Open Loop Strategy?


Test don't Guess
Aug 29, 2017
What is the open loop strategy for a power logger system? Problem I’m having is that when I start it cold in it will start but die. So I throttle it to keep it alive. Runs like crap even into CL but if I shut the car off after it gets above 150 degrees, then restart, it idles good with the WB hanging around 13 – O/2 around 750 but if you stab it the O/2 bottoms out to ZERO – WB hits 22+.
Did a fuel flow and it was low so I got a Racetronix 255 with their HW. No difference.

So with that said why does idle change after warm only if I turn the car off and re-start it. Almost like a re-set. It shouldn’t.
Why am I running lean? Seems like I should change something in the tune but the first problem is in Open Loop and the second is it stays lean.

TPS is right .43-4.6 Coolant temp is reading right. New MAF “same as old MAF” Idle 5.+
It’s a new reman ECM. I think It’s a strategy of some sort. Chip/ECM/Tune. Any suggestions?

1986 Grand National WE2 - Stock bottom - Stock heads - Stock Turbo
6.1 TT / 60# FlowMatched Injectors.
Racetronix 255 with their HotWire
Accufab regulator
Innovate WB
Heated 0/2
RJC FMIC Mega IC-475
CAT Deleted.
3" Stainless Exhaust
All new Ignition
In the case of the TT 6.1 chip, the PowerLogger is not involved with the control of the engine, but is only a monitor (it does process the wideband signal for the ECM and a few other things)

So, Eric can answer better about the cold start vs warm start strategies. But record some logfiles of the cold and warm starts and we can take a look.

I figured he would be the one that may have an answer. I cross posted on the TT forums as well. The lean thing is crazy. With a factory ECM being ROM I kinda figured it would still be the same, But being new to the PL I didn't know if there was some fancy voodoo I would be allowed to do. If he doesn't see or not able to respond by tomorrow I will hook an external fuel supply up " Snap ON Inj cleaner" as well just to make 100%. It ran good before the big change and oh yeah the ECM crap out, lol.
Yes I just saw your post over on my support forum. Lets see a log of the cold start so we can see what it's doing.
I screwed up the data file on dead cold but here it is after its already warm and in closed loop. This is with an external fuel source as well. And since I could I hooked up 3 more grounds at random spots on the engine. Still goes dangerously lean. If I was trying to drive.. I would be buying a new engine. This is with race gas.


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This is 2nd attempt. Unlike above if I wasnt throttling it would die. This is with out external fuel source. The KOEO drop outs on CTS was a little concerning hence why I hooked up extra grounds.


  • 2nd start 11-19-17.dat
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Your MAF reading is too low. When you started it up on the "2nd" log, the MAF reading should be much higher. You can see it's stuck on 4.6 gr/sec, which is actually the bottom limit in my chip.

I know you said you changed the MAF, but it's still not right. If you're using stock style MAF's, it might take a while to find a good one.
Got ya.. But I think there's something else. At half throttle when the big drop out happens the MAF is 33. and some change, GM likes to have around 45 so I see its low so I knew it was a player. Ill try another, this is the 3rd one, lol. Does yours reach 140+HZ at WOT or does your scale max at 128?
Thanks for the reply. I'll let ya know
OK I actually looked at the 2nd and yeah it's almost dead on that one. Sorry I was focused on the 3rd, which isint great but dam atleast it was there. I'll try another real quick.
New MAF - Absolutely has better manners but still stumbles on decell and still goes really lean. The stumble could be a dirty TB and a host of other things.. But the lean thing. Is the O/2 going lean - Is this normal for these cars. Stock cars goes lean for the ECM after a decell but will hit rich on WOT. "Good tip to see if you have a fuel delivery issue". Eric was right of course But still not understanding the lean thing.


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I don't any lean spots in that log.
But in general, since you changed the MAF, you need to reset the ECM to reset the fuel trims (BLMs). Then drive it around to let it relearn.
I would also adjust the IAC to 10-20, warmed up, in park, which might help with the idle speed dropping down when you let off.
So here is MAF #6.. It will start and run, actually to the point I thought I could at least put a mile on it.. WRONG. Now it runs so rich its ridiculous. I think it's still the MAF. So funny go from lean to rich.. Just cant find the middle. I'm not used to seeing Gp/s on MAFS. Gp/s are calculations and not input actual. We us HZ. So I decided to use the Pico on it. There are no drop outs and I can see it's trying to gulp in air but of course it stumbles so hard of course I will see some drop out. Is this the main reason everyone goes to the LT MAFs? Seems like just going SD would be the better way if I'm forced to give up on a reman MAF. Not possible that I went too big on the Chip/Injector 6.1/60# size with a stock turbo is it?


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Everyone goes to the Translator and aftermarket MAF. Trying to get a correctly calibrated stocker can be a nitemare. I think Kirbans are the only ones that sell correctly calibrated stock MAFs. 60's are fine with a stock turbo.
I figured they were, INJ Duty% are in line. Do you feel like just going SD would be the smarter move if cash wasn't an issue?
I figured they were, INJ Duty% are in line. Do you feel like just going SD would be the smarter move if cash wasn't an issue?

This is what I recommend. IF you understand SD...then by all means yes. If you don't...then stick with a 5.7 or 6.1 setup with a Translator and LT1, LS1 or Z06 MAF.