Idle instability issues after DW 700CC and fuel pump install

[D-VO]

Hey guys. I'm hoping someone can help me with this idle issue I've had for almost 4 years now. After installing a KW supercharger with a high boost pulley, I noticed I needed more fuel, so I went with a DW fuel pump and DW 450cc injectors. I calibrated everything per DW's instructions using the specified tables. I did find that I had to modify them a bit more than was instructed to get everything running properly.(fuel trims, tip-in, cruising)

After the DW 450 injector install start up there has been a strange fluctuating spin up; revs pop up to 1400rpm for a split second then drops to 1100rpm twice then stabilizes at 1400rpm. When the start up timer runs its course (100 seconds I think) and the RPM is supposed to drop down slowly, mine jumps up to 1700rpm back down to 1200 then back up to 1400 then starts slowly dropping down. However after touching around 650RPM the idle starts destabilizing again then the car stalls. After starting for a second time its fine. Also, after driving it for a while and coming to a stop the engine will sometimes stall.

Its tough to see whats going on because not all logging parameters are available to us open source guys. IAT's, coolant temps, oil temps, STFT and manifold pressures seem to be of no consequence. The only change I'm noticing, though possibly coincidental, is the fuel system status change just before the engine stalls going from OL/deceleration to CL for about a second and a half. (Attached screenshot of the fuel system change when it stalls)I came close to correcting the cranking portion of my issue using the cranking IPW tables but eventually ended up with the engine not starting at all so I went back to stock. If anyone can share some wisdom here it would be greatly appreciated.

*Edit* They were 700's

[steve99]

Originally Posted by D-VO

Hey guys. I'm hoping someone can help me with this idle issue I've had for almost 4 years now. After installing a KW supercharger with a high boost pulley, I noticed I needed more fuel, so I went with a DW fuel pump and DW 450cc injectors. I calibrated everything per DW's instructions using the specified tables. I did find that I had to modify them a bit more than was instructed to get everything running properly.(fuel trims, tip-in, cruising)

After the DW 450 injector install start up there has been a strange fluctuating spin up; revs pop up to 1400rpm for a split second then drops to 1100rpm twice then stabilizes at 1400rpm. When the start up timer runs its course (100 seconds I think) and the RPM is supposed to drop down slowly, mine jumps up to 1700rpm back down to 1200 then back up to 1400 then starts slowly dropping down. However after touching around 650RPM the idle starts destabilizing again then the car stalls. After starting for a second time its fine. Also, after driving it for a while and coming to a stop the engine will sometimes stall.

Its tough to see whats going on because not all logging parameters are available to us open source guys. IAT's, coolant temps, oil temps, STFT and manifold pressures seem to be of no consequence. The only change I'm noticing, though possibly coincidental, is the fuel system status change just before the engine stalls going from OL/deceleration to CL for about a second and a half. (Attached screenshot of the fuel system change when it stalls)I came close to correcting the cranking portion of my issue using the cranking IPW tables but eventually ended up with the engine not starting at all so I went back to stock. If anyone can share some wisdom here it would be greatly appreciated.

check fuel pressure is stable round 60 psi especialky if you have tripple stacked o rings in pump mounting


https://www.ft86club.com/forums/show...9&postcount=14

[D-VO]

When the startup process is complete the pressure drops slightly from 8 to 6 mPa. I realize this is at the DI pump and not the regulator. I don't think I have the correct logging param for the FPR. Searching...

[steve99]

Originally Posted by D-VO

When the startup process is complete the pressure drops slightly from 8 to 6 mPa. I realize this is at the DI pump and not the regulator. I don't think I have the correct logging param for the FPR. Searching...

the DI system works on a combination of pressure and injector open time for fuel delivery, both change to deliver required fuel volume


Try running 100% di at idle and see if idle stable

[D-VO]

Originally Posted by steve99

the DI system works on a combination of pressure and injector open time for fuel delivery, both change to deliver required fuel volume


Try running 100% di at idle and see if idle stable

I've got it 100% DI from .10 to .60 already at all RPM's. =(

[D-VO]

I'm noticing timing spikes right after the start process completes. Seems like its adding about 10 degrees of timing to normal idle when its done. Is this normal?

[steve99]

whats your " ignition timing post start" table look like

[D-VO]

This table was previously all -9.8. The current calibration is untested at higher ECT's.

[D-VO]

Originally Posted by solidsnake11

yours.......
..

..Attachment 193381Here is a stock one
Attachment 193380

Thanks I fixed it. The scaling was referencing uint8 instead of 16...? I forget. Anyway its fixed. Another item that confused me was the 2 different multiplier tables A and B. One seems to reference load and the other airflow but the values are the same. Very strange.

[D-VO]

Originally Posted by solidsnake11

Is the car fixed or just the table?

Table is fixed. Car still stalls after start up process is complete.

[D-VO]

The log is at post #6 for reference. Column F. It typically bounces around 3.5 to 4.5 as it's warming up and settles at 2.5 to 3. The DBW tables are factory until around 50% throttle. Car is also supercharged with a vented bypass valve. I noticed its closer to 2% when the IAT's are higher.