Please help! bucking at highway speeds

[Troybylt]

I am very interested in this thread I have the bucking under hard acceleration issue as well, it seems to be worsened by staying in too high a gear for too long (MT trans) like after going off a ramp in 5th 1500RPM and then down shifting to 3rd at 3k and WOT it will chug once about every 750k RPM climbed and only presents itself after 15-20mins of driving. It is irregular in occurrence.

The TPS is OEM and new and I have tested it's resistance, .57v closed 3.76 WOT.

Plus are NGK two prong replaced last year
Wires are NGK replaced last year
Fuel filter is Toyota replaced last year
Fuel is BP 87oct
Air filter is Toyota replaced 2k miles ago. (Issue was present before and after last change)
MAF was replaced 1.5 yrs ago cleaned two weeks ago
No check light no pending codes
No white smoke
"Normal exhaust water" Does not smell of coolant
no bubbles or exhast smell in radiator

The bucking or hesitation at warm WOT didn't occur until after my TPS failed 5k ago. After replaced the issue began Or at least it came to my attention after the change I was not previously aware of it.

Perhaps one of my coil packs is failing? They have 200k on them as far as I can tell they are original.

Hope my little check list helps with diagnosing what it isn't at least.

 

[Troybylt]

2) Bad coil pack. You can test the resistance with a volt meter to see if it's in spec.

6) Burnt misadjusted/valve

Could you explain how I can I test the coil pack with my volt meter and what resistances are in spec, or at least where I can find the spec?

How can I tell if I have a bad/burt valve? Compression test?

 

[Squirt]

when you guys figure it out let me know! mine is doing the same crap and I swear I have about decided the transmission is slipping and has nothing to do with the engine.
Replaced: MAF, FUEL PUMP/FILTER/SCREEN, REAR O2 SENSOR, TPS......

 

[Troybylt]

when you guys figure it out let me know! mine is doing the same crap and I swear I have about decided the transmission is slipping and has nothing to do with the engine.
Replaced: MAF, FUEL PUMP/FILTER/SCREEN, REAR O2 SENSOR, TPS......

Well I have the same issue and it's a MT so the trans may be ruled out. :shrug:

 

[Squirt]

given the parts I've replaced, its got better fuel/air management so I am at a loss. I even tested the injectors and checked for vacuum leaks (even though one of those two things would have left it stalling and addition to the problem is having)it's getting really frustrating and there's not that many parts left to check..really hoping someone will chime in with something I'm totally missing.

 

[BoarderDave]

when you guys figure it out let me know! mine is doing the same crap and I swear I have about decided the transmission is slipping and has nothing to do with the engine.
Replaced: MAF, FUEL PUMP/FILTER/SCREEN, REAR O2 SENSOR, TPS......

given the parts I've replaced, its got better fuel/air management so I am at a loss. I even tested the injectors and checked for vacuum leaks (even though one of those two things would have left it stalling and addition to the problem is having)it's getting really frustrating and there's not that many parts left to check..really hoping someone will chime in with something I'm totally missing.

The OP posted saying it was a bad coil pack as the culprit.
Check your coils.. or replace them all if you have the $$.



Oh and also, as I was just researching the cost of new coils for the 4Runner... I came across this little tid-bit of information. Bold notation added. :yo:

Coil on Plug
A leader in direct ignition technology, DENSO developed the auto industry's first compact stick-type ignition coil. The space-saving design, since adopted by many of the world's leading automakers, requires no high-tension ignition cable, fitting neatly into the engine's spark plug bore. Along with its stick coil technology, other advanced features pioneered by DENSO include micro-sized driver circuits and diagonal inductive windings. In the development of today's high-tech ignition systems, the automakers and DENSO are full partners.

That same expertise is put to use on all DENSO ignition coils regardless of their configuration. Each DENSO ignition coil is designed and optimized for its specific application, then continually improved by DENSO's global engineering team for maximum performance. One key to effective combustion in today's low-emission, high-efficiency engines is consistent, high-energy ignition output. DENSO direct ignition coils deliver it.

Features:
Improved coil efficiency reduces the need to generate high voltage
Driving circuit is integrated into top of coil
Cylindrical ignition coil eliminate the need for ignition wires
Diagonal windings used to eliminate sectioned bobbin reducing size and weight
Superior quality components and materials used to ensure optimal performance
Superior testing and inspection processes to ensure higher quality
Benefits:
Small in size, light in weight and easy to install
Eliminates phantom misfires
Maximum available voltage under all operating conditions

 

[gamefreakgc]

Don't replace coil packs for no good reason, pretty sure all three are not bad. See attached file on resistance values for the coil packs. Be sure your multimeter is set to the 20k setting.

 

[Squirt]

yeah guys, but if it was a coil or a misfire it would throw a code and mine has thrown none.

 

[Oneluv13T4R]

mine recently started doing the same. I will be installing new fuel filter, spark plugs and wires as general maintenance. Hopefully this resolves my issue. No CEL for me either, if i'm easy on the throttle it does fine, if i stab it it will misfire.

Exactly what mine does as well ease into taking off or passing.
Well low and behold guys I have CEL's popping up now ...

1 P0101 Mass air flow sensor - that's usually just dirty

2 P0103 Mass Air Flow Sensor - High Air Intake Volume?

3 P0346 Crankshaft Position Sensor (Bank 2) bottom left side of engine

Now obviously there's a ripple effect going on ...should I presume that maybe a bad coil pack could be creating my misfire which then over the last 3 months of this starting then getting progressivly worse and now just my daily bucking routine and now takes 2 turns of the key before she starts sometimes the first turn if she has cooled down but she barley holds on when doing so but you can immediately turn the key for second time and she fires up like nothing is even wrong runs great,quiet (but super low idle) no sputtering, shuttering at a stop or in park just sputtering and aggressive bucking if I hit the peddle and it usually at 2000-2500 Rpms. But yet I can hit a 105 mph like a champ after that ... Go figure if cars just stayed cars it so much simpler. Now computers on wheels with a few fragments of a car.

Open for Opinions / Suggestions ...Optimizum Lol
Thanks guys for letting me rehash this old thread

 

[Oneluv13T4R]

Hopefully this can help you guys showing no CEL's and look in another direction so we can all benefit and move forward continuing to enjoy our Runner's and stop throwing wasted money at them ...

And I do have a scanner which I can take a pic of the codes showing and freeze frame data when the codes initialized

 

[bama16]

when you guys figure it out let me know! mine is doing the same crap and I swear I have about decided the transmission is slipping and has nothing to do with the engine.
Replaced: MAF, FUEL PUMP/FILTER/SCREEN, REAR O2 SENSOR, TPS......

Mine has become progressively worse and more frequent. i would test it by applying a little throttle while braking before takeoff and it seemed to work without hesitation. I originally thought the tranny might be hurting, but if i hold the brake and mash the throttle...i get the misfire at about 2500 rpm and then it clears up. It also appears to only happen under load. If i pop the hood and rev it via throttle body, it does fine, no hesitation.

 

[Squirt]

yeah I'm so ready to figure this out. I'm a pretty decent wrench and I'm not one to throw parts at something just to see what works. each time I've changed something out it seemed the logical solution..even with the scanner I'm finding nothing.I grew up in the shop and my dad is a pro mechanic and he has no solution to the problem either. I put around 150 miles a day on this thing four to six days a week and the high RPM's its turning is not good for an engine with 250K+ miles on it.

 

[Squirt]

Well I have the same issue and it's a MT so the trans may be ruled out. :shrug:

I swapped out each coil pack individually with a new one I keep as a spare today ...same behavior, nothing changed.

 

[gamefreakgc]

The major sensors used on these engines are the TPS, MAF, O2 and Crank sensors. They monitor the timing, fuel, and air intake on the vehicle. I'd get a copy of the FSM and go to town with your multimeter to rule all of those out.

And for the one who posted the P0101 and P0103, I can't imagine that being anything other than a bad MAF. Depending on what year you have, you can get junkyard MAF's off of V6 Camrys as well as one of the Lexus models. Just look for the same part # that is on your current MAF. Mine went bad and only paid $50 for a gently used one and works great. Sure beats the $250+ for an aftermarket or $500+ for a DENSO!

 

[bama16]

I swapped out each coil pack individually with a new one I keep as a spare today ...same behavior, nothing changed.

luckily mine was easy. I swapped out plug wires today and my problem went away.

 

[Squirt]

TPS, O2, MAF all new/double checked, and good. was planning to test the crank sensor tomorrow along with the plug wires.I'll probably double check the plugs as well just to see how its burning. I've been lucky when it's come to cost for major parts, I get them through dads shop...makes it easier on budget! Still baffling to me that this thing hasn't thrown a code.I've been chasing this gremlin for 2 months now and with the miles that I put on it everyday one would think it had plenty of time to at least show a pending code.

 

[bama16]

yeah....my normal route is pretty mild so taking it easy isn't so hard. I tried to take it on the highway yesterday and it struggled pretty hard. It would not just sputter, but completely drop off and then pick up again.

 

[Troybylt]

TPS, O2, MAF all new/double checked, and good. was planning to test the crank sensor tomorrow along with the plug wires.I'll probably double check the plugs as well just to see how its burning. I've been lucky when it's come to cost for major parts, I get them through dads shop...makes it easier on budget! Still baffling to me that this thing hasn't thrown a code.I've been chasing this gremlin for 2 months now and with the miles that I put on it everyday one would think it had plenty of time to at least show a pending code.

Any O2 sensors in particular or just the O2 array in general, how many O2's in a non Cal spec Runner?

 

[Track34]

yeah guys, but if it was a coil or a misfire it would throw a code and mine has thrown none.

Not true. I work on vehicles all the time that have misfires, yet do not throw codes. One of those was my own 4runner.

 

[Squirt]

Any O2 sensors in particular or just the O2 array in general, how many O2's in a non Cal spec Runner?

mine has California emissions, therefore it has 2 o2 sensors..if you don't have California emissions you only have one.