Injector question for juice

[1DangerousV6]

right now im still running a dry system and a 120 shot (using a 63 jet that seemed to work good for James and Jonh D)..in the engine tech section it says that 95 - 98 3.8L f-bodies have 22lb. injectors..i know i have 22lb. from working with HP Tuners..however..in the media section it says that one of the "19lb. injectors James was using started to go bad"..so my question is..why did they say that??..do different years have different injector sizes or something??..John D and i have a 98..James has a 97..the 22lb. injectors seem to be working fine on the 120 shot..especially with the upgraded MSD pump..i guess im just curious about this..thanks!

[arthansen]

What is you injector pulse width while on the juice at 5900 rpms? I am just curious.

[12secondv6]

There is an error in the database.

19 lb injectors are stock for 1997.

I currently run 19 lb accel injectors.

[1DangerousV6]

cool..thanks James!

Arthansen..where do i check the injector pulse width in a logged run?..can i see it right on the gauge or line display?

[12secondv6]

Not a prob.... the question comes up here and there

[malice10985]

OK, so a 1999 has 19 or 22lb injectors?

I am guessing that I have 19's as well. When I installed 37lb injectors, my pulse width cut just about in half.

[12secondv6]

To my knowledge.... it is all 19's

[1DangerousV6]

are you sure?..the flow rate i see when i scan my PCM in HP Tuners says 22??

EDIT -- yeah..looks like they're 19lb ..i dont get why HP Tuners says 22 for flow rate then

[ March 29, 2005, 12:17 PM: Message edited by: 1DangerousV6 ]

[arthansen]

The injector pulse width should be seen in the scanner in a number of locations. They are labled "Inj B1 (ms)" and "Inj B2 (ms)". They are in the Chart, PID table, and the Dash. The best place to see them is in the chart. Scan a run with the nitrous and then post up the scan. I will take a look at it.

[1DangerousV6]

awesome..i should be able to do that this weekend..i know where you are talking about..on the stock injectors..what is close to maxing them out?..when it just goes all the way up or is there a certain number im looking for?..and as stated above..why does it say 22 for flow rate when we have 19lb injectors??

EDIT -- this is in the "Flow Rate vs. KPA VAC" ..the table that tells the VCM what size the injectors are ..the actual value is 22.18

[ March 29, 2005, 12:54 PM: Message edited by: 1DangerousV6 ]

[Nachius]

I always thought they were 22s :(

[1DangerousV6]

i just wrote to HP Tuners to see what the deal is..cuz i wanna know whether my injectors or computer is wrong! ..or if im just misunderstanding something

[12secondv6]

Well... I know... my stockers are 19's... and I run 19's now.

Stumps me how EVERYONE has to run bigger injectors. Oh well....

[1DangerousV6]

cuz one of your 19s went bad on a 120 dry shot..which is my current setup ;)

[arthansen]

Keep in mind, the number in the table is not nessasarely the rated flow rate of the injector. It is the calculated flow rate based on the amount of back pressure in the manafold in relation to the fuel pressure. A perfect example of this is the use of a FMU. With the FMU, the fuel pressure goes up so the injectors put out more fuel. The injectors are still the same but the flow is greater.

I pulled up two tables (see bellow) from the .bin depository. The first one is from a 1997 3.8 Firebird, the second from a 1999 (there were no 1998s). Notice that the 1997 is the same from 1-100 Kpa but the 1999 ramps up. This is because they figured out that as the back pressure increases, they need more fuel (the bigger the number, the less fuel)

1997
22.27 22.27 22.27 22.27 22.27 22.27 22.27 22.27 22.27 22.27 22.27

1999
21.39 21.43 21.48 21.54 21.63 21.72 21.84 21.96 22.08 22.21 22.33

So do not worry about what your injectors are or the table. It is what it is. What matters is the Injector Pulse Width.

There is a table in the Engine Tech section.

http://engine.firebirdv6.com/pulsewidth.html

It shows the % duty cycle for different RPMs and Pulse width. You want to stay bellow 90% duty cycle. For instance. At 6000 RPMs and 20 ms pulse width, you are at 100% duty cycle. If you go over 100% duty cycle, the PCM will be calling for more fuel then the injectors are capable of providing. This will result in a lean condition and can cause problems.

Log a run and post it up.

Keep in mind, if your injectors are too small, the car might run fine. It may actually get more HP....right up to the point you melt a piston!

[ March 29, 2005, 05:42 PM: Message edited by: arthansen ]