MPGs run, Aspire SE

[Zanzer]

A car running lean has hotter exhaust.


Don't think of it as less fuel but more oxygen. Like a blast furnace or blowing on hot coals and making them glow.

[TominMO]

A car running lean has hotter exhaust.


Don't think of it as less fuel but more oxygen. Like a blast furnace or blowing on hot coals and making them glow.

But....no fuel = no heat, i.e. if you were coasting engine off in 5th gear and the motor was just an air pump, driven by the drivetrain from tire to transmission. Still seems to me the less fuel that's in there, the cooler it will run. Fuel burning causes the heat, and the cooling effect of the gas does not come in until you are running too rich.

[1chrisapple]

I have to go with zanzer.thats y when u run to lean if bad enough can turn your exhaust glowing red by the manifold.

running lean is like fuel vapors it will burn quicker and hotter

[mattdickmeyer]

Both are true under different circumstances. In this instance, a lean condition will cause cooler EGT's down stream to the O2 sensor. This is how a choke works. It shuts off the air & adds auxillary fuel enrichment to heat up engine quickly. In a EFI system, in which no choke is present, the PCM reads inputs from the IAT & the coolant temp sensor until approx 150 degree's is achieved in opened loop a richer AFR is commanded to hassen warm up ( this is choke mode) After which PCM goes into closed loop. In these instances, you can see that a richer mixture is used to quicken heat up. In instances of forced induction, where cyl pressure is great, additional enrichment is used to cool combustion temps.

[jason_]

I have to go with zanzer.thats y when u run to lean if bad enough can turn your exhaust glowing red by the manifold.

running lean is like fuel vapors it will burn quicker and hotter

Depends on application. Glowing red manifolds isn't necessarily a lean condition. I had a carb richen ed to the max, manifolds still glow red after a drive. So I went back to factory settings, and it's been fine the past 18 years.

Sent from my rooted HTC Supersonic using Tapatalk 2 Pro

[TominMO]

Just FYI, I am waiting for parts to come in. Probbly no news until mid or late next week.

[mikeyjd]

1. I think the way it works is, more gas burned, more heat; less burned, less heat. However, if it's super-rich, then the gas that does not get burned acts as a cooling agent.
2. Excellent!

Correction to post #266: bought the adjustable cam gear from TH Motorsports, ~$103 with free shipping. It's blue.

What has happened over the past few days is that I am transitioning from MPG Tester 1.0 to version 2.0, with the wideband, header, and adjustable cam gear and FPR. From amateur status to advanced amateur.

On a further humorous note, just pulled the codes for my B6 Aspire: code 15, dead O2 sensor! So I can tinker with it too. It is a Denso, put in when the B6 was installed about 3.5 years ago.

It'll be cool to see what you can come up with using the computer. I hope you get everything dialed in so I can copy you You are doing important work Tom. Thanks

[TominMO]

It'll be cool to see what you can come up with using the computer. I hope you get everything dialed in so I can copy you You are doing important work Tom. Thanks

Back atchya. The next thing to test is whether just the cam and a heated narrowband O2 sensor is all anyone would need; I wouldn't want it to be prohibitively expensive for everyone to get better mileage. Matt's cam + a $30 O2 sensor would come to about $210; a good investment if I can get the MPGs up. I am actually encouraged by the fact that it threw a code when I aligned the cam properly; the most likely cause is that it is running leaner than the ECU is happy with, which is the whole point of the cam. If the heated O2 sensor does the trick, I am again expecting mid to high 50s on a run. Tune in to this same Bat-channel for further developments....

[TominMO]

Just got my Denso 4-wire narrowband heated O2 sensor (the stock Aspire rear one), and the Innovate MTX-L wideband kit today. Hooking up the 4-wire to a relay and installing it in the upstream position, and the wideband in the downstream. When I got the Aspire, I got a new exhaust B-pipe (behind the cat), which came with a downstream O2 bung, even tho it was for a pre-OBDII car; i.e. they only make them that way now, just like all rads are now the thick ones for the auto cars.

So let me pick your brains on how to wire up the relay.
Five terminals:
switched power in
unswitched power in
(2) power output
ground

The two outputs are obviously for the O2 heaters.

Relay ground goes to body ground (to ground the relay itself), or to the sensor ground? I.E. does the sensor ground go to the body/motor, or to the relay? Can I just ground the relay ground and the sensor ground together, and to the body or motor?

What do I do about power in? I want power to the relay (and therefore the O2 sensor) only when the car is running. Why are there switched and unswitched terminals? To give me an option, or do both need to be wired? Can I wire them together, to one 12v source that is 12v in run-only? Or is the unswitched directly to battery, and switched to a run-only source?

And finally, what would be a good run-only source under the hood? Keeping in mind that Aspires do not have a separate ignition module, with a coil lead going to the disty.

See pages 8 and 9 of the following to see the kind of mini 5-pin relay I have:

http://www.autoshop101.com/forms/hweb2.pdf

Ironically, the wideband only requires a hot and a ground to be hooked up! Plus some simple calibration steps.

EDIT: It's looking like I really need a normally-open 4-pin relay (see page 6), with both outputs linked together; I think the 5-pin will only give me power to one output at a time!

[TominMO]

Or should I just toss the whole relay idea and wire the O2 sensor directly--signal, ground, and the two power-ins going to a hot-in-run source in the fusebox?

[rmoltis]

I went ahead and bought "add a circuit"
Granted its coming in the mail.

It plugs into a stock fuse location and adds a second circuit to the connection.
It has 2 fuses.
One for the stock accessory and the second for the extra circuit.
It can use up to a 10 amp fuse in each circuit.
And it has the power wire coming off of it for splicing to the new source.
It seemed like the easiest and most "revertable" idea.
And ill just ground the heated sensor directly somewhere and splice into the signal line connector.

And if you choose this method
Make sure and buy the correct fuse size connector.

[TominMO]

Got the heated 4-wire O2 sensor in. I used the hot wire that previously went to my cruise control. Haven't installed the Innovate wideband kit yet, might do that tmw. But I really want to go on another run, to at least see if a code 17 gets tripped; i.e. is the heated O2 sensor keeping the cam in good standing with the ECU or not?

[TominMO]

Decided to hook up the wideband. Started it up and watched the digital readout start at about 12.5. As it warmed up, it gradually moved up the scale to between 16.2 - 17.2 at warm idle. So the MPG cam is definitely doing its part. Tmw or Friday I will go on a run and see what kind of mileage I get, and hopefully the heated O2 sensor will keep the ECU from throwing a code.

Got a call from Matt today, saying the header and FPR are in the mail tmw. He's welding on a flex pipe and a flange to simplify installation. Also, after this next run I will install the adjustable cam gear, and start fooling with different cam timings. The wideband should save me a lot of trouble.

[TominMO]

Went on a MPG run this morn. Cam timing straight up (I haven't installed the adjustable cam gear yet), ignition timing at 10 BTDC. AFR meter showing a hot idle of 16 - 17. While running, the meter's digital readout oscillated between low 14s and low 15s (14.7 is considered the "ideal" mix). I drove 145 miles and refilled with 2.86 gallons, for a MPG figure of 50.7.

When I started the car after filling up, it was idling rough. Ran fine on the way home, but rough idle at the next two stop lights. Got home and hooked up the timing light, and played around with the timing to see what the car liked. Turned out to be ~15 BTDC; idled better, at about 700. Checked the AFR meter and it was reading in the 18 - 19 range. So, as I expected, advancing the timing will lean it out more. (I tried going the other way, but it was really struggling to idle at all.)

Since I can get such lean readings with this cam and adjusting the ignition timing, I am thinking that an adjustable FPR might not be any help. What I would really like to do is get things nice and lean with just the cam (and the heated O2 sensor), and the optimal ignition timing. That would keep costs down for anyone else wanting to improve their car's mileage this way. After I see what 15* does for the situation, I will experiment with the cam timing. I talked to Matt a few minutes ago, and he recommends adjusting cam timing 2* at a time. He and I both felt that the right direction to initially try with the cam was in retarding it.

I should also add that Matt went rather conservative in designing this cam, because he was very concerned that while I might get great mileage with a more radical MPG cam, the car would have no power. So it's not like my results are set in stone for anyone else with a Festy or Aspire. With a more aggressive MPG cam, another tester might well get better mileage. But given that my AFR meter is lurking in the 16s to 19s in hot idle, I don't know how much better you could expect from a cam. My run Sunday morning will hopefully answer some more questions.

After that I will just drive around, city/hwy, and see what happens mileage-wise, until I leave for Madness Thurs morning.

[getnpsi]

I would think that the ecu catches that lean reading and starts dumping fuel to get it back in line, especially aspire with maf. Only time will tell. Remember the initial MPG CAM bragging numbers were done with a carbed festiva and outside of california no one has any of them to EPA specs anymore. Obviously getting the car to start up and scoot is the most important, id just hate to see the sensors fighting themselves. This is why im happy with your AFR brand purchase so you can at least run a narrowband voltage offset back to ecu to get it to think its running at 14.7 when you can lean it out some and it not know a thing. Just dont get greedy make everything white and burn something up and have to do your head over. Again I'd like to see longer trips being made. Simply filling up with a passenger in the car might get slightly more gas in there before the click and so on