Unmetered Air leak = Better MPG???

[Tygen1]

Good Job Moorecomp! That totally makes sence, a venturi needs flow.

[Tygen1]

I'm resurecting this old thread because I've installed a Wideband to see what's really going on. I've had a lot of projects sidetrack me from working on the car, but this I really wanted to follow up on.
I got a LC-1 wideband from Innovate with a nice digital display. I've only done one test drive to the grocery store and back, but the results were not what I was expecting... AFR is ocilating between 13.5-14.5, which I presume is the normal AFR, so no lean burn. Even WOT is 13:1, just as it should be. So it seems the PCM was able to compensate even though the fuel trims are maxed, the term "max" must not indicate it can not compensate any more, just that it has crossed some sort of threashold to set of an SES light.

So where did the gains come from??? I will reconect the vacuum leak after I fill up this tank so I can see what's going on. I've been driving with the vacuum leak since I started this thread, and my last few tanks have been real consistant. I have a pretty good feel for how the car is performing mpg wise, so I should be able to detect any differences pretty quickly.

[Phantom]

Did you make sure to calibrate the Wideband before the test?

Looking at the pics you posted a few pages I can see that the back portion is capped (see post 40) that is for running cruse ect. Try capping the pipe end and then hooking the currently capped part to the intake. Also have you tried capping the line off as it is now to see if you have any issues such as soft breaks at low speed ect?

[moorecomp]

I still have my air line disconnected, and I have never gotten an SES light. It was disconnected with a restrictor in the end of the hose, but I removed that and have been running it wide open since November of last year. I do not have the fitting capped as you do, and I do not have a filter on the line as you do. Runs great, idles great and I got several commutes last week over 44 mpg's. I don't have any knocking or hesitation, I don't know why it works, but it just does. BTW, the brakes have never been soft and the vacuum on the ZX2 stores a lot in reserve, I can do 6 full applications before running out of vacuum when EOC.

[Tygen1]

I did the calibration as per Innovates directions, it was easy. Now that I have reset the PCM, reconected the line and driven it 80+ miles, it seems to be trying to hit 14.7:1 when under a load. When I am feathering the throttle down hill, it goes to 13-13.5:1, so there is a tremendous amount of oppertunity here. I've also noticed that the idle AFR is 13:1, but in gear is goes to 14.7:1, although the increased load makes it a wash and the gph stays about the same. Overall, it seems to be acting the same with and without the line conected.

This mornings commute was all messed up with the PCM relearning and some bad traffic. However this evenings commute was pretty much on par with what I've been seeing, 45-47mpg in the evenings. This week will be a tell tale.
I have noted that the ignition advance appears to be identicle with the line pluged in as it is unpluged. GPH readings seem to be the same as well. I think there will need to be some ABA style testing to see if this is a trully effective mod, or we are just fooling ourselves....which I don't want to believe becauses I tested this a couple times to make sure. Either way, I will be attempting lean burn soon, so it will be a null point and I may not do any further testing except to make a baseline for the lean burn attempts. But the question is still burning in my brain....

The ZX2 actualy has a liter sized vacuum resivour under the dash, a very nice feature for EOC. I'm not exactly sure what you are asking Phantom, can you restate your question?

[mwebb]

on your system
the primary Engine load sensor is the MAF sensor

when there is an air leak the MAF sensor Under reports air flow , so the ECM provides IPW injector pulse on time to provide the correct fuel for the amount of air that it knows about .... blah blah , replay the fuel trim correction thing here

moving along -
now the ECM has been Looking up the indicated MAF value on a table
to help provide other values
Like IGNITION timing , since the ECM sees very light load , IGNITION timing has been adjusted to match what a light load would call for
so
IGNITION TIMING is more advanced than it would normally be for the ACTUAL load
and so on , the ECM is now providing commands based on a much lighter load and those commands are NOT affected by the fuel trim correction from the 02 sensor

so basically
the ECM is reading from the tables that provide commands based on light er engine load - and the ECM provides the commanded values from the tables for the lighter loads
not just Injector Pulse Width
which explains the difference in your FE

sorta
you may have a problem in your system as well , can not tell without seeing some of your
Scan Data at
idle
2k rpm
cruise
WOT

with and without
the self induced air leak - your condition should be repeatable by others with the same system - IF they can duplicate ALL of your conditions

i am assuming the self induced air leak is NOT the purge line from the purge valve on your EVAP system , if it is , it may be the problem is there and your system has a stuck open or leaking purge valve .

if you are near southern NY
i can log that scan data with AE and or Escan on MR laptop

[Tygen1]

What your saying makes sence, it is difficult to read the Scangauge and drive while mentaly recording the ignition advance. It could very well be slightly advanced. It is well understood the stock PCM's for ZX2's are starved for advance, the best PCM's for the ZX2 are simply just more timing and slightly leaner WOT mixtures. I do know that under very light load the ignition advance is maxed at 40 degrees whether pluged or unpluged. The typical advance I see is around 36-38 under normal light load and it seemed to be the same both ways, but again, I can't be sure.

I'm in Southern NJ, that's close enough for me. I may be able to arrange a meeting.

[LmidgitD]

Tygen1, been reading through your threads and am very pleased. Did you get lean burn to work yet, and did you ever really find if this vacuum line was a useful mod?

[slurp812]

Originally Posted by Tygen1

I can't believe all those folks who said Escorts were retarded were completely right? Sweet, my car is so dumb it can be run lean without it even knowing
I do have aa scangauge, but never checked the ignition timing. I did check the O2 output, but it is so ragged it's hard to tell, although it appears to be the same. I'll check timing tomarrow morning, but I won't be able to check it without till Saturday....maybe?
This is good stuff, I'm glad you have seen an improvement Moorecomp!

What color are the spark plugs?

[Tygen1]

Yes, I have gotten lean burn to work, and it helps quite a bit. You can cheack my fuel logs to see the benefit.
The vacuum leak thing helped by fooling the pcm into thinking that less air was passing by, and therefore it would be in a lighter load part of the ignition maps, meaning slightly more advance. I would say this will not work with all cars because this vacuum leak was unique in that it is a vacuum booster valve used for the the power brake booster, not a "true" vacuum leak. With lean burn, I no longer use the vacuum leak.
I've never checked the plugs, not worried about the color