Honda D Series Forum banner

1 - 14 of 14 Posts

·
Registered
Joined
·
16 Posts
Discussion Starter #1
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?
 

·
Registered
Joined
·
2,515 Posts
MAP / RPM. TPS generally only used for enrichment when rapidly opened.
 

·
Registered
1993 Cobra
Joined
·
4,036 Posts
MAP(manifold absolute pressure) sensor reads the amount of pressure in the intake manifold. It uses a certain voltage for certain parts of the rpm range to vacuum. At wide open throttle, theres hardly any vacuum so the voltage gets adjusted and is then sent to the ecu to take away timing and add fuel.

TPS(throttle posistion sensor) tells the computer how much throttle(again in volts) and load the engine is under, which works hand and hand with the MAP sensor. Then gives its .2 cents on how much fuel to add.


What car are you trying to tune? Is it obd-0,1 or 2?
 

·
Registered
Joined
·
16 Posts
Discussion Starter #4
I'm tuning my obd2 DX with emanage. After messing with it for a while, I have decided to just run open loop all the time so my ecu doesn't try and correct any adjustments I make (unplugged the o2 sensor). I've installed 240cc injectors and scaled them and I get a nice 14.9-15.5 a/f at idle and cruising. Boost clamp is at 2.9v which is right around 0 vac.

For everything above vac I have minimal fuel adjustments (since the injectors are 240s and the ecu gives the pulse width for 180s, the car runs a lot more rich. I only have a rough tune right now 2.8v-3.2v is 5-9% increase, 3.4v-4.2v is 7-11% increase. I need to up the 2.8-3.2v (a bit lean entering boost) and lower the 3.4v-4.2v (10.5ish a/f). I feel like I'm finally making headway with obd2 and piggyback. I might lean up cruising a/f as well.

I have a question though. Since the injectors are scaled back, it subtracted .25 from my map signal, which increases the timing. Does anyone have a general number that I should retard my timing across the board, given this advance? Also, since the MAP is clamped at 2.9v, everything in boost is given the timing figures at 2.9v, right?
 

·
Registered
Joined
·
16 Posts
Discussion Starter #5 (Edited)
update:

After the car has been running for a while, the idle jumps up to 16-17 a/f. I thought open loop was supposed to run slightly rich..? Also, the idle likes to run a bit low once the car is good and warm.

Are you positive on MAPxRPM? It 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).
 

·
Registered
Joined
·
16 Posts
Discussion Starter #7
Speed might not change, but manifold pressure does, and that's what really counts.
But the manifold pressure stays the same @ 5 pounds. So manifold pressure, speed, and rpm stay the same, but the a/f is lean at low throttle and rich at WOT.
 

·
Registered
1990 civic 4 door LX
Joined
·
2,121 Posts
I had a big issue understanding this. The oem maps are based on a MAP x RPM scalar.... the TPS gives it .02 cents yes BUT it is an extremely vital part that if you don't have both your better off not running. If you have one and not the other your are better off of a TPS based tune...

I broke a tps and it really made things a problem. Cracking throttle studders and stuff like that. Notice how quick even an n/a car pulls from vac....? Tps has to cover the rest of the adjustemnts ass...

The tps enrich plus how it switches a little (how fast the throttle is cracked / how much it is.. it won't ad the same amount of fuel from 25-50 percent throttle. Or timing.. it will do a lot more adjustment if a shift or 0-say 50 percent throttle is applied. Its how fast and what the computer can remember of how the car is being driven.... (like beating on it getting it hot will cause issues with the tune because it will want to richen up and retard timing fior boost based on ect and cause more issues.. piggybacks work but it sound like you need more time with it before your done..

When scaling the map back they don't really get aggressive until 7 inches or so before the end of vaccum... idle-7" will be harsh timing for partial throttle cruising.. after that it will get closer to wot voltage... you will probably have to pull 6-10 degrees depending on how much you end up pulling the map sensor back and for across the ecu maps...
 

·
Registered
Joined
·
16 Posts
Discussion Starter #10
(like beating on it getting it hot will cause issues with the tune because it will want to richen up and retard timing fior boost based on ect and cause more issues
Wouldn't this only matter if the car was running in closed loop? I didn't think there were any fuel or timing trims if the car is running open loop all the time.
 

·
Registered
Joined
·
16 Posts
Discussion Starter #11
(like beating on it getting it hot will cause issues with the tune because it will want to richen up and retard timing fior boost based on ect and cause more issues
Wouldn't this only matter if the car was running in closed loop? I didn't think there were any fuel or timing trims if the car is running open loop all the time.
 

·
Registered
1990 civic 4 door LX
Joined
·
2,121 Posts
Ect. Ait and the such. There are other variations. What if a your tps isn't hitting above a certain percentage. Let alone just unplugging it will make it run different almost everytime you drive it... sometimes cars don't have issues and some do... weird idle.. smelly... timing issues that you might already have. Like not knowing how many degrees you need to retard and the such...
 

·
Registered
97 honda coupe
Joined
·
7,611 Posts
All closed loop does is modifys the maps according to the o2 sensor the tps and the map sensor according to formulas. When in closed loop the computer monitors the o2 sensor and your throttle position/rpm and speed and calculates how much more/less fuel to add according to the AFR's that the o2 sensor is seeing. so thats why when you have a bad o2 sensor it runs rich because the ecu goes into open loop mode all the time. Wich the open loop maps are tuned for a car full of people going up a mountain. The closed loop condition allows the ecu richen or lean out the maps within a certain percentage (its about 35% both ways.)

Also, any time you go full throttle your not in closed loop anymore, when you go past about 50% throttle, over 4500 rpm's or have a lsmall load under that rpm it will stay in closed loop and monitor/ adjust accordingly Allthough if you do have a large load, it will switch into open loop due to the map sensor, sensing high load conditions (high vacuum).

Now if your in open loop the other settings like IAT temps ECT temps and what gear your in still attribute to final output of the timing and injector offset.
 

·
Registered
1990 civic 4 door LX
Joined
·
2,121 Posts
I still assume there has to be a small amount of change going on because then why would he have these issues. If your correct then its just his adjustments and I see the problem so goodluck... can't wait to see the outcome. I fuck with quite a few piggback systems...
 
1 - 14 of 14 Posts
Top