Strange Jerking/Bucking at Low Speed

[thecole1098]

Hi all, long time lurker on this site and it has been a tremendous help to me for any issues I've ever had on my 4Runner, however ever since I bought my rig this March, it's had a strange issue that I've never been able to trace down and is bugging the hell out of me. I am pretty knowledgeable with wrenching and I'm actually a mechanic at Toyota and have done all my own work on my 4Runner.

Basically the issue I'm having is the rig will feel like it's jerking in rhythm with the engine at very low speeds, such as crawling in traffic. It does this with the brakes applied or not, however once it starts to roll a bit faster you can't really feel it anymore, but this may be because of my tires. What's really strange about all of this is there's no pending or active codes despite it feeling a lot like a "secondary miss". I'm not entirely sure if the issue lies at the engine or transmission, but I'm sure it's one of those two. I've checked both driveshafts for play at the u-joints and everything is tight and it doesn't do this jerking while rolling in neutral, only in gear. I can actually feel it while in park or in gear. It is noted that before I purchased my 4Runner the transmission was rebuilt about 15k miles ago and the transfer case was also replaced at the same time with a junkyard unit.

Here's what I've done since I've had it:
NGK dual-electrode spark plugs and wires
Cleaned fuel injectors multiple times through tank and directly at the rail
Replaced all vacuum lines
Replaced intake manifold gaskets
Replaced drive belts
Valve cover gaskets
Timing belt and related pulleys
Water pump
Thermostat
Radiator
Checked fuel pressure (perfect 44psi)
Swapped coils from known good 4Runner
Cleaned throttle body and IAC valve
Replaced charcoal canister
Replaced all diff fluids
Drained and filled transmission fluid
New pads/shoes and rotors all around
New CV Axles
New LBJs
Upstream Denso O2 sensor
Fuel Filter
Both rear axle seals and bearings

Things I haven't done:
Checked compression
Checked valve clearance
Motor and tranny mounts
Cat Converter

I look forward to everyone's responses, thanks in advance.

 

[HiLife]

You say it doesn't jerk/miss while the trans is in neutral while rolling at low speed. But it does jerk/miss while it gear and rolling at low speed. What about while cruising at 30-40mph? And while accelerating?
Has it been doing this even before doing all the maintenance items?

 

[kolelt]

Can you possibly provide a video ? Are you sure this is related to engine ? Bucking/jerking.... you saying when you are in low gear/Rpms and tap on the gas pedal it feels like it's jerking ?

 

[gamefreakgc]

Bucking is normally a fuel delivery issue.

Have you replaced the fuel filter? I did see you read fuel pressure at 44 psi, did you try putting the engine under any sort of load or was that just at idle?

Any issues or errors with the Throttle Position Sensor (TPS)? It should never be moved or adjusted or the engine will cut fuel at low throttle.

 

[CdaleR4000si]

This sounds exactly like a problem that my 99 had. Really drastic lurching and bucking at low rpms. If I was stopped at a light, I could ease off the brakes and it would actually creep forward a few inches at a time. No codes, no CEL. After a few weeks, one of my injectors died on me (#4), which did eventually trigger a P0304. Bought some used injectors from Jwaldz, sent them to Witchhunter for cleaning/rebuilding, runs great now. Runs great now and the lurching is gone. I'm assuming that the lurching was the injector starting to fail.

 

[thecole1098]

Thanks for all the responses. Yes, my fuel filter was replaced and I tested the fuel pressure both at idle and while giving the engine throttle and it remained at 44psi. The jerking feeling is ONLY at slow speed/rpm, never while accelerating or coasting at high speeds. The engine seems to perform relatively well for having a lift and 33” tires, however fuel mileage is a bit subpar IMO. The fuel injector issue certainly is possible, but they are so expensive...

And yes, I have experienced this ever since I bought the rig.

 

[thecole1098]

Bucking is normally a fuel delivery issue.

Have you replaced the fuel filter? I did see you read fuel pressure at 44 psi, did you try putting the engine under any sort of load or was that just at idle?

Any issues or errors with the Throttle Position Sensor (TPS)? It should never be moved or adjusted or the engine will cut fuel at low throttle.

This sounds exactly like a problem that my 99 had. Really drastic lurching and bucking at low rpms. If I was stopped at a light, I could ease off the brakes and it would actually creep forward a few inches at a time. No codes, no CEL. After a few weeks, one of my injectors died on me (#4), which did eventually trigger a P0304. Bought some used injectors from Jwaldz, sent them to Witchhunter for cleaning/rebuilding, runs great now. Runs great now and the lurching is gone. I'm assuming that the lurching was the injector starting to fail.

I have never touched or adjusted the TPS, original unit. I'm not even sure if these are adjustable on 3rd gens.

Your symptoms sound exactly like mine do. Really annoying lugging when creeping in traffic, but would go away the moment you give it throttle. Feels almost like you're constantly driving over rocks when crawling from a stop.

 

[CdaleR4000si]

Thanks for all the responses. Yes, my fuel filter was replaced and I tested the fuel pressure both at idle and while giving the engine throttle and it remained at 44psi. The jerking feeling is ONLY at slow speed/rpm, never while accelerating or coasting at high speeds. The engine seems to perform relatively well for having a lift and 33” tires, however fuel mileage is a bit subpar IMO. The fuel injector issue certainly is possible, but they are so expensive...

And yes, I have experienced this ever since I bought the rig.

I would probably start by trying to get an ohm reading on your current injectors, the 3 on the passenger side are reasonably accessible, but the driver side you will have to pull the intake plenum. If you have never done that before, it is actually very easy, lot of write ups on this site and tacomaworld.

If it does turn out to be an injector(s), if you are in a position to be without your vehicle for a few days, you can remove your injectors and send them off to Witchhunter, right now their turnaround is 4 days. Cost is $22 per injector. That is probably the cheapest route.

 

[thecole1098]

I would probably start by trying to get an ohm reading on your current injectors, the 3 on the passenger side are reasonably accessible, but the driver side you will have to pull the intake plenum. If you have never done that before, it is actually very easy, lot of write ups on this site and tacomaworld.

If it does turn out to be an injector(s), if you are in a position to be without your vehicle for a few days, you can remove your injectors and send them off to Witchhunter, right now their turnaround is 4 days. Cost is $22 per injector. That is probably the cheapest route.

Ya I'll probably start by doing that or a oscilloscope on them. The intake plenum is a piece of cake on these, I've done it about 5 times on this already, so I could probably do it in my sleep haha.

Have you noticed a difference in MPG after you fixed your jerking? Currently I only get about ~200 miles out of my tank which is terrible.

Also I found what seems to be a pretty good deal for a complete fuel rail with injectors and the fuel pressure regulator on eBay for about $120. According to the ad it only has less than 50k miles on them, but I'm hesitant. Toyota Six Fuel injectors & Rail Pressure Regulator 3.4L V6 6 Cylinder 5VZFE OEM | eBay

 

[CdaleR4000si]

My mileage went from about 200 per tank to around 220/225. But I had also replaced the fuel filter and shortly after that, I did the plugs, wires and O2 sensors, so my improved mileage was likely from all of these things.

I'm usually pretty skeptical about eBay parts, but $120 isn't much to risk. You may still want to send your originals off to be serviced, that way you will have a back up if the eBay ones go south.

 

[thecole1098]

Went ahead and decided to test the resistance of the injectors today and they were all in the 14-18 range, which is spec according to the FSM. I also decided to pull the spark plugs to check their wear and sure enough, cylinder 1 was a lot more white Han he rest, indicating that cylinder to be running lean. This cylinder happened to also get a code for a misfire about 5 months ago but never came back when cleared. I’m staring to suspect injectors now.

 

[thecole1098]

Well I went ahead and did the fuel injector/fuel rail replacement today. It did not go as simple as it should've (as usual), however I managed to do it all in under 2 hours and that was with taking the intake off 2 times.

Once I swapped the rail/injectors over, I started the engine and it was missing BAD, so I was like what the hell. for shits and giggles I pulled the electrical connection for No. 1 injector and nothing changed. Okay, so that "new" injector isn't working. Tear it all down again and I put one of my old ones back in to cylinder 1. Put it back together and it was still surging and missing bad at idle, but smoothed out once I gave it gas. I wanted to be done at this point, so I just checked for vacuum leaks since I was getting a code for all cylinders missing. Sure enough I forgot to tighten the upper intake all the way :ybrick:

On the bright side, the jerking feeling I had seems to be almost completely gone and if I do feel it it's very subtle. I put some fuel injector cleaner in the tank so I'll let that do its magic.

 

[theesotericone]

It did not go as simple as it should've (as usual), however I managed to do it all in under 2 hours and that was with taking the intake off 2 times.

LOL. Do things ever go as simply as they should? The 1 out of 10 times they do go smooth I always feel like something really bad is about to happen. Glad you got the issue sorted out.

 

[JFunky]

Replaced Trany fluid

Hi all, long time lurker on this site and it has been a tremendous help to me for any issues I've ever had on my 4Runner, however ever since I bought my rig this March, it's had a strange issue that I've never been able to trace down and is bugging the hell out of me. I am pretty knowledgeable with wrenching and I'm actually a mechanic at Toyota and have done all my own work on my 4Runner.

Basically the issue I'm having is the rig will feel like it's jerking in rhythm with the engine at very low speeds, such as crawling in traffic. It does this with the brakes applied or not, however once it starts to roll a bit faster you can't really feel it anymore, but this may be because of my tires. What's really strange about all of this is there's no pending or active codes despite it feeling a lot like a "secondary miss". I'm not entirely sure if the issue lies at the engine or transmission, but I'm sure it's one of those two. I've checked both driveshafts for play at the u-joints and everything is tight and it doesn't do this jerking while rolling in neutral, only in gear. I can actually feel it while in park or in gear. It is noted that before I purchased my 4Runner the transmission was rebuilt about 15k miles ago and the transfer case was also replaced at the same time with a junkyard unit.

Here's what I've done since I've had it:
NGK dual-electrode spark plugs and wires
Cleaned fuel injectors multiple times through tank and directly at the rail
Replaced all vacuum lines
Replaced intake manifold gaskets
Replaced drive belts
Valve cover gaskets
Timing belt and related pulleys
Water pump
Thermostat
Radiator
Checked fuel pressure (perfect 44psi)
Swapped coils from known good 4Runner
Cleaned throttle body and IAC valve
Replaced charcoal canister
Replaced all diff fluids
Drained and filled transmission fluid
New pads/shoes and rotors all around
New CV Axles
New LBJs
Upstream Denso O2 sensor
Fuel Filter
Both rear axle seals and bearings

Things I haven't done:
Checked compression
Checked valve clearance
Motor and tranny mounts
Cat Converter

I look forward to everyone's responses, thanks in advance.

I recently got a 2000 4runner and was having the same weird lurching at crawling speeds. I found this forum and tried replacing my fuel filter first to see if that would do anything but it didn't. I figured it was the injectors like CdaleR4000si stated but after I replaced my transmission fluid and filter for a different issue the lurching went away. Not sure if the transmission is the problem for everyone with this issue but it was for me.

 

[brillo_76]

I can see fuel or transmission fluid causing this issue.

Plus I always figure it's good to keep the transmission filter clean. As that prolongs the life of the transmission.

Sent from my SM-A536V using Tapatalk