trucklt1

I have a 454 TBI with a whipplecharger. I am running the EBL and VRFPR with 23 psi base pressure, drops to around 12 psi with vacuum line removed, 31 psi at 8 lbs boost. I had this truck tuned in great for a little less than a year until the gasket on the block off plate for the stock regulator swelled and blocked off the return port. I removed the gasket and installed one with the center cut out and all of my fuel trims were then way off. After weeks of tuning and multiple WB VE learns and a few BLM learns I have it really close in all VE areas. I have a horrible looking VE table and I have had to raise the BPCvsVAC chart so high that I maxed it out and am still hitting overflow on VE in a few areas. I can't figure out why there is such huge spikes at 800 1500 and 2800 rpm. I have not learned any areas above 3200. Any cell I manually richen or lean results in that area been rich or lean. It runs great other than on decel. It is bucking on decel (manual shift) I have disabled DFCO, disabled async, and have been adding to the injector comp offset. The bucking is gone, but now it just goes dead lean on decel and is harsh when I start to open the throttle and the injectors come back on. Any help or suggestions would be greatly appreciated Thanks I am not sure how to attach a .bin file but I have attached the low speed and high speed VE tables

RBob

iTrader: (1)

Hopefully you saved the previous calibration. Something is wrong with the fuel pressure.

Not sure if it is a typo, check your first sentence:

> 23 psi base pressure, drops to around 12 psi with vacuum line removed, 31 psi at 8 lbs boost.

Have you checked the fuel pressure under load while driving around?

RBob.

trucklt1

Yes, sorry typo should read 23 psi vacuum line removed, 12 psi idle with vacuum line attached. I have monitored FP under load, pressure is pretty linear with boost/vacuum, definitely no drops in pressure. I reflashed and started working on my old cal again yesterday. with that cal It runs good under load just can not get enough fuel to it in the 1500-1600 rpm range at any map range. Holding under steady load at 1500 rpm 50 KPa (long grade 4th gear pull) at 100% VE 5.4ms 27% DC and it is falling on its face wideband is reading 19-20, If i blip the throttle and get some AE it will richen up a little momentarily and go right back lean. The way I got to the VE table I posted was by increasing the BPC 10% at a time to get enough fuel to it in that RPM range

RBob

iTrader: (1)

Injector connector terminals may have lost tension.

RBob.

RBob

iTrader: (1)

Well, there is definitely something strange going on. Is the BPC vs VAC table set up for a VRFPR? Although that would affect the fueling versus manifold pressure, not RPM.

It may be where the vacuum is being picked up from the intake manifold. That at certain RPMs there is an oscillation that is affecting the vacuum signal to the FPR.

RBob.

trucklt1

I appreciate your help, I checked and retensioned the injector terminals and there was no change. I have the vacuum line for the map sensor and the vacuum line for the FPR both hooked to their own seperate ports on the base plate of the whipplecharger. The BPC was set by the numbers in the EBL Utility and vacuum reference was checked. I ordered a fuel pressure transducer and a MAT sensor that should be in and hooked up this week. Once I get those hooked up I will be able to log FP and see if something shows up that I am not seeing with my pressure gauge.

trucklt1

I got the fuel pressure transducer hooked up and logged with the WUD and went through the data logs and the fuel pressure is consistent with the associated MAP reading. I have adjusted injector comp offset and was able to get VE under 100% in all ranges and the BPC table is under 255 in the low MAP range. It runs good, target and actual AFR are very close, VE learns are only showing 0-2% change except in short PW areas. I have tried with async and it is decent, if i disable async then It gets worse. The minimum sync PW I see with async enabled is 1.8 then it goes into async. With async disabled the lowest PW I see is 1.4 Every post i've read says to disable async, when I do that I can watch in the datalog where it pulses 1.4ms then the next 4 or 5 frames are 0.0. On decel I see large swings in AFR from around 13.0 to 22.0 that coincide with injector firing. Ive had to bump the idle speed up, otherwise when I am at idle when the PW gets short when it is not commanding the injectors, it goes lean, rpms drop, MAP rises, AE adds a little fuel and I get a constant surge. with ASYNC enabled there is a small surge when going in and out of ASYNC. Is there another adjustment I need to make when disabling ASYNC so that it doesnt keep shutting off the injectors and causing driveability problems? Is there an adjustment that needs done to make the ASYNC to SYNC transition smoother?

Ronny

iTrader: (1)

I would disable asynch for now. Once you get drivability you can consider asynch for more fuel at WOT. I idle 1.6 with 2 x 75 lbs injs at 21 FP. A/F is about 15.0/1. 7.4L TB.

Turn of DE if on.

Set idle a bit higher like 900 rpms for now. You could use TSS. And may see IAC steps zero.

Consider open loop idle for now. I also go CL over 10 mph otherwise in OL at 13.0-14.0.

Fast355

iTrader: (2)

Actually I would consider the other way around.......ONLY RUN ASYNCH. A roots/screw type supercharger is not like a dual plane. I never could get a single plane to run well without going full asynch either.

Ronny

iTrader: (1)

OK then. Why is it "asynch" cutting fuel to achieve a lower pulse width? If trying to achieve stoich(128) is the reason? Then is OL trial run with possible rich condition under 1500 rpms going to be helpfull to further understand what is going on? Or OL set for idle and <15 mph trial run may shed some light?

Is this a 350 or bigger engine?

Fast355

iTrader: (2)

454 and most of them ran open loop idle AND asynch only bins from GM.

trucklt1

Thanks for the replies, I am still running open loop, I have DFCO disabled, as far as idle I have 13.6 commanded AFR and It appears that the injectors can not be turned on for a short enough pulse width (sync) to obtain that. I have tried bumping up the idle speed and it idles smooth above 900 rpm, but I would like to idle closer to 750. I have tried richening up the idle, (12.8), idle surge is gone but that is too rich for idle, and the rich exhaust stinks! If i go back to async is there an adjustment I need to make for a smoother transition from async to sync?

RBob

iTrader: (1)

To get a smooth transition between sync and async the injector compensation values have to be perfect.

The only way the PW can go to zero in sync mode is if it has been calculated to that value. With DFCO disabled there has to be areas of the VE table that is too low.

If you want to try async always, change the values in this table to 13,000 usec:

INJ - ASync Transition PW - TBI Only

RBob.