Hesitation/Stutter Low RPM/Med Load
 

So it has been a LONG while since I was last here but I am coming to you guys for some assistance. I have recently started driving the car again after it was parked all summer (someone rear ended me, parked the car after new paint)

Anyway, my new work commute is all back road driving. The engine is acting odd though. At about 45pmh in 5th gear, if I tip into the throttle like say encountering a hill, the power begins to stutter. It feels almost as if the engine is losing power, or the bucking if you are too fast off the clutch w/o enough throttle. This only happens at low rpm medium to high load situations. As soon as the engine is above 2K she runs beautifully.

The car has 139,XXX miles on it. I am planning on seafoaming the motor for the first time this weekend and changing the plugs (which are LONG overdue). I also noticed when pulling the oils last night that the boot for the second plug from the front on the driver's side had some brownish powdery residue on it. About the same color as a well used spark plug.

Any thoughts on the cause of the issue would be super helpful. I've been in the mindset of dealing with an old Nissan for the past few months so I very well could be missing something.

Re: Hesitation/Stutter Low RPM/Med Load
 

When was the last time plugs/coils were changed? That would be my first guess.

Re: Hesitation/Stutter Low RPM/Med Load
 

def sounds like a coil issue. which is a well known problem , My stock coils on my mach got me to about 70k lol. The easiest way to test them is exactly what you are saying( put in 5th gear in low rpms and put it under a good load, it will normally start missing and misfiring and bucking ). Also that brown residue could be dried up water that got in from the cop covers or dried up oil from bad plug seals under the valve cover.

Re: Hesitation/Stutter Low RPM/Med Load
 

Any quick ways to determine exactly which coil is the one failing? I'm hoping its just old *** plugs. They have been in there 70k miles or so.....

Re: Hesitation/Stutter Low RPM/Med Load
 

I just went thru the same issue. My rear most cops on both sides would get water on them when it rained since I had a leak from my coil covers. Once I pulled the cops out and cleaned the brownish stuff off and sealed the coil covers all my problems went away.

Re: Hesitation/Stutter Low RPM/Med Load
 

Dont quote me on this procedure....but I believe I've read an easy way to check without a multimeter is start the car and start disconnecting the coils one-by-one. Pay attention to the engine....it should start to stumble and idle differently. If/when you get to disconnecting one and you dont notice a change in the engine....that's your culprit.

Re: Hesitation/Stutter Low RPM/Med Load
 

So it looks like seafoaming the engine and new plugs has resolved about 90% of the issue. I can now cruise (55mph) on the back roads without needing to downshift when I come up to small hills. I am still going to budget for all new coils next season as the car is high mileage and they will be needed at some point....