Transmission/Misfire Problem

[GamecockRooster]

Wanted to see if any of y'all could help me to diagnose this problem.

First off here's the details on my truck:
-99 Limited 4wd
-130k miles
-V6 Auto transmission

Yesterday, I was driving down the highway at about 65-70 miles an hour when as I tried to accelerate a little bit my 4Runner stuttered when I gave it gas and had a hard time engaging to accelerate. It did it a couple of times and definitely scared me. Felt like the transmission was going to drop out of the truck.

Something similar to this has happened in the past and it was determined to be a misfire. In that case, I got to the point where when on the highway, at low rpms if I tried to accelerate while coming up a hill the truck would struggle to engage and accelerate.

However, is it possible that I could:
A) have bad trasmission fluid that needs to be changed?
B) have another misfire?
C) have gotten a tank of bad gasoline?

What seems most likely? I appreciate anyone's insight. (I've done an extensive search on the forum and can't seem to find a thread that is specific to my problem.)

Thanks!

 

[techno]

Did the CEL come on or flash at all? A misfire will usually give an error code. I would check the fuel system first. Fuel filter and injectors. Also, whats the condition of the MAF?

 

[GamecockRooster]

Did the CEL come on or flash at all? A misfire will usually give an error code. I would check the fuel system first. Fuel filter and injectors. Also, whats the condition of the MAF?

I did not get any type of error code or warning light. Actually, last time when a misfire was diagnosed, the code would pop up just for a second, and my mechanic had to keep trying to get the truck to misfire in order to write down which coil needed replacing. (He basically told that the stealership just says to replace all the coils instead of trying to isolate the problem. He managed to isolate the problem to one coil and replaced it.)

If the problem persist, what I'll do is ask my mechanic to check out the fuel injectors, filter and MAF sensor to see if they need to be cleaned. I feel everything a vehicle does, and I have definitely noticed a slight difference in how the truck responds since yesterday morning.

You don't think it might relate to the transmission fluid do you?

 

[jperez19]

I did not get any type of error code or warning light. Actually, last time when a misfire was diagnosed, the code would pop up just for a second, and my mechanic had to keep trying to get the truck to misfire in order to write down which coil needed replacing. (He basically told that the stealership just says to replace all the coils instead of trying to isolate the problem. He managed to isolate the problem to one coil and replaced it.)

If the problem persist, what I'll do is ask my mechanic to check out the fuel injectors, filter and MAF sensor to see if they need to be cleaned. I feel everything a vehicle does, and I have definitely noticed a slight difference in how the truck responds since yesterday morning.

You don't think it might relate to the transmission fluid do you?

Hey just run some fuel injector cleaner through it, and see if it helps. I had the same thing happen to me before. Try it and see if it helps

 

[GamecockRooster]

So here's the deal. I had to replace coil #1. The coil burned out the spark plug and there was an indication that the wiring might have been faulty as well. Got a new coil, replaced the spark plugs and the wiring, ran a little injection cleaner in it and everything works good again. I've now replaced coils 6 and 1. I have one left which knowing my luck will go bad soon. At that point all the coils will be new and I should be good to go for a while.

The misfires happened at highway speeds and felt like the transmission was going to drop out. It's one of those deals where I can't afford to throw parts at it due to time and money. Therefore, I let my mechanic keep it for about 3 days so that he could work on it to try and find the right problem. Finally, once he took it out on the highway, he was able to duplicate the problem and diagnose correctly.

 

[chillinied]

I registered yesterday and was just going to mention it's been my experience that misfiring under normal opr conditions are usually caused by something in the electrical system. I had bought new single prong spark plugs and they would misfire like this. You've got to have split prong OEM plugs in this motor. Also if it misfires when it's high humidity means your wires have lost their insulating properties.

 

[ZombieDave]

My 97 4runner just started doing the same thing and i thought it was the trans it has the same feel as if the trans is going. I ve been through that with like 3 other cars i had but i was unable to find anything wrong with the trans other than the need for new fluid as mine is dirty. I remembered that i put in new plugs but i dont belive that they hade the double prong and after reading my manual i saw that those are the only ones that should be in there.:bash: So now that ive realized my error i hope i can get this fixed before it gets worse and i start crying and smacking my head on the floor like a 3 year old.