3S Fueling issues...

[RAd28]

Hey all, My old man is building an engine for my brothers ST185 GT4, so far everything is together, and KINDA running... he can get the car started, but it won't rev less then about 3k and is using SOOO much fuel it isn't funny... he's isolated the issue to the Injectors, which apparently are running about 20ms pulse width instead of 2-2.5ms they should be (at idle). the ECU has been sent off and tested (and confirmed A-OK), the injectors aren't the ones from the original motor, but they flow less then the standard ones. he's checked all the sensors, and everything is measuring up as it should. Any ideas what could cause the pulse width to run out so far?

any help would be greatly appreciated, and if anyone has a GEN II ecu they could lend it would be brilliant too, he's still a bit suspect about the ECU.

cheers

[Celica RA45]

have you tested the ohm rate of the injectors to make sure they are the right 1 s .
are they low rate or high rate injectors as in ohms
most turbos were low rates 4agze 7 mgte 3sgte etc about 2.3 ohms
na 7mge 3sge and 4age were 13.8 ohms
check that 1st

[RAd28]

apparently it's been checked and re checked, the injectors in it now are from a Gen I 3S, they're around 2.4ohm.

the head was also taken from a Gen I, however it's been extensively ported and polished (not flow tested though).

[wilbo666]

Checked the water temp sensor for the ECU?

Perhaps if it thinks it is very cold it is injecting much more fuel...

Btw, why the wrong size injectors? :S

Cheers
Wilbo

[Cuts]

ide be finding some gen2 injectors that are known to be good.

you havnt put in a diff fuel pump or fuel preasure reg have you?

[RAd28]

Wilbo - checked all the sensors, everything appears to be within spec. Not sure why the different injectors, i vaiguely remember hearing there was a difference with the feed? but i can't be sure.

the injectors from the original (gen II) head are fine, no new pump, but we've included a malpassi regulator just to see if the original reg was buggered... but the issue is injector pulse width, not fuel pressure so far as we can tell...

[RAd28]

OEM Gen II injectors were side feed, Gen I were top feed, so i think it was just a matter of ease of fitment that the injectors aren't the same.

Is there any way that fuel pressure can alter the injector pulse width, because the OEM regulartor is still there, just had the vacuum hose removed, ie max pressure...

[RAd28]

okay well... just had it running, and it'll idle at ~1000rpm with a pulse width of ~27ms (not 2.7) take it up to ~3500rpm and pulse width drops to ~20ms. after that the garage it too full of smoke to continue...

also, reconnected the hose to the fuel pressure regulator (oem one) and it didn't make any difference (that we could measure)

anyone got a Gen II 3S ECU to lend?

[wilbo666]

Pulled the check engine codes if any?

Also charles might have and ECU he can lend?

Cheers
Wilbo

[RAd28]

nah haven't, engine warning light is only on when it's running <2500ish... over that the engine light went out, but it was still running like a dog...

I'll PM charles...

[blakeg]

i have a 3sge gen 2 one, but i assume you want a turbo one

[RAd28]

yeah that's right mate, thanks anyway...

would also prefer local, just for ease...

[thechuckster]

a couple of things could be wrong:
-dump the malpassi - they better for hi-flow low press applications like big carbs (they also make things worse if they are Rising Rate).
- are you sure you have a clean vacuum line from intake manifold to the FPR?
- are you sure the vacuum line are correct (including the turbo boost control)
- nothing stuck inside the AFM?
- is the wiring right for injector power supply? (is there a resistor pack somewhere, see page 3 of this PDF)
- standard electrical issue - are engine earths from ECU to intake manifold tight and earth strap from motor to chassis good?
- you really want injectors that flow the same or higher than the stock gen I items.

And an idle PW of 27ms is stupidly long - it should be about 2-4ms

[RAd28]

a couple of things could be wrong:
-dump the malpassi - they better for hi-flow low press applications like big carbs (they also make things worse if they are Rising Rate).
- are you sure you have a clean vacuum line from intake manifold to the FPR?
- are you sure the vacuum line are correct (including the turbo boost control)
- nothing stuck inside the AFM?
- is the wiring right for injector power supply? (is there a resistor pack somewhere, see page 3 of this PDF)
- standard electrical issue - are engine earths from ECU to intake manifold tight and earth strap from motor to chassis good?
- you really want injectors that flow the same or higher than the stock gen I items.

And an idle PW of 27ms is stupidly long - it should be about 2-4ms

-the malpassi was put in initially 'cause we hadn't identified the pulse width as the problem, we thought we might be able to drop the pressure enough to lean it out. but it's had the opposite effect, so malpassi goes in the bin (back in my car)
-vacuum for FPR is coming straight out of the throttle body (now i think about it, that COULD be pre-throttle plate
-"vacuum line ARE correct"? lol... goodest english i've seen... I haven't personally checked each and every vacuum line, so i can't comment on that one.
-stuck where in the AFM? it's opening and closing freely if that's what you mean, it's been tested (out of house) and confirmed A-OK
-will have to get dad to check the power supply
-will have to get him to double check the earths too.
-the injectors ARE GenI items, but i assume you mean GenII (since that's the original engine). Apparently a flow test (again, out of house) showed the Gen I injectors (installed) are only very slightly behind the Gen II injectrs (1 or 2cc/min).

do you know if the injectors are normally open (+ve voltage to close)? or normally closed (+ve voltage to open)? because the chart was showing ~27ms <0V and about 15-17ms >0V

cheers

[wilbo666]

do you know if the injectors are normally open (+ve voltage to close)? or normally closed (+ve voltage to open)? because the chart was showing ~27ms <0V and about 15-17ms >0V

cheers

The injectors have ignition switched +12V on one side, and the other side is connected to GND via the ECU to turn the injectors on.


What are you using to measure the 'injector on time' ?



Cheers
Wilbo