Main Injection Fuel Flow Rate Question

[JrTuner]

I finally got to the track to do some tuning with EFILive. One thing I noticed was that the Main Injection Fuel Flow Rate was only going to 79.7 mm3 for the entire run. And since this is one of the values it uses to calculate Main Injection On Time I wasn't getting the amount of fuel I thought I should. Anyone have any ideas?

[GMPX]

Unfortunately that has been an issue for all Diesel tuners, TechII suffers the same problem, however, we fixed it :-)
Choose the PID "Main Injection Fuel Flow Rate 2" GM.FUELQ_MAIN_DMA
This will give you values beyond the 79.7 limit, however, it uses 2 channels of data. Remember to unselect the standard GM mm3 PID if you are logging this one.
Same problem occurs for boost, you are better off logging GM.BOOST_DMA

Also, the 79.7mm3 limit you saw is just a scantool issue with the ECM, it is still processing numbers higher than that for the fuel calculations.

Cheers,
Ross

[JrTuner]

Thanks I will try that.

[JrTuner]

The other issue I was seeing was that in 5th gear, top end of the track, I felt the truck start to lay over. Looking at the data I noticed that the fuel delivery decreasing, the EGTs proving that. At the end of the track my EGTs were only 1050 degrees F. The main rate started decreasing and in turn so did the on time. Any thoughts?

[GMC-2002-Dmax]

If you did not set any codes then the truck is running out of fuel pressure because you may have commanded too large of a main rate pulse width and if so then the truck will lay over.

Try adding a lift pump to help supply the low pressure side of the CP3 which is the high pressure pump for the injectors.

There are several options available and if you need help just send me a PM or Trippin.

Good Luck,

T:) NY

[JrTuner]

There were no codes set and I have a lift pump setup. I just reviewed my log from my last run and when the EGTs starting dropping the the desired fuel pressure was 159 Mpa and my actual was in the 140's. After the EGTs had dropped to 1200 and below the calculated fuel rate was dropping and the actual fuel pressure actually spiked to 180 Mpa. The main injection on time was dropping drastically due to the calculated fuel rate dropping I would guess.

[GMC-2002-Dmax]

If you can send me your email I can send you a PID for logging.

It appears that the mm3 rate is being reduced for some reason, if you would like I can look over your log file and see if I can help you diagnose the problem.

Just let me know and I will PM you my email for the log file.

T:D NY

[JrTuner]

PM sent.

[sweetdiesel]

how bout doing a bottle test?