96' Rough Low Idle...Not Likely Plugs, Coils or Injectors

[tkc74]

Oi,

Been experiencing some rough idle at low RPM's. No fault codes are present, have also searched with Torq App and nothing shows up. Any thoughts?

Some relevant history:

1. Was experiencing the same problem about 6 months ago to the extent that a fault code was appearing. It said there was a misfire in cylinder 3. After checking the plugs, coils and replacing the wires I determined that it was the injector. After I replaced that the engine was fine and the code cleared itself.
   
   
2. More recently I forgot to change my oil after ~10,000 km (I know, I'm an idiot). When I did remember to do it the dipstick (no...not me hwell was showing oil just below the bottom bump on the stick (this related to about 3L IIRC). Once changed the rough low idle went away but has now returned, not as bad but still noticeable.

Is it possible I damaged my engine with low oil? What is the best way for myself (or a mechanic) to check?
OR
Is it possible this came from the bad injector/previous miss firings and just now the damage caused by it is appearing? What is the best way to check?

 

[jgue467]

I don't know much about the 3L engine but I'd suggest to clean it's MAF, IAC and intake. The symptoms you describe are pretty similar to what'll happen on a 5vz (3.4) and cleaning those items does the trick. Plenty of how to's on here and you tube. Luck. :cowboy:

 

[kolelt]

Is it possible to damage a engine with low oil. Come on dude. It’s common sense answer.

Check the resistance on your injectors. Takes 1 min to do.

 

[tkc74]

I don't know much about the 3L engine but I'd suggest to clean it's MAF, IAC and intake. The symptoms you describe are pretty similar to what'll happen on a 5vz (3.4) and cleaning those items does the trick. Plenty of how to's on here and you tube. Luck.

Sry, forgot to mention, 3.4L-V6/4WD/300,000 km (~185,000 miles). The MAF, IAC and intake were all on the list of things to check when experiencing the initial rough idle but didn't get to since replacing the injector worked...at the time... Perhaps time to revisit. Thanks!

Is it possible to damage a engine with low oil. Come on dude. It’s common sense answer.
Check the resistance on your injectors. Takes 1 min to do.

Phrased like that yes, obviously low oil will cause damage to an engine, but how low? No low oil or check engine light and temps never got above normal. Was fielding whether 3L/bottom bump on dipstick was really low enough to cause damage. I will check resistant on injectors tho as I have yet to do that.

Cheers

 

[thecole1098]

Sry, forgot to mention, 3.4L-V6/4WD/300,000 km (~185,000 miles). The MAF, IAC and intake were all on the list of things to check when experiencing the initial rough idle but didn't get to since replacing the injector worked...at the time... Perhaps time to revisit. Thanks!


Phrased like that yes, obviously low oil will cause damage to an engine, but how low? No low oil or check engine light and temps never got above normal. Was fielding whether 3L/bottom bump on dipstick was really low enough to cause damage. I will check resistant on injectors tho as I have yet to do that.

Cheers

As long as the oil still registered on the dipstick, you should in theory be fine.

Also, by rough idle, are you talking low rpms/stumbling or simply a vibration felt through the vehicle? And if the latter, is it felt only in gear or all the time?

 

[Texasrunner46]

Throttle body

Have you cleaned your throttle body!?

 

[jgue467]

...

Is it possible I damaged my engine with low oil? What is the best way for myself (or a mechanic) to check?

I don't think the low oil is the cause of the low idle/vibration. If the oil gets really low, the oil pump will suck air and instantly trigger the oil pressure light on the dash. Did you see this happen at all, many times? If not, I think it's ok, the problem is linked to something else like Kolet said. :cowboy:

 

[tkc74]

Hokay so bit of an update!

Cleaned my MAF, IAC, throttle body (fully took it apart, sprayed and cleaned) and replaced my air filter and I'm still getting the occasional rough low idle that's slightly less frequent l.

Not sure what else to do? Would changing my PCV have much effect?

Any thoughts?
Cheers,

 

[gamefreakgc]

Hokay so bit of an update!

Cleaned my MAF, IAC, throttle body (fully took it apart, sprayed and cleaned) and replaced my air filter and I'm still getting the occasional rough low idle that's slightly less frequent l.

Not sure what else to do? Would changing my PCV have much effect?

Any thoughts?
Cheers,

Check hoses for improper fitment or cracks that would allow vacuum leaks. That's been the cause of every rough idle I've ever had.

There have been cases of these 4Runners running on oil with over 30,000 miles or less that 1 qt of oil with no internal engine damage. I doubt it was your oil.

Personally, I bought a sludgey engine with oil that'd been in there at least 10,000 miles, the mechanic that changed it said it was some of the blackest oil he'd ever seen. Runs like a top and I've boosted it to 10 PSI with perfect compression across the cylinders. These engines are very forgiving when it comes to maintenance.