16197427 PCM swap

[JeepsAndGuns]

I think you guys are blowing it up to be a little more then it really is.
The conversion is nice in that it allows for more future options like electronic trans and such. For an engine with a big cam the idle tables do allow for improved idle. The faster baud rate is a plus when tuning. Elec fan control.

But if the 7747 ECM was tuned properly then the swap to the 7427 PCM with the same good tune is not going to show a performance improvement.


So while it is something new to play with, it really makes no "performance" gains.

So if a guy already has an ECM based TBI system running fine on his basically stock engine and no real plans to go to an electronic overdrive trans in the future, then the only reason to swap is to have something new to play with.

Just don't want every guy reading these, thinking it's something he needs to do.

But learning new things is always a plus.

I dont really know how to discribe my very noticeable improvements then. My old 7747 system was (after a lot of work) running very good. (about as good as I thought I was gonna get it) I transfered my timing table over to the 7427 bin in the areas I could, then manualy filled in the other areas to make it match. I did just a touch of smoothing to the fuel tables, and took it for a run. From the very first moment it fired, pretty much everything was noticeably better. Now I'm not talking huge, but definately enough to tell. And I hadnt even tuned the fuel maps yet. I always just thought it was because of the pcm being newer/better/faster with better (programming/logic/whatever??)
It definately has a learning curve to it. And if I had not put together and learned how to tune on the easyer 7747, I dont think I would have had as good of sucess.
I would definately reccomend to any new people looking to do tuneable injection, to start with the 7747.
My biggest reason for swapping to this pcm was because of my desire to have mpfi. So I wanted to go ahead and get a head start on learning this pcm. The improvements it made to my tbi system is a added plus while I put together my mpfi intake.

[Revhendo]

I dont really know how to discribe my very noticeable improvements then. My old 7747 system was (after a lot of work) running very good. (about as good as I thought I was gonna get it) I transfered my timing table over to the 7427 bin in the areas I could, then manualy filled in the other areas to make it match. I did just a touch of smoothing to the fuel tables, and took it for a run. From the very first moment it fired, pretty much everything was noticeably better. Now I'm not talking huge, but definately enough to tell. And I hadnt even tuned the fuel maps yet. I always just thought it was because of the pcm being newer/better/faster with better (programming/logic/whatever??)
It definately has a learning curve to it. And if I had not put together and learned how to tune on the easyer 7747, I dont think I would have had as good of sucess.
I would definately reccomend to any new people looking to do tuneable injection, to start with the 7747.
My biggest reason for swapping to this pcm was because of my desire to have mpfi. So I wanted to go ahead and get a head start on learning this pcm. The improvements it made to my tbi system is a added plus while I put together my mpfi intake.

I'm watching you like a hawk, pal. I am absolutely intrigued with all the advances you are making. Keep it up, I am learning with every post you make. I've been doing fuel injection conversions for something like fifteen years now for the shop I work at. Started with tuneport 350s, then LT1s and now LS engines. Somewhere along the line I cheated myself of a learning curve. The harnesses and computers were supplied by another company and the basics of the programming weren't an issue. I'm pretty good at troubleshooting the wiring when there is a problem. I'm just lost on the tuning parts. So now, I am going back to the basics. I am doing a TBI from the ground up, (the first will probably end up in my 76 GMC parts chaser). I figure if I learn the simpler system, I can get a better grasp on the more elaborate ones.

I truly do appreciate what you are doing and am thankfull that you are sharing it with us. I hope you don't mind if I ask a question here or there along the way, I can be a bit thick at times.

[JeepsAndGuns]

So now, I am going back to the basics. I am doing a TBI from the ground up, (the first will probably end up in my 76 GMC parts chaser). I figure if I learn the simpler system, I can get a better grasp on the more elaborate ones.

Sounds like a good plan. Back when I first got into it, going from a carb to the 7747, my head wanted to explode!
But after lots of reading, researching, and bugging the crap out of bill and the guys at binderplanet with questions, I finally started to get the hang of it.
Just get tunerpro rt and download the defination file for your ecm, and if you can, also pull up the bin (or any bin for the ecm you are gonna use) and then just load it up and start looking it over. This helps you get famillar with tunerpro and lets you look at all the diffrent paramiters there are in there. You can then click on them and see what they are set to. And then load up a diffrent bin and compare them. This actually helps more than you might think. Also read through the user manual tunerpro has.
When you get ready to start tuning, just make sure you do your homework and dont just start randomly changing stuff. Like said by people smarter than me, just because something can be changed, doenst mean it should. Also, dont make more than one or two changes at a time. Sometimes a little change can make a drastic diffrence in how the engine runs, and sometimes its not always for the better. So if you made a lot of changes, you wont know what change made the diffrence.
Another bit of good advice, every time you make a change, save it as new. (got to file, save as new, instead of hitting save) That way if you change something, and it made things worse, you can simply go back to where you were before the change. This way you also keep a stock copy of your bin, if for some reason you need to start over.
The way I do it, is I take my bin, and every time I change something, I add a number or letter to the end of the file name. So if I start out with a stock bin, and I change the fuel table on it, I would save it as new, and add a number to it. (example ASDU-1, if I change the table some more, then it would be, ASDU-2) Then after I got the fuel, then I would switch to timing. So then my files would change to something like ASDU-2-T-1. Translating into fuel map #2, timing table #1, etc... Its just my own little code to help me remember and keep track of what I have been doing to the bin. Tunerpro also creates a text file that shows everything you have changed, witch is also real handy, incase you forget.

And last, ask lots of questions! Lord knows I have, and still continue to do so today. Even with what I know now, I still concider myself a noob.

[FSJ Guy]

Fifteen bins later and the truck is running SWEET!!!!

I agree with JeepsAndGuns. My butt-dyno says there is more power.

Nice solid idle at 800 rpm, exactly where I set it.

[Bill USN-1]

I think the faster buad rate just help compensate for a so so tune.

[FSJ Guy]

I think the faster baud rate just help compensate for a so so tune.

You joke, but I think you're absolutely right. Since the BLM cells are reporting more often, I think it WAS easier to get a good fuel map.

Since the fueling is different than the 7747 computer, I had to start with the Chevy 350 fuel map and adjusted it from there.

[JeepsAndGuns]

15, wow. Only took me like 5-6 and I dont think I can do too much better. All my cells are between 125 and 130. And thats the extreems. Most hover between 127-129.
For some reason it just seems like even though there are two fuel maps, the 427 has been easyer to tune them versus the old 7747's single map.

So whats your fuel maps look like? My open throttle map has a nice smooth almost 45 degree angle too it, curves up to a specific point, then just goes flat. Looks kinda strange, but cool at the same time. But what am I to question what my engine needs. Kinda intrested in what your timing tables look like too once you got them transfered over. We both have 401's, but built slightly diffrent and live in diffrent parts of the country.
Care to compare? I can post up some screen shots of mine in the morning.

[JeepsAndGuns]

Ok, just for fun, heres my fuel and timing maps.
First is the fuel.






Next is the timing table. I have had the heads shaved a bit and run premimum fuel. I also have a manual transmission so I have been playing around with the idle timing table and it has helped it when pulling out from a dead stop.

[FSJ Guy]

I'm still playing with my fuel map. I don't have a WB, so it's hard to tune the WOT areas. I'm going to disable the PE (or just set it to 14.7 AFR) and take it out to tune the WOT areas. I read somewhere that you're not really supposed to be able to tune the high MAP areas because of the PE. But if you set the PE to stoich (14.7), I think I can tune those areas, too. We'll see.

The big news is that I hooked up the Park/Neutral switch. I never had it hooked up before, even with the old ECM. That made a huge difference in my idling when not in gear.

[JeepsAndGuns]

I dont have a WB either. I am thinking about getting one, since it can stream with the datalog.
Interesting info on the PE. I just know when tuning mine, the low map areas were rich, and the high map areas were lean. Middle ground was not far off. I dont drive at wot very much, usally only a couple times when datalogging so I can have some readings up there.
I have noticed one funny thing. The datalog dash has the boxes where it shows AE and PE. The AE will come on any time i jab on the gas, but no matter what I do, I have never seen the PE come on. Thought it was kinda odd, but never really paid much attention to it.

What pin did you hook up the P/N switch to? The 7427 doesnt have a input for a P/N switch. It was my understanding it used the inputs from the trans to know what gear it was in.

[FSJ Guy]

IIRC, it was the 3rd gear pin for the Park/Neutral input. I'll check in the morning.

Mine goes into PE all the time. Any time the MAP goes to 70-75 or above, it's usually in PE mode. There are tables specifying at what MAP setting it goes into PE and at what TPS point triggers the PE.

For a wideband, you can implement the input it into the regular datastream or just hook it into one of the AutoProm inputs.

EDIT: It's pin E5. Labelled Range C. When it sees ground, the PCM will show as in Park/Neutral. When it is not grounded, it will show as in gear.

[JeepsAndGuns]

There are instructions in the defination on what needs to be done. Its up at the top where the adx read me was. But you hook the WB output wire to the pin on the ecm for "egr pintle position" Then do the required tweaks to the bin and now the WB adta will display on the datalog. You wont be able to do anything but read the data, you cant use it to controll fuel.

I will have to look at my PE settings, see if its turned off in this bin or something.

[JeepsAndGuns]

Well I looked at my PE and didnt find anything out of the ordinary. I found another $0E 454 defination and it was all the same as the one I am using, so I then looked at another $0E defination but it was for a 350. I looked and they were all diffrent. So I copied all PE setting from that bin into mine. Tried it and it might be my imigineation, but it seems to run a little better at wot/high throttle. But still no matter what I do, I still can not get the little box in the datastream to say active, not even for a split seconds. So either I'm never going into PE, or its just not displaying that it is in the datastream.
I will have to do some more research on the matter.

[Bill USN-1]

Should be fairly easy to figure out.
You said you run the WB O2 into the stream didn't you?

Are you still in closed loop at WOT?
If yes then your not in PE.

Is the AFR still hovering around 14.7 and correcting?
If yes then your not in PE.

If the AFR drops to about 12.5 and maintains it until you let off the throttle then your in PE.

So, are you in PE or closed loop?

[JeepsAndGuns]

No, I have never said I have a wideband O2. I would like to have one, but do not. One day I will, but right now I am working on my mpfi build, so a WB is on the back burner at the moment.

So it goes into open loop when in PE? I know the open/closed loop dislpay part works. But I never really pay attention to it. I will definately look at it next time I make a run with the laptop though.