know what needs doing until you get a baseline test complete, but you can probably guess HC's will be your problem area

Paul

I presume that you are refering to "Base Timing" when you say 6 deg.

Like Paul said I would try to go a little leaner and would defenately give it a little more Base Timing.

Now I know that it was with an NT. We are talking about setting up for an e-test here; I ran as much as 12 deg BTDC on my NT. That was only for Lapping days and was with 94 Oct. Thing ran fine with that much Advance.

I would suggest that you set it to 7 or 8, put some good "swill to her" and stay off boost.

Giving it more Timing Advance allows for more burn time and that is what the "little birds like".

Again, you'll find out after you get the test done. Remember that you have the "tool" to tune for whatever would be the flavor of the day.

Keep us in touch.

Ghislain.

No 6 degrees actual advance. The EMS likes very little timing at idle. What does advance does the stock ECU use for idle?

Sorry but I do not understand that question...

Maybe you could compare Timing values (at Idle) with a car that has just past it's e-test.

I'm sure that it should be way more than 6 deg while ideling. Again if that is the case it would not allow for much "burn time".

Ghislain.

Failed.

Idle
HC limit 150 reading 362 FAIL
CO limit 0.70 reading 0.46 PASS

2500 rpm
HC limit 150 reading 97 PASS
CO limit 0.70 reading 1.55 FAIL

For idle the a/f ratio was mid 14s but for 2500 it was mid to high 13s. For idle timing I had it at 14 degrees.

Can someone with a logger tell me what your timing is at during idle?

Advancing the timing seems to make sense but I distinctly remember setting my base timing back to like 0 to get my 92 FWD to pass.

FWIW, I think it idles around 11 or 12deg advance on a 1G.

I think that's why I failed. I have been doing some reading around the web and I keep seeing "retard the timing to bring down the HCs".

I should have left it at 6 degrees

I'll try again tomorrow with less timing at idle and less fuel at 2500.

I'll also throw in some normal heat range plugs and some crap gas to make sure.

Would a new air filter do anything meaningful?

Looks like you are lean at idle and rich at cruise. I wouldnt change too many things at once as you wont know what is making it worse or better.

Crap gas... everybody has their theory on that. I had 94 in mine for my etest.

I can't see the air filter doing much at those rpms, but everything little thing might get your through. The K&N recharge kit is $25ish at Canadian Tire.

You have a brand new cat right? That should clean things up. If you don't have a cat, you are welcome to use my exhaust.

Brand new 3" hi-flow cat.

I think I have a bit of missfire at idle which would lead to more HCs. Does anyone have suggestions of how to tackle missfire? So far I have changed plugs and wires and dropped a bit of 87 octane in the tank (1:4 with 94 octane).

Have you asked around to an "AEM EMS" UBB to see what most do in order to pass emission???

Maybe their is some guru out there with an answer for you.

Ghislain.

I have asked, no answer there yet.

I have the misfire at idle as well. I just prayed it didn't go off to much during test.

I only heard it pop a couple of times which was pretty good.

You might have better success with a Black Top CAS. It sends a "cleaner" signal.

Have you tried one???

Ghislain.

I have not tried a black top CAS (yet;)).

I just failed again.

I put 10L of 87 in and a bottle of some emissions helper fluid. I also changed to the stock heat range plugs (BPR6ES) and swapped the plug wires.

For idle I dropped the timing down to 6 degrees and richened it just a tad to around 13.8:1. It passed both HC and CO%.

For 2500rpm I leaned it way out. During the test the a/f ratio was around 15.3:1 . This created a new problem... lean miss. It was missing every 2 to 3 seconds and so I failed both HC and CO%.

So I will try again leaving the idle alone and richening the 2500 back to around 14:1 or so... as lean as I can get without missfire.

Oh crap. The guy told me the 2500 failed but it looks like it was the idle that failed when I look at the paperwork.

Idle
HC ppm limit 150 reading 301 FAIL
CO% limit 0.70 reading 3.01 FAIL

2500rpm
HC ppm limit 150 reading 64 PASS
CO% limit 0.70 reading 0.26 PASS

Now I am really confused. Idle was smooth and 2500 rpm was missfiring. I figured the 2500 failed too.

Guess I need to lean out the idle again. I have to take even more timing out I guess. I don't know how to drop the HCs in half since 8 degree of timing retard only netted me 60ish reduciton.

I need more ideas.

Where did you read pulling timing out reduces HC's?

Typically, an increase of timing increases heat (and Nox), improves the time the mixture has to burn and reduces HC's.

13.8:1 is way rich for idle, bring that up north of 15:1.

Where's your idle RPM sitting at?

Paul

I read it several places. Something about having the flame front finish burning on the downstroke of the piston allows a greater area for it to burn longer and fuller.

14.5:1 gave me missfires at idle... but after hearing the missfires at 2500 and passing that I no longer am afraid of them . Next try I will have the idle closer to 15:1.

Rpm is sitting at 1050 which netted a real result of 1076. It has to stay below 1250 though in order to pass.

Timing at 2500 was around 20 degrees.

I guess I should also mention that I don't have o2 feedback on so there's no lean/rich oscilations occuring. It's just one value.

I'm hoping leaning the heck out of idle fixes things. Not sure what to do with timing since retarding it seems to have helped HCs but hurt CO%.

Retarding the timing sometimes reduces the temperature inside the chamber as the gas will mostly burn outside and therefore would reduce the NO and maybe other things.

that is what EGR does(reducing temp)

I have now setup the o2 feedback. I'll set it for 15.2 the first time through and see what happens.

I still don't know what timing to use. 6 degrees seemed to help HCs but kill CO%. But it was runnign richer which hurts CO% but should have hurt HCs as well. So maybe there is something to retarding the timing helping HCs.

Maybe I'll go back to 14 degrees, but HCs were way over the limit the first test. Arg .

For reference I have also found several references confirming that advancing the timing increases the NOx emissions. I still haven't found much on what it does to HCs but it makes sense that it would reduce them allowing more time for the mixture to burn. I found one decent page but all it said was "improper ignition timing can lead to high HCs."

Edit
Okay I found this:

"Ignition-Advanced ignition timing will raise HC emissions at idle speed and under light load. Retarding the spark will lower HC and, in many instances, the level of NOx, even if detonation is not present. Ignition timing has no direct effect on CO but can impact it by changing the rpm of the engine and the amount of throttle angle needed to maintain idle speed. A high-energy aftermarket ignition system allows the spark plug to burn for more of the crankshafts rotation, cleaning up the level of HC. Multiple-strike systems also have a positive impact on HC production. Spark-advance curve tuning, by means of adjustable vacuum-advance units and spring kits, is essential for any drive-cycle testing. "

Data point:

idle - 14.7 A/F, 14-16deg timing
2500 - 14.7 A/F, 25-30deg timing

YMMV.

Make sure the cat is good and hot (do some hard 2nd gear pulls and take the test right away).

My car had stock cams though... But if I remember correctly, PPG passed with 272's.

Failed again

So close this time. I ran both idle and 2500 targets at 15.3:1. I ran idle timing of 6 degrees. Timing for 2500 is around 16.

Idle
HC limit 150 reading 165
CO% limit 0.70 reading 0.34

2500
HC limit 150 reading 38
CO% limit 0.70 reading 0.21

Brought HCs at idle from 360 to 300 to 165... so close.

Guess I'll lean idle a bit more. Maybe bump the timing back a little. Guess I'll have to pay to find out if retarding timing helps HCs or not .

I can't just drive it hard then into the test, there always seems to be a car or two in line.

Wow, so close. This is going to end up costing you $140. I'm glad I got through first try!

Is there not an option of paying $150 to keep it on the road for a year but there are stipulations like not selling the car until it passes?

So far it's been $40 + $20 + $20 = $80.

But now it starts over at $40 agaian next test.

I'm pretty sure I will pass next time a little leaner with a little more retard at idle.

Looking at test 1 vs test 2 since the a/f was so much richer in test 2 the CO% went through the roof and you should expect to see higher HCs right? But they actually decreased, which leads me to beleive that's from the reduction of the timing advance. That's the best conclusion I can draw until I test it again.... maybe this afternoon.

There is a $450 limit. If you spend $450 at an approved dealer you will get a conditional pass. They are talking about upping it to $600 soon.

I did find yet another reference saying timing advance hurts NOx and HC emissions:

" 1.Retard the spark timing a bit. From a performance standpoint, many cars respond well to advanced spark timing. Unfortunately, this is not good for either HC or NOx emissions. Retarding the spark timing up to 4 degrees will usually help both. Keep in mind that this trick may hurt CO emissions. "

Passed.

-I put the idle a/f target at 15.5.
-I dropped the timing to 4 degrees
-I upped the rpm to 1075 from 1050 (read 1130 on machine)

Idle
HC limit 150 reading 122
CO limit 0.70 reading 0.34

2500
HC limit 150 reading 38
CO limit 0.70 reading 0.40

Hee haa!!!

Happy for ya.

It's amazing what a little tuning can do.

Ghislain.

Nice! You passed 3 of 4 fairly easily. Way to go Mike.

You want to kill as much timing as possible. Run the tank almost dry and run 87 octane and stay out of boost etc.

Due to the fact higher octane fuel burns slower, without the increased timing or temp to burn it you will end up with a burn with high HC left over.

A trick I used to use on some cars with a knock sensor that will kill timing is run 87 and flog the car pretty good to get the computer to pull ignition timing and get the cat REALLY hot.

This condition pass is only good if you are keeping the car. You can't transfer the car with a conditional emissions test.

The conditional pass is also only good for 1 year, then you have to pass the next. There is no limit the second time around so it's better not to get the conditional. If any one has a modified talon that needs emmisions let me know, I'm an inspector at Trust auto at keele and steeles.

Interestingly enough... one of our board members posted this:


have heard the "rumor" of race gas to help pass an e-test, well today I said what the hell, I had been trying to get an 1994 Astro van for work e-tested and the damn thing would not pass, even with the guaranteed to pass sh!t i the tank etc....

I stopped by Stinson's this morning and picked up a 20L pail of Mark 5 Pro race fuel. The van's tank was almost empty, so I put 15l of race fuel in. Got it nice and hot, and rolled her down to the test shop.

The f*cker passed with flying colors

I was told this only works with Mark 5 fuel.

Only $75 bucks for the pail, that wouldn't even have gotten me an hour's labour at a repair shop.

Nicely done.

The biggest problem people have with the "guaranteed to pass" stuff, is they don't read the instructions.

I used it on my escort. And it worked AWESOME.

My car failed BAD, put that in, did what it said, and passed no problem.

Why dont you guys just get e-tests? you waste all this time and money trying to get it to pass meanwhile you can get the test for $100....

Dominik,
Some of us like to do things the legal, proper way, and don't feel like driving around car spewing out ton's of polution.
People like Mike and others that have children sometimes look at things in a different way as well.
I put on my cat 3 years ago with the intention of pulling it off after I got the e-test, well the test pipe still sits in the garage.

I second Tim, but there's also a bit of a challenge in it for us.

Tim,

while what you said is very true, it is going to be void if Mike changes his tuning at all. If he never changes the setup and keeps the current tuning completely intact, then yeah, otherwise the etest is in reality worthless and not proper per se.


While on this etest thing, What is the most likely cause of high HC? bad cat? that is one category my car was close to fail