Ive been away from prom burning for a year or so. Ive learned a lot just playing with things. Open loop is the way for my setup. When I make a change for the better the computer doesnt screw with it after. Keeping things simple works for me.

Ive reached a point where I have Idle, part to moderate throttle pulling very well. But, PE enrichment seems like one more thing Too tune into my fueling. Wouldnt it be better just to zero it out? The point where it comes in? And the added fuel? And just use the Ve tables to give the motor the fuel it needs at those loads and rpms?

I dont have a WB yet, but is a must for what im doing i know. But Till then IM going slow. when i add/subtract fuel if the motor responds i know im going the right way. This has worked well for me so far. The wot was tuned on a dyno at one time so i know im not way off there.

Ive found some helpful posts on openloop tuning. If anyone would like to share how they are doing things i would love to hear.

I would really like to seem some VE tables that have been tuned openloop with no pe adders to see the shape of them?

Mike

 

I like running with a PE mode. But, I like absolutely the best drivibility possible, mixed with at least good if not really good mileage.

I've done some tunes both ways, and for me I perfer to use it.

 

Hi Bruce....I just came in from a full day of tuning. I have the PE coming in at 30%. It took me lots of work to come up with this setting. I worked on the VE tables and AE also over the past few days. The car is a beast right now.. And will only get better. I dont want to touch anything that is going to make a major change in the tuneup right now. So i think IM staying with PE enrichment for now.

I read about the problems you had with the lockup converter with a low pe enrichment. Have to watch out for any signs of this guess.

Gas mileage is something to think about with the high gas prices right now.

 

Moped!
But seriously...if the engine is makingthe most/best power it can (being efficent) it should also get the best mileage it can......just a random thought.

 

don't forget that PE and gas mileage are two totally different parts of the fuel curve. for daily driving around, you shouldn't be in PE mode hardly at all... n' when you smash the throttle and go into PE, wouldn't you just totally forget about gas mileage anyway?
I think what Grumpy meant, was that the base fuel curve is mostly for fuel economy, while PE takes care of the extra fuel when he want's to go fast. Therefore, he can cruise around in a wide range of the VE table without really messing up his mileage.
Personally, I think that zeroing the PE AFR change vs. RPM table and relying on a good VE table just makes it a little simpler.

 

*Both* my tunes are using about 30%, right now. I've modified both the codes so that the PE enable/TPS, is now a table graduated by RPM. So if I want to scoot from a light quickly, I can get into PE at lower then 30, and then at the higher loads, have it set to like 35%, so that a bad head wind doesn't put me into it.
I was towing the GN once, with the truck with the PE set too low, yikes, a BBC, with 5,000#s in PE for 300 miles can burn some fuel.

I bought a brand X car, and a spare ecu. I have to do some digging but I want to change it over to a GM ecm

 

Are you setting up the open loop AFR to change as the load varies? IOW, as the load increases the AFR decreases. When doing this tune the VE table to match the WB AFR to the commanded AFR. Once this is done the AFR will follow any changes made to the commanded AFR.

Then PE mode isn't required as the AFR will be commanded at a WOT high load to be the proper value.

RBob.

 

Kind of a tricky statement. Some engines like to be slightly richer then best power for cruise. Then some of the oems toss in alot of EGR, and crank in alot of timing, so they can lean things down.

For years, I though tuning for lowest TPS was the best guage, but anymore I just do that to get close, and then dither the tune to get the best MPG.

 

when I mash the gas in either the car or truck, I can hear dynosaurs groan..........
I think an earth quake was caused by some rolling over in their graves, when I was at the strip on night.

 

If you change altitudes a lot, I would recommend keeping PE enabled. Going up a mountain or something at WOT, but 85 kPa, and leaner than 14.0 for example will have less power than at 12.5. You're not running a cat (I hope), so that's no problem. I'm not sure if there's much chance of engine damage either, unless your cooling system is underperforming.

Be sure to zero out all the open loop multiplier vs temp when warm in order to get full control, and zero out the OL vs MAP table.

Wouldn't it be nice if there were a AFR vs MAP and RPM table for Open loop (that would assume the VE is based on a 14.7 tune), and then a PE AFR table that knows how much to add based on the open loop AFR? You could do all the math by hand though. %PE = 100% * Current AFR/Target PE AFR, where if you were at 14.7 and wanted to go to 12.5, you add 17.6%, but if you were at 13.8 and wanted 12.5 you add only 10.4%. If you look closely at the math you may think it doesn't add up (14.7 to 13.8 = 6.5%, 13.8 to 12.5 = 10.4%, 10.4%+6.5%= 16.9% not 17.6% (% changes don't add together like I just showed)) but when the base changes, so does the % required to make the same effect. (take 2000 * 1.065 *1.104 and compare to 2000 * 1.176)

 

The purpose of PE is...
.....
Suppose you're at 3000rpm cruising,
then you want more power, and open the throttle,
to 50 percent, vaccum goes to zero, a-f is 14.7:1...
...
then you want max, open throttle to 100 percent,
PE in effect,
a-f goes to 12.5:1, timing advances a few degrees,
vacuum is still zero,
and you get five percent more power [because of PE]
.....
or something else,
please enlighten me.

 

RBob....I found an old post of yours. When I get the WB...I would very much like to try setting it up this way. IM happy with the car now, for the most part. Just some little things to work out. The tune could always be better. But im feeling the power peaks and it pulls strong.

Now I just have to fix the small dent in my passenger fender. Grrrr...I still dont know where that white mailbox came from.