I'm having a problem with my cars idle. It idles rough and when i let off the gas to slow down it idles down to far and cuts out and acts jerky like. Here is the data that i've come up with so far:

Fuel Pressure: 48 engine off, 38 Engine ideling.

Scanner Data:
PROM ID: 3418
Coolant Temp: 204
Start up Coolant Temp: 194
Throttle Sensor: .54 Volts
Engine RPM: Ragning from 610 to 708
Vehicle Speed: 0 MPH
O2 Volts: Ranging from 184 to 812
O2 Cross counts at end of test were at over 500
Block learn: 108
Block Learn Cell: 0
Intergrator: 120
Idle Air Meter Position: 33-48 steps
Desired Idle: 650 RPM
Engine Load: 57
Manifold Air Temperature: 118.4 'F
EGR: 0%
CCP: 0%
Battery Voltage: 13.7 Volts
Fuel Pump Sense: 13.4 Volts
Spark Advance: 15.7'
Knock Retard 0'
Injector Pulse: 1.6 ms
Engine Run Time 230 seconds
Mass Air Flow: 7-8 gr/sec
CCP purge: off
Air Diver Solenoid: On
Air Switch Solenoid: Off
Learn Control: Enabled
Rich Lean Flag: Switches between rich and lean about every second or two.
Loop Status: Closed

This Data was taken with an Auto Xray using the capture mode. The data was from 14 seconds of running at idle.

Can any of you tell me if this looks like an electrical problem or a mechanical problem? I'm pretty sure i don't have any vacuum leaks but i'm not sure about things like the egr and such. It started doing this after installing the Accel 21 lb injectors. I figured that since these injectors were slightly smaller than my stockers it would help slightly to correct the factory's richness. Thanks in advance!!!

 

All things working properly with your BLM of 108 means you are running VERY rich...

and, 108 is usually the lowest that BLM can go so you could be, and probably are, much richer than that!!! at least 18% rich, probably more!!! If all is "well" with your electronics/car/etc, that is.

Is your PCV working and not plugged up? the lack of airflow from a blocked PCV could make your ECU want to lean things out, I suppose, how much, Not sure... Just a thought.

 

Your fuel pressure sounds way too high to me. I'm not a TPI expert but I thought you were supposed to set the pressure with vacuum line disconnected. That's what we've always done with my buddy's T/A.

 

That is how I measure my fuel pressure (Vacuum line off), but I do like to monitor occasionally what my actual is while driving.

Regardless, I agree with Fast Broker that you are running too rich. I personally like higher fuel pressure than stock and I run 46 psi (measured with the vacuum line off). To get my fuel correct, I had to do a combination of increasing the Injector Size inside the eprom (to shorten the pulse width globally) and then "fine tuned" by adjust my VE tables (since I am SD) for the specific rpm/load ranges.

With MAF, you would have to "fine tune" in the MAF Scalar Tables, which is not recommended for a "beginner". Rather you should tune to try an attain 128/128 as much as possible with your MAF Tables (as is) by a combination of altering the Injector Constant in the eprom and fuel pressure itself. Also, there is not a "straight linear" relationship between fuel pressure and the injector constant. I have found the increasing fuel pressure (by itself) has it's greatest effect at WOT and least effect at idle. That is why I am recommending a combination of "Injector Constant and Fuel Pressure" to get as many of the BLM/INTs at 128/128 throughout the operating ranges of your engine.

Try and keep a fuel pressure somewhere above 42 but don't go much higher than 48 psi if you are running the stock fuel pump. High fuel pressure seems to cause the stock fuel pump to die pre-maturely.

 

Also, I noticed you cut your MAF screens. As I drive an SD car, I cannot comment on the significance of this on the ECM. But I am sure others might. Did you ever measure your BLM/INTs when the MAF screens were still there?

 

I never measured them before i cut out the maf screens. I didn't have a scanner at that time. The thing that has me stumped is that the car ran fine before the injector swap ??? Nothing has been changed except the injectors. The fuel pressure regulator is the factory gm one so i'm kinda wondering why my pressure is so high. Could my return line be blocked? I haven't even begun to start burning my own chips, i figured i would start out kinda slow with just a scanner....lol. I'm thinking that this summer i'm gonna go through the car again and start burning my own chips. Thanks for the help so far, this is getting very agravating.