injectors!!!

[turbo6man]

My buddy has a cyclone and it has an Accel gen6 and 40lb injectors. It was tuned and runnig great using a wide band 02. He was maxxed out on injector duty cycle so he bought a set of 50's. Here is the problem:

Runnining perfect before. Only thing changed is 50 lb injectors. Will idle and run fine with 30 to 35psi fuel pump pressure. will not start with fuel pump pressure at 35-42psi.

We are pretty sure the injectors are not opening with higher fuel pressure during start up. Can turn down pressure, start, then turn up pressure and it will run good from low into mid range(did not try any higher due to lack of tuning). tried messing with software tune(small and large adjustments) at higer fuel pressure=does not start.

old(40 lb) injectors all ohm out to 16ohms. New all ohm out to 12 ohms.

Are the drivers in the DFI having problems with the lower impedance(more current flowing)? Accell manual states they should work. Or could the injectors be sticking closed at higher fuel psi. I have heard of them sticking open, but never closed?

any info would be apreciated. Turbo6man

 

[turbo6man]

I would like to add that the origianal 40 lb injectors have been put back in and it starts/runs fine at higher fuel psi.

 

[turborayjay]

May get more responses in the Syclone typhoon arena.

 

[humberto]

Maybe a new chip reburn?Just an idea.

 

[bruce]

Originally posted by turbo6man
My buddy has a cyclone and it has an Accel gen6 and 40lb injectors. It was tuned and runnig great using a wide band 02. He was maxxed out on injector duty cycle so he bought a set of 50's. Here is the problem:

Runnining perfect before. Only thing changed is 50 lb injectors. Will idle and run fine with 30 to 35psi fuel pump pressure. will not start with fuel pump pressure at 35-42psi.

We are pretty sure the injectors are not opening with higher fuel pressure during start up. Can turn down pressure, start, then turn up pressure and it will run good from low into mid range(did not try any higher due to lack of tuning). tried messing with software tune(small and large adjustments) at higer fuel pressure=does not start.

old(40 lb) injectors all ohm out to 16ohms. New all ohm out to 12 ohms.

Are the drivers in the DFI having problems with the lower impedance(more current flowing)? Accell manual states they should work. Or could the injectors be sticking closed at higher fuel psi. I have heard of them sticking open, but never closed?

any info would be apreciated. Turbo6man

You should be able to trim the fuel back 20% going from 40s to 50s. All things being equal it should start.
How sure are you that they're 50s?.
35 to 40 PSI won't lock up a port injector, I've seen some injector data sheets showing most injectors going to 100 PSI and being linear all the way.

 

[turbo6man]

Thanks for all the reply's, sorry it took so long for me to reply(Me, the wife and kids went to Disneyland). So the 40's were taken back out (again) and I have 72's for my GN and we put the 72's in the cyclone. They work great and we are able to trim the fuel curve back just fine. It starts fine at different fuel psi settings. I just dont know what is wrong with those 50's, but his original high imp 40's work fine as well as my low imp 72's. Thanks again for the reply's turbo6man

 

[cheatham 2492]

There is a setting in the .bin with the code $58 .
the adress 0x040E F28 is the injector constant wich has to trimmed for the injector size difference. HOW ever I have not had any luck finding out the math to come up with this figure... all's I know is the figure gets smaller, with the larger injectors. If you got the driver upgrade some one would hopefully burn you a .bin to match the injector size you whent with.

Dose someone know the math to 00x040E-F28
that would be incredibly helpfull.
Dan
dannycheatham1@hotmail.com

 

[Chuck Leeper]

A SWAG...

Let me guess. The 50's are not new, and have been lying around for some time since being removed from an engine????

VERY common problem I see w/ used injectors that come to me for cleaning and flow testing, is they are allowed to dry out w/ fuel in them.
I have taken an inj, cut the body open on the lathe, and had to use a hammer to drive the pintle out... Other than it being frozen up, I found no other causes for the lockup....only dried gas deposits.

If the units are new, I'd really surprized if they are "locked up" w/ a reasonable pressure on them.
BTW, 12 ohms is ok.

Want to test and clean??
Send me a PM

 

[bruce]

Originally posted by cheatham 2492
There is a setting in the .bin with the code $58 .
the adress 0x040E F28 is the injector constant wich has to trimmed for the injector size difference. HOW ever I have not had any luck finding out the math to come up with this figure... all's I know is the figure gets smaller, with the larger injectors. If you got the driver upgrade some one would hopefully burn you a .bin to match the injector size you whent with.

Dose someone know the math to 00x040E-F28
that would be incredibly helpfull.
Dan
dannycheatham1@hotmail.com

;-----------------------------------------------
; BPC = 1461.5 * (VOL / RATE)
; VOL = Vol of 1 Cylinder in liters
; RATE = Injector flow in gms/sec
; gms/sec = (lbs/hr / 3600) * 453.6
; 50#/hr = 6.3 gms/sec
;-----------------------------------------------

I always seem to have to fudge some on it.

 

[cheatham 2492]

At the risk of sounding stupid could you kind of spell this out for me. Pretty please .I think this is exactly the math we need when change injector sizing. thanks so much,
Dan Cheatham

 

[bruce]

Originally posted by cheatham 2492
At the risk of sounding stupid could you kind of spell this out for me. Pretty please .I think this is exactly the math we need when change injector sizing. thanks so much,
Dan Cheatham

;-----------------------------------------------
; BPC = 1461.5 * (VOL / RATE)
; VOL = Vol of 1 Cylinder in liters
; RATE = Injector flow in gms/sec
; gms/sec = (lbs/hr / 3600) * 453.6
; 50#/hr = 6.3 gms/sec
;-----------------------------------------------

The constant you want to figure out is called BPC.

If you have a say a 3.6L engine then each cylinder is .6L
If your using 50 PPH injectors then that would be 6.3 gm/sec

So your BPC, would be, 1461.5 times, .6 divided by 6.3....
Or 134

 

[cheatham 2492]

Ok I thought that was right. How do those #'s correlate with the F28 table. the entry's are in hundreths's and lower. where dose the decmile go? The stock chip has a factor of .089 for a 28lb inj in the F28 table. How dose the BPC=296.96846 work in to code $58 x040E F28? Is this the way to find the constant for the buick ECM? Maybe different on the Typhoon 7749 ECM $58 code.
TIA
Dan

 

[bruce]

Originally posted by cheatham 2492
Ok I thought that was right. How do those #'s correlate with the F28 table. the entry's are in hundreths's and lower. where dose the decmile go? The stock chip has a factor of .089 for a 28lb inj in the F28 table. How dose the BPC=296.96846 work in to code $58 x040E F28? Is this the way to find the constant for the buick ECM? Maybe different on the Typhoon 7749 ECM $58 code.

Ya lost me on what your asking, in those first few sentences.

The buicks use the Injector constant type code, and are SEFI instead of batch.

 

[cheatham 2492]

Well i guess what I am tring to say is, when i open my editor to the stock .bin file and I look @ address 0x040E the value is .089 in every slot. now that dose not coincide with the way you suggested to figure the BPC Vs EGR. wich would be 4.3L 28lb. BPC=296.68 is there something missing?

Dan

 

[bruce]

Originally posted by cheatham 2492
Well i guess what I am tring to say is, when i open my editor to the stock .bin file and I look @ address 0x040E the value is .089 in every slot. now that dose not coincide with the way you suggested to figure the BPC Vs EGR. wich would be 4.3L 28lb. BPC=296.68 is there something missing?

Look at it with a hex editor. Then convert that raw hex value to decimal.