Cold Start Sputter

I have a 99 PreRunner with a 2.7l engine. For a while now the truck has had these....."sputters". I'll turn the key and the engine will fire, and then it will start to sputter and vibrate and idle really low. After about 15-25secs the truck will start to slowly idle fine. I've replaced the fuel pump a few months ago,replaced fuel filter 2 months ago,replaced the air filter,replaced plugs and wires,replaced both O2 sensors,cleaned the throttle body and IACV,and replaced PCV valve. The truck has 449,8XX miles on it,if that helps at all. Have any ideas of what could be the problem??

 

450k miles? Well done lol That's all I got, sorry.

 

your head gasket may be failing. but with 450K that's not bad!

 

Check the compression on it.. Could be valves need to be adjusted some.. OR

One more thing could be your injectors could be going bad or fuel regulator..

 

Which should I check first?? The injectors and fuel pressure regulator,or the compression and valves??

 

check compression first. look in the cylinders to see if you see any coolant on the pistons, if so, you have a HG leak. the injectors would either work or not work, so I say look at HG. if you have unlimited money, then keep throwing parts at it. Otherwise, try to diagnose by troubleshooting. Troubleshooting is simply isolate and eliminate---check different parts/systems and isolate them and eliminate them as a cause.

 

For anyone else stumbling on this thread-

Just ran into the same problem, turned out my EGR was stuck open, leading to a gurgling exhaust ‘leak’ back into the throttle body and really rough idle.

Easy way to test for this-

With engine dead cold, start but don’t rev motor. Let idle 5 min. If the EGR is hot, it’s stuck open.