Like the title says, is the oem map that is used for open loop based on throttle position and rpm or map signal and rpm?

 

TPS.

MAP was added into systems like Hondata and NepTune for special circumstances. On a supercharged vehicle, for instance, the engine may be fed a lot of air even at light throttle.

 

Ok so this is what I'm doing. I have an obd2 Civic with emanage and I'm planning on forcing open loop by disconnecting the o2. Since the MAP is not used in open loop, the only way to tune is by throttle position?

Are you positive on this as well? On another forum, a member said its MAPxRPM, which doesn't really make sense to me. When I'm hovering at around 3500rpm in a high gear @ 5lbs boost, my a/f will be lean, but as soon as I go WOT, my a/f will instantly be a nice 12.5 (even when rpm doesn't change).

 

Ahhh, I mistook the meaning of your question because of how you worded it. It's clear you're a little confused about how this works.

Closed loop is disabled/enabled by TPSvsRPM stock, which is what it sounded like you were asking about.

The regular fuel maps operate by MAPvsRPM regardless of closed loop operation. Closed loop simply adjusts from there when it's active. There's also a table that adds in a little extra percentage of fuel during open loop which is also MAPvsRPM.

 

Well then explain this to me

If im cruising in lets say 4th gear at 3500rpm, with the full 5lbs of boost, my a/f is in the 14s. But as soon as I go WOT, the af's drop to 12.5 (with the same rpm, load, and speed, only difference is throttle position).

Also, I've unplugged my o2 to force open loop, and while the car is cold it idles at around 15:1, but once it's warm, its at 16 to 17:1. Is this normal? Technically shouldn't the af ratio get lower when the car is warmer since warmer air is entering, thus a richer mixture?

 

how are you "cruising" at 5psi of boost? anytime you are in boost, you need to be giving the engine fuel. turbo boost is load/rpm dependent (much easier to go into boost at light loads with a supercharger) and you cant cruise at a constant speed and be in boost unless you are going uphill.

TPS and MAP have some similarities. When you increase throttle percentage, you increase MAP pressure until then engine stops accelerating.

When you give the engine more throttle, it gives the engine more fuel thus the reason it gets richer.

I think you are having a hard time understanding what is going on and are using the wrong words lol.

 

First off, hitting the gas means you'll get extra fuel from TPS tip-in. Then, again, based on TPS vs RPM closed loop will get disabled which adds extra fuel.

As far as your warmup a/fs, sounds like you just need proper tuning. It will get leaner as it warms up. There's an ECT enrichment that is applied when an engine is cold and decreases as it warms up.

If you download the free NepTune software from hrtuning.com and take a look at some of the settings that are available for closed loop and fuel enrichments it'll probably help you understand what the ECU is doing.

 

Also, unplugging the O2 does not "force open loop" it sets the ECU into Fault Mode, which riches the mixture and retards the timing. It is a form of open loop, but not what you're looking for.

 

Are you sure? I thought this was only the case for later obd2 cars? Mine is a 96, the fuel mixture isn't any richer with it unplugged.

So the fuel mixture in open loop is based off MAPxRPM, with additional fuel added for TPS tip-in (I'm assuming this means quickly opening the throttle)?

 

turning closed loop off via engine management and turning closed loop off by disconnecting the sensor from the harness are two different things. You could just disconnect the sensor or remove the sensor altogether if you disaable closed loop in the tuning program.

When you disable closed loop in the program, you can tune the areas that closed loop had an effect on, tune the compensation tables for startup, warmup, intake temps,etc. When you fully tune an engine, it shouldnt need an o2 sensor making changes in the background.

basically, you need to go into your program and turn closed loop off.

 

it's that way for even OBD0 cars... a problem in the fuel delivery system causes fault mode. (some call it limp home mode, all though that's different in this case)

the initial fuel value is pulled from the table based on MAP and RPM, this is then used to figure out how much fuel should be applied into the engine based on ECT, IAT, VTEC output state, TPS, relative TPS position compared to past position (tip out and tip in) [tip in = quickly applying throttle, tip out = the opposite], the O2 reading is used if in closed loop... and a few other parameters I'm sure I'm forgetting right now.

It's really not as simple as one, two, three, this is the value. It's very involved and dynamic as everything with the engine is constantly changing.


BTW, of the three people that have replied, I'm the least involved in tuning. 98vtec and HRTuning know their stuff better than me.

 

Is this the same limp mode as not using a voltage clamp and letting the ECU see positive pressure? When that happens on my car, the car does run extremely rich. But with the o2 unplugged, it doesn't run rich at all (actually runs leaner than I would like).

So lets say I plug the o2 sensors back in and regain closed loop operation. Is there really no effective way of tuning for boost pressure while in closed loop with a piggyback, short of an o2 calibrator? Ideally I would like the car to switch into open loop at any sign of positive pressure. Am I asking too much from my emanage?

What do people with afc hacks generally do for closed loop boosting on an obd2 car?

When does the car actually transition from closed to open loop? Just a certain throttle position? I've heard 50%+, and I've also heard 90%+.

That actually did help quite a bit. Since I have my injectors scaled back from 190 to 240, the MAP signal is reduced going to the ecu (according to the emanage, by .25 volts, or 9 kpa). I was able to look at a stock map and see how much my timing is advanced because of this (only 3-4 degrees).

Thanks for all of your help so far. I really appreciate it.

 

you wont see any boost in closed loop unless you have it setup that way in the program. Closed loop typically turns off above a certain amount of vacuum or TPS input in stock form. When you go anywhere close to WOT, the ecu will open the circuit coming from the o2 sensor and thus will not get readings aka open loop.

Define what is really rich? When you are in boost, the engine MUST get fuel. No ifs ands or buts. The stock map sensor can read up to approximately 10psi so yea...

 

Unplugging the O2 actually does not put it in some limp home mode and it certainly doesn't effect timing. It does disable closed loop operation.

The software also shows the closed loop settings as well as some of the corrections you've asked about. That will answer some of your other questions.

 

Well I have a really small turbo (td04-15g), so boost around 30-40% throttle is possible. Around 3500-3600 at partial throttle the car is building boost and the a/f is at stoich. BUT, if I'm 70-100% throttle, at the same rpm and pressure (going by MAP voltage so like 3.4-3.6v), the car is running a nice 12 a/f.

As for the limp mode/open loop thing, my test went like this.

closed loop car is idling 14.7:1, went for a 5 pound run without voltage clamp, and the car was thrown into limp mode. Idle was then 10:1 to 11:1.

open loop (sensors unplugged), car idles at 15:1 cold, 16.5:1 warm. If unplugging the sensors threw the car into limp mode, wouldn't it be idling at 10-11 a/f like it was when I didn't clamp the MAP?

 

its not limp mode. The car will HARDLY run in true limp mode. it will not rev and barely drive. There is a rev limit of 3000rpm in this mode. disconnecting the sensor just gives the ecu an error, an error meaning the ecu is no longer getting help from the o2 sensor to adjust fueling and it reverts to the base fuel tables. You arent going to get anywhere trying to fix a closed loop system that isnt running an o2 sensor. All you are basically doing is confusing the ecu. Take your setup to a tuner who is familiar with the program or upgrade to something better.

what do you mean by a voltage clamp? your term usuage is getting a little confusing.

I dont know what emanage you are using but i highly doubt it has the options that Hrtuning and I are referring to. If you want this thing to run the right way (being able to adjust closed loop shut off, turn off closed loop, etc) then you need to get an engine management system that will do it. Those piggy back systems just are not near as capable as the OBD1 managements.

You can contact either of us if you are interested in learning more about neptune.

 

lets get some terms straight....

failure mode - failure of a secondary sensor that relates to the fuel delivery system. (O2, knock sensor, IAT, ECT, etc) ECU runs the engine directly off the maps, with some fuel added to prevent causing issues due to it having no idea how the engine is running.

Limp Mode - failure of a critical sensor, you're literally simply trying to get the car to run at this point. (missing distributor sensor, internal ECU failure, etc) ECU runs the engine at primal settings, 3k rev limiter, super rich, pulls a ton of timing. Again, runs but barely.

Voltage Clamp - does the same thing as a missing link, prevents the ECU from seeing boost readings from the MAP sensor.


BTW, I'm refering to how the stock ECU handles things; Neptune, Hondata, Crome, eCtune, EManage... may handle things differently.


OP: you mention emanage and a voltage clamp, how is the emanage seeing boost if you have the MAP sensor clamped to not show positive pressure?
or are the terms being used getting skewed somehow?


Lastly, I agree with 98vtec, emanage is worth its weight in diaper filler when compared to any of the other honda tuning tools out there. Even the free tools (Uberdata or Crome Free) would be better. Neptune, eCtune or Hondata would be light years ahead.

 

I have the emanage set to clamp the MAP sensor voltage at 2.9v. The emanage still reads the sensor to the full 5v (actually reads to 4-4.2v on my car considering my 5-6psi boost), but only lets the ecu see up to 2.9v. So I can still tune via the stock sensor, its just everything after 2.9v is given the values at 2.9v and I need to alter the emanage fuel map to compensate.

So pretty much 0-2.9v is the 0-2.9v ecu values, and 2.91-5v is 2.9v PLUS emanage corrections.

I know an obd1 conversion would be ideal, but I am determined to get the piggyback working on my obd2. I think of it as a learning experience.

Since my injectors are scaled back by the airflow map, it alters my timing. When the MAP sensor is reading 1v lets say, the emanage is letting the ecu see .75v. I did some conversions and it turns out to be right around 9kpa difference, and looking at stock d16 maps, this is averages a 4 degree increase. So theoretically I should retard my timing -4 degrees across the board, correct?

 

the ignition issue is the main reason why I'll never use piggybacks like you're trying to do... what convinced me... http://wikitest.pgmfi.org/twiki/bin/...PiggybacksSuck

ignition timing can make and break engines... very quickly too. you're 4* average may work fine, but if it is off under heavy load, you may end up rebuilding sooner than you want to.
Your desire to learn is admirable, but you're learning on a very slippery slope. One that's been trecked many times and easy to avoid.