ScionDad

I just wanted to get the topic of fuel management into one thread.

To start,

stock injectors are 372cc as I understand it.

TRD supercharger includes 410cc injectors at 6 PSI (questionable management with ECU flash)

ZPI stage 0 uses stock injectors at 6 PSI successfully with no additional management

ZPI runs 550cc injectors with their stage 1 and use emanage successfully.

Scionspeed runs 550cc injectors with no fuel management as I understand it.

Dezod runs 550cc injectors and working with emanage as I understand it.

No one knows what the supercharger flash consists of.

Our TC has a wideband sensor and a very smart ECU and appears to handle the small boost of 6 PSI.

The issue of the turbo TC dying is due to not recirculating the BOV. The ECU seen what the MAF sent and adjusted fuel, but throttle plate closed and BOV dumped to atmosphere.

sounds right. the bogging and dying with an atm bov is common in maf settups. hondas can dump their's to the air because honda uses map places on the throttlbody. though i think new hondas may be maf now for emmissions reasons. subbys, 300z's i know have the same issues dumping a bov instead of recirculating it.

*wishing toyco ecu was cracked wide open like honda

scionlife

This is the official Scion tC Fuel Management and ECU topic. Please discuss...

Dyltone

Just my .02 worth...

My car has stalled after reving up in neutral (dumps tons of fuel) but most times the ECU/Emangae compensate and get the car back to normal idle.

If I don't rev up and dump fuel, the car doesn't stall or burp or spudder, it just idles. I'll notice the A/F moving from one side to the other (lean to rich) as the two computers are fighting each other. Can't speak to the Stage 0 but this is fact for my Stage 1.

Good job ScionDad.

ScionDad

That ECU is a huge pain. Probably the same for stage 0, but rev up is only done in park. When I rev up in park it will rough idle for a sec or 2 then smooth back out. At least it used to before the plugs change. I haven't tried it since.

Do you run stock plugs?

toastbox

You aren't doing neutral drops in your daughters car again are you???? You know it's not a 69 Charger RT, right??

ScionDad

She asked me about doing this. I told her as long as her hatch is empty....need room to put the tranny somewhere when TOWED"

rhythmnsmoke

So, it dosen't stall out on you if you are in Gear and you rev it? What about reving while in motion? Do you think a fuel regulator of some sort will help this minor problem. Also, you should think about changing to a colder plug like ScionDad did, if you haven't already done so.

Dyltone

I'm considering changing out the plugs like ScionDad did, but for now I'm running the stockers.

I'll see how she runs at the track this Friday (hope it doesn't rain me out), then decide.

For now Pig Rich is Safe to beat on the car. When I start to lean out the maps and bump up the boost I'll have to get the whole fuel system in line.

lo_bux_racer

Has anyone tried moving the maf after the turbo? I've seen this done on a GN, and the owner claimed a huge improvement in part throttle driveability. It would also kill the whole issue with the BOV venting to atmosphere.

kungpaosamuraiii

Wouldn't the MAF need not only to be placed after the turbo but also behind the BOV too?

Seeing as how most kits put the MAF right after the filter, the ECU is probably seeing something that is at least somewhat significantly different from what is actually being combusted. But placing the MAF after the turbo would only be so effective if it's still sensing the amount of air before the vent so it'll still see boost while there is none.

I don't know for sure but it seems to me the best placement for the MAF is right before the TB.

Of course, the best would probably a MAP conversion..



Now that I look at it, I think I just said the same thing lo_bux said..

lo_bux_racer

Yeah, that's what I meant. Sorry, I wasn't clear. I've seen a MAF mounted in front of the throttlebody.

There are lots of theoretical arguments about why this is not going to work, but since I've seen it done by a reputable tuner, I'd rather not open that can of worms. Just asking if anyone's tried it.

ScionDad

^^^Not sure if anyone tried that, but I do remember Kenny telling me ZPI spent alot of time thru trial and error figuring out where to place the MAF.

depogrig

wouldnt moving it post cooler interfere with the readings? the whole thing is designed around the assumption that the air is around normal atmospheric pressure. maybe the computer would assume you are way the hell below sea level though and compensate readings to work.

Joe_Dezod

If you place the MAF after the turbo but before the TB you will need to do a decent amount of tuning with the emanage. The stoxk MAF won't have as accurate of a reading because compressed air has different flor characteristics of non compressed air. It'll work well, but only after some good tuning, because the stock ECU will be making incorrect fuel adjustments off the bat. It will prevent the car from stalling/rough idle though.

depogrig

i kinda figured it wouldnt work well because of the compressed air. 300z guys say its a bigger pain to move the maf and correct the issues than to just recirculate the bov.

ScionDad

The problem I guess is any changes to emanage....the ECU will change it back?

Joe_Dezod

So far at idle it's been hard to adjust, but that may just be at idle. Our car has been holding an 11.5 AFR for a while now so we're still working out the bugs. Some cars go into a default loop at WOT anyway. If that's the case, then the right tune will always be there when you punch it. We're still working things out though so I'm not 100% sure yet.

TurboCustomz

The main reason you can't move the stock MAF post turbo is because your car wont run under boost. The stock MAF is a 0-5volt unit. If you reach 5 volts the car thinks that the MAF is bad and basically shuts it down. Car goes into "limp home mode" or "safe mode" or whatever you want to call it. I had some issues with this when I was using a smaller inlet pipe to my turbo.

Not only this, but the maf has a built in IAT sensor. Placing it in the boost path, (again, on these cars) shows the ECU a hotter intake charge temp. The ECU's then leans the car out to compensate for the less dense air charge and you have to fight it with the emanage.

Using the emanage is more of a close to WOT tune. Its a little different with the tC's because of the a/f sensor and not the typical 02 sensor. The ecu switches back and for from open to closed loop as you drive. A typical ecu will not fight the calibrations made by the emanage when its not reading 02 feedback from the sensor under heavy throttle. The tC's ecu seems to react basically the same under WOT once it "learns". Tuning the car for good part throttle driving gets a little trickier because the car wants to achieve its perfect 14.7:1 afr when the engine is not under load. Having such quck spool up with this turbo kit means you have to be able to add fuel in the lower rpms ranges and under what is typically not a WOT voltage range for the TPS.

Charles.

Kaeon

Im going to sticky this for now seems like some good info will be posted in here...

depogrig

maybe the flash for the supercharger is more than just for emmissions then. they would have had to change some of the ecu's habits to get a more rich a/f ratio to be on the safe side. especially since there is a warranty included. we need someone to crack this ecu and tell it to run like normal but replace 14.7:1 with something more usefull for FI. people with wrecked tCs need to start pulling their ecus and obdII connecters before insurance totals and takes the car so the community has spares to donate to people willing and able to try this.