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Evo 8 stutters and goes lean above 20 psi.All of a sudden.

Old Jan 18, 2018, 05:56 PM
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Angry Evo 8 stutters and goes lean above 20 psi.All of a sudden.

Whats up guys. So all of a sudden my car started acting up on WOT.

Fp red
E85
All supporting mods.


Car went from running great to now when i do wot pulls as soon as i hit 20 psi or so you feel either a studder or misfire. And wideband spikes lean.

Any thoughts? Do the evo 8s have fuel pressure relay issue like x?

If it was a lack of fuel pressure lets say. I dont think it would stutter.

Any thoughts?
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Old Jan 19, 2018, 09:49 PM
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Have you logged this?
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Old Jan 20, 2018, 07:56 AM
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Yes did a log this morning. I don't see anything that catches my attention in the log.

It all started with my check engine light coming on. For fuel trim code. I had -11.9 fuel trim so I adjusted accordingly. Trims are with in 5 % now and chek engine lamp off.

Still didn't fix issue.

Im beginning to think this is a outside influence such as coils or wires.

I swapped out my plugs also. They weren't brand new but good known units.

I just don't understand if its a misfire or a fuel cut or boost cut.
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Old Jan 20, 2018, 08:01 AM
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NOTES:

This vehicle is on speed density Running a OMNI 4 bar and running on fuel temp.

Omni has been replaced with good known unit.

Exhaust cam position sensor has been swapped with good known unit.
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Old Jan 20, 2018, 08:48 AM
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How's the fuel pressure?
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Old Jan 20, 2018, 08:59 AM
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Originally Posted by Evo9_Dubai View Post
How's the fuel pressure?
Have not performed fuel pressure test.

Also I can take the car to 6500 rpm part throttle
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Old Jan 20, 2018, 09:01 AM
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The condition is pretty violent.

I don't think its a misfire but I may be wrong. Feels like I hit a brick wall.
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Old Jan 20, 2018, 09:24 AM
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Coil ohm testing

Short SPARK CABLE- 2.794 kOHM
Long SPARK CABLE- 5.66 kOHM

Coil Boot 1.7 OHM
Coil Boot 2 1.0 OHM

Coil 1 10.3 kOHM
Coil 2 9.86 kOHM

Last edited by 4b11slayer; Jan 20, 2018 at 09:53 AM.
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Old Jan 20, 2018, 09:56 AM
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check to make sure your oem hanger assembly internal filter isn't clogged? When mine clogged it was almost the exact same symptoms. new hanger assembly fixed it all.
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Old Jan 20, 2018, 10:57 AM
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Originally Posted by razorlab View Post
check to make sure your oem hanger assembly internal filter isn't clogged? When mine clogged it was almost the exact same symptoms. new hanger assembly fixed it all.
I Will do that next. It has a walbro 450 in it so I wanted to check make sure its still seating up on the hangar. Any one who as installed one of these knows it has to be ghetto rigged lol

Thanks.


Any other thoughts razorlab?

How can I identify boost or fuel cut? Through a log? Would I see injector duty suddenly get cut? Cause my IDC seems normal.

Also If it is boost cut I would see WGDC get cut?
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Old Jan 20, 2018, 11:01 AM
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I just want be clear that this just happened from 1 day to the next.

Went out for a cruise with the boys and felt it on a wot pull. Hour later mil set for fuel trims. Adjusted fuel latency accordingly and fixed the trims. Problem still there. Maybe coincidence.

What other sensors might cause this?
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Old Jan 20, 2018, 03:04 PM
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UPDATE: Checked fuel pump assembly for proper pump fitment and also inspected pick up screen. Dirty but not clogged. Cleaned with brake cleaner and air.

Any other thoughts? Im going to Close the spark plug gap down to .020 see if it helps.

Currently running 0.21-0.22
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Old Jan 20, 2018, 03:36 PM
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Also checked hobbs switch operating normal
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Old Jan 20, 2018, 03:56 PM
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Is this 91 or e85? If your trims are pulling fuel like you said that would make me think blend change on e85. -11 is pulling alot of fuel, where you able to verify if the ecu was hitting stoich when it was pulling that much fuel? If you change your scaling back to the way it was before compensating for the trims, clear them out by pulling the battery and then testing, does the problem persist?
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Old Jan 20, 2018, 04:08 PM
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Yes e85 here in socal.

So just did a pull in 2nd the break up is less violent now with the plug gap set to 0.19. So maybe my coils are tired?
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