Very Bad Constant Sputter

1996 4Runner SR5 3.4 - 280,000+ miles

I have a constant sputter when the gas pedal is pressed. It is especially bad at certain speeds (55-65) and going up hill. The sputter seems to be getting worse despite the recent work to cure it. I recently replaced

• Spark Plugs
• Spark Plug Wires
• All 3 Coils
• All 6 Fuel Injectors
• Both O2 Sensors (upflow/downflow)

I also used 44K and filled with premium gas on two occasions, back to back.

Nothing helps! My CarMD reads 0 errors. Any suggestions?

 

Fuel filter clogged and starving for fuel? Dirty MAF?
If you've done all the above on your own then both of these would be pretty easy to do without having to pay a mechanic to diagnose.

 

Thanks for your reply. I'll try the Fuel Filter. I would think the scanner would pick up the MAF...? But if the filter doesn't work I'll try the MAF too.

 

Well OBD would have picked up a faulty MAF or injector also so the fact they were changed and not part of the issue doesnt surprise me. MAF could just be really dirty if it's never been cleaned. If it isnt throwing codes then no need to replace, just inspect/clean as necessary. They have specific MAF cleaner at an autoparts store

 

had the same thing happen to mine multiple times-

Want my advice - buy a bunch of hoses to fit your vaccum hoses all over the engine bay, then replace them one at a time - doesn't take a super long time -seems like I had 3 different sizes and 3 feet of the really small diameter, 4 feet of the medium diameter and 6 feet of the larger diameter and had plenty of extra. The 3.4 is a vaccum pig man - if one of those hoses comes loose or cracks, all hell breaks loose.

I would recommend trying to pull and locate as many as you can - I would be willing to bet if the fuel filter doesn't fix it - the vaccum hoses would be the culprit. Armed with this knowledge I found a bad running one and fixed it for my buddy on a test drive, then we removed the vaccum I had found and put it back to how it was when we drove off the lot for test drive. He bought it for super cheap, and we fixed it before we drove off.

The main reason I'm thinking it's vaccum is it won't throw a code, sometimes it will throw an inefficiency for vaccum related issues but that's not guaranteed. Just food for thought, and it's super cheap to do the hoses IIRC to replace all of them was under 20 bucks for me, warning though some are extreme pains in the ass.