engine stutter and hiccuping idle

[pstur11]

2001 4Runner with 170k miles. Symptoms starting with small hiccups during idle, like one of the cylinders was missing a fire. At that point I ran a can of sea foam through the gas tank. Then, more recently, during acceleration with a cold engine the engine significantly lagged to accelerate, like it was missing many times in a row. This issue seems to be more significant when the engine is cold. I've owned the 4Runner for 30k miles, and the spark plugs and wires were last changed at 132k miles. No check engine light is on.

Any ideas on where to begin trying to diagnose and fix this issue? Thanks for the help.

 

[jgue467]

Sounds like a coil is starting to intermittedly fail. Any CEL codes set or pending? That would help isolate the particular coil then you could swap one with another to verify if the codes switch cylinders or simply test each coil, one is likely weak. Don't overlook the wires even though somewhat new.

Luck. :cowboy:

 

[Mudeprived]

2001 4Runner with 170k miles. Symptoms starting with small hiccups during idle, like one of the cylinders was missing a fire. At that point I ran a can of sea foam through the gas tank. Then, more recently, during acceleration with a cold engine the engine significantly lagged to accelerate, like it was missing many times in a row. This issue seems to be more significant when the engine is cold. I've owned the 4Runner for 30k miles, and the spark plugs and wires were last changed at 132k miles. No check engine light is on.

Any ideas on where to begin trying to diagnose and fix this issue? Thanks for the help.

Have you done a full clean up of the intake, TB and its sensors since you got it?

 

[MaineRunna]

I'd look at coils, wires and spark plugs first. Check coil and spark plug boots for oil contamination due to leaking spark plug tube seals in the valve covers. Check the inside of the boots and the spark plug insulators for carbon tracks, dark lines that won't rub off the spark plug's insulator that build up over time and allow the spark energy to arc out into the body of the spark plug or the spark plugs tube. I find that a lot on Toyota trucks. If you have cylinder misfire codes focus on that cylinder first.

 

[stecow]

Let us know what happens and what you did to solve the problem.

I've got a similar thing going on that I've been trying to pinpoint. With a colder engine I have slower acceleration, particularly in 2nd gear its most noticable to me. I'll shift into 2nd and accelerate, it'll have a bit of power at first but then tapers off as I give it more gas.

 

[SoCalDucky]

Any update? I have been experiencing the same thing while stopped at a light (Intermittently) or while on the freeway while accelerating from 50-60mph. Never happens during street driving tho?

 

[pstur11]

Thanks for all of the feedback everyone! Update: pending P0302 Cylinder 2 Misfire Detected. Next steps are to first follow recommendations of MaineRunna and jgue467.... due an inspection to look for oil contamination and then switch the coil from cylinder 2 with another cylinder to see if the misfire stays with the coil or cylinder, and if it stays with the cylinder then try switching the spark plugs around.

 

[pstur11]

Have you done a full clean up of the intake, TB and its sensors since you got it?

Never! In general, what are the symptoms of these items being dirty?

 

[velomatt]

Had a similar problem. Misfire code. I replaced plug on the indicated cylinder and the hesitance is gone. I still get little hiccups on idle. No codes.