Hello, my 4Runner is having some issue where it runs ok, but stutters/sputters a couple times then runs ok again. Today I went to start it (first time in about a week) and it sounded like it was having an asthma attack at first, but then the idle smoothed out for a minute, then sputtered twice then ran fine the rest of the trip.

Other times I will be driving on the highway and it will be cruising along and then all the sudden it will sputter a bit then run fine for 10 miles

It also tends to idle rough (only sometimes) when the engine has been run for an hour or so

How do I begin to diagnose this and find the issue? Air filter and fuel filter are relatively new.

 

Anyone have an idea on where to start looking? Or should I post in the regular tech forum?

 

When was the last tune up? plugs, wires, cap and rotor?

 

Plugs have only a few thousand miles on them. The wires are from 1998 (lol) but none of them have corrosion on the leads. I tested them for resistance in ohms and they are all good. Cap and rotor I have not looked at.

 

Do that cap and rotor...super cheap. Run down to autozone and slap them on. Take ya 5 minutes to install.

Have to eliminate the easy maintainance stuff first.

 

Is there an easy way to test them? I will do a replacement, but I'd like to see if they are faulty

 

Not really any test Ive ever heard of....other than visual inspection.
Look for cracks..carbon build up..etc.

I understand your desire to test things...we will get to that after you do that cap and rotor!

Its totally random correct? hot or cold? first start of day? while running on road or sitting?

 

The highway stutters are pretty random. The rough idle happens when i've run the engine for at least 45 minutes to an hour. Yesterday when it had its asthma attack at startup was the first time I had run it in about a week.

I'll go pull the cap and rotor really quick

 

Here's the cap



all 4 terminals have corrosion, rotor looks ok

 

Well...go get a cap and rotor. That thing looks terrible.

Then we will go from there.

 

Haha yea I'll have to get them tomorrow, the dist o-ring is also completely fried. Thanks!

 

No problem. Make sure to post up tomorrow when you get that cap on it.
Im involved now. LOL.

 

Alright so I got the new cap and rotor in and the truck is running good: no hiccups and seems to have more pep in its step, too. I think I got off easy, the cap and rotor were less than $10 out the door