19lb injectors on stock S.O ecm ?

Topic: 19lb injectors on stock S.O ecm ? (Read 1611 times) previous topic - next topic

19lb injectors on stock S.O ecm ?

November 24, 2005, 09:16:36 PM

Well today i swapped out my old worn leaky stock injectors for a set of late model 19lb injectors...

now i have a sputtering idle....is this a product of more fuel ?

car feels stronger throughout the rpm range and smoother.No miss or issues under load or off idle.

I am waiting on a mustang ecm to arrive for it I am aware i will have to move the injector plugs due to the firing order.What else should i expect? Will it fix my idle problem?

19lb injectors on stock S.O ecm ?

Reply #1 – November 24, 2005, 09:47:41 PM

OK, I'm gonna go on limb and say you have an SO cam still due to the fact you have an SO ECM. On a bone stock SO engine 19 pound injectors with the factory fuel pressure regulator is just too much gas and not enough air or cam or cylinder head.

You can run those 19 on an SO computer but, you need the engine upgrades to make it necessary OR an adjustable fuel pressure regulator.

The stock fuel pressure regulator on return style Ford fuel injection systems is 39 PSI. Raising the fuel pressure on a 14 pound injector to about 60 PSI will allow it to flow as a 19 pound injector would at 39 PSI (provided you have enough fuel pump to feed it)

With the 19 pounders on a stock SO I would get an adjustable regulator and set it for about 30 PSI with the vacuum line disconnected.

This chart shows how pressure affects injector flow rate.....Remember, you need enough pump to support the fuel pressure/flow and a bigger injector with less pressure is better than a smaller injector with more pressure

19lb injectors on stock S.O ecm ?

Reply #2 – November 24, 2005, 09:52:27 PM

Quote from: Paul Flockhart

OK, I'm gonna go on limb and say you have an SO cam still due to the fact you have an SO ECM. On a bone stock SO engine 19 pound injectors with the factory fuel pressure regulator is just too much gas and not enough air or cam or cylinder head.

You can run those 19 on an SO computer but, you need the engine upgrades to make it necessary OR an adjustable fuel pressure regulator.

The stock fuel pressure regulator on return style Ford fuel injection systems is 39 PSI. Raising the fuel pressure on a 14 pound injector to about 60 PSI will allow it to flow as a 19 pound injector would at 39 PSI (provided you have enough fuel pump to feed it)

With the 19 pounders on a stock SO I would get an adjustable regulator and set it for about 30 PSI with the vacuum line disconnected.

This chart shows how pressure affects injector flow rate.....Remember, you need enough pump to support the fuel pressure/flow and a bigger injector with less pressure is better than a smaller injector with more pressure

thanks ,

the car has 1-5/8 long tubes, an h.o upper and lower intake and 60mm throttle body,mac lers off road h pipe, 3.73 gear, a 255 fuel pump, underdrives etc,

I am fixing to do

b303 cam, set of ported e7's, trickflow intake, mustang ecm ,

On a interesting note i unplugged the act sensor and it idles better but still not great.

19lb injectors on stock S.O ecm ?

Reply #3 – November 24, 2005, 09:52:37 PM

Paul is correct...

you can create a vaccum leak of a couple hundred RPMs, to lean out the idle a bit.

Also it it NOT necessary to move the injector pins in the EEC plug. The computer determines firing order, not the harness...

19lb injectors on stock S.O ecm ?

Reply #4 – November 24, 2005, 09:54:46 PM

Quote from: TurboCoupe50

Paul is correct...

Also it it NOT necessary to move the injector pins in the EEC plug. The computer determines firing order, not the harness...

cool anything else to expect? I know we have talked about it before. I would like to keep the factory trip minder also.

19lb injectors on stock S.O ecm ?

Reply #5 – November 24, 2005, 09:54:54 PM

My car is running at about 32lbs of fuel pressure on an HO motor with stock(HO) fuel pressure regulator. I thought it was a result of bigger injectors and the pump not able to keep up, but the drivability is great and the fuel pressure jumps to about 40-42lbs with the vacuum disconnected.

I agree, the 19lb injectors are too much for a stock HO.

19lb injectors on stock S.O ecm ?

Reply #6 – November 24, 2005, 09:58:14 PM

Quote from: Sick88Tbird

My car is running at about 32lbs of fuel pressure on an HO motor with stock(HO) fuel pressure regulator. I thought it was a result of bigger injectors and the pump not able to keep up, but the drivability is great and the fuel pressure jumps to about 40-42lbs with the vacuum disconnected.

I agree, the 19lb injectors are too much for a stock HO.

And thats exactly what the pressure is supposed to do...

19lb injectors on stock S.O ecm ?

Reply #7 – November 24, 2005, 10:05:52 PM

Quote from: TurboCoupe50

you can create a vaccum leak of a couple hundred RPMs, to lean out the idle a bit. ...

I may try this as a temporary "fix"

19lb injectors on stock S.O ecm ?

Reply #8 – November 25, 2005, 01:27:45 AM

Quote

My car is running at about 32lbs of fuel pressure on an HO motor with stock(HO) fuel pressure regulator. I thought it was a result of bigger injectors and the pump not able to keep up, but the drivability is great and the fuel pressure jumps to about 40-42lbs with the vacuum disconnected.

Like Tom said. Your pressure goes up with vacuum disconnected. You should always set your pressure with the vacuum line disconnected. It's like setting base timing....Always disconnect the spout.

Quote

I agree, the 19lb injectors are too much for a stock HO.

A bone stock HO will respond well to a fuel pressure drop of 3 or 4 PSI.

19lb injectors on stock S.O ecm ?

Reply #9 – November 25, 2005, 03:58:36 PM

Quote from: SLEEPER T-BIRD 87

thanks ,

the car has 1-5/8 long tubes, an h.o upper and lower intake and 60mm throttle body,mac lers off road h pipe, 3.73 gear, a 255 fuel pump, underdrives etc,

I am fixing to do

b303 cam, set of ported e7's, trickflow intake, mustang ecm ,

On a interesting note i unplugged the act sensor and it idles better but still not great.

:yuck: what a wonderful day:nono:

19lb injectors on stock S.O ecm ?

Reply #10 – November 25, 2005, 05:05:59 PM

Quote from: TurboCoupe50

you can create a vaccum leak of a couple hundred RPMs, to lean out the idle a bit.

YOU DUMB ASS!!!! Don't you know that only works on Mass Air????

UHHH.... OH yea, I forgot...:shoothead

19lb injectors on stock S.O ecm ?

Reply #11 – November 25, 2005, 07:44:34 PM

I remember when I changed my injectors cause of a cracked tip. Ford dealer sold me a set of 19lb (they said they would work and i didn't know any better then). When I fired it up within seconds my eyes were watering from the exhaust. I could barely keep it running at idle but once i gave it throttle she was good. Needless to say i was pissed when i found out they were supposed to be 14lb.