Stumble on cold starts, then clears up.

[underscorepatrick]

Hey guys .

I’m getting a really bad studder when cold starting . For the first 10-15 seconds ,my truck has that “low rpm vibration” feel,where it almost feels like it’s gunna stall. I also notice that when I shut the truck off,it literally “kills itself” rather than the little 1 second lag of everything turning off (I hope it makes sense).

Sometimes ,when driving & letting off the throttle ,the RPM’s will dip low below 1000RPM,then jump back up to normal value . Any ideas ? No check engine light ,& after 15 or so secondary it’s back to normal(Minus the short drop to a low RPM then back up to normal).

Spark plugs changed about 15k miles ago. Cleaned MAF & TB. Haven’t changed out fuel filter . I want to do a fuel pressure test to see if it’s related . One thing I do notice is,when filling up gas,it’s difficult to get the pump to stay on. It’s always shutting off & I have to play with the trigger the whole time . I read that the charcoal canister might be clogged so I plan on trying to air that out. Would this cause any issues I’m having?

Thanks in advance

 

[underscorepatrick]

I forgot to mention . 2006 v6 4.0 4wd

 

[underscorepatrick]

Bump?

 

[Seasparrow]

Off hand most people have started such problems with changing plugs, cleaning MAF sensor and cleaning throttle body. could also check vacuum hoses.

 

[08TxRunner]

I hate to be the one to suggest this, but you do have an '06 - read some of the head gasket threads and see if you suffer any of those symptoms.

 

[Seasparrow]

I wrote this ysterday,

MAF Mass Air Flow cold idle hiccup, bad but not failed ??

You could test the charcoal canister by unplugging the hose from the canister

 

[kcdehart]

Have you disconnected your battery recently? For probably 50 miles after disconnecting mine, my 4Runner has a really hard time idling. It eventually re-learns, but it definitely takes a bit.

Depending on your build date, you should be fairly safe from headgasket issues. Those were solved (to the best of my knowledge) mid-2005 model year by a headgasket redesign. I have a headgasket leak right now, and it's not fun (shop will be fixing it next week and it's gonna run me around $2k. Which is cheap from what I'm hearing). If your check engine light and VSC/TRAC lights start coming on during the rough idle, beware.

 

[underscorepatrick]

Have you disconnected your battery recently? For probably 50 miles after disconnecting mine, my 4Runner has a really hard time idling. It eventually re-learns, but it definitely takes a bit.

Depending on your build date, you should be fairly safe from headgasket issues. Those were solved (to the best of my knowledge) mid-2005 model year by a headgasket redesign. I have a headgasket leak right now, and it's not fun (shop will be fixing it next week and it's gonna run me around $2k. Which is cheap from what I'm hearing). If your check engine light and VSC/TRAC lights start coming on during the rough idle, beware.

Battery hasn’t been disconnected prior to idle issue. I did disconnect to reset the ecu & still having issue. Hopefully not headgasket. No CEL . Were you throwing a cel ? What other symptoms were you having for the hg?

 

[underscorepatrick]

I wrote this ysterday,

MAF Mass Air Flow cold idle hiccup, bad but not failed ??

You could test the charcoal canister by unplugging the hose from the canister

Hey.

If I unplug the canister from the hose ,what’s the truck supposed to do? Or am I supposed to do any maintinence ? I read to blow air into one side of the canister,but to make sure it’s the correct side because there’s a one way valve in there ? I’m not sure how the canister works .


Please more unfocusing would help. Thanks for your help!

 

[kcdehart]

Battery hasn’t been disconnected prior to idle issue. I did disconnect to reset the ecu & still having issue. Hopefully not headgasket. No CEL . Were you throwing a cel ? What other symptoms were you having for the hg?

I believe it has to misfire for a certain period of time for it to throw a CEL. I've noticed that if I rev the engine to ~2,000RPM while it's stumbling, the misses clear fast enough that no CEL is thrown. Sometimes if I don't rev it's fine and starts normally. The rest of the time, it will stumble for 10-15 seconds pretty badly, throw the CEL and VSC/TRAC and then it'll drive perfectly once it's cleared all the coolant out of the cylinder (cylinder 4 in my case).

The only other symptoms I have are slow coolant loss and a wiff of burnt coolant when I start the truck. No smoke at all and no overheating (because I keep the coolant topped off. It would overheat if I just let it burn it all out).

 

[AuSeeker]

Have you disconnected your battery recently? For probably 50 miles after disconnecting mine, my 4Runner has a really hard time idling. It eventually re-learns, but it definitely takes a bit.

Depending on your build date, you should be fairly safe from headgasket issues. Those were solved (to the best of my knowledge) mid-2005 model year by a headgasket redesign. I have a headgasket leak right now, and it's not fun (shop will be fixing it next week and it's gonna run me around $2k. Which is cheap from what I'm hearing). If your check engine light and VSC/TRAC lights start coming on during the rough idle, beware.

Battery hasn’t been disconnected prior to idle issue. I did disconnect to reset the ecu & still having issue. Hopefully not headgasket. No CEL . Were you throwing a cel ? What other symptoms were you having for the hg?

What's the build date on the VIN sticker on the driver's door jamb?
If 12/05 or later you should be fine concerning the head gasket issues, from 12/05 and onward the head gaskets were of the new design.

 

[supergrappler]

Have you disconnected your battery recently? For probably 50 miles after disconnecting mine, my 4Runner has a really hard time idling. It eventually re-learns, but it definitely takes a bit.

Depending on your build date, you should be fairly safe from headgasket issues. Those were solved (to the best of my knowledge) mid-2005 model year by a headgasket redesign. I have a headgasket leak right now, and it's not fun (shop will be fixing it next week and it's gonna run me around $2k. Which is cheap from what I'm hearing). If your check engine light and VSC/TRAC lights start coming on during the rough idle, beware.

Uh oh.... did your headgasket issue cause those symptoms?

 

[kcdehart]

Uh oh.... did your headgasket issue cause those symptoms?

It caused stumbling/hard idle for the first minute or so, but that went away after a while. Eventually the exhaust gasses leaking out were just spewing coolant out of my reservoir on long drives. I think it leaked for at least the 40k that I drove it before replacement. So it can definitely be sat on for a while.

It ended up costing me $3k for the HG and another $3k for all timing components and the oil pump.

 

[325runner]

You need to get the vehicle nice and hot. Let sit, overnight is best, pull spark plugs on driver side and get a borescope down in the cylinders so you can see the coolant leaking in the cylinder