I getting ready to order prom burning equipment the victim I will be trying to learn to tune; THE STEPCHILD 6870. How much trouble is this child going to be for a very green beginner.MR. KIDD Norfolk VA. Anyone in this area that could give some hands on help would be very helpful.Thanks for all or any replys.

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Not to discourage you or anything. But from what I have gathered threw notes and reading. The 870 has the baud rate of a TBI computer(160k), and is trying to run a MPFI setup. Has very little memory capacity and i don't know of anybody on here that runs one...

Brendan

 

I run that one too....can't burn squat since I don't have the ECU file for WinBin...I guess it depend what you wanna do...if you are like me, where the car is a daily driver, then I think it's worth to stick with it and burn a "better chip"...if you go in the Racing end, then swap the ecm....

 

Maybe I am missing something here how was GM able to make it work in the 85 corvette I know the programming has to be different than it is in a 85 Iroc.

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All they did was change the Calibration(prom chip) for the 85 vette. You should be able to download a vette imagine off of diy-efi.org

Brendan

 

The ECM is wired differently, therefore you can't run a Vette chip in an 85 iroc. I have tried, I baught a stock vette chip hoping it would work, but it didn't...now if you use the calibration out of the vette and burn it yourself, then yea, it would work...
When I put the vette chip in my IROC, the check engine light stayed on, and you couldn't put the ECM in test field mode, nor get the codes out...I've tryed it about 6 times....then I looked at the wirering diagram for Vettes, and there are some diffrences...that's too bad for us...guess GM new some guys like us would slap in a 350 in those IROC....

 

The absolute best you'll be able to do is OK. The ecm is slow, the program primitive, the communication rate slow.
The reason it's an orphan is that no one wants one, when there are better ecms available.
I'd strongly suggest you research what is possible. The easy way ain't easy if it's a headache

 

I will give my thoughts on this.
The 870 will do OK. let me firstsay this.
I ran a 14.3 with a 99.00 performance resource chip. with that smae chip and engine mods I ran a best 11.98. The 85 is very forgiving. My bud runs 11.55 in his 85 383 vette with the 870. My other bud runs 11.8's with a 350,afr190,219cam and the rest of the normal bolt ons.
The problem will be learning HOW TO TUNE with the 85 ecm. data is very slow. its gives no timing advance or retard info. very,very general.
Also when linking with diacom(not shure on other data loggers)
Daicom adds 3-6 degrees of timing when linked. Well its not diacom but the load on the serial data,ecm....
I did confirm this a while back with Jim formato.
The tuning table are also very general. You dont use the injector constant like 86 up. You have to tweak the base LV8 fuel constants.

If you wanted to spend $$$ on a formato or ed wright chip then that may work fine for you but if learning how to program for yourself I would upgrade to the 165 or 7730.

Dennis

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85 vette,383,miniram,ZF6,4.10's..best ET 11.56@119.00 60' 1.59
w/100HP nirous 11.05@127
http://geocities.com/bowtie8

 

Performance resource did the one in my vette and my Iroc they had some trouble the one in my iroc so I sent them my old vette prom and they worked it from there it runs ok just needs that hands on touch up. Thanks for the replys and keep them coming. NICE TIMES BOWTYE8.

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OK so what did they or you actually do to the chip?.
This is about DIY Prom stuff, while you had great luck with an aftermarket chip that really doesn't mean much in the light of what this list is about.

C3s can be worked with, but without a full hac, it's real difficult. There were lots of GN running 10s at Bowling Green last weekend with the ol 148, but it's been a long road to figure the ecm out to get them to do that.

Toss in old MAFs are falling out of the sytem now, and to continue with an ecm that doesn't have the sensors to go with it is a slippery slope.

 

For most of the 85 chips I have seen. I would say 70% of them only adjust timing tables. Hypertech Seems they like to run off the knock sensor becuase they have the highest timing values .

My info was a little off topic. But I justed wanted to show the 85 870 ecm will get you down the performance road.
easy to tune ...NO. Should you start programming your first chips form the 85 ECM....NO. If you have done some chip programming then go for it.
bowtye8


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85 vette,383,miniram,ZF6,4.10's..best ET 11.56@119.00 60' 1.59
w/100HP nirous 11.05@127
http://geocities.com/bowtie8

 

I am getting ready to purchase the equipment to burn the chips with so I could not tell you what was done I hope at some point I will be able to tell what was done.I see 870 isnot the one to learn on but before I try to upgrade I think I will have to try, notthing lose I hope I can get some help from all of you.THANK ALL OF YOU for all of excellant information.