Extra injectors for boosted NA motor.

[feral4mr2]

What's a cheap, effective way to supply fuel to a supercharged NA motor? I was thinking along the lines of a hobbs switch mounted to 2 extra injectors, one at say, 5psi, one at 8, to dump extra fuel. Any better ideas?

RM.

what are you useing? sc12 with gze wiring ecu etc? or are you going to bolt on all the s/c gear and keep the ge ecu set-up?

[Starfire]

Can the nissan ecu be reprogrammed? I'm not overly familiar with those. If it can a bit of dyno time might have it in spec.

Increased rail pressure and extra injectors are really a bandaid effort but if you arent overly concerned with potentially damaging things then you could use one or both.

Retard the base timing a few degrees and make sure you use premium fuel. That along with a decent intercooler should have the engine surviving.

[MWP]

The MAP sensor will be a 1bar sensor so it will not work above 0psi.

Itll be almost impossible to trick the ECU so itll supply more fuel, as said above the only way youll get the ECU to behave properly is to have it re-programmed.

So basically your screwed for doing it by the gheto aproach.
If it was AFM sensed, you would be ok, but not MAP.
As soon as the manifold pressure goes above 0psi the engine will lean out and go bang.

So your choices are:
- reprogram your factory ECU
- use a ECU from a boosted version of the engine (make sure you grab the MAP sensor too)
- use a separate ECU and separate injectors to give more fuel over 0psi.

[MWP]

Retard the base timing a few degrees and make sure you use premium fuel. That along with a decent intercooler should have the engine surviving.

This wont work... itll still run lean.
No matter what the timing and intake air temp is, the engine is still getting more air so it still needs more fuel.

[Starfire]

With the addition of the increased rail pressure and/or extra injector(s) that is.

[oldcorollas]

megasquirt.

[mullett]

I think I can supply the fuel it needs once boost comes on, but is the consensus that when it does go over 1bar (atmo), the ECU will stop supplying fuel at all? Or just behave like normal and run lean as hell because it's unaware of what's going on?

RM.

[Starfire]

The ECU will keep supplying fuel but not be aware of any boost - it will just act as if it was at WOT.

[Lonewolf]

See if you can pick up a megasquirt ECU cheaply, should be able to get that working with the engine, just put some time aside to program it.

[CrUZida]

You have a DELCO ecu.

Just get a boost compatible MAP sensor, rock up to any Pre VT Commodure tuning centre, and get it retuned.

[mullett]

Are you serious? +rep. The stock computer is reprogrammable in standard from, and coupled with a better MAP sensor would run the boosted engine with tuning? Brilliant. Being in WA, is there anyone you could recommend?

RM.

[CrUZida]

Sorry, but I don't know anyone who can do it.

What they'll do is remove the stock ECU, plug in a 4cyl KALMAKER unit, tune it, then burn that mapping to a chip, and replace the stock chip in the ecu.

It doesn't touch cold start/idle/cruise funtions either.

PM MaxPower on these forums.
I know he has one of the chip burners, but I'm not sure if he can do any 4cyl stuff or not.

Another thing to try is to get the chip from a Camira, as that is designed for 2.0L
You'd want to check the AFR's before doing anything though.

[Toysrme]

Adding actual extra injector<s> (with management), is *the* most affective way to add fuel period. Provided it's not a Honda, and you can't chip a programmable chip in it for $50...
On any descent piggyback / management you can not only setup a normal map, but scale it via extra variables. As such, tuning becomes little more than an excessive in some fairly basic math.
Off-boost driveability is obviously stellar...
On-boost driveability is also improved from easier, more accurately done for the masses tuning.
For example purposes... When applied to an N/A-T, or N/A-S/C conversion.
The ECU:
A) Re-learning in closed loop is non-existent because the ECU is driving the car out of boost... There are not *minutely* tuned injectors twice as big as stock to fool with across the entire driving range, taking up loads of time to dial in.
B) Because the engine will be fed the correct amount of fuel, regardless of what it wants, fast enough not to create fuel trim adjustments. There is no danger of lean out from having boost in closed-loop.
C) Closed-loop in non drive-by-wire Toyota systems is easily tripped to open/loop at any time, by simply feeding the VC supply voltage back across the VTA signal...
Installation: Easier... Far easier for anyone that can't rip their manifold<s> off in a few min. I can... It's inconsequential to me.
Fuel pattern: Injector<s> should be pointed into the incoming air stream, before the throttlebody. The mixture will naturally be effectively delivered fairly evenly across any manifold.


Too many people write off adding injectors. When in fact, the majority of the time. It *IS* the better option. There really is *no simpler way* of getting *highly accurate* fuel into a boosted engine than adding injector<s> that can be tuned via boost.
Even in the event of not being tuned by boost, with nothing more than a BPS to turn the tuning on & off at 2psi, you avoid OBD-II close-loop transition problems (Even when not triggering open loop), and the majority of any re-learning problem, WITHOUT worrying about tuning too far into closed-loop...

That in itself puts it above the majority of setups where injector swaps are done.



AFA slapping a BPS(Boost Pressure Switch), and a couple of cold start injectors on an engine. I've recommended & done it for some time now, but NOT in the waymullett is thinking of using them. Face it... Most people are dumb, and most tuning shops are just not *that* much better when it comes to piddling with some unique setup they see for 20-30min. That extra 15-35bhp worth of gas can go a long way into making sure you can drive to someone that knows how to tune, or that you don't just destroy something if you're too in-experienced to get in a safe ball park's range of what you want to do.
If you're hell bent on doing it... Figure out the fuel supported via the injectors VS the power created & for god's sake don't set them so conservatively. Set one of them at 2psi, and the other at 5psi, then check your A/F ratio to see where you stand.
I DO NOT recommend this as a way to fuel substantially more power. Use it as nothing more than a SAFETY NET for another system / tuning.





There's also another way to do it. I'll plant the seed for someone smart to figure it out... I'm not going any farther on that front. I fear someone attempting to do it, then screw completely up.
Anywho...
It takes a few dollars in parts, and some brainpower to get simply massive amounts of semi-tuned fuel from batch/simultaneous fire injection setups. The 4a-gze's are a batch fire injection that fire in 2 alternating groups (1&3, 2&4).

[oldcorollas]

couple of points.
most toyota ECU's do not have chips you can change, or tune.
almost ALL ECU's do NOT run closed loop under load, because they do not have wideband oxygen sensors.
how many ECU's actually do "relearn" and retune themselves?
OBDII is an american issue generally
most toyotas are NOT drive by wire.

There's also another way to do it. I'll plant the seed for someone smart to figure it out... I'm not going any farther on that front. I fear someone attempting to do it, then screw completely up.
Anywho...
The 4a-gze's are not sequential injection. They're a batch fire injection that fire in 2 alternating groups (1&3, 2&4). It takes a few dollars in parts, and some brainpower to get simply massive amounts of semi-tuned fuel from such a system...

when injectors are open 80% duty cycle, or even 30% duty cycle, there is very little to be gained from sequential injection except for individual cylinder trim.
you may improve emissions, or get a couple of percent more power in part throttle operation, but for WOT, just having sequential is not the holy grail that it's made out to be...

fwiw, in Australia there are many aftermarket fully programmable ECU's, and it is not that diffuclt to tune them properly.
i would think that any engineer in australia would NOT approve a system where a fuel injector is place in FRONT of the TB. and nor should they

Adding actual extra injector<s> (with management), is *the* most affective way to add fuel period.

not trying to rain on your parade, but THE most effective way to tune for boost is to use the correct size injectors and an appropriate AFM or MAP sensor... (triple period )

also, any decent management will have a "normal map" that covers the entire manifold pressure vs rpm range and have adjustments for the full range of coolant and intake temps etc etc...

in this day and age, when full management is so cheap and larger injectors are easily available, it makes very little sense to install a TBI style extra injector (esp since modern manifolds are designed to distribute air only, not air/fuel mix.... fuel drop-out can be a real problem with manifolds...)
just a few thoughts

[Toysrme]

couple of points.
most toyota ECU's do not have chips you can change, or tune.

Exactly... These are not Honda's. Only a few of Toyota's OBD-I ECU's can be re-programed. Which in itself is a difficult thing to have done. I still only know of one person in the US that can handle the 3s-gte re-programming.

almost ALL ECU's do NOT run closed loop under load, because they do not have wideband oxygen sensors.

Actually they do. The first specification for almost all Toyota ECU's to enter open-loop when running is >/= 75-80% throttle deflection. If you haven't achieved that, you're still in closed loop, and running too lean.


The classic example is also the most common situation needing large amounts of extra fuel. An N/A-T conversion using a well chosen turbo that will support a broad powerband.
Many times you can find yourself in boost simply driving around lightly, or cruising on the highway. This creates havoc over time to OBD-II fuel trims as they try to adjust to the fuel consumption of the engine both on & off-boost.

However long it may take to a given setup, eventually you're going to hit the gas & find two bad things:
1) The transitional areas between cruising around in closed loop & having boost & needing open loop are going to be far under fueled to what they once were
2) Open-loop itself will have leaned out.

how many ECU's actually do "relearn" and retune themselves?
OBDII is an american issue generally

All OBD-II Toyota ECU's have a tenancy to do it. The extint of which depends both on the setup, and how the stock system itself worked.
In the grey areas where you need to be running more fuel in closed-loop it can get hideous as a choice must be made.
Either don't tune/fully tune the area in closed loop where substantially more power is present, or tune it & have the ECU apply it's fuel trims while you daily drive. Only to have them carry over into open-loop. Thus leaning you out anyway.

Depending on the setup, some are not bad. Others can be relatively horrible. Toyota TCCS/OBD-I in general inconsequential; provided you are roughly in open-loop when you need more fuel. It's single fuel trim is not a factor in open loop. OBD-II's LTFT IS a factor in open-loop.

most toyotas are NOT drive by wire.

Correct. But most late model/newer/upcoming engines are. Which is why I made the point not to try to trip the ECU into open-loop on such setups.
It's an exception to the rule.

Quote:
There's also another way to do it. I'll plant the seed for someone smart to figure it out... I'm not going any farther on that front. I fear someone attempting to do it, then screw completely up.
Anywho...
The 4a-gze's are not sequential injection. They're a batch fire injection that fire in 2 alternating groups (1&3, 2&4). It takes a few dollars in parts, and some brainpower to get simply massive amounts of semi-tuned fuel from such a system...

when injectors are open 80% duty cycle, or even 30% duty cycle, there is very little to be gained from sequential injection except for individual cylinder trim.
you may improve emissions, or get a couple of percent more power in part throttle operation, but for WOT, just having sequential is not the holy grail that it's made out to be...

You're dead-on right! Unfortunately, what I was "planting a seed for" has nothing to do with what you're thinking I was talking about.

in this day and age, when full management is so cheap and larger injectors are easily available, it makes very little sense to install a TBI style extra injector (esp since modern manifolds are designed to distribute air only, not air/fuel mix.... fuel drop-out can be a real problem with manifolds...)
just a few thoughts

I completely disagree with everything you just said, for the reasons in the previous post.
The tuning is far easier, more consistent, and a great deal cheaper.