Pulsing under hard acceleration on highway

[willduggins]

Hey Everyone,

My 2000 Limited has this weird pulsing of the engine/transmission under hard acceleration on the highway. It occurs during the downshift into 2nd gear and kind of feels like the car needs more gas or something. Has anyone else experienced this? Thanks in advance for your help.

 

[PitbullRescuer]

Any check engine light? How does the engine sound when it's doing this? Could be as simple as a bad ujoint, could be a misfire in the engine. You're going to have to give us more detail to help you diagnose it.

 

[IanV]

I had a similar issue. My 4runner is standard though but under a decent amount of gas it would shudder almost like it was slipping. Check your ignition coil, plugs, wires. Mine ended up being the ignition coil. They dont go bad right away, its a slow process so you don't have enough spark to run right under load. Hope this helps.

 

[foxrider56]

That's kinda what happened to me but mine was at low toms on the highway it did what you are describing. I just replaced the plugs and wires and it fixed it.

 

[1985taylor1925]

Plugs and wires first as already stated. I had a similar issue and it was #3 fuel injector. But for that your CEL should be on. Have autozone scan it.

 

[SCSPerformance]

It sounds like random misfiring under load. Do the basic tune up parts first and go from there? Did you do anything to the engine prior to this happening?

 

[willduggins]

The car is bone stock. No engine mods or anything of the sort. This weekend I was driving up in the mountains though and the check engine light came on while turning high RPS climbing a large hill. To describe the problem in further detail: it only happens while at highway speeds and generally on an incline when the 4runner downshifts to 2nd gear.... so RPMs around 4-5k. Its not a jerking sensation but rather feels like the engine just isn't quite getting enough juice. The tach doesn't read any differently but it does feel almost like a wave with power coming thru and then dwindling in a sort of repeating pattern. After shifting back to 3rd or 4th gear everything goes back to normal. Would plugs and wires lead to a CEL being activated? My initial thoughts were O2 sensor (after the CEL came on), fuel pump, or ignition coil/wires/plugs.

 

[WillK]

I read a thread over the weekend where someone had the same symptoms as you (even the CEL) and they replaced the fuel filter and it solved their problem.

Mine has the same symptoms, but not CEL, plus, I notice my gas mileage is getting pretty bad so I'm going to do the same thing (plugs//wires), except I'm going to change the fuel filter as well.

Probably clean the TB and MAF sensor, too.

If it that doesn't help, then try I'm going to replace th O2 sensor.

 

[Dougal]

OK - I have a developed a sputtering on acceleration.
Here's the details.
2000 SR5 manual ~ 116K miles
- Had sparks and wires replaced 800 miles ago (3 weeks ago) - typically I only put ~ 3000 miles a year on this vehicle but I went for a long drive.
- I Noticed an intermittent misfire about every 10 mins when driving (about 200 miles after wires and plugs changed)
- Sputtering upon acceleration got really bad after I filled up at a gas station ~ serious sputtering even on light acceleration.
- I put some red heet in the tank (1/2 a tank ago) in case I might have had bad gas and the engine has improved by about 60% although it will still sputter on moderate+ acceleration.
- It now runs perfectly on idle and runs normally at any speed as long as not accelerating.
- I accelerated moderate to hard to see if I could get a check engine light to come on and codes: p0303 01/02 and P0303 02/02 came up.

I have no tools and need to take it to a shop for any work

Any suggestions to the main things I should have them check.

Thanks

 

[octanejunkie]

OK - I have a developed a sputtering on acceleration.
Here's the details.
2000 SR5 manual ~ 116K miles
- Had sparks and wires replaced 800 miles ago (3 weeks ago) - typically I only put ~ 3000 miles a year on this vehicle but I went for a long drive.
- I Noticed an intermittent misfire about every 10 mins when driving (about 200 miles after wires and plugs changed)
- Sputtering upon acceleration got really bad after I filled up at a gas station ~ serious sputtering even on light acceleration.
- I put some red heet in the tank (1/2 a tank ago) in case I might have had bad gas and the engine has improved by about 60% although it will still sputter on moderate+ acceleration.
- It now runs perfectly on idle and runs normally at any speed as long as not accelerating.
- I accelerated moderate to hard to see if I could get a check engine light to come on and codes: p0303 01/02 and P0303 02/02 came up.

I have no tools and need to take it to a shop for any work

Any suggestions to the main things I should have them check.

Thanks

Mark your coils and try swapping coil packs around and see if misfire code follows the now #3 coil

Sent from my Nexus 5X using Tapatalk

 

[Dougal]

Mark your coils and try swapping coil packs around and see if misfire code follows the now #3 coil

Sent from my Nexus 5X using Tapatalk

Thanks.

SOLVED I managed to get someone to look at it and apparently a spark plug was installed with cracked insulation. One the simplest things it could have been fortunately. It was under warranty so $0 total. Nice

Drives at 90% now which is good enough for me

 

[Dougal]

Update I also found the coil pack was also bad (engine inconsistently misfired after plug replaced when accelerating fairly hard but otherwise normal) so I fixed it and the engine is now running normally. Going through the posts on the various threads it seems that for something like I had, the problem is mostly associated with the plugs wires then coil packs, then a few bad O2 senors then more unusual is a bad MAF sensor, TB, fuel injector, then most everything else appears to be remote unless there are other symptoms. I'm not taking this 4runner to the salt belt so hopefully it will keep going for a while yet.