I was wondering if I should upgrade my fuel injectors on my 88 GXL?

Currently I'm running a S5 6 port motor and intake manifold, S4 NA ecu and tuned with a SAFC2

I'm wondering would it help to use the 550cc Turbo II injectors in the secondaries or just leave it stock?

I can get some for pretty cheap and was wondering if i should just go ahead and do it.

 

Nope, you won't ever max them out.

 

why couldn't he max them out?


a modded N/A flows as much as it can handle, more air needs more fuel.
he didn't say whether he had any port or intake/exhaust mods done.

 

You would need a bridge or a pport to max out the stock n/a fuel injectors...

 

They seemed to fill out on my SE. (Drop in K&N (which will soon be a FIPK) and 2 1/4 inch exhaust with high flow mufflers).

 

I doubt you need any fuel mods right now on a fairly unmodded car..

 

True. But next paycheck its a Full Racing Beat exhaust for the headers back for my SE (no more cat-back). Hopefully that'll help. I just did the mods at the time because both were free.

 

not on the stock ecu, I disagree

 

I've got intake, headers, exhuast and all the other little cheap mods(TB mod, remove everything that doesn't make it go faster, ground wires, pulleys, FD alt. Etc.) and my S-AFC is still telling the ECU to put in less than stock fuel all the way across the board. Until your ported and I mean REALLY ported your A-okay on the 460s.

 

The N/A is already pig rich at high rpm. It probably wouldn't be worth it unless you do extensive mods.

 

listen to 1Revvin7 and if you doubt him search for other posts on upgrading n/a injectors. it's just not worth it because at the rate that a ported manifold and streetported engine breathe you won't still max out the stock injectors without some sort of forced induction.
Well i guess that's why 1Revvin7 uses a haltech eh?
And anybody who knows much about those ports knows that you SHOULD for best performance use a standalone.


Matt

 

The ECU has nothing to do with how much fuel the injectors can flow. That's determined by fuel pressure and their physical size.

The three factors that determine how much fuel is injected are pressure (from the pump), opening time (controlled by the ECU) and physical size. If the pump can't maintain the required pressure you upgrade it. If the injecors aren't being opened long enough you need a fuel controller. The injectors don't need to be replaced until your mods or tuning forces their duty cycle over 85%.

I've heard people say they've replaced their injectors because they've "maxed" them, but don't state any duty cycle measurements, so they don't really know that at all. NA injectors can support ~250hp, which you're not going to get with just a street port.

 

If u have an SAFC which u claim is *tuned*, there is no way u need to ask this question. If ur fuel correction is in the +50% range above 4k rpm then yes, larger secondaries will help cure a lean condition up high, but I highly doubt a stock port NA, no matter how many bolt ons it has, will ever need 550's.


I used to think I needed them on my large street port six port NA until I backed off my timing. Now, with my 550 secondaries, I'm at like -15% at 8k rpm, which corresponds with the rough amount of flow of the stock 460's ........

 

And you have a heavily modded n/a that is ported...

 

Ok i forgot to add some things
the car now has exhaust fromt he stock header back, with some other little things, I plan too within the next to have a heavily street ported 6 port motor with a T4 turbo strapped to the side, so what do you think now?

 

I've still got my stock main cat. It's okay, I'll be building a Mazdaspeed7 catback here shortly, with a magnaflow highflow cat. Mmmmmm, top end power.

 

Without question, a stock port n/a will never come close to maxing out it's injectors. I was refering to more etremely ported motors (large street port etc..)

The problem with the safc in my experience is that it's great at taking away fuel, but it's not that great in adding in additional fuel. Henrik touched on this a little bit in some of his older threads; there are lot of safeguards built into the stock ecu in regards to acceptable voltage ranges for it's various sensors.

I think the greddy e-manage would be a better application on n/a's with it's ability to directly control the fuel injection by adding in additional ground pulses, as opposed to altering the afm signal.

 

I'm concerned about the condition of the injectors on my 91 N/A with K&N Cone filter, Bonez high flow cat and RB Cat-back exhaust. Last weekend I did a track day with track run segments of about 15 minutes each on a 1.3 mile track. I kept the RPM in the 4500-7000 range throughout the session. After my last session, the inside of the exhaust tips was going gray rather than the normal black. I love playing on the track days, but don't want to haul my car back on the flatbed because I blew the engine from running too lean.

The earlier posts answered one of my questions. I'm not going for TII injectors. The other question is this: Are my current inejectors going south on me? The car has 91,000 miles and as far as I know is on the original engine.

During normal street driving I'm getting 16-18 mpg and 25 on trips, so I know they aren't too rich in that range.

 

I think that right now, if you put the 550 injectors in the engine........it'll run even MORE PIG RICH than it should be running right now. As things stand now, even if you put a RB dual exast from header back on the car, you need a wide band plus SAFC to REMOVE fuel. Stock RX run somewhat RICH. Too rich IMHO.

Larger injectors right now will cause the engine to BOG DOWN. Or fall on its face if you want. It NEEDS to be LEANED OUT. If you LEAN IT OUT, it will run stronger, crisper.

Spend the money on a SAFC WITH a Wideband or SAFC and a dyno tune to REMOVE fuel.

OR...install the 550's so you won't get a ticket for speeding. It won't go as fast. humor

 

That's a good point. If you have enough airflow to fully open the airflow meter OR you send a modified airflow signal that equates to a fully open airflow meter (i.e. 0V on a 0-5V sensor), then the ECU won't add any more fuel because the airflow signal can't go any higher.

Personally I think if you actually get to that point then you should've upgraded to a standalone well before then.

 

Please, don't try and analyze the AFR's by looking at your exhaust tips.
PLEASE CHECK THE SPARK PLUGS IF YOU WANT TO DO THIS RIGHT.


-Ted

 

Well right now my SAFC2 is dyno tuned with a wideband and currently it is only removing about 2% fuel under about 2000 rpm anything above that it is adding fuel, and at about 7k rpm it is adding about 10 % more fuel.

 

can I see the dyno sheet?

 

What afr's are you tuning for? What mods do you have? This seems very unlikely for a stock port N/A.

 

Might want to also add, that if you want to check a certain load/rpm afr you have to get to that point then shut the motor off, then check the plugs..