Timing pull only on one cyllinder

[Dj_Quik]

hello gents/ladies,

I have been trying to diagnose a misfire/timing pull issue in cylinder 4. background on the car: 2018 f80 comp dct with about 55000 miles. i picked it up sept 2022. stock tune but ive been using my bm3 license to log and monitor.

the timing pull can be anywhere from -1.5 to -6. partial throttle and on tip on just before WOT it almost always exclusively pulls timing on cylinder 4. and when full throttle, timing is pulled all the way up to redline on just that cylinder. initially i thought it was a fuel issue so i have been enriching the fuel from my local gas station with about a gallon and a half of e85. timing got better overall on the other 5 cylinders but cylinder 4 timing corrections still remained. next up i changed all my plugs and coils to brand new ones. plugs are oem on stock gap .032". along with the splash of ethanol, the results is pretty much no timing pull on all cylinders except number 4. its not as bad but its there. i hooked it up to ISTA this morning and reset all adaptation. idle and throttle response improved but the corrections are still there. so now, im stumped on my next step, am i gonna have to just pony up and replace the injector next? or do a compression test? or leave it alone? worth noting that im still on stock tune and im hesitant to go bm3 stage 2 91 map if the injector is indeed faulty or on its way out or if worse case scenario my compression is low.

what do you guys think? any insight would be helpful!

logs for review:
https://www.bootmod3.net/log?id=6418...729bcb7c276e15

https://www.bootmod3.net/log?id=6418...0b43bc84223b78

https://www.bootmod3.net/log?id=6418...0b43bc84223b77

[TopJimmy]

If you’ve tried changing/swapping plugs and coils then next would be examining the cylinder 4 coil wires and connectors very closely. Then you would do a leak down test on cylinders 4/5/6 to compare. It could also be the injector…but that’s last step due to complexity of swapping and coding in ISTA.

[Dj_Quik]

Ok i will check the wires. I was kinda hoping i wouldnt have to do compression/leak down tests yet lol i got quote $800 to get that done fml.

Do you think this is a serious enough problem that i shouldnt tune it at all?

[TopJimmy]

You need clean timing to tune stages.

[Dj_Quik]

Originally Posted by TopJimmy

You need clean timing to tune stages.

fair enough. im starting to think this car was abused and neglected by previous owner. if i had known there was a potential problem with cylinder 4 i wouldve never bought this car

[Wanted_M]

Try closing the plug gap from .032 to .028 on that cylinder and that should help.

[RAT3DM]

As already stated the plugs re-gapped, but I have a feeling it could be an injector issue, these cars are pita to work on the plugs & injectors but have you tried moving any of the hardware to see if the problem follows? Otherwise if it doesn't there could be a compression issue with cylinder 4?

[heitzke]

Originally Posted by Dj_Quik

Ok i will check the wires. I was kinda hoping i wouldnt have to do compression/leak down tests yet lol i got quote $800 to get that done fml.

Do you think this is a serious enough problem that i shouldnt tune it at all?

Yeah i'd be a little wary of tuning on top of an existing potential problem like that. I think you're about at the point of doing a compression/leak down just to be safe. Ruling out a more mechanical issue like that is a big one.

[Dj_Quik]

Originally Posted by BAD_M4

As already stated the plugs re-gapped, but I have a feeling it could be an injector issue, these cars are pita to work on the plugs & injectors but have you tried moving any of the hardware to see if the problem follows? Otherwise if it doesn't there could be a compression issue with cylinder 4?

Yeah compression loss is my worse fear. I think ill go ahead and change this one injector. Coz if im gonna try and move injectors around i might as well replace coz ill be removing them anyways.

[Dj_Quik]

Originally Posted by heitzke

Yeah i'd be a little wary of tuning on top of an existing potential problem like that. I think you're about at the point of doing a compression/leak down just to be safe. Ruling out a more mechanical issue like that is a big one.

If regapping plugs and/or changing injectors doesnt do it, then yes defs doing a comp/leakdown test is the next logical step.

But i dunno how accurate a virtual dyno is, but when i plugged in a recent log
It only showed 384 whp and 370 wtq. And the other showed 403 whp and 384 wtq. Now im sure these numbers are low for a comp s55 and if theyre true then something is DEFS wrong with the car. However, driving the car it doesnt feel like its 385 whp. It feels stronger than that but yah.

[theweebabySeamus]

Originally Posted by Dj_Quik

hello gents/ladies,

I have been trying to diagnose a misfire/timing pull issue in cylinder 4. background on the car: 2018 f80 comp dct with about 55000 miles. i picked it up sept 2022. stock tune but ive been using my bm3 license to log and monitor.

the timing pull can be anywhere from -1.5 to -6. partial throttle and on tip on just before WOT it almost always exclusively pulls timing on cylinder 4. and when full throttle, timing is pulled all the way up to redline on just that cylinder. initially i thought it was a fuel issue so i have been enriching the fuel from my local gas station with about a gallon and a half of e85. timing got better overall on the other 5 cylinders but cylinder 4 timing corrections still remained. next up i changed all my plugs and coils to brand new ones. plugs are oem on stock gap .032". along with the splash of ethanol, the results is pretty much no timing pull on all cylinders except number 4. its not as bad but its there. i hooked it up to ISTA this morning and reset all adaptation. idle and throttle response improved but the corrections are still there. so now, im stumped on my next step, am i gonna have to just pony up and replace the injector next? or do a compression test? or leave it alone? worth noting that im still on stock tune and im hesitant to go bm3 stage 2 91 map if the injector is indeed faulty or on its way out or if worse case scenario my compression is low.

what do you guys think? any insight would be helpful!

logs for review:
https://www.bootmod3.net/log?id=6418...729bcb7c276e15

https://www.bootmod3.net/log?id=6418...0b43bc84223b78

https://www.bootmod3.net/log?id=6418...0b43bc84223b77

Not sure why gapped to .032, stock is .028. I'd try that and see if it helps, or even try .022 which is what most of people who are tuned would run.

[Dj_Quik]

Originally Posted by theweebabySeamus

Not sure why gapped to .032, stock is .028. I'd try that and see if it helps, or even try .022 which is what most of people who are tuned would run.

Oh im still stock tune. But ill recheck the gaps. I bought the oem plugs and installed them. I tjought stock gap was .032 but ill recheck

[TopJimmy]

If you didn’t check the plug gaps that’s a must-do. Since changing out injectors is a pricey job and also requires ISTA recoding I’d hold off on that.

To make leak down testing cheaper ask your local Indy shop if you can park in their lot and do the disassembly yourself, then they do the leak down. That can save you a bundle of money.

[Dj_Quik]

Originally Posted by TopJimmy

If you didn’t check the plug gaps that’s a must-do. Since changing out injectors is a pricey job and also requires ISTA recoding I’d hold off on that.

To make leak down testing cheaper ask your local Indy shop if you can park in their lot and do the disassembly yourself, then they do the leak down. That can save you a bundle of money.

If i check the plugs and lets say theyre indeed .028, should i attempt to gap down at all?

The changing out injectors i have no problem working on it myself and i di have ISTA but your right, that should be last resort.

[TopJimmy]

Originally Posted by Dj_Quik

If i check the plugs and lets say theyre indeed .028, should i attempt to gap down at all?

The changing out injectors i have no problem working on it myself and i di have ISTA but your right, that should be last resort.

If they’re all 0.028 then you’re good for all stock tunes (base, ZCP, CS and GTS). Check your ceramic insulators really good for cracks.

[papasmurf_m3]

Doesn't look bueno.

Get a compression and leakdown test.

Don't start throwing parts at it.

You could have an underlying issue and loss of compression causing those timing corrections. GL

[Dj_Quik]

Originally Posted by papasmurf_m3

Doesn't look bueno.

Get a compression and leakdown test.

Don't start throwing parts at it.

You could have an underlying issue and loss of compression causing those timing corrections. GL

That seems to be general consensus. Ill go ahead and do that. Hopefully the motor isnt toast. It runs generally fine and no codes so i dunno if its just starting to fail.

[Wanted_M]

Originally Posted by theweebabySeamus

Not sure why gapped to .032, stock is .028. I'd try that and see if it helps, or even try .022 which is what most of people who are tuned would run.

Lol, that was my point

[NCM2C]

any update? i'm in a similar boat with constant cylinder 4 misfires. Mechanic used a scope and saw some "shine" on piston 4. I am holding my breathe until tomorrow when they do compression/leakdown.

[sly1types]

The middle cylinders are the first to pull timing b/c of the extra air flow on the manifold design.

[papasmurf_m3]

Originally Posted by Dj_Quik

That seems to be general consensus. Ill go ahead and do that. Hopefully the motor isnt toast. It runs generally fine and no codes so i dunno if its just starting to fail.

GL and keep up updated.

[sly1types]

One thing that is crazy is you are running 28lbs of boost. Stock is around 20. I would guess the car is tuned.