I have a 98 Toyota seinna and it has started making a thud noise and skipping a bit when accelerating or going up even a slight incline. I have been told everything from it needs new plugs/wires to a new transmission. Could these cause similar problems? Or what do you suggest?

Is the Check engine light on? How many miles on the vehicle, when were the plugs last changed?

Can you email me at this site is difficult to navigate on my phone.

No check engine light. About 120k miles. I bought it used a little over a year ago, never changed plugs.

I don’t e-mail. Your vehicle calls for either a plug replacement at 120k miles with Iridium or a 60k interval with platinum plugs, either way you are due so it wouldn’t be a loss to try those first.

Check your transmission fluid for color. It should be a clear bright red on the dipstick. If it is not, then you should go and have the fluid drained, the pan removed and the filter cleaned, then refill with the Toyota T-IV ATF only, use no other type of transmission fluid. BTW, it doesn’t cost that much anyway, just inconvenient to have to go to the dealer to get it. It takes about 4 qts.

Do not allow some quicky lube place to flush the transmission and use a generic ATF with additives, that can ruin the transmission. The reason they will give you for this is that only about half the transmission fluid will drain out, about half of the old will stay in. Supposedly, a flush will get it all, that is not true unless the fluid is drained first.

If you have an independent mechanic who will use only the Toyota T-IV and wants to use a fluid exchange machine after draining the transmission first, this will get better than 90% of the fluid that way, but unless the fluid is really dark brown or black, I don’t think that is necessary, a drain and refill will be fine.

If the problem persists after all this, post back.

BTW, if you have spark plug wires, and you won’t if you have coil on plug type ignition, the wires will not be bad so you don’t need to change them. That is unless you see actual physical damage to the wires.


Your transmission actually requires Dexron 3

Here is your scheduled maintenance guide, in case you don’t have it.

So then dexron 3 can be used instead of the Toyota T-IV ATF fluid?
Its so confusing, in looking at this problem i have had people say i needed a flush and fill, and people who say that would ruin transmission. I have had people say try Lucas transmission helper, and people say that would ruin it.
I am poor, out of work, and confused as to what the best, least expensive first step should be. Àaaahhhhhhh!


No flush
Drop pan
Replace filter and gasket
Reinstall pan
Refill with Dexron 3

With all due respect to other guys, Dexron 3 is the correct ATF, because that’s what’s called for in your manual.

If you want to be economical, just do a drain and refill. Don’t remove the pan. I believe your pan may have a drain plug. It would be ideal to replace the filter and gasket, but if that’s too complicated and/or pricey right now, forget it.

Are you pretty handy?
Do you have the tools necessary to replace the plugs yourself?

I suggest finding a good local mechanic. Ask your friends etc. for recommendations.

When going up an incline it puts a greater load on the engine and xmission, and that’s the situation where symptoms of “iffy” ignition systems and xmissions will show. I suspect the cause will turn out to be deferred maintenance. I concur w/above comments, the first step is to schedule a routine transmission maintenance and spark plug service.

One more thing. It seems most auto transmissions have a problems early when they don’t get their fluid changes. It seems many problems happen when the transmission fluid is not replaced regularly. For reasons unknown too few people including those who should know better let the. Transmission fail for lack of a cheap simple fluid change. Note: please look for someone who will do a real change and replace the filter etc,

@JosephEMeehan I agree with you about the filter. I only suggested the drain and refill if money is extremely tight.

Whatever you do, DO NOT FLUSH the transmuission. It will have whatever problem you have WORSE!