Fuel pressure at idle

[Rizzer1]

Hey guys, I did a search and got results of 43 without line hooked up. What I was wondering is....if I have a fuel pressure guage where should my fuel pressure be at idle with 50# injectors? Also what is the best guage to have to help with detonation and where to get it? Will a scanmaster work? I am asking as i just replaced the head gaskets on a GN I just bought that is modded and I am going to be in the process of tuning it and want to know what was the best things to have to let me know its detonating while I am doing it. I have a fuel pressure guage, aftermarket boost guage, aftermarket tach, aftermarket temp guage and I wanted to know if I need anything else? I have an adjustable fuel regulater and wastegate so any help on anything else to help me tune it would be great. Thanks

 

[Murt TTA]

fuel pressure w/ vac off depends on your chip setting. What chip are you running?

If its an old chip, get rid of it and get a turbo tweak chip.


The scanmaster is fine for monitoring knock just keep an eye on things and if Knock retard stops, take your foot off...

How did the head gasket blow the first time? previous owner?

Start off with lowboost and adjust from there... then add alky and your all set. good luck

 

[jcj53115]

A knock gauge make monitoring knock alot easier too as you can keep your eyes on the road instead of the SM.

 

[Rizzer1]

Not sure hoew it blew the first time. He said he ran out of gas going up a hill???? Anyways I am running alky and I just got a turbo tweak chip . So you guys think if I start nice and low and watch my boost and fuel I should just get a scanmaster to moniter the knocking? And do you know what my fuel pressure should be at idle? My guage is showing roughly 33 ? What do you guys think? Any tips will help I am tuning this thing slowly.

 

[Rizzer1]

If I get a scanmaster should I get a knock guage? if so where can I get one?

 

[incubus2432]

Start with fuel pressure at 42-43 psi with the vacuum line off and work from there.

FULL THROTTLE SPEED - Store Front Page for the Scanmaster and I believe knock gauges are available there as well. It's up to you if you feel the knock gauge is necessary or not. I'm happy with the Scanmaster alone and others feel the knock gauge is a "must have".

 

[Junior Samples]

Start with fuel pressure at 42-43 psi with the vacuum line off and work from there.

i turned mine down a hair from 43@ idle but need scan tool to see 02's to make adjustments

 

["Turbo-T"]

fuel pressure w/ vac off depends on your chip setting.

Just curious how does the chip affect fuel pressure?

If I get a scanmaster should I get a knock gauge? if so where can I get one?

You can if you want to, you can get them some of the Caspers electronics, ebay or even Summit racing. Just type in "Caspers".

The gauges are sometimes finicky, but not a bad tool to have. I just keep an eye on the Scanmaster when building boost.

 

[DavzGN]

Just curious how does the chip affect fuel pressure?

The chip is programmed based on an expected fuel pressure. If your fuel pressure is too low, you won't get as much fuel and it's goodbye headgaskets.

David
87GN

 

[Just a Six??]

Scanmaster & Audible knock guage from Caspers. It starts beeping & gets louder with more knock. Acts fast & you hear it! No looking. Starts beeping & you let off!

 

[jcj53115]

I just keep an eye on the Scanmaster when building boost.

Thats why I like the knock gauge, I can keep my eyes on the road instead of inside the car. The gauge is nice and bright and you cant miss it when its reading knock.

 

["Turbo-T"]

The chip is programmed based on an expected fuel pressure. If your fuel pressure is too low, you won't get as much fuel and it's goodbye headgaskets.

Would you recommend I keep the PSI a little higher tyhan what the chip calls for? For example the chip calls for 43 PSI, could I get away with 45-46?

Scanmaster & Audible knock guage from Caspers. It starts beeping & gets louder with more knock. Acts fast & you hear it! No looking. Starts beeping & you let off!

Does the beeper use the same sensor wire off the ECM the knock gauge does?

Thats why I like the knock gauge, I can keep my eyes on the road instead of inside the car. The gauge is nice and bright and you cant miss it when its reading knock.

I hear you. In my experience the knock gauges may read false KR, I have mine eye level but sometimes when it's day time it gets washed out and I look up to see an LED on. I might try the beep one though.

 

[RatFink]

Would you recommend I keep the PSI a little higher tyhan what the chip calls for? For example the chip calls for 43 PSI, could I get away with 45-46?

Nope, 43psi is enough. A proper chip should do your fueling, with a Turbo Tweak chip you can adjust the settings as well. I was running 43 psi /line off with 60# inj/ alcy/ 24psi and it was too rich at the top of 2nd and 3rd. Took it back to 41psi/Line off and it feels better. I have no time slips to prove this, but I felt that it picked up. I'd say 45 or more would just be too rich. IMO.

Another great tuning tool is a Wideband 02 to accurately read your air fuel ratio.

 

[Junior Samples]

Same here, I set mine back to about 40, felt better, sounded better and my egt's looked better

just depends on your motor

 

["Turbo-T"]

Thanks I just figured a little more was better than not enough.

 

[Rizzer1]

Thanks, I am buying an audible knock beeper and a scanmaster. That should help.