LTFT (New to the forum)

[pormgb]

Question: does the IFR match the FPR (i.e. non-referenced FPR means the IFR has to be sloped)...?

Also check: connect pressure gauge to fuel rail, do key on several times, check that pressure holds for at least a minute (and drops very slowly after that).

If it stalls when decelerating to a stop then this means it's not getting enough air, you may need to address throttle cracker/follower and idle:

Done quite a bit since my initial post. yesterday I installed brand new SVO red top 30lb injectors, I set my IFR as per SSpdDmon .tun file and parameters, I also took a bunch of perimeters from his tune file and tuned some of the parameter from idle tips and tricks.

The car runs much better but occasionally stalls, this tells me i have some more tuning to do. Fuel pressure is set at 58 PSI, I stuck a camera in front of my gauge connected to the fuel rail, here are the results;

50 PSI at prime (Key On)
58 PSI running + revving to 4K
Engine off drops to 50 PSI
2 min down to 40P PSI
After about 10 min down to about 29 PSI

This is with new injectors, Porsche 944 Turbo Fuel Pump, external FPR with return.

[slows10]

Did you hook up your vss yet? I swapped in a 411 pcm in a 97 S10 4.3 I did not have the vss connected. It would almost stall coming to a stop, and seemed like it was holding back during acceleration. Generally just ran strange. I hooked up the vss a couple of weeks later and it ran perfect. I believe and also have read that the pcm needs the vss input to run correctly. Hope this helps. P.S can anyone else confirm if the pcm needs vss input for proper function?

[pormgb]

Did you hook up your vss yet? I swapped in a 411 pcm in a 97 S10 4.3 I did not have the vss connected. It would almost stall coming to a stop, and seemed like it was holding back during acceleration. Generally just ran strange. I hooked up the vss a couple of weeks later and it ran perfect. I believe and also have read that the pcm needs the vss input to run correctly. Hope this helps. P.S can anyone else confirm if the pcm needs vss input for proper function?

It's funny you mention VSS!!

I just installed a 34 teeth wheel on my drive shaft with a 24225896 GM VSS sensor, I hooked up the sensor to the PCM but I don't see any pulses when logging. I'm going to do some more trouble shooting tomorrow.

[joecar]

The throttle cracker/follower tables mention MPH... this tells me VSS is required.

How did you connect the VSS sensor (the signal return cannot be grounded)...?

[joecar]

External FPR with return: is the manifold reference hose connected...? This means a difference in whether the IFR is flat or sloped.

[pormgb]

External FPR with return: is the manifold reference hose connected...? This means a difference in whether the IFR is flat or sloped.

I have the reference disconnected, here is my current IFR;

[joecar]

Ok, I was just sanity checking.

[pormgb]

Ok, I was just sanity checking.

Thanks!!

[pormgb]

I done some logging and found My VSS wasn't working due to a bad connector at the PCM, I fixed the connector and recalibrate the VSS perameters and it now works like a charm, the car also does not stall when coming to a stop.

From a mixture perspective, the car is still not running right, I have to do some more logging to figure whats wrong. The fuel trims show the car is running lean but it smells and feels like its running rich.

[joecar]

Are you getting any misfires...?