Hello. I just got a 15k mile Final Edition. It has a slight hesitation and therefore some bucking on takeoff. I have cleaned MAF and AP shows voltage ok. Plugs are a nice chocolate color. No CIL's, no knock, no misfire.
AP reads throttle position ok. reads secondary 02 ok. Stock injectors cleaned and tested ok. DW fuel pump holds about 50psi. Running 93 only. perrs like a 15k mile car while cruising. No leaks found or heard. All hoses triple checked and clamped.
I'm running out of ideas here.

Any advice is much appreciated.

 

Did you check the fuel pump relay?

 

Yes replaced 4 orange and 1 gray today. Any other ideas other than the tune?

 

Hmm, if the fuel pump relay passes salt shaker test, then I will have a hard time thinking which common part could be causing this problem. Maybe check the FPR hose?

Another possible cause could simply be that the car is cold. Evo's including mine hesitate to takeoff when cold. The problem goes away when the car warms up:

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increase the idle rpm to 1k, see if the hesitation is still there I had/have something like that issue, not sure if accessories are too heavy or some vacuum/PCV issue

 

Hello All. logging works, but loading logs to view does not display the data. I get solid lines across the chart. I have 2.0 selected, and have logged with mistuiii as well as RAX fast which is what seems more common. What am I missing here?
Evo x FE

 

Adjusted RPM to 1k. Still has stumble at very low throttle. Like takeoff slowly and cruising in 5th on hwy barely touching pedal. Entire fuel system seems to have checked out good. Tuner said not in the tune and he couldn't figure out. We see TPS position is at -2 and 97% respectively. Could this be related? Thanks in advance.

 

As soon as its turned off the car falls on its face and stalls. A restart re-enables ASC so back to "normal". Being that ASC is logically controlled, I would think that if it saw bad sensor/values, turning OFF would bypass those readings. Any thoughts?

 

Did you ever find a fix? from your description of bucking is sounds like fuel delivery issue....what fuel rail / injectors are you running?

 

No. Still have this once in awhile.
Radeon Rail. With Gauges.
Stock injectors.
DW300 pump.
50/60 psi
Boost leak test done.
FPV good. Hose good too.
I feel like its fuel related but everything is checking out ok. Injector and or coil would produce misfire I think also and no codes thrown.

 

Have you done the fuel pump hanger mod

 

60psi fuel pressure is way too high. you could be overrunning the return with too much FP?
Either drill the return siphon in the hangar or replace it with a radium jet venturi if you haven't touched the return siphon yet
Does the problem happen only at half tank or less?
If you pump is hard wired then this would especially be true