Please help super frustrated
Thread Starter
Newbie
Joined: Mar 2026
Posts: 4
Likes: 0
From: Marana AZ
2014 c250 sport 1.8T, 2016 mustang gt supercharged 734WHP, 2020 c300
Please help super frustrated
Hello all!!
I have a 2014 c250 sport with the 1.8 turbo. I have a misfire in cyl 2 &3 past 3k only while driving, I can power brake car and tire start to brake loose with out a miss.
257k on car checks I've done so far
compression test- all at 160-170
leakdown test less than 3%
new plugs and one coil, miss doesnt follow the plug or coil when moved to a different cyl
new HPFP less than 100miles
smoke test good
dealer did timing chains, phasers, guides less than 20k ago
fuel pressure at1500-1900 at rail
never lose signal from pcm while the miss occurs at coilpacks (oscilloscope)
injectors all flow a similar amount and hold pressure at different speeds. (idle, accell, on inj test machine)
all cam lobes are clean and clear of damage, valve springs all look to be at same height.
I'm lost any help would be apprciated
I have a 2014 c250 sport with the 1.8 turbo. I have a misfire in cyl 2 &3 past 3k only while driving, I can power brake car and tire start to brake loose with out a miss.
257k on car checks I've done so far
compression test- all at 160-170
leakdown test less than 3%
new plugs and one coil, miss doesnt follow the plug or coil when moved to a different cyl
new HPFP less than 100miles
smoke test good
dealer did timing chains, phasers, guides less than 20k ago
fuel pressure at1500-1900 at rail
never lose signal from pcm while the miss occurs at coilpacks (oscilloscope)
injectors all flow a similar amount and hold pressure at different speeds. (idle, accell, on inj test machine)
all cam lobes are clean and clear of damage, valve springs all look to be at same height.
I'm lost any help would be apprciated
Out Of Control!!
Joined: Apr 2019
Posts: 12,191
Likes: 6,889
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Hello all!!
I have a 2014 c250 sport with the 1.8 turbo. I have a misfire in cyl 2 &3 past 3k only while driving, I can power brake car and tire start to brake loose with out a miss.
257k on car checks I've done so far
compression test- all at 160-170
leakdown test less than 3%
new plugs and one coil, miss doesnt follow the plug or coil when moved to a different cyl
new HPFP less than 100miles
smoke test good
dealer did timing chains, phasers, guides less than 20k ago
fuel pressure at1500-1900 at rail
never lose signal from pcm while the miss occurs at coilpacks (oscilloscope)
injectors all flow a similar amount and hold pressure at different speeds. (idle, accell, on inj test machine)
all cam lobes are clean and clear of damage, valve springs all look to be at same height.
I'm lost any help would be apprciated
I have a 2014 c250 sport with the 1.8 turbo. I have a misfire in cyl 2 &3 past 3k only while driving, I can power brake car and tire start to brake loose with out a miss.
257k on car checks I've done so far
compression test- all at 160-170
leakdown test less than 3%
new plugs and one coil, miss doesnt follow the plug or coil when moved to a different cyl
new HPFP less than 100miles
smoke test good
dealer did timing chains, phasers, guides less than 20k ago
fuel pressure at1500-1900 at rail
never lose signal from pcm while the miss occurs at coilpacks (oscilloscope)
injectors all flow a similar amount and hold pressure at different speeds. (idle, accell, on inj test machine)
all cam lobes are clean and clear of damage, valve springs all look to be at same height.
I'm lost any help would be apprciated
Your new HPFP still reads low...
I wonder if it is starved?
- Read the in tank pump pressure
- Read the LTFT at warm idle.
Last edited by CaliBenzDriver; Mar 4, 2026 at 06:18 PM.
Out Of Control!!
Joined: Apr 2019
Posts: 12,191
Likes: 6,889
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Thread Starter
Newbie
Joined: Mar 2026
Posts: 4
Likes: 0
From: Marana AZ
2014 c250 sport 1.8T, 2016 mustang gt supercharged 734WHP, 2020 c300
well,
I guess i relied on the dealer too much
tank pressure @71 at tank. Rail pressure at idle is at 930
and 2075 is the max I'm getting out of it and when it misses terribly
I guess its back to the dealer for repairs. I'll update when I get it back, Thanks
I guess i relied on the dealer too much
tank pressure @71 at tank. Rail pressure at idle is at 930
and 2075 is the max I'm getting out of it and when it misses terribly
I guess its back to the dealer for repairs. I'll update when I get it back, Thanks
Out Of Control!!
Joined: Apr 2019
Posts: 12,191
Likes: 6,889
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Yet your high pressure pump is unable to build pressure.
You said pump is already new, so perhaps the cam lobes have been flatened by old roller.
At least you know unstable fuel rail is causing your lean troubles.
Last edited by CaliBenzDriver; Mar 6, 2026 at 04:27 PM.
Thread Starter
Newbie
Joined: Mar 2026
Posts: 4
Likes: 0
From: Marana AZ
2014 c250 sport 1.8T, 2016 mustang gt supercharged 734WHP, 2020 c300
thx for your help, I appreciate it. Correct me if I'm wrong but isnt this pump run from the back of the cam and doesnt have rollers? more like a keyed drive?
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Out Of Control!!
Joined: Apr 2019
Posts: 12,191
Likes: 6,889
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
1000 to 2000.Psi is a huge swing
Confirm what Trim say: LTFT=+20?
Last edited by CaliBenzDriver; Mar 6, 2026 at 09:04 PM.
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