dizwiz24

Hello!

I tried setting power enrichment throttle position thresholds to 0 for 400 and 800 rpm to bypass closed loop and achieve an open loop idle.

It does NOT work. When starting the car up cold, after battery has been disconnected, it still settles right into closed loop idle.

Its like it completely ignores the fact ive put 0% throttle into the 400 and 800 rpm columns....

(If youre wondering why i want an open loop idle, its because the overlap in my cam tricks the ecm into thinking its seeing false air and it dumps fuel. No amount of tuning can fix this other than an open loop idle. At higher rpms (highway cruise), its not so much an issue)
http://smg.photobucket.com/user/dizwiz24/media/TPS%20threshold_zps4z1ruryh.jpg.html?sor t=3&o=0

FrankieD

can you provide a datalog to see what the BLM/INT are doing at idle?
I would suspect your idle RPM is not in that range. You may have to zero out the 1200 rpm (%TPS) value as well

dizwiz24

Frankie D:

Typically it idles around 875 rpm, so having 0% throttle trigger PE should have me covered @ 800 rpm, or am i missing something?

FrankieD

If you are idling at 875rpm you are not covered. Like I mentioned previouslyl you need to zero out the 1200 rpm value (%TPS).

The way you have it now you are only covered up to 800rpm.
I will explain how the Tables are viewed:
"400" rpm box represents (from 0rpm up to 400 rpm)
"800" rpm box represents ( from 400rpm up to 800 rpm)
So the "1200" rpm box represents (from 800rpm to 1200 rpm" ) and this is range value you are at for 875rpm idle.

dizwiz24

Ok. If you are sure on the rpm boundaries then This is a problem.
I want closed loop operation for highway operation.

At 65 mph, 6th gear, i am seeing 1500 rpm.

I can only adjust power enrichment tps threshold cells at 400,800,1200, 1600, 2000, etc
So the method you propose would not allow for closed loop operation at less than 1600 rpm.

So id be running open loop any time less than 1600rpm on the highway which would be bad for fuel economy.


Can i leave 400 and 800 rpm pe thresholds set to 0% but change blm cell rpm boundaries (currently at low 850 rpm, mid 1200rpm, and high 2000 rpm) to do something favorable to my situation?

For example if i raise low boundary rpm to 1200 (with pe throttle thresh hold set at 0% for both 400 and 800 only) will that make it not do closed loop until 1200 rpm or up?

tequilaboy

If your tune is pretty close in other areas, you can always limit the authority of closed loop by limiting the min and max BLM to +/- 8 and limit the min and max INT to +/-12 or similar values.

If you run up against the limits...improve your tune or adjust accordingly. Just keep an eye on it when conditions change (cold weather).

dizwiz24

I dont trust my other ve values enough to do that! Also, there can be Altitude changes, temp, etc.

Btw i did (just today) raise min and default pulse width to 1.69 msec (up from 0 msec default and min for stock $da2)

You had suggested this to me 2 years ago due to split left/right blms. (One side had settld around 120 and the other arnd 138).

The reason why it took me so long to do that was because i couldnt find the table in tunercat. But just yesterday i found those settings under the 'constants' (Duh!)

I will see how that works out. Perhaps i wont need an open loop idle to help out with the exh smell issue at idle..

Specs on my car:
60 lb inj/ 93 6spd vert/ $da2 with 2 bar map via tunercat /224/236 lloyd elliot 114 lsa cam/ supercharged p600b 12.5 psi boost at 6000 rpm / meth/water inj

FrankieD

I think you are misunderstanding what you are trying to accomplish.If you set the 1200 rpm cell (TPS%) to zero. This means that whenever the TPS% is zero and under 1200rpm you will be in PE mode. This will not be the case if you are at Highway speed in 6th gear as your TPS% will never be zero. Only if you totally lift off your gas pedal on the Highway..which is rare

dizwiz24

Sorry i must be having a hard time understanding the definitions/ boundaries of these settings.

Its cAlled threshold. My understanding (which might be wrong) is that once its crossed, its in power enrichment mode until it sees the next rpm (and its threshold Requirement).

If the rpm threshold at 1200 rpm (the next step) is set at less than the throttle position %, it will remain at PE.

Or if its set higher, then the throttle position needs to be higher than its set point to maintain PE else it goes into closed loop.

Setting the TPS theshold to 0% would mean any throttle % 0 and greater would trigger PE mode (if in the rpm range that is commanded to have a 0% threshold).

So the highway crusing you mention (ex. 4% throttle) would still be greater than 0 (where you have the threshold set at for the rpm range you are in) and it would have to be in power enrichment.

FrankieD

I must apologize, as my explanation was not completely correct with regards to the Highway cruise rpm.

If you put the value zero in the 1200 rpm cell ( for TPS% PE) this means that any rpm up to the 1200 rpm limit and with a TPS% above 0% would enable PE mode.
So in your case at highway speed with rpm of 1500 rpm will not be in PE mode as it is above the 1200rpm.

dizwiz24

Awesome. Thank you for clearing up my misunderstaning.

Totally understood about the threshold (as i thought).

You have turned my tuning world 'upside down' by mentioning that the next rpm in a table is not where the entered value (for that rpm up to the next rpm entry) starts, but rather the endpoint of where it stops. (Between that rpm and the rpm before it).

Are you 100% sure on this? Is it like that for all the tables?

For example pe mode %fuel adder vs. rpm.
So consider a hypothetical table below:
3600: 5%
4000: 10%
4500: 15%

In the past i assumed that from 3600 to 3999 rpm that table commanded 5% fuel added

Only until i hit 4000 rpm would it begin adding 10% more fuel.

now you are saying i am wrong and between 3600 and 3999 rpm it would be adding 10% more fuel.

Once it hit 4000 rpm it would add 15% more fuel because thats what i put in at 4500 rpm.



If I am wrong, this explains why i thought zeroeing out the PE TPS threshold table ONLY to 800 rpm would satisfy my goals of an open loop idle.

BTW using tunercat $da2 for 2 bar MAP

FrankieD

CORRECT
The value of the RPM Cell represents the upper limit(rpm) for that cell