Critique my idea that might help people with piggyback fuel controllers

[virus77]

PLEASE READ

Alright I have this idea that can possibly help people that have piggy back fuel controllers as fuel management but I wanted to bring it up here to see if there is a gap in my logic and to get a few leads on a device im looking for to make this happen, here it goes it may seem offtopic at first but read along as I will explain myself.

I got the idea from a article I read about making a toyota prius more efficient while not using the electric motor by allowing a more aggressive fuel map during all motor operation by bypassing the 02 sensor. This got me thinking a similiar thing might work with our cars in a different manner, please read along. basically in stock form the prius would use the o2 sensor to keep a 14.7 afr for emmisions/fuel saving, in fact on a prius even at WOT it keeps it at 14.7 being the fuel saving/enviro car that it is. The guy writing the article wanted better performance due to his uphill drive every day so after alot of work he came up with this. He would have a device (which wasnt mentioned in the article, but I was hoping I could get help about this here on NICO) that was wired into the 02 sensor circuit. The unit also took in another voltage input and would open/close a circuit at a given voltage, in this case being the o2 sensor connection to the ecu. When a certain voltage was reached via the TPS i believe(could be mafs, MAP sensor, i can remember but read on it doesnt matter) it would disable the o2 sensor circuit to the ecu, therefore not alowing the ecu to adjust to 14.7 afr with no sensor present, and it would throw the car into a default rich map which yielded an 12 or so AFR. In this scenerio he didnt even have a fuel controller (safc, emanage, etc) and with that alone gained like 10 hp/10tq and it allowed the car to not be affected by the 02. It also had no adverse effects swithing back to a 02 sensor operated car when the voltage droped lower than the switchover point so you would still get good gas milage while cruising.

NOW HERE IS WHEN OUR CARS COME IN

We have a problem on piggyback opperated cars where on part throttle the car wants to keep the 14.7 AFR. Now normally aspirated thats fine but at 10-15 percent throttle the KA boost my car to 5 psi no problem in fourth gear and the ecu has no idea of this as it thinks were in cruise mode and this leads to lean conditions and non tunable maps so to speak. My idea for our car is as follows. Have a similiar circuit disable our 02 sensor when a certain voltage is reached. In my case I have a electronic boost controller in which the boost sensor sends a certain voltage, as do most other sensors. So lets say from 0-1.99 volts its vacuum, and 2-5 volts is boost (just an example) I would set the device at 2.0 volts to disable the 02 sensor circuit. So now whenever the car sees boost the 02 sensor will be disabled throwing it into a default map like when you are at WOT (open loop), which is not effected by the o2 sensor so it can be controlled by a piggyback without the ecu trying to fight your adjustments via the o2 sensor (more accurate, more standalone type fuel adjustment). If a boost sensor is not available, MAFS voltage can be used as well, just pick a number that is normally in boost range.

Assuming we have a boost senor for arguments sake lets look at the diagram bellow and now ask questions and critique away so I can further explore,elaborate or quit cuz my idea is missing some logic. It seems doable to me and it would be a nice thing for the piggy back boys, I bet it would retard timing some aswell. If some of the more educated members on the board can verify some potential i would be willing to try it and datalog timing and AFR and everything, i have the tools. I JUST DONT HAVE THE DEVICE I SPEAK OF, IT THINK ITS A SIMPLE DEVICE I ASK OF SO HOPEFULLY SOMEONE CAN HELP ME OUT

I will be back in an hour or so to check on this there better be some good responses

EDIT: DEVICE FOUND, thanks to Red-kat, waiting for trial run

Modified by virus77 at 6:26 AM 3/15/2005

Modified by virus77 at 7:02 AM 3/15/2005
Modified by virus77 at 11:01 PM 3/17/2005

[hannibal]

Ouch, I have a headache. I'll reread it tomorrow...

[LEMHEAD16]

I am gonna run this by my brother in law. he is an engineer and would love this.

[virus77]

I am gonna run this by my brother in law. he is an engineer and would love this.

Good, ask him if he knows of a device that will do what i want.

[virus77]

ahem..

[Red-KAT]

I WIN!

http://www.mohdparts.com/emanage/

GReddy e-manage O2 Sensor Adapter #1 - #15900908 ONLY $25* Disables O2 sensor signal input above a settable RPM. Wire to O2 and Ground wires. Will require setting the E-Manage VTEC jumper. Does not work on VTEC vehicles or vehicles with two MAF's (i.e. GTR) For vehicles with multiple O2 sensors, a corresponding number of adapters is necessary. For certain vehicles, the engine check light may light, or the vehicle may go into fail-safe mode

[DRIFTEADOR]

do nissan ecu's only take throttle as an input to switchover? I'm not sure if oem manufacturers are the same, but I know aem ems takes both tps and map/maf where either one trips it to open/closed loop.

what rpm would you set that thing at anyways if youre building boost at 15% throttle in 4th gear? virus, what turbo are you using? you shouldn't be under boost while cruising.

[virus77]

I want to use boost sensor voltage not rpm myself. But how does my idea sound? C'mon people I expected more from NICO.

[virus77]

do nissan ecu's only take throttle as an input to switchover? I'm not sure if oem manufacturers are the same, but I know aem ems takes both tps and map/maf where either one trips it to open/closed loop.

what rpm would you set that thing at anyways if youre building boost at 15% throttle in 4th gear? virus, what turbo are you using? you shouldn't be under boost while cruising.

I dont get boost while cruising, jsut under 10-20% throttle and I agree RPM isnt the best method to go about this. Its a 50 trim t3/t4 .63 hotside.

[Red-KAT]

Well my thing is I cant say if its a good idea or bad... I don't think I need one because I always monitor my AFR's with my wideband and I don't ever have a part throttle lean issue. I am using an E-Manage with all the extras.

Funny enough I left my stock 02 undone after my last install and the only thing that was wrong is the idle was lean... Other then that I was still 14.7's cruzin and high 11's when on the gas. It was weird after my catch can install the car was lean idle for like a week... But now its back to 14.7-14.9 at idle when warm.

EDIT: Ohh and with that Greddy switch the only thing you should have to do is attach the wires that went to the E-Manage Vtec to a hobs boost switch for the same affect... I'm sure you could make it work with little effort.

[virus77]

Well my thing is I cant say if its a good idea or bad... I don't think I need one because I always monitor my AFR's with my wideband and I don't ever have a part throttle lean issue. I am using an E-Manage with all the extras.

Funny enough I left my stock 02 undone after my last install and the only thing that was wrong is the idle was lean... Other then that I was still 14.7's cruzin and high 11's when on the gas. It was weird after my catch can install the car was lean idle for like a week... But now its back to 14.7-14.9 at idle when warm.

EDIT: Ohh and with that Greddy switch the only thing you should have to do is attach the wires that went to the E-Manage Vtec to a hobs boost switch for the same affect... I'm sure you could make it work with little effort.

When you are headed up a hill in 4th gear around 3 grand, and get slightly on the gas and it starts boosting do your AFR drop to 12's or so. Damn closed loop o2 sensor is screwing me.

HMM.. hobbs switch and that might work, thanks for the find, Ill probably go ahead and do this and if it works, some people im sure can benefit from it.
Modified by virus77 at 12:12 AM 3/16/2005

[sil80drifter]

So all you're looking for is for the ECU to kick into a High Throttle map (HT) earlier than it usually does (earlier in terms of load vs. throttle position).Hmm... yeah that would be nice, but, you understand that the HT map that you use in the high load/low TP position is very different from the HT map you'd use in a WOT situation. And the SAFC can only do one HT map. for E-manage you ddon't even need the device you describe, but for simpler piggybacks... you'd have to have two different HT maps available, and the possibility to somehow switch between them.Hmm...

sil80

[virus77]

even with the emanage the car has part throttle problems. However on teh way home from work I realized I can set the boost alert on the profec eo1 to send an output signal for a light, but hook it up to the greddy device that disables the 02 sensor. You can turn the alert noise off no it wont bother me coming on aswell. Either way its worth a try Ill see what kind of AFR and timing numbers it gives and if there is any complications, worth a shot.

[PapaSmurf2k3]

I am an engineer (in training), and yes, this could work. You just have to make sure that you know exactly what the ECU does when its denied an O2 signal. A better idea would be to alter the signal so that the ECU makes it run richer, based on the signal, that way you know what the ECU is doing. Basically this would require a box that would input a resistance as a certain TPS signal or MAF signal is reached.

[virus77]

you know what, the original article I had read, they had tried to imitate a o2 signal to achieve what you speak of and it turned out to be too complicated and disconnecting it entirely worked better, but I see what you were thinking, they had thought the same.

[DRIFTEADOR]

are you sure your map isnt lean in low rpm? are you logging with the emanage? if so, can you post a sample

i know the ecu enters limp mode when it doesn't see a signal (like greddy states) within a certain time period but what if its intermittent? would it assume the sensor is faulty and light up the cel anyways.

[Red-KAT]

Me or Virus77?

I could record a little bit and take a pic I guess...

What gear, rpm, boost would you like a sample of? (if its me)

[virus77]

are you sure your map isnt lean in low rpm? are you logging with the emanage? if so, can you post a sample

i know the ecu enters limp mode when it doesn't see a signal (like greddy states) within a certain time period but what if its intermittent? would it assume the sensor is faulty and light up the cel anyways.

NO, if I go WOT it gets 11.5 AFR from 2.5 grand to redline, its only in low part throttle, any throttle input above 40% runs fine its just that the damn car builds like 6 pounds of boost no problem at like 10% throttle. I am aware of the possibilities of a CEL causing problems and limp mode thats why I am gonna test to see if there are any complications. Also I have the boost warning I will be using to deactivate the 02 sensor set to only go on if the AFR is above 12.5 so it wont disable the o2 when im at WOT or 40% above throttle, it will only do it when she gets lean. Im just waiting on the greddy thing to get here now. Ill post my results good or bad.

[DRIFTEADOR]

it was aimed at virus but either would do. i just want to see when the trasition occurs, so i guess low to mid throttle in any gear/rpm with afr, tps, and load (btw, is it still called load even though its flow and not pressure that's being measured?) parameters showing.

I just can't believe that the sensor has to see so much airflow before it will switch to the maps. if it doesn't switch at 5psi on a boosted motor, they i'd never switch on a n/a one right? am i missing something? virus, do you have a bigger mafs?

[virus77]

for instance 70% throttle, or a certain rpm (like 5k or so, im not sure) will make the ecu switch to open loop which will bring the AFR down. So when I am at 10-20 percent throttle the ecu is till trying to keep stoich, also you have to take into account the injector correction which almost halves the maf signal so it doesnt think much air is coming in so it will still try to keep it stoich. I have a stock mafs but it maxes out around 8 psi, I tune with a map sensor after that. Hehehe, one of the only guys putting down over 300 whp on stock mafs. I need to get my knock meter hooked up and see if I get knock when it hits 5 psi with a high 14 AFR, if not i guess its not even that bad, Ive got a lot to do these next few weeks.

[pr240sx]

There is a similar device used on Grand Nationals and Turbo GM products.Its a O2/TPS simulator. It uses MAP sensor (they have both MAP and MAF) signal with RPM signal and trick the stock ECU by keeping "closed loop" operation (note the quotes)Dunno how the KA ECU will work wile boosting and open/closed operation, but checking this will clarify this.

[Red-KAT]

Are you tuning with the MAF voltage Virus77? I swapped mine over to manifold pressure right away due to tuning issues with MAF.

That could make a difference.

[DRIFTEADOR]

you have to take into account the injector correction which almost halves the maf signal so it doesnt think much air is coming in so it will still try to keep it stoich.

ah, didnt think about that. so with injectors twice as big, the ecu needs to see twice the flow before it switches to closed loop? i guess that goes for any piggyback, huh? a chip doesnt affect this, right?

Quote »I have a stock mafs but it maxes out around 8 psi, I tune with a map sensor after that.[/quote]why not tune with the map only?

[virus77]

Are you tuning with the MAF voltage Virus77? I swapped mine over to manifold pressure right away due to tuning issues with MAF.

That could make a difference.

Boost sensor, I wouldn't touch the maf.

[virus77]

ah, didnt think about that. so with injectors twice as big, the ecu needs to see twice the flow before it switches to closed loop? i guess that goes for any piggyback, huh? a chip doesnt affect this, right?

why not tune with the map only?

I do tune with map only, sorry it was a poorly worded sentence. And yes that does go for piggybacks, but a jwt ecu or something isnt like that, they actually change the ecu parameters.

[huguetpj]

Maybe I'm missing something here... but couldn't you just use an electrical relay ($2) to open the O2 sensor circuit to the ECU into fooling it? Maybe I'm jumping a bit late into the conversation... but makes sense to me. You would just need 12V (or less depends on the relay) to open it when you want to throw the ECU into open loop.

In my case I just run my AFC low throttle point at 15%, I know my turbo won't spool at anything below that... maybe in 1st or 2nd gears but haven't really tried that, I always cruise in 4th 5th maybe 3rd.

[virus77]

relays dont work intantaneously.

[huguetpj]

relays dont work intantaneously.

I really don't think that your turbo is gonna spool in anything less than .1s which would be the slowest relay I've ever heard, and that is an automotive relay. If you get an IC relay it's WAY faster. Just my .02

[virus77]

I guess you are right you should have chimed in earlier but its too late. I already ordered the part, and im a greddy buff anyways so its over with and theres no looking back. I guess its also better to use a part that was intended to do what I want.