Emissions saga and a home test for idle setting/tuning tip

[Zed Head]

I just got my car checked for emissions again so that I can renew my tags.  We're on a two year cycle here so that gives plenty of time to mess around and get it screwed up .  I had my car running greatly and went straight to the emissions check station without doing anything to help it pass.  It failed, of course, so I spent the next few hours dinking around with the idle air bypass and my fuel pressure and failed three more times.  So I went home and realized that I was using my MSA AFM that I had bought new nine+ years ago and that it had always run rich.  I don't know why, it just does.  No matter how far I back out the idle air bypass I couldn't get it to lean out.  I pondered drilling out the bypass passage to let more air past the blade but it's not an easy operation.  So I pulled my last old AFM down from the shelf, an original 75/76 AFM, and installed it.  Then I leaned out the idle air bypass until removing the oil filler cap caused it to stumble to barely running.  I went back to the test center the next day and passed on the first shot through.

I realized as I was tuning that I could remove my oil filler cap and the engine would not stumble, when I had bad results.  I had forgotten about that basic "running rich" test.  Even though it was not noticeably rich, it wouldn't pass, and I could leave the cap off with no problems.

Anyway, the short story is that if you can remove your oil filler cap and your 280Z doesn't notice, you're probably going to fail the idle emissions test.  So that's the tuning tip.  If you're in CA with the 2500 RPM requirement the same test might still help.

And even though I could leave the filler cap off, it still only failed CO.  Not HC.  It was very close.

 

[rcb280z]

13 minutes ago, Zed Head said:

MSA AFM that I had bought new nine+ years ago and that it had always run rich

I have one that runs rich(er) from MSA also. I don't use it though. I forget were I got the one I am currently using. I have one that is adjusted to pass smog with. I swap it out for one that my 280 likes until it's time for emissions testing.

We have rolling dyno tests done here. One at 15 mph and one at 25 mph. Along with the idle test.

[Zed Head]

I sent you one a couple of years ago.  I was wishing I hadn't yesterday.    But the one I had left did the job.  I'm going to leave it on and the MSA will be my emergency AFM, on the shelf.

I wonder how they set those reman AFM's.  Maybe they have the wrong calibration settings at Fuel Injection Corp.  I was told that the FIC remans had a thicker and more durable carbon trace.  But it doesn't help much if they won't pass emissions.

Not clear if they actually run air through them or just set mechanical settings and assume that they will work right.

https://fuelinjectioncorp.com/products/air-flow-meters/

@Joseph@TheZStore

@James@TheZStore

[rcb280z]

3 minutes ago, Zed Head said:

I sent you one a couple of years ago.

That's what I thought. But I still don't pass with it either and I didn't want to mess with it. The 280 likes it.

And that's funny, I wonder if the one I tweak to pass emissions is an MSA one. 

[Zed Head]

3 hours ago, rcb280z said:

And that's funny, I wonder if the one I tweak to pass emissions is an MSA one. 

That would be good to know.  Should have the blue Fuel Injection Corp. sticker on it.  No Nissan stickers.

[Zed Head]

Any chance you could check the label on your other AFM?  I'm curious.  I notified the MSA guys, thinking that we had two rich MSA AFM's.

@rcb280z

[mbz]

21 hours ago, Zed Head said:

I had forgotten about that basic "running rich" test.

You're welcome! ?

Edited April 5, 2019 by mbz

[rcb280z]

On 4/5/2019 at 12:43 PM, Zed Head said:

Any chance you could check the label on your other AFM?  I'm curious.  I notified the MSA guys, thinking that we had two rich MSA AFM's.

@rcb280z

Sorry for late response, just getting back into town.

There is no label on it.

On 4/4/2019 at 9:09 PM, Zed Head said:

Should have the blue Fuel Injection Corp. sticker on it. 

Neither of the 2 AFM's I bought from MSA have any type of identification.

I will verify as soon as I can.

[rcb280z]

Okay, I was thinking of a different AFM Zed Head. So ignore previous post.

The one from MSA does have a label. A31-604-000 on the box and AFM.

 

[Zed Head]

1 hour ago, rcb280z said:

Okay, I was thinking of a different AFM Zed Head. So ignore previous post.

The one from MSA does have a label. A31-604-000 on the box and AFM.

But does it run rich?

[rcb280z]

2 hours ago, Zed Head said:

But does it run rich?

Yes

I've been in it to adj. the clock spring CW to lean it a little. IIRC about 2 teeth is all it needed.

Edited April 8, 2019 by rcb280z
added content

[Zed Head]

Thanks, good for everyone to know.  Maybe I'll send Fuel Injection Corp. an email if I get time.  I've never liked that AFM for passing emissions, it's never worked, except for when I had the original set of clogged injectors on my car.  It worked great otherwise but might also explain my typical 18-19 mpg.