1996 Toyota Tacoma, 3.4l V6, 5 speed manual, 208k miles.

So I've been noticing for a while now that my truck would occasionally have a hesitation or stutter when accelerating in second gear, but i never noticed it any other time. I believed that I must have just been bogging the engine a little and that it was my own fault. I also noticed that I pretty much started losing power above 3000 RPM.

Today I put on a new muffler (a turbo style) and reset the ECM by pulling the fuse in the engine compartment. Now I have a really bad hesitation/stutter around 2000-2250 RPM. It doesn't happen in first gear, but it is very noticeable in 2nd-4th. No check engine light. I changed the fuel filter today, but that did not do anything to help the problem.

I did some searching online and so far I've come up with a few things to try such as cleaning the MAF sensor, changing the spark plugs and wires, and checking the coils.

Has anyone on here had a similar problem or have any ideas of what I should try or check? I don't feel like the new muffler is the problem, more just a coincidence that it got worse today.

 

I had the same issue around the same RPM's a couple thousand miles ago, happened to be my plugs and wires. When did you last change them? I'm not really sure if the muffler should have anything to do with it, but yeah definitely check those plugs in wires, maybe do a compression test if you have a gauge, hopefully it's nothing worse.

 

My 4runner would sputter also when slowly accelerating on the freeway up until around 2k rpm and then clear up. I don't think the previous owner ever changed the plugs and the wires still said 1996 on them. Pulled the plugs and they were NGK on one side and Denso on the other. Installed new plugs and wires and the sputtering is gone. If those were the original plugs they lasted 181K miles.

 

Thanks for confirming what I was thinking. I don't know when/if the previous owner ever changed the plugs and wires, so those will be the first things I do. While I'm working on it, I'll also clean the MAF and a few other little things. Sadly with my work schedule, I probably won't be able to fix it until this weekend, but I'm going to try and get on it sooner if I can.

 

Plugs for sure - no need to replace the wires, the only time I've ever heard of the wires causing problems is if they get crimped when doing other work.

Cleaning the MAF and throttle body is a good idea - I would also run a few bottles of fuel injector cleaner through it.
I always recommend Chevron Techron but any of them will do the job most likely.

Fink

 

Well I drove the truck today and it got worse, but now the check engine light is on and throwing code P0303-Cylinder 3 misfire. That's kind of helpful so now I at least know where the problem lies. I'm not going to drive it anymore this week and I'll work on it on Saturday.

I'm going to get plugs, boots, and a new coil just to be safe. Then clean the MAF and TB since I'll be working on it anyways.

 

Yeah, when mine got a few weeks in my CEL would start up. Sometimes it would go out, sometimes it would stay on, it was weird. But sounds good man what you're gonna do, let us know how it goes!

 

I think changing the coil right now is throwing $$ down the crapper. I suggest doing things one at a time unless the labor time dictates to do everything together (like the timing belt and water pump). Coils are expensive and since it's not missing on hole #6 also, the coil is probably just fine. If you still have problems after the plugs and boots, get a coil pack and install it in 5 minutes or less. I do recommend all new coil boots though - but at least they're cheap and should be replaced by now anyways. No need to do wires for now because hole #3 isn't even connected by a wire so that's not your problem.

 

Thanks for the advice. I guess I'll try all new plugs and boots and see if that fixes it. If not, I'll test the fuel injector with an Ohm meter like the FSM says and then start replacing the more expensive parts.

 

Just thought I would update this thread with the solution in case anyone comes across this thread later.

It turned out to be the coil-plug boot in cylinder 3. I started replacing the spark plugs with Denso plugs and when I got to cylinder 3, it was pretty obvious that something was wrong with the boot. It was brown in color (all others were black) and the end where it meets the spark plug was brittle and cracked. I could also see burn marks down the side of the plug where it looked like the electricity was arcing down the side of the porcelain instead of reaching the electrode at the end of the plug.

Long story short, I replaced all the spark plugs (they were very worn) and the boot, then I cleaned the throttle body and the MAF. Now my truck runs perfectly and actually feels like it has a lot more power than before.

 

Glad you figured it out!

Thanks for posting the solution, this thread will definitely help somebody.
I appreciate it.

Fink

 

I have a '98 Toyota 4-Runner and had the same similar symptoms. This thead gave me a great starting point. After working my way down the passengers side and replacing the plugs and coil boots I started with the number one cylinder and that bank of cylinders. When I pulled the first spark plug boot I found half of the internals of the boot stayed connected to the spark plug and had broken. I had found my problem. I made my way back to the parts store for a double hinged set of pliers to retrieve the broken internals so the socket would fit on the spark plug and also picked up a set of new plug wires. All of this fixed my problem.

This forum gave me a starting point so thanks to all here.

 

Any check engine light?

 

Cool.....fixed!