After owning this 4Runner for about a month, it has developed somewhat of a stutter at seemingly random intervals. My first fear was that it is the transmission slipping. It is an '88 V6 4Runner with nearly 200K miles, so that's not really an unreasonable fear. The challenge though was being able to watch the tach when it was stuttering since it was intermittent and didn't last long. I wanted to see if the RPMs were increasing when it stuttered (indicating a slipping transmission in my opinion) or decreasing (indicating an engine related missing issue).

I was finally able to catch a glance at the tach when it stuttered and noticed it was kind of jumping around. It would go up and down. However, I was able to watch it go from one reading at cruising speed, stutter, and jump up 500 or so RPM and stay there while the truck continued to pull fine.

So here's my current "arm-chair" diagnoses and hope someone else has confirming words of wisdom. I'm wondering if the transmission is trying to shift between gears when it stutters and can't make up it's mind. I plan to change the filter and fluids in the near future and also look into adjusting the kickdown cable. If that were out of adjustment, wouldn't maybe cause the shifting issue?

Has anyone else experienced this?

Thanks,
Patrick

 

Sounds like the torque converter isn't holding lock up. I would unplug the ECT unit and do a manual shift. You will lose 2nd gear because the shift solenoids will not be working. L will be 1st, 2 will be drive and D will be OD. Lock up only happens in D and OD. The computer for the tranny (ECT) is at the front of the console.

 

If the tach is giving random, errant readings, jumping back and forth up to 500 rpm's quickly, the likely problem is towards the engine, probably somewhere in the ignition system. The torque converter and auto-trans itself will dampen changes in engine RPM's and keep the engine from making seemingly random jumps in RPM's.
Even if the torque converter or trans were slipping, the tach would somewhat smoothly increase or decrease its indications: it would take one heck of a large air bubble to enter the converter to cause a jump of 500 rpm's in anything less than one second, and a bubble that size would cause the transmission to jump out of gear suddenly and just as suddenly shock the driveline with torque. So if acceleration remains 'smooth', the problem is likely not in the transmission / torque converter.

 

I'd say its driveability. Does the engine always seem to lurch or shutter in the rpms change? Does it does the RPMS jump when not shuttering? I'd say check your ignnition components. Make sure theres no broke wires or bad grounds. Leaning toward ignitor wiring and or coil...

 

When it stutters you can definitely feel it, but it is slight enough to not slow the truck down. I think when I saw the RPMs jump up the 500 or so that it did, I was catching it on the tail end of one of its stutters, which makes me think it is a shifting problem.

I do have a new development though: This evening, after making my post, I drove the truck out to run errands. I decided to take it out of Overdrive to see if that made a difference. Sure enough, while I can't say it eliminated the stutter (might have MAYBE felt it hiccup ONCE!) it did seem to at least be drastically reduced. I'll drive it around a little more with the O/D off to compare.

Thanks!