japery

Im running only in the summer months with a 77 vette with HSR and wondering if i really need closed loop? I dont have emissions to deal with and I dont have a good grasp on tuning. Can I turn it off some how?

ULTM8Z

What year is your TPI system from? If its 90-92 you can run the SAUJP bin which has an open loop feature you can activate.

the thing is, switching to open loop isn't a cure all if you have tuning issues.

the only other way to do it is disconnect the O2 sensor, but thats likely to generate error codes.

RBob

iTrader: (1)

Easiest way to disable closed loop is to set this parameter to a high temperature:

L8489: FCB 120 ; 50C, (122F) MIN COOL FOR CLS LP

RBob.

ULTM8Z

Good point. Forgot about the temperature aspect of it.

japery

Im using the 91 AUJP 1227730 ecm. Iv got the Moates hardware and Tunerpro RT software. Bought all that stuff but forgot that i cant understand any of it. Iv been slowly learning but still have major issues with the tune.

heat seeker

iTrader: (5)

I run in open loop all the time. Disabled it with temp setting. Since it's a performance build I wasn't looking for good mileage, and no emissions tests here either.


Made tuning so much easier.

ULTM8Z

I run open loop at idle, but that was after years of trying to dial in the Miniram idle and off-idle transition until I finally "flipped the bird" to the ECM and disabled closed loop idle... But you need S_AUJP to do that (I have mine set to go back into closed loop at 1500 rpm... when I'm fully out of idle).

Otherwise, you can disable closed loop as RBob suggested, but it disables it everywhere.

I whipped the non-idle, non-WOT operation into line by playing around with the O2 voltage thresholds to richen it up (kept wanting to give me a ~15.5:1 AFR as reported on the WB, even under moderate, non-power-enrichment acceleration). If it wasn't for that, I probably would have gone fully open loop as well. But as it stands, it runs extremely well in closed loop. I actually tried full open loop once just to compare, and it didn't run any better than my dialed-in closed loop.

That said, if there are "major issues" with the tune, switching to open loop is not going to cure it. For one thing, Power Enrichment, Accelerator Enrichment (and by definition, open loop itself) are areas where switching to open loop won't help anyway.

japery

How did you disable the temp setting?

japery

I have 10 to 1 compression, better heads and a bigger cam,so the stock bins are giving me problems. its running VERY rich.

ULTM8Z

In TP, do the following.... and then set the temperature to something ridiculous like 300F.

ULTM8Z

Depending on how much "bigger" the cam is (which is really what's going to drive the tuning, much more so than the compression and heads), it's not likely going to open loop will solve all your problems.

What you should do is get a WB O2 sensor on there, hook it up to TunerproRT, then take some data so we can see what your issues are. There are guys on this board who do custom chips... TunedPerformance, MrWilly's, etc... They can take your data and do your retune if you're not up to doing it yourself.

Most likely it'll be a matter of recalibrating the VE and spark tables as well as the open loop and power enrichment tables. After doing those things, and if you're getting hesitation or bogs, then you'd need to work on the accelerator enrichment tables as well.

japery

Cam Type: Flat Tappet
.480 Intake .486 Exhaust
229 Intake / 230 Exhaust duration
@ .050

japery

And thank you for the help. Not only do I have to learn the software and hardware but I have to figure out how to navigate all the different tuning forums.

ULTM8Z

Yeah, I'd imagine a factory tune having problems with that cam...

I think you can probably stop looking for tuning forums. It doesn't get any better than thirdgen.org for OBD-I tuning.

heat seeker

iTrader: (5)

My car idles just fine can drive around town fine, and cold/hot starts are dead on. But I'm using a WB gauge and a Tunerpro RT dashboard with all my data logging gauges on one screen.

I'm not saying it was completely easy, but it was enjoyable and I get exactly what I was hoping for. I wouldn't even try tuning a large cam in closed loop, which is really for fuel efficiency.

ULTM8Z is correct......switching to open loop won't fix major tuning problems.

Mlm0

Tuned Performance

iTrader: (92)

You can raise cl enable temp degrees. This will disable cl until the desired temperature is hit as long as the o2 is warm enough. AFAIK you can’t just have ol at idle it’s all or nothing.