lean burn rules~!

[diesel_john]

Originally Posted by JohnnyGrey

John, how are you certain you're in open loop, is the O2 unplugged? I tried doing this on my Cavalier, but the variation in AFR was too wild to run reliably for any length of time. I would advise against slowing down your pump. If it produces less pressure than the regulator needs to open, the fuel supply line will slow to a crawl and the return line will stop. Depending on the design of your pump, it may be cooled by the fuel that runs past it, which will not be much if you go below regulator pressure. Try finding an adjustable fuel pressure regulator instead.

Be careful if you do this, because you will have leaned out your WOT mixture as well. If you need a sudden burst of acceleration, you could cause severe detonation. My car stays in closed loop at around 16.5:1, but if I stomp it, open loop is still around 12.5:1, so I can still get full power out of my engine safely.

I unplugged the 02 signal from the ECU but still monitor it with my DVM. seems to be leaning much better now. still throws my mileage computer for a loop, cause it uses pulse width to calculate fuel flow. but it was off anyway cause i don't think it counts miles when the injector pwr is cut during engine braking.

[Joseph Davis]

That's interesting.

Not all vehicles run correctly with O2 sensor unplugged; some ECU interpret this as a full lean condition (0 volts on the O2 signal line) and start dumping in fuel. Poor mpg and trailerhitching @ cruise are the usual symptoms.

[JohnnyGrey]

That's interesting.

Not all vehicles run correctly with O2 sensor unplugged; some ECU interpret this as a full lean condition (0 volts on the O2 signal line) and start dumping in fuel. Poor mpg and trailerhitching @ cruise are the usual symptoms.

Most ECUs aren't completely stupid and they will only believe the "lean" condition for so long before they ignore the O2, throw a CEL and switch to open loop.

[diesel_john]

Ford trucks were a bit primitive yet in the early 90's and really until the 4.6L modulars came along. They definitely need a tow fuel map and an economy fuel map. That mega squirt looks like a lot of fun to me.

Interesting side note, when I am running along steady state, O2 unplugged, and I dial in more in series resistance with the injectors, I can get the O2 voltage to drop down between 0.2v and 0.1v. But at that same resistance setting if I go to WOT the O2 voltage still goes up to 0.8v. So at steady state the ECU cannot compensate for low injector voltage but at WOT it can.

[Joseph Davis]

Megasquirts either work well, or have issues.

I am currently having issues with the manner in which Megasquirt controls coil dwell w/ the TFI ignition. Defaulting to 50% duty on the coil signal results in misfiring 4000+ rpms, completely poopy. The Ford intake and coolant temp sensors are not supported by default and if you are paying for the modifications run ~$140 extra for the hardware modifications needed, and then the idle control motor's cold/warm duty cycle routine ends up incorrectly handled so there *is* no idle control.

IMO convert to 89-93 MAF from a Mustang, using one of the A9L ECUs. You can fiddle to your heart's content via the J3 port, Moates.net and TunerproRT are the things you need to check out on that.

[diesel_john]

Originally Posted by Joseph Davis

Megasquirts either work well, or have issues.

I am currently having issues with the manner in which Megasquirt controls coil dwell w/ the TFI ignition. Defaulting to 50% duty on the coil signal results in misfiring 4000+ rpms, completely poopy. The Ford intake and coolant temp sensors are not supported by default and if you are paying for the modifications run ~$140 extra for the hardware modifications needed, and then the idle control motor's cold/warm duty cycle routine ends up incorrectly handled so there *is* no idle control.

IMO convert to 89-93 MAF from a Mustang, using one of the A9L ECUs. You can fiddle to your heart's content via the J3 port, Moates.net and TunerproRT are the things you need to check out on that.

Thanks for the warning.
i'll check it out the A9L.

[88CRX]

If you have a honda, can we just use an Air Fuel Controller, like an Apexi S-AFC?

[oldertech]

[QUOTE=Joseph Davis;25837]Last count I had twelve P07 ECUs on hand. While they can be modified there has been no actual development on them, so they are effectively paperweights. I drop the OBD1 ECU plugs off of them and use them to make pass-through harnesses for various reasons.

Hi,

Is there a way to identify the CA ECU by numbers? I have a '95 VX and I'm sure is a California car with 4 wire O2 and the car's book is in a California dealer folder. But if I look for the 49 state Ecu, how can I be sure I have the right one, as mine says P07?

Thanks,
Scott

[Joseph Davis]

Probably. I don't know off the top of my head, though.

The last three digits of the ECU part number would tell all, though.

[oldertech]

Originally Posted by Joseph Davis

Probably. I don't know off the top of my head, though.

The last three digits of the ECU part number would tell all, though.

Hi,

I did more digging and found the answer, so I'll post it here.

ECU for 49 state:
37820-p07-a01

Calif:
37820-p07-l02

I know there are many threads about making leanburn happen in a Calif. emission car but I'm kind of boggled when I read that there are several adaptors to make the 4-wire car into a 5-wire care, while others I've read say "add one wire, but make sure it's shielded" to the 4-wire loom.

I have lots of electronic experience and don't mind tackling the project, but don't really want to have to do more head-scratching than necessary.

If someone can summarize the simplest solution, I'm welcome to suggestions.

Thanks!
Scott