Jumpy RPMs while driving

[mikesayboom]

Hey guys, ran into a recent problem with my 98 4runner the other day. When I was on the highway cruising around 60ish I noticed my car was kind of jumpy. I looked at my gauges and the rpms were jumping up and down sort of like my car was surging for power.

It jumps were pretty mild and when I got up to speed (highway is kind of hilly) it went away. Then again on another incline the rpm jumps came back probably around 2300-2100 rpms speed below 60 and when I get above 60 it goes away. There is no check engine light so I can’t check any codes. I cleaned the throttle body/maf maybe 10k miles and Spark plugs were also changed around the same time. Idk what it could be but hoping it’s something simple.

I attached video for evidence: https://youtu.be/gFLUmKaiyrU

Sorry for the rattle. I’ve been needing to do the weld for the steering column mod for some time now as the shaking has been getting worse the past couple of months. But that as well as some big upgrades coming in the next couple of Months that I’ll be starting a build thread for

 

[Kyngfish]

Is it jumping - or is it hesitating/stuttering? if it's a hesitation, and only happens when you're under load, the first thing I'd check is spark plugs and wires. Go ahead and replace them. It's a cheap and easy job.

In my particular case, I would get a hesitation or a stutter, or a drop in power while cruising, generally at highway speed, or under mid-throttle acceleration.

New plugs and wires and the problem disappeared.

 

[spartacus]

http://www.toyota-4runner.org/3rd-gen-t4rs/109798-97-4runner-jerking-between-50-55-mph.html

 

[gamefreakgc]

Cleaning the MAF doesn't hurt at all either. Shoot some brake cleaner/MAF sensor cleaner with the sensor disconnected to allow it to read the airflow more accurately. You can search for pictures if you need to see how to remove it.

 

[mikesayboom]

Is it jumping - or is it hesitating/stuttering? if it's a hesitation, and only happens when you're under load, the first thing I'd check is spark plugs and wires. Go ahead and replace them. It's a cheap and easy job.

In my particular case, I would get a hesitation or a stutter, or a drop in power while cruising, generally at highway speed, or under mid-throttle acceleration.

New plugs and wires and the problem disappeared.

I would say more jumping then hesitation. I changed the plugs and the wires maybe 10/15k miles ago. I don't have my little book with all my documentation on there. Would plugs/wires go bad in that short of a time? The wires are OEM and the plugs were the DENSO 3289. I planned on changing my plugs again this summer after i do the whole seafoam treatment because apparently it can foul the plugs. but I will re order some OEM wires and change those while Im in there changing everything else out to!

 

[Kyngfish]

I'd be surprised if plugs and wires were causing that issue in that short a time period. But depending on the brand, there's a chance something was faulty. When you say jumping, do you mean it just jumps up in the revs like it's slipping into neutral, then re-engaging?

Here's what I'd do:

- Check plug and wire connections, disconnect and reconnect at each plug and make sure everything is torqued properly and connected properly and in the right order.

- When you did the plugs and wires - make sure all the vacuum lines are correct. When I did mine I had a vacuum line connecting to the wrong place and the car ran fine, except it would randomly shut off 1 time out of 5. Dumb mistake.

- Some people have advised to clean the the throttle body and the MAF, I'd go ahead and do that, but I'm not sure that's it, but since you have to pull most of it off to get to the plugs, it's a good idea.

- Check your transmission fluid.

All of those things are cheap.

After that I'd replace the plugs and wires AGAIN because it costs next to nothing. If that doesn't fix it, then I'd just be guessing if I told you what I thought it was, but it'd be time to check all possible culprits, maybe bad coil? injectors?

 

[mikesayboom]

ordered new spark plugs and wires again.

Im leaning towards it being a fuel injector problem. So this summer when i take everything apart to replace the cam seals im going to replace the intake manifold gaskets, spark plugs, wires and send my injectors off to www.witchhunter.com for them to do their thing to them and hopefully my issue will be fixed. I know its probably overkill but witch 255k miles on the motor and being 20 years old its better to do the job once and be done with it instead of replacing only one injector.

Also im going to watch a few more videos and how to's on the timing belt. ive never attempted to do one myself but hoping after some more research ill be comfortable enough to complete the task this summer.

 

[gamefreakgc]

I would say more jumping then hesitation. I changed the plugs and the wires maybe 10/15k miles ago. I don't have my little book with all my documentation on there. Would plugs/wires go bad in that short of a time? The wires are OEM and the plugs were the DENSO 3289. I planned on changing my plugs again this summer after i do the whole seafoam treatment because apparently it can foul the plugs. but I will re order some OEM wires and change those while Im in there changing everything else out to!

I used to run seafoam regularly on my vehicles with high mileage. They do foul the plugs but only for a short period of time. Once you romp on it to clean out all the carbon the heat cleans them up real nice again until they are mocha colored again.

Your O2 sensor though? Not so much. If it's about to fail Seafoam will put it over the edge.

 

[mikesayboom]

I used to run seafoam regularly on my vehicles with high mileage. They do foul the plugs but only for a short period of time. Once you romp on it to clean out all the carbon the heat cleans them up real nice again until they are mocha colored again.

Your O2 sensor though? Not so much. If it's about to fail Seafoam will put it over the edge.

after doing some more reading. I decided to seafoam my car this past weekend and it probably white smoked more then any other of my cars that ive used in the past. its always interesting to see all the confused looks going down the road. But my hesitation is still there. but after I do my work this summer im going to replace the exhaust and o2 sensors to hopefully get rid of the horrible smell from the exhaust.

 

[mikesayboom]

Alright, bringing back this old thread as ive done a lot of maintenance (fuel injectors, spark plugs, spark plug wires, vc gaskets, half moons, cam plugs etc etc) and finally was able to drive it and it did drive better but i still had the jumpy rpms around the some mph.

odd thing is I accidentally turned on the ECT button while driving and getting on to the highway I noticed that my rpms were no longer jumping up and down. Ive been driving like that for the last couple of days and its been so smooth. But as soon as i turn it off it goes back to jumpy rpms. I still want to fix the jumpy rpms and will still replace the coil packs the next time I get paid. But I want to know what exactly ECT affects when it is turned on and how its fixing my problem.

 

[2016 4Runner SR5]

Not sure if this will help but I had something like this happen with my Jeep years ago. Would actually do it every time I hit a bump, drove me nuts. Turned out to be a bad TPS, replaced it and never had a problem again.

 

[turbodudey2]

It's the brake light circuit unlocking the torque converter

I know what your issue is. It's not spark plugs/wires, fuel injectors, or any of those other things...

It's your turn signals. My truck is currently doing the same thing, but it's because I installed LED tail light bulbs.

Have you noticed that the RPM only jumps when the turn signals are on? The turn signals are backfeeding voltage into the brake light circuit. When the brake lights are lit, that causes the torque converter to unlock. Normally you would never notice this, because the only time the brake light should be lit is when you are stepping on the brake pedal - in which case the torque converter is already unlocked anyway (during deceleration).

When you are cruising on the highway the torque converter is locked up. Then you hit your turn signal and the backfeeding voltage into the brake circuit causes the torque converter to unlock in sync with your turn signal. Hence the bouncy RPM.

THE FIX:

Check all your turn signal and brake light bulbs. If you have one that is burned out, that could be the problem. (especially the third brake light)

Alright, bringing back this old thread as ive done a lot of maintenance (fuel injectors, spark plugs, spark plug wires, vc gaskets, half moons, cam plugs etc etc) and finally was able to drive it and it did drive better but i still had the jumpy rpms around the some mph.

odd thing is I accidentally turned on the ECT button while driving and getting on to the highway I noticed that my rpms were no longer jumping up and down. Ive been driving like that for the last couple of days and its been so smooth. But as soon as i turn it off it goes back to jumpy rpms. I still want to fix the jumpy rpms and will still replace the coil packs the next time I get paid. But I want to know what exactly ECT affects when it is turned on and how its fixing my problem.

 

[2016 4Runner SR5]

Just an FYI, if this is your converter locking and unlocking constantly, you WILL fry your transmission pretty quickly. This causes quite a bit of heat and unnatural wear. Get it fixed as soon as you can.

 

[mikesayboom]

Well what the hell. Got home checked all my brake lights and my third brake light was out. Bought a new bulb and put it in, took it for a test drive and no more bouncy rpms!! I owe you a beer if your ever in the dallas area!! Who would of thought an out brake light would be the problem!


Thanks again!


Also my little pigtail thatbgoes into the wire harness was burnt to hell. Going to go to Toyota tomorrow morning and get one ordered to replace.

I know what your issue is. It's not spark plugs/wires, fuel injectors, or any of those other things...

It's your turn signals. My truck is currently doing the same thing, but it's because I installed LED tail light bulbs.

Have you noticed that the RPM only jumps when the turn signals are on? The turn signals are backfeeding voltage into the brake light circuit. When the brake lights are lit, that causes the torque converter to unlock. Normally you would never notice this, because the only time the brake light should be lit is when you are stepping on the brake pedal - in which case the torque converter is already unlocked anyway (during deceleration).

When you are cruising on the highway the torque converter is locked up. Then you hit your turn signal and the backfeeding voltage into the brake circuit causes the torque converter to unlock in sync with your turn signal. Hence the bouncy RPM.

THE FIX:

Check all your turn signal and brake light bulbs. If you have one that is burned out, that could be the problem. (especially the third brake light)

 

[Dyarbrough]

Resurrecting an old thread, I have a 96 sr5 and whenever I turn my right blinker on the RPMs will jump and hold then when I turn it off it will go back to normal. It will also disengage my cruise controle. I had LEDs for the brake lights and turn signals and went back to OEM and it’s helped but hasn’t solved the issue. Any suggestions.

 

[gamefreakgc]

Resurrecting an old thread, I have a 96 sr5 and whenever I turn my right blinker on the RPMs will jump and hold then when I turn it off it will go back to normal. It will also disengage my cruise controle. I had LEDs for the brake lights and turn signals and went back to OEM and it’s helped but hasn’t solved the issue. Any suggestions.

Did you or the previous owner install a resistor to run the LED's? If it's still there I would take it out.

Other than that, check your grounds and makes sure the battery connections are clean. That's always the best place to start with electrical gremlins.

 

[turbodudey2]

Resurrecting an old thread, I have a 96 sr5 and whenever I turn my right blinker on the RPMs will jump and hold then when I turn it off it will go back to normal. It will also disengage my cruise controle. I had LEDs for the brake lights and turn signals and went back to OEM and it’s helped but hasn’t solved the issue. Any suggestions.

Sounds like the turn signal is still feeding enough voltage into the stop lamp circuit to unlock the torque converter.

The other place to look is the trailer light converter box (if you have one). Sometimes they go bad. Replacing or removing the trailer light converter box may solve the issue.

If all the brake lights are working (especially the 3rd brake light), I'm not sure where else to look. To be sure, I would double check the 3rd brake light to ensure it's not an LED bulb and that the incandescent bulb is not burned out.

 

[phattyduck]

If all the brake lights are working (especially the 3rd brake light), I'm not sure where else to look.

The flex circuit board on the back of the gauge cluster can go bad and do some odd things too... I had turn signals feeding my running lights and some odd PRND2L lights before I replaced it.

Suspects so far to check:
- Bulbs/load resistors
- Trailer light converter
- Broken wires in tailgate harness flexing area
- Gauge cluster flex circuit board

-Charlie

 

[Dyarbrough]

I just replaced all the brake light bulbs with incandescent. I’ll check the trailer box as well. Thanks!

Sounds like the turn signal is still feeding enough voltage into the stop lamp circuit to unlock the torque converter.

The other place to look is the trailer light converter box (if you have one). Sometimes they go bad. Replacing or removing the trailer light converter box may solve the issue.

If all the brake lights are working (especially the 3rd brake light), I'm not sure where else to look. To be sure, I would double check the 3rd brake light to ensure it's not an LED bulb and that the incandescent bulb is not burned out.

 

[Dyarbrough]

I have no idea if they did and I lost their contact I for to ask them. I’ll check for that as well!

Sounds like the turn signal is still feeding enough voltage into the stop lamp circuit to unlock the torque converter.

The other place to look is the trailer light converter box (if you have one). Sometimes they go bad. Replacing or removing the trailer light converter box may solve the issue.

If all the brake lights are working (especially the 3rd brake light), I'm not sure where else to look. To be sure, I would double check the 3rd brake light to ensure it's not an LED bulb and that the incandescent bulb is not burned out.

Did you or the previous owner install a resistor to run the LED's? If it's still there I would take it out.

Other than that, check your grounds and makes sure the battery connections are clean. That's always the best place to start with electrical gremlins.