Using a stock 85 ECM. I changed from 24# to 30# injectors and now have a nice flat fuel curve at WOT.....only problem is it's 11:1. What's the best way to raise the curve without reshaping it. I've tried changing the injector constant, which doesn't seem to have much of an effect. Nor do the enrichment tables which i've set from +25% to -25% without much change to the curve. Cruises around at about 14.7 and drops like a stone to 11:1 as soon as it hits the TPS enrichment threshold. Any help would be appreciated.

 

Injector constant is only for the mpg display on the dash.

You need to correct the Injector Pulse Width Vs. Load table to adjust the fueling for larger injectors (Multiply stock settings by 0.8).

 

 

Hey, ralph

Dunno if you ever saw it, but there is a guy here who upgrades the original GM ECM boxes with new memory, I/O, data stream, and operating software, etc:

http://www.dynamicefi.com/

The builder is the moderator of the PROM board over on the ThirdGen site, Bob Rausch(?), very skilled and helpful guy. The new box is pretty-much a plug in for the original. However the udated programming is MUCH easier to use than the old stuff, and gives vastly improved engine information. JMHO

If you are going to do much programming it might be worth a look, save you some heart-burn.

Dave

 

Thanks.......you guys are great. I suspected i'd have to adjust the pulse width vs load table, but was a little hesitant. I also suspected the injecotr constant only affected the mpg reading.......my fueling didn't change a bit, but my mpg went to hell as i increased the constant....lol.

Let me ask another question. What is the primary enrichment fueling? is it the enrichment % vs RPM or is it the erichment % vs coolant temp? And are they additive or multiplicative or neither? I zero'd out the enrichment vs rpm to get a baseline, but it didn't seem to change my AFR. Then i increased and decreased it a bunch without much of an effect. Yet as soon as i hit the TPS threshold, it goes into enrichment and AFR drops to around 11:1. So i'm assuming the enrichment vs coolant is the primary adjustment? But not sure how the erichment vs rpm is applied.

Doc, I looked at that system a while back, but wasn't sure of it's quality or support. I wound up getting a FAST Classic system from a friend, and about killed myself trying to get that work work along side my stock computer......which i needed to lock the converter. The FAST system was setup for a crank trigger and didn't like working with the inductive pick up in the stock distributor......rotor phasing was way out (advanced) and it about killed my starter as it was kicking back. Finally raised the white flag on that one and figured i'd try to tune these 30# injectors using the stock system. To my surprise the AFR at WOT was pretty flat, but just too rich. I'm hoping the pulse width adjustment does the trick and i'll probably never mess with it again.....it i can avoid it. Know anybody looking for a FAST Classic

Thanks again guys.

 

I don't know what mask your using but generally they are labeled something like this.

Inj PW vs Airflow

This is the MAJOR fuel table. MAF valules look to this table and fuel is added. Changes in here would effect the fuel ratio in nearly all circumstances.

Accel Enrichment (AE?)

This is like the pump shot on a carb. As you crack the throttle open it adds a short increase in fuel before the MAF and O2 sensors catch up and take back over. If you think - the instant you crack open the throttle you pull the air out of the plenums before it starts sucking through the MAF

Power Enrich (PE)

This controls your rich/power fuel. As you know 14.7:1 is best for cruise (sort of) but to make best safe power 12.8:1 Ish is going to be better. The PE tables are a % of your non PE fuel

For example - if your fuel map WITHOUT pe provides you a flat AFR of 14.7:1 at WOT then you would need the value of around 14% to get where you want.

14.7/12.8 = 1.14

 

There are obviously additions to this but that is the basic.

Anything against Coolant is going to be more consitant a change then vs RPM obviously. PEvsPRM can be used to flatted the WOT fuel curve and the coolant to globally set the specific WOT AFR.

The biggest issue with the 85 ECM is its sooo god damned slow to show datalog readings.

 

Sorry i wasn't more specific about the enrichment. I meant Power enrichment in my post above. I'm using two systems to read/program.....GMPro (DOS based) and Tuner Pro (Windows based). Each does something the other can't.

Anyway, there is a power enrichment table vs coolant temp. It's set at 23% at operating temp. That seems to high to me. Per your example, 23% enrichment would take the AFR down to 11.90-12.......which is about where it is. However how does the PE vs rpm factor in? In other words, if the PE vs rpm is 20%....and the coolant based PE is 23%, is the total enrichment 43%???

I also have a question about Accel Enrichment. She's blowing heavy blue smoke if I rev the engine in neutral. I assume i've got to tone down the AE, but which parameter? There is a max AE pulse width (5.6), several rate of change factors and a muliplier for coolant temp. I assume the major parameter is the max pulse width. I assume i should change that to say 5.6 * .8 = 4.5??????

BTW, i made the changes to the LV8 vs pulse width table and took it for a blast. I was chicken to go down to 80% in one shot so i cut the values by 85%. Now the AFR at WOT is around 12.5 vs 11.5.......so i'm getting closer. I'll give it another try after burning another chip, but i've got a double header of racing in 2 classes tomorrow, so i've only got time for about one more shot before i load up.

Any help, particularly on AE, would be greatly appreciated.

 

Are you getting these readings with a Wideband O2 Sensor?

 

Also - what XDF are you using?

 

1F.XDF

Using an Innovative Motorsports LM-1 wide band O2.

That last chip didn't work as well as i expected. I was getting a weird lean spike half way up through first gear (like 20:1). Guess'n maybe i pulled too much AE out. I'll use the prior chip tomorrow......actually after looking at the logs, the WOT AFR wasn't too bad......12.7 to 13.0 range and i'll get a few more WOT logs tomorrow. BLMs around town are generally 120-128. I'll probably try pulling the full 20% out of the base pulse width vs LV8 table and see if i can get closer to 128. But that will have to wait until next week. Meantime she's still blow'n heavy blue smoke if I rev it in neutral.....any idea how to correct that? I don't remember it doing that with the 24s, but then again i don't usually rev it in neutral very often.

 

Blue smoke sounds like Oil? Black is fuel. Lets hope you haven't washed the bores. I've seen it happen when WOT is down to 10's and 11's. Any smoke on over run?

 

Also don't forget that adjusting the injector pulse width will also effect WOT. IE if you have the WOT where you want it and need to lean the rest of the map then you will need a higher percentage in the PE vs Coolant.

 

Thanks Dan.

I hope it's not oil, but it wouldn't surprise me. It's been using some oil lately and has been down on power a little in the second half of the season, before i even started messing with the injectors. I also have a slight leak in the oil pan that needs to be welded over the winter.......I attributed the oil lose to the leak, but I'm starting to think i'm using more oil than it's leaking Might be time for a compression and leak down test.

Anyway, i'm glad i didn't try to lean it out any. At the track yesterday, the AFR was around 13.25-13.5 on average.....at the extremes it was 12.7 at the bottom of the gear and as high as 13.9 near the top. I probably need to increase the PE vs coolant a little and then try to flatten the curve a little more. It's better than it was with the 24s.....it would get as high a 16:1 briefly at the top of first gear and I had 100% enrichment in the upper rpms.....i think it was just going static.

Another question: Is there a parameter that adjusts PE for air temp. It was cold yesterday and the adjusted DA was close to 1000 ft below sea level in the evening. I can't help but think that it was a little lean due to the conditions and that in the summer it will be fat. Oddly, my ETs didn't change much from 200ft above to 1000 ft below. Maybe i just didn't have enough fuel.

 

Fingers crossed the oil is escaping else where...

To flatted the curve use the PE vs RPM tables. sounds like you want higher numbers in the upper RPM's and lower in the bottom. When I start tuning I normally set PE vs RPM to zero's - get the general AFR correct with the PE/Coolant table and then flatten it out via the PE/RPM.

As far as temps go - I'm not sure on your setup. There is a good chance there may be although I would say its probably not going to be a big enough effect for you to worry about too much and in the heat of the summer a little fatter on the AFR might help to keep temps down and knock away.

 

ralph,
Another thing to keep in mind. If you are still running the big engine, you are most certainly saturating your MAF sensor, in datalogs it will probably be just sitting at 255 over about 4500 rpm. So that leaves you to just keep cranking up the fuel on the load table as RPM increases on that top row.

However a kink in this is that you will notice the RPM that you hit saturation will change with temperature, naturally in the cold with the denser air it will hit 255 at a lower rpm.

 

Phil??? That you??? I didn't realize you were still on the forum. I guess when last we spoke you were working on some sort of engine management system....Big Stuff?? or was it Megasquirt? I send you a PM later......maybe we can catch up. It's been a while.

Dan, thanks again. I think I'll be able to get the fuel pretty close with enough experiementation. I'm surprised there's not more parameters for air temp.....it certainly has a huge affect on performance. You really have me thinking about the smoke being oil. I hardly ever lost oil and have gotten into the bad habit of not checking it very often. A couple of weeks ago, i decided to check it in the lanes between rounds. It was hard to get a good reading because the oil was still hot and had sloshed up the tube.....but it looked like i could have been down 2 quarts. I through in a quart i had with me and forgot to check it again when i got home. This past weekend I added almost 2 quarts at the track (again i couldn't get a good reading), and now that it has cooled and i can get a good reading...it's still down 1/2 quart So i've added almost 3 quarts over the last two races and i'm still a 1/2 quart down! Either i was damn near empty the first time i checked it or this thing is burning oil at a very fast rate....WTH?????? Did i break a ring or something?

 

It is me... I have been strolling by from time to time lately

 

A freind of mine installed larger injectors without the tune being adjusted properly. It dipped into the very low 10's at WOT a few times... that was enough that from then on it started burning oil. It simply washes the bore of the cylinder so the oil control rings are less effective.

His engine was always used pretty hard so I'm not saying that with every motor this will happen. But maybe those that are starting to wear the bores get accellerated by the washing effect.

How does your rear bumper look? Speckled black is a good sign of oil.

I beleive the MAF should be good to around 400hp. And fuel can be adjusted via the PE tables up to 6400 independtly so even if its maxed you should be able to get a fairly accurate tune.

 

I don't think the AFR ever went below 10.7 and only went below 11.25 for very breif periods.....so i don't think i washed out the cylinders. Plus the oil consumption started before I messed around with injectors and computers. I pulled the plugs last night and #8 was completely oil fouled Can't check compression yet, cause the starter is being rebuilt, but this doesn't look good. i actually had this happen once before and it was an issue with the intake..........so i still have some hope