96 4Runner acceleration problem; transmission or fuel delivery problem?

[Sweetrobot]

I have a 1996 SR5 4Runner (5VZE), 4x4, automatic transmission. Mileage is at 134,000.

About a week ago, I was on a 3 hour drive during which I drove at an average of about 85MPH, sometimes about 100. I hardly drive the car for over an hour, so it's not used to longer drives. About 130 miles into the drive, something weird started to happen (for the first time ever); while cruising at about 70mph, when I press the accelerator pedal, insted of either revving up, or dropping gears, the engine would shudder, accelerating in little bursts, or not at all, (sort of "farting around a little") and then suddenly accelerating. All you feel is increased vibration, as either the engine struggled ato get gas, or the transmission had a hard time catching the gears (or matching the engine revs). This only occurs during acceleration, seemingly at all speeds and gears. This also occurs in over drive as well when 4x4 (high or low) mode is engaged.

I have reviewed some topics related to tranny and aspiration/ fuel systems describing similar symptoms, though I'm still uncertain. Can anybody offer some advice?

Thanks for reading! Really would appreciate some pointers.

[KimMG]

Check the air intake. Make sure it is clean. When was your last tune-up?

[fourwd1]

When's the last time you replaced the fuel filter?

[Sweetrobot]

Originally Posted by fourwd1

When's the last time you replaced the fuel filter?

Never- Toyota servicemen and other threads claimed it isn't necessary. I do use 87 octane, so you may be right.

[Sweetrobot]

Originally Posted by KimMG

Check the air intake. Make sure it is clean. When was your last tune-up?

I read another post claming that cleaning the air intake with some techron and a toothbrush did the trick. I haven't done a tune-up since I've had the car- over the last 40,000 miles. I've changed the air filter (I think) within the last year. Are there separate air filters for cabin and engine? What does it include and what is typical cost of one?

Thanks.

[4Wheel]

Air cleaner, every oil change. Have you changed the oil in the last 40k?
100mph? SUV?
No tune up 40k

[Sweetrobot]

Originally Posted by 4Wheel

Air cleaner, every oil change. Have you changed the oil in the last 40k?
100mph? SUV?
No tune up 40k

I change it every 3000 mils, with fully synthetic, along with a premium oil filter.

What do you mean by air cleaner? As in an air filter? I have change one under the hood, though I'm not sure if its air for the cabin or engine, or even if they are separate.

[KimMG]

Spark plugs, wires, cap, and rotor can cause the problem. Recommend getting a manual and becoming more familiar with your truck. autozone.com has some free repair and maintenance guides on their website. A Haynes manual will show you how to inspect your truck, perform maintenance and make repairs.

When was the last time you changed your transmission oil, differential oil?

[Sweetrobot]

Originally Posted by KimMG

Spark plugs, wires, cap, and rotor can cause the problem. Recommend getting a manual and becoming more familiar with your truck. autozone.com has some free repair and maintenance guides on their website. A Haynes manual will show you how to inspect your truck, perform maintenance and make repairs.

When was the last time you changed your transmission oil, differential oil?

I have never changed either oil. I'm assuming it has never been changed alltogether.

Could this possibly help? - http://www.4x4wire.com/toyota/mainte...throttle_body/

I'm going to try this, possibly later today.

[KimMG]

Did cleaning the throttle body help?

[Sweetrobot]

Originally Posted by KimMG

Did cleaning the throttle body help?

Unfortunately it did not. I have a couple of other ideas as to troubleshooting- could it possibly be a slipping belt?- mine are sqeaky when cold. I live in Florida, and when it is slightly cool here, the belts are sqeaky, but NOT to the point that I have to rev hard to get them to stop, as you sometimes hear someone at a stoplight whose belts are so lound, then they rev hard to overcome it. I do smell a slight burning rubber smell when I open the hood which I am certain is cominf from the belts (again, when colder outside).

Or,

Is it possible it is a misfiring spark plug. The plugs/ cables haven't been done since I've owned the car (50,000 miles), and I have doubts they've ever been done (140,000 miles). I do drive at very high speed for extended periods of time, so this causes high temperatures, and certainly wears the plugs more than typical. I am just wondering if the shuddering (which is fairly violent), that occurs only under acceleration, especially if I am coasting at 50mph and want to get up to 60mph, can be caused by this?

My check engine light came on recently, during one of the shudderingmoments. I have yet to have it diagnosed.

Or,

Could it be that I need to have my transmission flushed. Though this happens at most speeds, it is especially prominent when accelerating after coasting at about 50mph. It seems to be affected by the rate of acceleration as well. It seems that slower acceleration increases the severity of the shuttering, whereas if I were to accelerate faster from 50, it sometimes doesn't shutter at all. When accelerating from a stop, it feels more as if it's short on gas, and during higher crusing speeds, the problem is as stated above.

I just picked up a Haynes book, and will refer to it for any torubleshooting.

Thanks for reading; input is always appreciated.

[Sweetrobot]

UPDATE:

I finally made it to a well known Acura/ Honda/ Toyota specialist (not the darn dealer) who diagnosed the problem, along with a few others.

The jerking/ buckling was caused by a cylinder misfiring (number two to be exact, as per the computer readout). So, as some of you suggested, and thank you, I was in need of a tuneup. I also told Lee (his name is actually Bruce Lee) that I had a spongy brake pedal, and sqeaky belts. I had replaced my calipers, rotors, drums, pads and shoes, as well as a master cylinder all at once. Actually, I replaced the master cylinder TWICE in one year, and still a spongy feeling. My regular mechanics insited it was a failed booster. Lee told me immediately, after doing the typical test, that the booster was fine, and that the remanufactured master cylinder had failed. I guess BOTH had failed in my case, all within one year. I agreed to that conclusion with ease, as it is very seldom a booster fails- it's nothing but a valve and two chambers. And it happens to cost double the price of a MC.

In all, my baby is well overdue for a complete tuneup at 140,000k-

-all belts
-complete timing system(timing belt, water pump, he mentioned some gaskets/ seals, etc)
-fuel filter (only one, excluding the one in the tank)
-air filter (though changed fairly recently)
-fluids (engine, tranny, steering, brakes)
-plugs, wires, & ignition coil

separate of tuneup:
-master cylinder

Lee wants to charge 470 for parts and labor of complete timing system, for all genuine toyota parts (he does order exclusivly from toyota). this seems very frickin expensive. should it be less, even though he is using oem?

For the master cylinder, he wants 282 for parts and labor,
and 200 for the rest of the tuneup. I found the original MC by Aisin for 119, brand new. No way it can cost 160 for labor.. can it? From past experience, it takes well under an hour to replace (including bleeding the brakes and adjusting).

[KimMG]

What kind of warranty are you getting with the OEM parts? Some replacement OEM parts have a lifetime warranty. An example is the fuel filter.
The one that came with my truck didn't have a lifetime warranty, but the replacement one I purchased from the dealer does.
How much does Lee charge per hour? When he replaces the master cylinder, will he be removing the wheels to inspect and adjust the brakes?
I have saved money on OEM parts by buying them from aftermarket sources.
New clutch from dealer was $200-, I got one from the same manufacturer for $100-. The only difference was the packaging.
I'm not familiar with what things cost in Florida, but where I live, San Francisco, labor rates are $100- or more per hour. Differential oil change (2WD) alone where I live is about $100- (not a dealership, a drive-thru oil change place).

[4Wheel]

He's right check your prices!
Some will be even lower at the stealer. (I have a business discount)
Belts have an ironic twist to them, at the local HP parts store belts made in China are more expensive than the ones sold over the counter at Toyota, and where are the Toyota belts made?.......USA!!!!
Seals at Toyota are 50% less than the HP store too.
But Toyota is a lot higher in other areas.
After market fuel filters AAAARRRGGGHHHHH!!!!!!! the one I installed was not machined properly in the flange area a shoulder that prevent it from sealing.
Make sure he gaurantees that all this work WILL slove the problem or he eats the labor to fix it right.

[Sweetrobot]

He orders direclty from Toyota- he mentioned he has to purchase a minimum quota of parts (in dollars) fom Toyota every months so they will sell to him. All parts are from Toyota and come with whatever warranty stealler gives. Labor prices are cheaper here- 60's or so, a little more at the dealer. I am going to buy brand new (non remanuf.) oem parts online. I have found many of the original parts already- fuel filter, water pump, master cylinder- most parts are Aisin/ Denso components, or subdivions of those companies. Actually, event ehbelts come from Japan. He showed me the timing set, and it did say manuf. in jpn on the packaging, and belt themselves. Anyway, I'm going to buy all the parts online, and let him install. I know I am already getting better prices for exactly the same.

Lee does guarantee his labor, and said it's on the house if has misdiagnosed the problem (so long as I only bring in oem parts).

Thanks for the replies. I will post my success/ failures once I bring in all the parts and get them installed. At the moment, I'm basically buying what I need as I find the best deals all over the net. So far, so good.

Will have new info soon- should be in the garage by the weekend.