How to diagnose and resolve engine issues using Durametric.

[jb92563]

After Replacing AOS, and a new MAF there is still a random hesitation on acceleration.

Here are some graphs of
1) FRA RKAT fuel trims, 2) RPM, 3) MAF
Seems to show a need for a bit extra fuel (lean) but nothing drastic and nothing that would indicate a serious vacuum leak. Blue line does spike every now and then, wonder if thats normal.


After replacing plugs and fuel filter, some improvement but not cured.
Showing a need to reduce fuel trim (rich) a bit, perhaps the replaced fuel filter is allowing the extra fuel now.


Another trace after cleaning the throttle body actuator (E-gas) Seems to work same as before. Seems even more balanced than before. Not Likely a vacuum leak
as it would cause the line to be much higher on the + side above +10 (+ indicates Lean condition being compensated for -5 +5 is very normal from what I have read)


After checking fuel pressure, flow rate and smoke test to check for vacuum leaks. No Leaks, pressure and flow to specs.


The hesitation does not necessarily occur where the blue yellow lines spike. Not sure what those are.

I think the next place to look may be fuel pressure.
I'm thinking that the pressure regulator may not be responding properly and causing a hesitation.

Perhaps the thin vacuum line controlling the pressure regulator is leaking.