Hey all,

I have had good results adding ~4* of timing in the cruise areas of the map (same as where leaned out afr's go). You can actually see the results quite simply. Pick a stretch of road you drive regularly. Watch your boost gauge, note how much vacuum you tend to stay in to keep up a certain MPH. Now to add the 4* (or whatever) of timing, and your vacuum should be consistently lower.

 

I'll post my map if you post yours. :-) Seriously, I'd like to see your timing map. I'll add my current one shortly. Did you try more than 4 deg?

 

Here is my ignition map (running E85) that I loaded before leaving for work. The values in the cruise cells should be about +3 deg over stock. I started from a non-stock map, so some values may be +2 deg and some may be +4 deg. During the drive home, timing went as high as +43 deg with no knock at all. Throttle response felt improved despite the AC running full blast and an outside temperature of 100F.

I am seeing in my logs though that on occasion the timing suddenly drops from normal expected values (+30 to +40 deg) to somewhere between +0 to +9 deg. There is no knock associated with it, and the timing immediately back to the expected values, e.g., the timing in my log would show:

.
.
.
32
32
29
0
29
31
29
.
.
.

I'm seeing at anywhere between 1000 and 3000 rpm, always at loads of about 40-70. I went back to cruise logs from my standard timing maps with pump gas, and I'm seeing the same thing there, although much much less frequently. Anyone else see this?

 

Are there any issues running so much timing @ idle? 14 is quite a fair amount of advance over stock.

 

I looked through my logs again. The drop out in timing is mostly occuring at low rpm (1000-1500 rpm) when taking off from a start. There are only a few instances where it occurs during cruise conditions.

 

just a general question here:

isn't running so much timing going to cause knock? (obviously it doesn't, but why???)

ie low RPM requires less timing to get best torque, usually we are talking numbers of sub *10 (at high loads).

so how come we can run *30+ in the 1500-3500 range at low loads, I would have thought that this would be causing knock...

 

I tried the vacuum observation before going to work this morning. I tried my +0 deg, +2 deg, and +3 deg maps. All had essentially the same vacuum (about 28) and load (50) when cruising at 60 mph on the same stretch of road. What I did notice was much better throttle response and better power when accelerating with the greater advance. With the +0 deg map, I'd have to push up to 1-2 psi boost to get decent acceleration, but with the +2 deg and + 3 deg maps, I could get what felt like the same acceleration while still staying in vacuum.

 

Very little air in the cylinders at low loads probably takes its sweet time to burn as opposed to tightly packed high loads, that burn very quickly.

 

exactly

 

yah makes sense...

anyone able to convert rpm+advance into "time" like milliseconds or something - would be an interesting exercise...

 

Ignition advance will still be PPP no matter what the load, rpm, etc. Who know's how to find it without a test engine lab, sensors, and whatnot, but it's likely a couple degrees more than stock at cruise. Then 1-2 more degrees to account for the leaner burn. In addition, this is on top of the 3-8 degree advance added at cruise for recirc too so expect it to be like 48* highway driving.

 

The EGR Advance adder is pretty minimal in the cells traversed in relatively normal cruising:

- EGR advance adder = 0 after 2500 rpm.

- EGR advance adder = 0 after 60 load.

- EGR advance adder at 2000-2500 rpm at 50-60 load (60 mph on flat ground) = 2 deg.

- EGR advance adder at 2000-2500 rpm at 40 load (40-45 mph on flat ground) = 2-3 deg.

The EGR system operates up to 80 load and 4000 rpm. I'm thinking about adding EGR advance values out to 80 load and 3500 rpm which better covers my highway cruise conditions (lots of open road with 65-70 mph speed limit usually drive at 10 mph over).

What does PPP mean?

 

how do you go about changing EGR characteristics?

 

What does PPP mean?

if I can, C6... must be busy,
ppp= peak pressure something, it refers to the point in the crank revolution where you want the peak pressure of the gas bomb to have climaxed. I've read its around 15 degrees ATDC

 

If you search this forum on EGR, you'll find a thread (or maybe two) that discusses the EGR system and gives tables that can be added to your ROM xml file to access the EGR system duty cycle and the EGR-enabled ignition advance table.

Thanks.