1500 rpm stumble, issue or I just don't know how to drive?

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kelly2310

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I've put about 1500 miles now on my new-to-me '99 (173k total miles) and I'm trying to figure out if I've got a problem or it's just the way these things are geared with the v6, 5-speed and the 4.11s.

For example, if I'm driving along at 45mph in 4th and then slow to 25-ish for whatever reason (corner, or traffic or what have you) and drop into 3rd, when I go to accelerate again the truck stumbles sometimes as it passes 1500 rpms. If I go into second instead and keep it over 1500 it's just fine. It doesn't seem like normal lugging of the engine as it will pull from 1000 to 1500 rpm just fine and then buck a few times until it gets up past 2000 or so then smooths out again if I just keep on the throttle.

So either the truck is just geared tall and I need to re-program my brain to go down one more gear than seems necessary, or I've got the start of some issue with the engine. Haven't pulled plugs yet.

Otherwise the rig runs great and I'm averaging about 20.5 mpg on the highway and an amazing 17.5 mpg in mixed driving.

Being kinda paranoid, I got a really good deal on the rig and I keep thinking "what's wrong with it?". I noticed one of the coils looks brand new, so maybe there was the start of something before the rig got traded in? :eek:
 
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Stumbling/misfiring below 2000 rpm with an automatic has been found to be spark plugs/wires numerous times. Could be the same thing happening with your 5 speed. I'd start with a tune up.
 
Replace your wires and plugs. Make sure to use Toyota parts too. It will get worse as they wear more, but it is not your transmission.
 
I'd check the fuel filter. A slight stumble when accelerating after coasting is a classic fuel filter/pump symptom, especially with returnless fuel systems. I just changed mine (and it was excessively dirty).
 
I feel like these threads come in waves one week it'll be head gaskets, then strawberry milkshake, and now its shuddering. But honestly it just sounds like you need to give it more gas to get it up to speed for the gear or gear down to second, but I'd probably check the plugs then the fuel pump.
 
None of the links seemed to be the same as my issue, and lots of searching turned up nothing exact either. Thanks for the pointers though, learned more about problems I might have in the future.


I'll pull the plugs and check them out and see about swapping out the fuel filter. It looks crazy easy to get at and can't cost that much.

I'll report back what I find.
 
1500 RPM is about as slow as you can reasonably expect your engine to produce torque without stressing. If you go too low, you'll lug it and on these particular engines get a good amount of valve clatter. Essentially, you should never be driving it under 1500 RPM unless you're in first or MAYBE second and going down a hill. Keep the needle close to 2K RPM while driving. Downshift at 1500, upshift around 2500. It may seem counterintuitive, but you'll get better gas mileage at around 2000 RPM than at 1500 (check a torque curve). Your cooling system is also not as efficient, and driving up hill at low RPM can cause unneeded stress as well.
 
Fancy looking plug (this is the forward most drivers side plug, seemed to be the easiest to get to), but that center looks worn to me based on the pictures of plugs like this I see on-line. Pretty even though.

4runner_plug.jpg
 
spectre6000 said:
1500 RPM is about as slow as you can reasonably expect your engine to produce torque without stressing. If you go too low, you'll lug it and on these particular engines get a good amount of valve clatter. Essentially, you should never be driving it under 1500 RPM unless you're in first or MAYBE second and going down a hill. Keep the needle close to 2K RPM while driving. Downshift at 1500, upshift around 2500. It may seem counterintuitive, but you'll get better gas mileage at around 2000 RPM than at 1500 (check a torque curve). Your cooling system is also not as efficient, and driving up hill at low RPM can cause unneeded stress as well.
Click to expand...

+1 if the engine is under load that is just way too low of an rpm to be accelerating at. Our modest 3.4l's dont have enough torque to accelerate in third from below 1500. Sounds like this could just be normal for that type of engine load.
That being said new spark plugs and cleaning of MAF and throttle body should improve power output at the low end. Hope the new spark plugs help!
 
While you shouldn't really lug the motor by trying to accelerate in 4th at 25ish mph, and under 1500rpm, i do do it and i don't get the stutter you get, mine just pulls through.

So i would first change the fuel filter, run some fuel injector cleaner, wait a week, if the problem is still there, then change the plugs and wires. If the problem still persists i would just ignore it until/if it ever develops into something important.
 
JohnsD90 said:
in 4th at 25ish mph, and under 1500rpm, i do do it and i don't get the stutter you get, mine just pulls through.
Click to expand...

:roadkill:

Really? Maybe mine also isn't producing the power it should at those RPM's. I am way over due for the fuel filter change hope that is the culprit.
 
JohnsD90 said:
While you shouldn't really lug the motor by trying to accelerate in 4th at 25ish mph, and under 1500rpm, i do do it and i don't get the stutter you get, mine just pulls through.
Click to expand...

Well now mine does the same thing. :lmao:

Today I did the following:

- plugs
- wires
- MAF cleaning
- throttle body cleaning

Now you can do dumb stuff like drive around at 20 mph in 4th and just slowly accelerate up to whatever speed you want. Not that I'll do that, but clearly the motor is happier than it was before. I don't know which item cleared it up but I wasn't about to do them one at a time when everything came apart so nicely the first time to do the plugs.

Here are the plugs I removed:

4runner_plugs.jpg
 
ajonesnv said:
Those looked as bad as mine...
Click to expand...

Now that I've seen new ones, I can say those were due to be swapped out.

Had to drive in today in stop-and-go traffic and I must say that it's smooth all over the RPM band, even trying to roll on at 15 mph in 4th. It will pull (slowly) from there if it has to now without any bucking. Obviously that's not the ideal way to drive but at least I have some more flexibility in which gear to use when.
 
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Color. You have two close to white and four brown (healthy). Google "reading plugs" or something to that effect and I'm sure you'll find dozens of charts. It's hard to tell from that photo, and I don't know which plug came from which cylinder, so that's on you.
 
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