That blows. Be sure to get an entire ACDelco or Delphi sending unit and replace the filter. Not just a pump.
That blows. Be sure to get an entire ACDelco or Delphi sending unit and replace the filter. Not just a pump.
Well before dropping the tank, I decided to check the fuel pump relay, and it turned out to be the culprit. More than 14 years in service. Replaced the relay today. Hopefully will do some logging this week.Originally Posted by SiriusC1024
Excellent
Well did some logging with the latest tune today. I have got more observations as listed below:
- The bucking issue has become worse. when I put in 1st gear, start rolling going into a curve, I get this bucking below 20 mph. This happens also happens when in 2nd gear below 20mph. Also, bucking happens when making a u turn at a stop light.
-Another thing is more frequent idle drop below desired idle rpm. Also, before stopping the log I started revving the engine while in stopped condition, the idle drops below desired idle rpm, then picks up to 750rpm.
- The worst dip I had to the extent that it dipped and engine died after making a turn while slowing down in 2nd gear. You will noticed this a few minutes before ending the log.
- Also, engine surges when IAT went above 100 deg F.
I think the idle might have become worse because of the desired idle change from 800rpm to 750rpm, and maybe the timing.
Just realized that I forgot to reset the LTFTs prior to scanning. Could this be the cause for the above issues?Thanks.
I would say load SD_2 and apply changes to main spark in the opposite direction of SD_3 to see if that has a positive effect. From the log at 13:13, where the idle dips, it looks like the engine does need more spark even at 1200rpm. Make sure to update changes at base spark to the idle spark tables.
You'll be able to make changes a lot quicker on your end to see what effect settings have on the bucking issue.
Thanks for the input. Honestly I am still learning as mentioned before, and did not get exactly what you meant by ?applying changes in the opposite direction of SD_3?
However, my biggest concern is the surge issues when IAT goes high as noticed in the log and idle dip because of it. Not sure how to overcome this issue.
Hey man been extra busy lately. I'll get to this in a while for you.
No issues man. You have helped a lot with the tune.
I am currently adjusting the timing and doing logs to observe any improvements in the idle dip issues.
What's confusing is that those adjustments I made to on SD_3, decreasing the rate of change in spark, should've improved the symptoms you're having.
So, what else is there? Fuel reaction to O2 feedback. If it was me I'd try the converted set of data. The offset provided in the FIC data is a lot shorter than that class of injector typically behaves.
My biggest issue is the idle dip and engine dies when the clutch is fully pressed in 2nd gear while making a turn. However, this is not happening all the time though.
You can bump up idle spark and BRAF, or even add rolling idle.
Open the log at post 44 and move the cursor to 20:54. Now hold the cursor and drag it to 21:20. Do a few back and forth drags and watch O2's and RPM's. See how surging is being caused by the O2's? Return to idle issues are caused by VE not matching real world conditions. Fuel trims seem ok, but look at the O2 mV trace.
Still a proponent of tuning VE with the converted 36lb GTP data.
Will have a look at the log again. Here are the injectors data files for 36lb GPT data and FIC Data. You can see the FIC data lacks injectors min pulse width as well as fuel to transient wall table as well.
Offset and SPA are the biggest factors.
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