Open Loop Learning or Tuning?
Thread Starter
Safety Car
Joined: Sep 2003
Posts: 3,597
Likes: 22
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
Open Loop Learning or Tuning?
I've got an '87 with a Mini Ram 383. It has been sitting for quite a while (battery disconnected), but I finally got a chance to fire it up today. I am using a mail order PROM tune (from Formato), and plan on going for a dyno session this spring to help fine tune it.
When I first started it up, it ran pretty rough (hesitation, rough idle, seemed to be loading up, running rich, etc) while in Open Loop mode. Once it switched to Closed Loop mode, it got better, but really didn't start driving / idling well until I made a few WOT romps (within the speed limits, of course!) to clear it out. Once in Closed Loop mode, the BLM and INT numbers were right on 128 (which actually surprised me - I figured I would see a slight deviation from 128 since this was the first time with the new chip and the computer was still "learning"). Is dead on 128 for BLM / INT normal for a new chip right out of the box?
When I got home, I pulled a few plugs. They definitely looked like they were carbon fouled at one point (carbon at the end of the threads / base of the ground strap, and a little at the porcelain base), but the ground strap, center electrode, and MOST of the porcelain looked fine.
I am thinking that it was running rich in Open Loop mode, but once I got to Closed Loop (and "cleaned it out"
), it was able to run where it should be.
My question is - does the computer "learn" in Open Loop mode as well? Meaning - as long as I don't disconnect the battery, will the ECM eventually come up with an ideal cell(s) for cold, open loop start up, so that it is not running so rich until it goes Closed Loop? Or not, because it doesn't know that it is rich? Is this something I need to address with my tuner and the PROM chip?
Sorry for the long post. I also posted in Tech / Perf, but it probably belongs here.
Thanks very much!
Dan
When I first started it up, it ran pretty rough (hesitation, rough idle, seemed to be loading up, running rich, etc) while in Open Loop mode. Once it switched to Closed Loop mode, it got better, but really didn't start driving / idling well until I made a few WOT romps (within the speed limits, of course!) to clear it out. Once in Closed Loop mode, the BLM and INT numbers were right on 128 (which actually surprised me - I figured I would see a slight deviation from 128 since this was the first time with the new chip and the computer was still "learning"). Is dead on 128 for BLM / INT normal for a new chip right out of the box?
When I got home, I pulled a few plugs. They definitely looked like they were carbon fouled at one point (carbon at the end of the threads / base of the ground strap, and a little at the porcelain base), but the ground strap, center electrode, and MOST of the porcelain looked fine.
I am thinking that it was running rich in Open Loop mode, but once I got to Closed Loop (and "cleaned it out"
), it was able to run where it should be.My question is - does the computer "learn" in Open Loop mode as well? Meaning - as long as I don't disconnect the battery, will the ECM eventually come up with an ideal cell(s) for cold, open loop start up, so that it is not running so rich until it goes Closed Loop? Or not, because it doesn't know that it is rich? Is this something I need to address with my tuner and the PROM chip?
Sorry for the long post. I also posted in Tech / Perf, but it probably belongs here.
Thanks very much!
Dan
Thread Starter
Safety Car
Joined: Sep 2003
Posts: 3,597
Likes: 22
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
Hey Mark!!
From what I can tell (and have read) - you are right! Nothing to learn in open loop mode.
I believe it is something that Formato can re-program though - just need to make sure.
Once the car went into closed loop and I made a few WOT runs up the road (within the speed limit!), which seemingly cleaned up the plugs a bit, it ran FREAKIN' GREAT!! HOLY CRAP THAT THING IS FAST!! There seemed to be no upper rpm limit, though I kept it under 6k. I was really impressed, especially with part throttle cruising, where I had a lot of issues with the old chip. It seems the Formato tune is pretty damn close. With info from a dyno session, they should probably be able to get it right on. I'm glad TJWong steered me in their direction - the Formato tune seems a LOT better, especially during part throttle cruising. The cam surge is hardly noticeable now, which was another issue with my old tune. Bottom line - i'm happy
Dan
From what I can tell (and have read) - you are right! Nothing to learn in open loop mode.
I believe it is something that Formato can re-program though - just need to make sure.Once the car went into closed loop and I made a few WOT runs up the road (within the speed limit!), which seemingly cleaned up the plugs a bit, it ran FREAKIN' GREAT!! HOLY CRAP THAT THING IS FAST!! There seemed to be no upper rpm limit, though I kept it under 6k. I was really impressed, especially with part throttle cruising, where I had a lot of issues with the old chip. It seems the Formato tune is pretty damn close. With info from a dyno session, they should probably be able to get it right on. I'm glad TJWong steered me in their direction - the Formato tune seems a LOT better, especially during part throttle cruising. The cam surge is hardly noticeable now, which was another issue with my old tune. Bottom line - i'm happy
Dan
Burning Brakes
Joined: Aug 2004
Posts: 1,110
Likes: 1
From: Geneseo Illinois
St. Jude Donor '06
Originally Posted by byebyeL98
Hey Mark!!
From what I can tell (and have read) - you are right! Nothing to learn in open loop mode.
From what I can tell (and have read) - you are right! Nothing to learn in open loop mode.
Yeah, i was quoting CFI-EFI, i figure if i post an agreement with everything he says i ll be an expert in no time!
He knows his stuff.
