sisters 4runner having running issues - please read

so my sister called me this morning and told me to listen to her 3.6L 4runner which was running rough and much louder than normal

she drove it home the night before perfectly fine

it was idling around 1500 rpm

told her to drive it around the block, she did and it was way way down on power, almost couldn't get it home

where would you start in diagnosing this?

the plugs are new in the last year so it's not them, possible coil pack problem?

any ideas would be great

thanks guys

UPDATE: loud "exhaust" noise is from the engine bay, not from the back of the truck

 

possibly a compression / firing issue. 1 or more cylinders not hitting correctly.

 

ya i figured one cylinder might be out.....but why would it be sounding louder than normal?

 

sounding louder as in just idling higher as you stated at 1500?

 

i dont know much.. but this is the first thing that popped into my head, maybe the timing belt/chain streatched causing your timing to be a wee bit off?

 

Fuel filter plugged, fuel pump is going bad, one of the coil packs bad, there are three of them on the passenger side valve cover. Could be any of those or something else.

 

ya not engine sound but exhaust sound

i was wondering if it might be a fuel problem (that would account for possibly rough idle and low power....but the "loud" exhaust doesn't seem to make sense

again, this was all at 6am, i was half asleep and she was panicked....so i'll take a look at it on saturday to see if the exhaust really is louder or what might be up

i'd assume the fuel filter has never been changed (although they are life time...and i changed mine on my tacoma), i'd change it but that's money she doesn't have

how can i test the coil packs?

how can i test the fuel pump? where can i disconnect it from and test flow?

i'd like to start by testing the coil packs and fuel pump and go from there

thanks guys

 

I had a similar issue on my 99 4runner. It started happening after I installed a K&N Filter. Apparently, it had too much oil on it, and it clogged the Airflow sensor. It ran really rough, and coughed and spit until it was cleaned. It continued happening until I put a factory air filter back in.

 

she's got a brand new oem filter in there

so i just talked to her again, apparently the "loud" exhaust sound is coming from the engine bay, not the back of the truck

so i'm hoping it's a loose spark plug (over night?)

or what else could have gone over night....head gasket? i sure hope not but anything else?

 

no CEL either apparently

 

ok so i went and look a look at the truck, within 2 seconds i knew what it was...looked under the truck and confirmed. some asshole cut off the cat

so that's getting taken car of today

thanks for the help guys

 

not sure...cheap fix is like $150-$200 at a mufler shop

insurance would be $300 but then she get's all new exhaust pieces that were damaged

she's checking with insurance to see how much they'll cover