Jim85IROC

iTrader: (2)

Sorry for the extremely basic question, but I've spent hours searching, and I'm finding very little about $6E open loop idle tuning. I dabbled with tuning when I did a 350 swap in my IROC, along with a 165 ECM swap. I never did get it to idle well, and I always had to use the throttle to keep it running until it warmed up. Now that motor, along with new Vortec heads, is in my GTA, and I'm experiencing the same thing. I'm not seeing any obvious ways to pull fuel during open-loop idle in the $6E parameters except for the "Open Loop AFR Ratio % Change vs. Coolant Temp" table. I've pulled the % numbers down a fair amount, but it's not doing much. My plugs are black, and when the motor is cold if I blip the throttle it falls on it's face.

Unfortunately I can't do any data logging at the moment, because neither one of my 165 ECMs wants to play nice through the ALDL. Neither my handheld Auto X-Ray nor my Moates ALDL1 can establish communication.

The tune is based on APYP, but I've made some basic changes like setting my injector constant to 27lbs (I'm running 24lb SVOs), messed with fan turn on/off temps, and I'm using a mild Spark Advance table that's similar to the B-Body LT1 table.

Should I be changing the values in MAF table 1 to get it leaner instead of the Open Loop AFR Ratio table, or is there a better technique entirely?

Update: It appears that the car is going into "limp home" mode with any of the chips that I've burned, as well as with the ostrich. The only configuration that isn't forcing it into "limp home" is with the stock chip in place. This explains why none of my changes are making a difference. I'll revisit this issue when I sort out the reasons for being in "limp home".

RBob

iTrader: (1)

Being in limp mode is also why it is so rich, and may also be causing the no ALDL connect. That is, if the scan tool connects with the stock chip, and not with the replacement chip, limp mode won't have ALDL connection.

When I was doing chips I always looked for the SES blink at key-on, engine-off. That is, the SES turns on briefly, blinks off, then turns on solid. The blink off verifies that the ECM is running from the chip.

Can re-run the test after at least 10 seconds of key-off.

RBob.

Jim85IROC

iTrader: (2)

I was looking for the blinking "SES" and didn't see it... even with the stock chip. However, I may not have been keeping the key off long enough in between cycles. Tonight I need to do more diagnosis. I'm sure that the car isn't in "limp home" mode with the stock chip because the fan doesn't come on with the key, and the SES light goes out when I start the car. With any of my replacement chips or the Ostrich, I get the typical "limp home" behavior, i.e. the fan is on with the key, the SES light is on all the time, and it runs so rich that my eyes burn (I have 27lb injectors). What I haven't figured out yet, is why I'm getting "Limp home" with my chips. I've tried a few... I started with a 27C256 that I doubled the BIN file for, as well as a couple 27sf512 chips that I used the 0C000 offset for when burning. The only thing I haven't done yet is revert back to a 27C128, but provided that my one good one erases & programs properly tonight, I'll try that too. I never had these problems when I used the 27C128s in the IROC previously, so I'm not sure yet why I'm having them all of a sudden.

With respect to the datalogging, my fingers are crossed that it'll work ok. With the 165 that I had in my IROC, it was a disaster. My Auto X-ray would connect roughly 5% of the time at most, and then it was a crap shoot for how long it would stay connected. So far I've only been able to get the auto x-ray to connect to the 165 in my GTA twice, i.e. neither of my 165s are playing nice through the ALDL. Hopefully my Moates ALDL1 will be better than the Auto X-Ray. So far the only attempts that I had with the ALDL1 was before I realized I was in "Limp Home", so they were unsuccessful.

Orr89RocZ

iTrader: (20)

I had similar issues from time to time with bad chip burns. Can burn and read that chip, save to new file and view it. Looks all funky so you know it never went thru properly.

My latest 730 ecm started doin it on every chip. Some new some old chips. Two different burners. Buffer never verified to chip burn and car didnt run.

So happy i ditched that system.

But in general, seems open loop vs LV8 is what you want, but also maybe some coolant temp adjustment. It may run fine warm at a set lv8 but not when cold.

If none of those work well then it may be a startup enrichment and decay thing?

Jim85IROC

iTrader: (2)

I just had 2 more unsuccessful attempts to burn a couple 27C128s, along with a couple unsuccessful 27C256s, but on my 5th attempt, one of my chips actually burned. I just brought it out to the car and tried it. When I first turned the key on, the SES light came on solid (no flash), but the fan never came on. I started the car and there was no SES light and it didn't have the ridiculously eye-burning rich condition, so I'm pretty sure that it wasn't in Limp Home. Of course, my Auto X-Ray still won't talk to the ALDL.

I'm curious why the SES doesn't flash when I turn the key on. It's the same way with the stock chip and this new chip, but at least it looks like it's running from the chip.

Now for the Ostrich...

Jim85IROC

iTrader: (2)

now that I actually pushed the bin to the ostrich properly, that appears to be working properly too. The car starts and runs with no SES.

I tried to play with the open loop AFR ratio vs. LV8, but the lower values were already at 0 and it wouldn't let me use negative values. I played with open loop AFR vs. coolant temp, and it actually seemed to want higher numbers, not lower. The higher I went, the more the idle smoothed out. However, it may have just gotten better because the car was warming up. I'm going to let it cool, then try again. Based on the exhaust smell, I'm having a hard time believing that it's NOT rich though. When the headers cool I'll check a plug, but I'm not sure if running for a minute is enough time for the plug color to change.

Jim85IROC

iTrader: (2)

I think I was going the wrong way with these open loop AFR ratios. Because it wouldn't idle when it was stupid rich, I assumed it was still stupid rich when it wouldn't idle after getting it to recognize my tune. Tonight instead of playing with the open loop AFR vs. coolant temp table, I played with MAF table 1. Thinking I was still rich, I lowered the g/s numbers by 2 in the bottom 2/3 of Table 1 to richen the mixture. It ran worse. I put the numbers back and the idle got better. I put an additional 2 g/s in those cells and the idle stablized. I added 1 more g/s for good measure and it got real good. I think I just got my idle stablized, but I won't know until tomorrow night now that the motor is warm.

Tomorrow I'm going to try a tune that puts the MAF tables back to stock, but raises the AFR % change vs coolant temp numbers in the cells 44*C and under approximately 25%. Hopefully this will have the same effect without needing to change the MAF table values. I'd rather get this thing to run in closed loop before I mess with the MAF table values.

Anybody care to comment on my thought process?

Orr89RocZ

iTrader: (20)

Lean burn can also smell rich. Weird but it happens. I would watch idle vacuum during those fuel changes to see what it does and look for highest value. And definately look at plugs but they will need a few min of run time to see changes

And adding grams air flow should richen, subtracting will lean.

Jim85IROC

iTrader: (2)

I just assumed that I was still fighting a rich condition because the car behaved similarly to how it did when it was stupid-rich in Limp Home mode. Because of that, I was assuming that I still had too much fuel. The beauty of the Ostrich was that I could change my AFR in real time and get immediate results.

Now I just need to be able to datalog. I've got ECU #3 on it's way. Hopefully this one will work.

Jim85IROC

iTrader: (2)

Overall the car seems to idle pretty well after the first 30 seconds or so. Upon immediate startup, I have to give it gas or it'll immediately die. Once I give it gas, I need to slowly feather the throttle down to an idle, then it'll stablize. If I blip the gas and let the RPMs fall too quickly, it'll stall. I added fuel to the "startup enrich vs. coolant" table at lower temps, as well as extended the "startup enrich decay delay vs.coolant" at lower temps and added percentage to the "start up enrichment decay amount vs. coolant". None of it really seemed to make any noticable difference. I bumped all of them about 15-20%, which I'd hoped was going to be enough of a difference to notice one way or another, but I can't seem to tell a difference.