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MODIFICATIONS => Chip Tuning => Topic started by: DefEddie on February 03, 2010, 04:34:34 PM

Title: Fuel Injectors,fuel pressure and pcm limits.
Post by: DefEddie on February 03, 2010, 04:34:34 PM
Just a few questions I need answered for my build.

What is everybody using for injectors?
Rewiring the injector harness is no problem,I even have injector plugs.
I need at minimum a 36lb injector,ideally 40-42lbs.
Cobras? Any height issue's I should know of?
I have a set of LS1 26lb'ers but they aren't enough even with more pressure.
I can use them for mockup (and will) but figured you guy's have already tried this so..

Is there an adjustable pressure regulator available for these rails or do I have to alter mine?
It is boost regulated right? (rising rate with boost?)
Anybody have part numbers to an adjustable drop in replacement so I don't need to braze anything?

Lastly,I've talked to someone here about doing my chip when i'm ready.
I regularly tune OBDII pcms but haven't the equipment or desire to mess with OBDI.
Will I run into any issue's with this large of an injector programming wise?
Anything I SHOULD NOT do whilst altering the fuel system?

I plan to run about 10psi more fuel pressure than stock (already have the pump to support it).

Thanks for any tips,tricks,hints,advice or links.
Def
Title: Re: Fuel Injectors,fuel pressure and pcm limits.
Post by: TurboGTU on May 02, 2010, 11:42:13 AM
Most are using ford yellowtop replacements. But thats with a semi stock tune.

I've used the ford blue top 25lbs, ford red top 35lbs. They flow little more on gms fuel pressure. But we all know their max duty cycle is about 80. Talk to Kuntzie what he went with. I have not gone that high in fueling yet.

But yeah. Ford Pintle style injectors work well on the tgp. The Multec II styles have some hight issues that youll need to slot the fuel rail end to make them work. I yet to try other styles- siemens -heard good things. The obI has issues trying to drive the multecII at idle. but other than that its cool.

As far as the fuel pressure regulator, you'll have to mod it with a aftermaket inline unit so yeah, bust out the torch.

As far as tunning, like I said before, OBD1 is not user friendly as far as idle goes when it comes to large injectors or multec2. Not much for driving them (only one FET driver) . Just watch the wideband where it counts and then fine tune idle later cuz it will take a while. Start with the EGRvs PW to get a ball park fueling and then mess with the other VE tables. Don't keep going back to the EGR table unless something is way off otherwise you will throw your whole tune off. Stick with a set base fuel pressure using what you will think you will have as far as HP goals and what the injectors will support at that HP level.