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Old 10-15-2009, 01:41 PM   #1 (permalink)
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4DRTeg - '95 Acura Integra LS SE
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Experimenting with tuning leaner and ignition timing.

Hi, I have a 95 integra that I'm preparing to experiment HHO on.

I have modified the ECU to let me have full control over it. I'm using crome to edit the roms.

I installed a Wideband O2 and EGT probe. I have the wideband outputting to the ECU and the EGT probe is installed about 1.5" from the head on the 3rd cylinder.

Before I experiment with the HHO, I want to see how much I can improve FE with tuning.

I have changed the fuel and ignition timing on the cells I cruise at (60mph). I'm experiencing low EGT's with advanced timing and trying to understand the data. I'm also not hearing any pinging/knock.

This is what I have noticed so far from the datalogs.
A/F set to 18.5:1, Ignition timing at 50deg, EGT ~1000F.
A/F set to 18.5:1, Ign. timing at 45deg, EGT ~1080F.
A/F set to 18.5:1 Ign. timing at 35deg, EGT ~1100F.

From the researching I've done, this is what I understand.

1. If you lean out the mixture, it takes longer for the fuel to burn.
Timing should be advanced to start combustion sooner, so it can burn the leaner mixture completely.

2. Advancing the timing should lower the EGT assuming it's not overly advanced.

3. Retarding the timing should raise the EGT to a certain point because fuel is still burning as it leaves the head.

4. I've also read that advancing the timing with a leaner mixture will increase temperatures.

Since I am working with a significantly leaner mixture and not stoich, Am I correct in saying that the EGT will also be significantly lower, since there is less fuel to burn?

When I had the timing set to 50deg and noticed the low EGT's, I thought I may have advanced it too far, even though drivability was fine.

My thought was, increasing the EGT may increase the engine efficiency with the leaner mixture. I read sdsefi's EGT article and they say "It is safe to say that peak power will occur at an EGT somewhat colder than peak EGT."

I started retarding it in 5 degree increments to see what happens. I noticed the EGT did rise a little. In terms of drivability, I can't say I noticed much of a difference from 35deg. to 50deg. But the MAP and throttle position did rise.
At 50deg, the map would hover around 400-500mbar and throttle position was around 10-12%.
At 35deg, the map would hover around 570-650, and throttle position around 14-15%.

So with the lower timing, the hit points are at a higher MAP.

This is what I have observed so far and trying to see which approach I should take.

Should I continue retarding it until EGT starts falling off?
Should I continue advancing it until I hear pinging?

Sorry for the long post. I just wanted to get my thoughts out and see what others have to say.

Thanks for reading

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Old 10-15-2009, 05:45 PM   #2 (permalink)
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Watch the duty cycle at X rpm and pressure. That is what you're trying to drop and since you have logging it will be easy for you to see.

Too much advance result in more negative work being done thus more wear/stress, external hp produced will diminish. If you get really far out of bounds you will encounter detonation, but may not hear it. Install some fresh plugs before tuning and read them frequently for detonation and combustion temps.

Hold you variables as constant as possible and use caution on how much manifold pressure you attempt to run lean afr's.

A thermocouple is good for a supplement and to take note of what's going on. Personally, I feel their importance is less and less but definitely good to compare timing with fuel in what you're doing.

As soon as I can cough up the initial investment of another whole tuning setup for the 2nd car, I'll do the same thing, to the same exact car as yours (LS?). Only, crome makes me say bad words. Best of wishes to your success.
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Old 10-15-2009, 09:56 PM   #3 (permalink)
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Looks like a nice setup.

Are you running crome gold with datalog capability?

As for tuning timing I made sure that I use the same level streatch of road and just read map values and tps values. I set timing to achieve the lowest tps and highest vacuum values. Then retarded 2 degrees for a safety net.

I did all this while watching knock sensor readings.

Good luck with your project!!!
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Old 10-16-2009, 12:22 PM   #4 (permalink)
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I've been mainly using freelog and crome for editing the rom. I use the EasyMap excel worksheet to look at the data. My friend has a copy of the dealer version, but everything in crome just seems buggy, even the goldbin. The closed loop function doesn't even work. I set the target stoich to 18, and it just hovers at 16. I tried setting it to 17 and it still just stays at 16. I've been tempted to get a ostrich 2.0 emulator, but i'm not impressed with a lot of the available software.

I'll have to try and tune on the same stretch of road. I've just been using the average values over a 30 mile trip. There's a lot of elevation change during the 30 mile stretch.

Grease monkee,
Yeah I have a LS. heh. a 4 door Auto.

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