I have a 3rd gen 1999 4runner 3.4L and just changed the oil, oil filter and air filter. It was running fine before the change but after putting it up on ramps and taking it out it is sputtering upon acceleration and up hills. Not sure whats going on? I checked the MAF sensor and its clean, cant see any vacuum line problems. Any other ideas? This is weird and frustrating. It hasn't thrown any CEL. Is there an O2 sensor below the oil filter that could have possibly got oil on it? Other ideas?? The truck feels like its slipping and then catches and seems to run relatively well once up to speed, but accelerating and up hills it sputters and shutters and feels like its slipping. Seems to shift fine though.

 

Dumb question... but are u sure u didnt drain the tranny fluid by mistake? I have done stupid things like that b4 (usually copious amounts of beer involved), thats why I ask.... LOL

 

I don't think so. It was located under the skid plates and I removed both. Hole with the oil drain plug in the skid plate was the one I removed and drained. The drain plug closest to the motor. There was another pan towards the rear of the truck but didn't do that one. I don't think its a transmission problem as it shifts fine but and sputters on idle in park. Only seems to have problems below 2000rpms.

 

Is the check engine light on? does the check engine light work? It sounds as if you may have a cylinder miss. Back track your air filter instal to make sure you didn't break any wires or knock of a vacuum hose.

 

No check engine light on and it does light up when I put the key in so I know if works. It seems like it may be a vacuum leak but can't find anything. It is so confusing because it ran fine before I changed the oil. Shifts fine, and seems to have problems just in park at idle so I don't think its a transmission problem. Just weird it was running well before the oil change, now sputtering. Worst case I might take it to a mechanic and see if they can find anything wrong. I will look at it at lunch and see if I can find anything wrong.

 

It is below 1/4 tank full of gas and the gas light is on, but it just came on. Shouldn't be sputtering because of that, should it??

 

Those years have a known problem with acuracy of the gauge. Fill it up and see if its better.

 

Update: It just blew a couple CEL. I went to had them scanned and they were coded P0300 and P0304. I am going to remove the MAF sensor and start with a good cleaning then see how it goes. I filled the tank and it was still sputtering so I know its not the low fuel level.

Autozone says P0304: cylinder 4 misfired, weak/missing spark, plugged fuel injector, engine mechanical fault, large vacuum leak specific to cylinder
P0300: lean air/fuel ratio- fuel pump, faulty MAF, large vacuum leak, ignition system fault.

I guess it can be any of the above. If anyone has had these CEL codes let me know what you had.

 

Heres another dumb question.... You DID put the oil filler cap back on and tightly after you filled'er up.... right???


If the cap is not on, or not on tight enough. it WILL cause a rather large vacuum leak....

 

LOL, ya I put the cap back on.

Well, I took it to a mechanic and he called me back. Looks like the timing belt threw a couple teeth, slipped and threw off the timing of the engine. Also, said the cam sensor was bad, so it lasted 138K miles but it was the timing belt. I just bought the 4r and was saving up to have it done but this is gonna wipe out my emergency fund.

 

Wow... quite the coincidence. I usually end up forgetting to put the oil cap back, then drive 40 miles, wonder why my rig is running so bad, and why I smell oil, just to pop the hood and realize I should not drink beers while working on my rig...lol

 

Lol that's funny! Sounds like something I would do!

 

Worst part is... I usually dont start drinking beers till I'm almost done, but I leave the cap off, and the drain pan under the truck, this way if the wife comes in while I'm just standing there drinking beer w my buds, it looks like were just taking a break