I'm guessing I have done something wrong...

As the sig states, 92 350 TBI.

I just got back into tuning my car after it has been out of commission for over a year. Engine wise I installed 55# injectors as opposed to the 45# stock injectors and put in a TPI pump, and changed the regulator and spring out to support the pressure increase to 26lbs (adjustment is all the way down, least spring pressure, least amount of fuel pressure I can produce). The 26 lbs on the guage is not steady by the way, not a huge variation but maybe a 25 to 27 lbs very fast flutter, if that... ISSUE?

Anyways, I have been tuning away after upgrading tunerpro, EBL software version and EBL firmware. I got my tune where I would consider to be great when it is good and warmed up, but maybe morning vs night drives each time I start there are areas that want to change by 10 or -10 percent. Maybe my IAT actually being a resistor needs to change to an IAT sensor?

So I'm looking at my VE tables in tunerpro and notice in the top left corner there are a few zeros where there was not before and it never even gets good values to do a BLM Learn that low of RMP and MAP. Below you can see what I see, I have compared my most recent two bins with the EBL corrections to compare, I see differences all over the tunerpro VE table that according to EBL were not made. Should the compared changes in tunerpro match the EBL areas of change?

Please help me understand.

 

> Should the compared changes in tunerpro match the EBL areas of change?

The smoothing changes the other locations. If you set the smoothing factor to zero then nothing else but the learned values will change.

> down, least spring pressure, least amount of fuel pressure I can produce). The
> 26 lbs on the guage is not steady by the way, not a huge variation but maybe
> a 25 to 27 lbs very fast flutter, if that...

This isn't good. The fuel pressure isn't under control of the FPR. Likely the pump is overwhelming the return system.

RBob.

 

I am aware of two TBI GM springs. One low pressure(11-13 or so) and one high pressure(approx 32 lbs for 7.4L 1994-1995). If you need one in the middle, top down solutions can provide. Do you need 26 lbs to support a modded engine?

 

I replaced the TBI pump with a TPI pump and found out the hard way that the regulator spring did not support that much PSI. I however happened to have an extra (maybe 3) 2" TBIs from the local you pull it place, so I hijacked a spring. I did not want to change the pressure by too much being afraid it would be harder to tune, so I left the adjustment all the way out. I wanna say this tbi regulator is actually off a newer suburban that had an equivalent 305 injector (different part #) with a larger pump. I don't actually know what I "need" to support the engine. I just know before the change I ran outta pump up top.

 

I know once I read somewhere that having the regulator adjustment at minimum could cause funny readings.

The return system, as in a line blockage? Maybe I should disconnect the rubber return line up front and dump it to a can while reading the pressure?

Funny thing is, before I even had the tank fully mounted I did a test and had 26 lbs rock solid. Did not want to have to drop that tank again. I wonder what changed?

 

OK, that would be the 30 psi spring. Which is why you can't get the pressure much lower. Which also means that it likely isn't a return system issue.

You will need to increase the fuel pressure, say to 29 - 30 psi. This is so that the FPR is actually regulating, not just providing a restriction.

With L03 55#/hr injectors that 30 psi is good for a little over 300 HP. While L05 61#/hr injectors will bring that to 350 HP.

RBob.

 

Idle BLM is 128 and drops straight to 117 and back to 128 for a bit and repeats. EBL is trying to correct by 0 for learn. why would BLM be jumping around only at idle? Idle is pretty smooth.


Posted from Thirdgen.org App for Android

 

Look at the WU display and see if fueling is going asynch-synch-asynch. At idle you may have excessive PW causing BLM changing.

I would locate a stock early TBI spring for sure. Actually I would go to top down and buy theirs as you could benefit from a bit more fuel pressure.....

 

fuel pressure is 100% decreased already, i can increase with my current spring. already changed asynch transition PW exit and enter to 0. That would typically cause fluctuating idle, mine stays smooth and BLM alternates from 128 to 117 skipping all numbers between. I also had already previously increased injection correction offset for the larger injectors, also helping to smooth idle.



Posted from Thirdgen.org App for Android

 

Likely switching between cell 0 and 2. IIRC, the stock RPM setting for this is 800 RPM. With a higher idle RPM due to the cam, should bump that up, say to 1000 RPM:

BLM - Idle Cell RPM Threshold

RBob.