maxing out 450cc injectors

[mitsubishimanic]

ok i finally got my data logger. so i decided to turn the boost up a little. when im doing my logs im logging knock, injector pulse and injector duty cycle. my mods are 450cc injectors, wally 255,afpr,k&n, dejon intake pipe, full 3in exhaust and fp racing header. any way i got it up to 15 psi and around 6k rpm my logger reads my injector pulse is at 20 ms and my duty cycle is 90% with no knock. then from 6k to 7k they start jumping up and down and the knock sensor is reading about 14 and the car sputters hard. only did this twice for log purposes then i parked it and turned the boost controller down a quarter turn. haven't driven it since. i figured it was hitting fuel cut and i was maxing the fuel system just wanted input to verify this. thanks for the input.

 

[DSM1491]

I dont think your maxing out your injectors.ive ran 25lb of boost on my 16g with no problems with stock injectors. What is your fpr set up at? It should be setup at 40 to 43.

 

[Bud92gsx]

Wrong.On a 1g the fuel pressure for 450s has to be 43psi. @38psi They dont flow 450 ccs,they flow around 411.

So start with 43 psi of fuel pressure and go from there.

 

[96awd16g]

I dont think your maxing out your injectors.ive ran 25lb of boost on my 16g with no problems with stock injectors. What is your fpr set up at? It should be setup at 40 to 43.

WTF seriously? and never hit fuel cut? Were you logging duty cycle? It had to be well over 100%.

I personally know a member here on the forum with a 2g, walbro pump, and 6an feed line, he was maxing his stock injectors at 23 psi with a 14b thats got a mangled turbine. This was after significant tuning and alil fuel pressure (I believe) and duty cycles were still up into the 90% range.

 

[snowborder714]

I dont think your maxing out your injectors.ive ran 25lb of boost on my 16g with no problems with stock injectors. What is your fpr set up at? It should be setup at 40 to 43.

This says nothing around if you're maxing your injectors or not. This just says you either don't have a data logger and are clueless as to what your actual IDC% is, or you just don't care if your injectors are open all the time and could possibly create a lean condition since they can't flow enough to keep up with the car's needs.

Next time, either post hard data (i.e. IDC%) or don't post at all.



OP, you can run your car with the duty cycle over 100% and not experience these issues, but that is definitely a good possibility that your setup just couldn't flow enough. Feel free to post up a log with more data captured if you want us to look over it.

 

[mitsubishimanic]

@ snowboarder714 i havent got my fuel pump rewire kit done yet could that be it? the pump its a wally 255. and i will try to post a log im new to using a logger. and what should i log for you guys to see?

@bud92gsx i thought the 1g was set at 38 from the factory and 2gs were 43 and flow at actual 450cc's

 

[clipto]

Save up for bigger injectors and tune with ecmlink, maybe sell old ps3 or xbox and some stuff around the house to get it. Then you will be good. Why try push 16g with stock setup, just get it done right with a nice tune.. Bumping up fuel pressure will also cause a drop in fuel pump flow.

 

[Mike02rt]

Wrong.On a 1g the fuel pressure for 450s has to be 43psi. @38psi They dont flow 450 ccs,they flow around 411.

So start with 43 psi of fuel pressure and go from there.

Straight out of the FSM...

1g Manual trans = stock BFP: 36-38 @ curb idle
1g AUTO trans = stock BFP: 41-46 @ curb idle

 

[crash89]

I dont think your maxing out your injectors.ive ran 25lb of boost on my 16g with no problems with stock injectors. What is your fpr set up at? It should be setup at 40 to 43.

Im not real sure about this.. When I was first on my 20g I had a wally 255 and stock injectors. ~13 psi I was seeing 120+ IDC at red line. 25 psi on a 16g and no issues? Id like to see a log of this as well.

 

[snowborder714]

@ snowboarder714 i havent got my fuel pump rewire kit done yet could that be it? the pump its a wally 255. and i will try to post a log im new to using a logger. and what should i log for you guys to see?

No, that shouldn't cause any issues like this. An unwired 255lph pump will still support a ton of flow.
http://www.dsmtuners.com/forums/articles-tuning-ecu/366003-injector-fuel-pump-supported-airflow.html

I'd be interested to see knock, timing, IDC%, airflow, RPM, and anything else you think might be helpful. The more data the better.

Id like to see a log of this as well.

I don't think I've ever seen a log from one of these people who claim to use really small injectors for high boost/high hp applications. I think they usually take the "ignorance is bliss" approach and if they don't have data, they think everything is just peachy.

 

[Bud92gsx]

@bud92gsx i thought the 1g was set at 38 from the factory and 2gs were 43 and flow at actual 450cc's

^ Correct bro.
Rewire kit,Make one,Costs like 20 bux.

 

[snowborder714]

That Mike guy knows what he's talking about Bud. Figured you should know this by now with how many times you've quoted it and been corrected.

1G auto - Spec 42.7psi (Standard value 41 - 46 psi)
1G manual - Spec 36.3psi (Standard value 36 - 38 psi)

They have different fuel pressure since they had different sized injectors.
Auto 1g = 390cc
Manual 1g = 450cc

 

[Bud92gsx]

I'm gonna go put that in my fpr article so the confusion stops.

 

[96awd16g]

The most i have seen on my own car without fuel cut is 17-18psi with my 16g. But thats because I trusted someone knowing what it ment to turn the boost controller up a quarter turn. I have the tools to log and tend to be more conservative now that I can see how reckless a few of my choices were in the past.

Log or don't run over 13 maybe 14 psi with a 16g. Anything more and a dirty fuel filter could lean it out enough to be catastrophic

 

[mitsubishimanic]

ok im going for a drive later tonight im going to do a good run or too. ill log rpm, knock, inj pulse and inj duty maf. then one with the 02 and fuel trims