intermittent misfire. Showing some signs of HG but not all. Something else?

[underscorepatrick]

Hey guys.


For the past year,I’ve been losing a small amount of coolant somewhere . Changed hoses where I found small leaks . Still,strong coolant smell persisted till this day.

I started having an intermittent studder. It happens during load,like cruising highway foot off throttle ,get on throttle & misfire . Not every time . Some are worse then others . Some are small baby studders. orhers will cause me to pull over and restart the car. It happens maybe once every 30 or so miles?

Another thing going on is,my cooling system keep pressure well throughout the night . even after 2 days. Still have pressure & as soon as I release the cap,it’ll air out. The hoses don’t bulge ,but they are stiff when cars running & after ,until I release pressure . No coolant is syphoning back into the radiator from the resevoir . Resevoir fills up.

I just pulled the code & it’s throwing a catalytic code now. No missfire code . P0420 I believe .

Any idea where I should look at before calling it a hg issue ?

 

[Captsolo]

I have 2005 SR5 with 150,000 miles. Bought it new. No HG issues.

I check my coolant level in the overflow tank 10 times a month and note if I've lost any. It never drops so much as a fraction of an inch - indicating no HG issue.

If you are not loosing coolant it's unlikely you have a HG issue.

Any white spoke from the exhaust?

What year 4runner is yours/? How many miles?

It sounds to me like you may have a blown HG - based on the studder of the engine at startup.

 

[That_Titanium_4RNR]

Hey guys.


For the past year,I’ve been losing a small amount of coolant somewhere . Changed hoses where I found small leaks . Still,strong coolant smell persisted till this day.

I started having an intermittent studder. It happens during load,like cruising highway foot off throttle ,get on throttle & misfire . Not every time . Some are worse then others . Some are small baby studders. orhers will cause me to pull over and restart the car. It happens maybe once every 30 or so miles?

Another thing going on is,my cooling system keep pressure well throughout the night . even after 2 days. Still have pressure & as soon as I release the cap,it’ll air out. The hoses don’t bulge ,but they are stiff when cars running & after ,until I release pressure . No coolant is syphoning back into the radiator from the resevoir . Resevoir fills up.

I just pulled the code & it’s throwing a catalytic code now. No missfire code . P0420 I believe .

Any idea where I should look at before calling it a hg issue ?

What are the details of your ride? V8? V6? year?

 

[rumfoord]

Hey guys.


For the past year,I’ve been losing a small amount of coolant somewhere . Changed hoses where I found small leaks . Still,strong coolant smell persisted till this day.

I started having an intermittent studder. It happens during load,like cruising highway foot off throttle ,get on throttle & misfire . Not every time . Some are worse then others . Some are small baby studders. orhers will cause me to pull over and restart the car. It happens maybe once every 30 or so miles?

Another thing going on is,my cooling system keep pressure well throughout the night . even after 2 days. Still have pressure & as soon as I release the cap,it’ll air out. The hoses don’t bulge ,but they are stiff when cars running & after ,until I release pressure . No coolant is syphoning back into the radiator from the resevoir . Resevoir fills up.

I just pulled the code & it’s throwing a catalytic code now. No missfire code . P0420 I believe .

Any idea where I should look at before calling it a hg issue ?

If you're not getting a misfire code I wouldn't worry about head gasket issue (I've had the dreaded HG issue).

What I would look at is maybe the timing components, solinoid etc. But you would most likely get a code related to that. If you are getting check engine with a code I'd trust that code and start there.

 

[underscorepatrick]

hey guys,

sorry its a v6 4.0 4wd

 

[underscorepatrick]

If you're not getting a misfire code I wouldn't worry about head gasket issue (I've had the dreaded HG issue).

What I would look at is maybe the timing components, solinoid etc. But you would most likely get a code related to that. If you are getting check engine with a code I'd trust that code and start there.

whats happening now is i'm pushing coolant out of my resevoir. im building up pressure in my cooling system & i cant find where. I was having intermittent missfire. I'm thinking timing is off. Stretched chain,but what about the pressure buildup?

Codes are crank position sensor & a bad catalytic

 

[underscorepatrick]

I have 2005 SR5 with 150,000 miles. Bought it new. No HG issues.

I check my coolant level in the overflow tank 10 times a month and note if I've lost any. It never drops so much as a fraction of an inch - indicating no HG issue.

If you are not loosing coolant it's unlikely you have a HG issue.

Any white spoke from the exhaust?

What year 4runner is yours/? How many miles?

It sounds to me like you may have a blown HG - based on the studder of the engine at startup.

Hey. I am loosing coolant. I found out its pushing out of the overflow tank. It's building pressure while hot.

No smoke, missfire very intermittently. The pressure build up is whats making me think head gasket. The pressure will stay overnight ,& will release a hiss of air if I removed the cap the next day.

What do you think?

v6 4runner 189xxx miles. 2006, but manufactured late 2005