What's the deal with 30# injectors?

9

9 Deuce GT

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Dec 10, 2003

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Geneva, NY

Jun 20, 2005

#1

• Jun 20, 2005

• #1

I recently upgraded injectors to 30#ers from 24#ers. I also installed a TFS Stage 1 cam. Well, I know have severe idle issues. I see a lot of guy's are running 30#ers, and was wondering if you have the same problems? I still have to try putting my stock injectors and mass air sensor on to see if this is the case, but I think it may possibly be my C&L 73mm mas. Are any of you guy's running chips, or will I be able to get this thing to idle close to stock with better tuning?

 

89CopCoupe

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Jun 20, 2005

#2

• Jun 20, 2005

• #2

You did upgrade your maf to match your 30's right?

A 30lb injector requires a greater air supply to run "stock like" at an ideal a/f ratio compared to a 24#r ...

Also, your TF cam has a decent overlap which decreases idle speed vacuum as well ...

If you do have a maf calibrated for the 30's, try turning up your idle speed a bit and your fuel pressure down a little ... , too low and the injector won't receive enough pressure to develop a good spray cone.

However, based on the mods in your sig, I don't see a need for 30's

 

9

9 Deuce GT

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Jun 20, 2005

#3

• Jun 20, 2005

• #3

Yes, I have the MAS calibrated for 30's. The reason for the 30's is I have a 351w that will be installed in the near future, and I ran across a swap type deal that worked out great, (before these issues). I have been told that turning down the fuel pressure is a band aid fix, that will only last as long as the time it takes for the computer to learn the setup. I will try both the idle speed adj, and turning down fuel press. Another issue I am having, is it dies when driving and coming to a stop. I assume this is a related problem.

 

5spd GT

"the 5.0 owns all"

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#4

• Jun 20, 2005

• #4

Yeah I have 30lb injectors (a very slightly more aggressive setup than you) on my daily driver.

It idles fine (rich though) and is harder to start when the car is hot. To much cranking fuel...

I have my timing at 16*, fuel pressure at 39psi (vaccum off). Plugs gapped at .045. Pro-M Bullet MAF.

 

Grn92LX

Fidanza Man!

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#5

• Jun 20, 2005

• #5

My car before I added the afm pms would idle pretty poorly on cold starts and warm starts. It would also randomly stall @ stop lights sometimes. I bought a pms to fixed all my surging problems and in 1 day I pretty much fixed everything. No more surging, stalling or any idle woes. We'll see how the 347 idles in a few weeks hopefully. My idle tune for the 302 should be dead on for the 347 so it should do alright. I run 30's and a pro m 80mm.

 

9

9 Deuce GT

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Jun 21, 2005

#6

• Jun 21, 2005

• #6

Anyone else?

 

T

thompsonsd

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Jun 21, 2005

#7

• Jun 21, 2005

• #7

I seem to have the same issue as you... Although I did have a custom chip made that helped at the rest of the RPM range, it didn't help the idle. I've been kind of blaming it on my Cam being too aggressive, but I'm not really sure about that...

I've check for leaks dozens of times, played with my valve train in ways I probably shouldn't have, and anything else I could think of to help with the idle issue, all to no avail...

Plus I get all kinds of "bucking" going on under around 1,800 rpm...

 

89CopCoupe

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#8

• Jun 21, 2005

• #8

There is no need to step up to 30's until your n/a power level reaches more then 290 - 300 rwhp. A 24#r will supply enough up to this level (on stock computer settings) .

A 302 with any h/c/i combo is not going to need a 30's fuel supply until up off of idle where it can consume the fuel due to increased vacuum ... without taking the car in for a good tune/adjustment the issue will always be magnified.

From the mods in the sigs I have yet to see a combo that would benefit greatly from a 30# injector.

 

1EVIL88VERT

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Dyess AFB, TX

Jun 21, 2005

#9

• Jun 21, 2005

• #9

mine does the hot start surging too, and it also bucks below 1800rpm just have to deal with it, i just like having the peace of mind that i can still do more little stuff and not worry about going lean.

 

cobradvm

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Sep 2, 2003

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Woodinville, WA

Jun 21, 2005

#10

• Jun 21, 2005

• #10

I have a 331 with 30# injectors and a ProM MAF. It starts and idles like stock. i might consider seeing if you can get your hands on a Pro M unit and see if that helps. I do not have any engine management setups - my tune up basically consists of adjusting timing, fuel pressure, and making sure the TPS is where it needs to be.

 

89CopCoupe

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#11

• Jun 21, 2005

• #11

cobradvm said:

I have a 331 with 30# injectors and a ProM MAF. It starts and idles like stock. i might consider seeing if you can get your hands on a Pro M unit and see if that helps. I do not have any engine management setups - my tune up basically consists of adjusting timing, fuel pressure, and making sure the TPS is where it needs to be.

Click to expand...

Amazing a 331 (that pulls more air) will run better with a 30#r
This is what I've been tryin' to say, sheesh.

Damn fellers, why not just put some 42's on the beatch ...

 

5spd GT

"the 5.0 owns all"

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#12

• Jun 21, 2005

• #12

Yeah a stroker will accomadate the 30's better. I will be running the same injectors (30's) when/if I go stroker.

24's would be fine on my car...30's would be nicer if I could get a tune with it. More room for a tuner to play with so the injectors don't reach near full duty cycle when the air really starts flowing

 

9

9 Deuce GT

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Jun 22, 2005

#13

• Jun 22, 2005

• #13

5spd GT:

I remember seeing a post where you mentioned Ed Curtis recommending 30's to you because of the tuning thing. Did he say that a custom tune with a chip or a hand held tuner was neccesary? I have actually heard a lot of people say that they were told to go 30's. I'm just trying to put this all together.

I actually got the thing to hold an idle today by bumping up the idle speed. Seemed to do the trick for the surging and dying. It still surges a little, but after a few seconds, it will settle to where it needs to idle. Even when driving, it holds an idle. Now I just need a PMS to tune this thing the way I want.LOL.

 

5spd GT

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#14

• Jun 22, 2005

• #14

9 Deuce GT said:

5spd GT:

I remember seeing a post where you mentioned Ed Curtis recommending 30's to you because of the tuning thing. Did he say that a custom tune with a chip or a hand held tuner was neccesary? I have actually heard a lot of people say that they were told to go 30's. I'm just trying to put this all together.

I actually got the thing to hold an idle today by bumping up the idle speed. Seemed to do the trick for the surging and dying. It still surges a little, but after a few seconds, it will settle to where it needs to idle. Even when driving, it holds an idle. Now I just need a PMS to tune this thing the way I want.LOL.

Click to expand...

When I conversed with Ed he was referring to dyno tuners (chip)...not the handheld video games He said the dyno tuners he had been accompany to said that they have their best luck with 30's because they have more room to tune with. I say go 24's if you can't get the car tuned. They have less issues. So 24's with no tune available. 30's for tuner available. I still get good gas mileage. I got 24mpg a while back and average 20-21mpg and I'm not easy on it and I'm not hard on it.

I have my idle at 750-800rpm.

Good Luck with it