[cedenker]

Gen 2 (2007) Sienna Minivan, about 250K miles. Been a great car, used for 500 mile trips to family homestead multiple times per year since purchase. About 3 years ago, engine had problems when starting and felt like it was severely missing, replaced a few coils and been fine since, although hardly used anymore.

Started using again recently, on a 1000 mile trip - everything perfect. After I got to destination, parked it and let it sit for a couple of hours, started it up and engine was missing badly, and check engine light blinking. Parked it (said some curse words and some prayers), and didn't drive it until a couple of days later - but then everything was perfect again. A couple of days later, started it it and it wouldn't start. Engine turned over and it sounded like it was getting good fuel, but just wouldn't kick on. Didn't want to kill battery so waited a couple of hours and then it started fine, so headed home (on a prayer). Drove 1000 miles perfect over a couple of days, no problems. After I got home, drove it a couple of errands, and still perfect.

Today, when returning from an errand (drove it about 10 miles or so), I started it, but engine was missing and check engine light blinks again. Just gunned it and made it home (again praying). Waited about 30 minutes and started it up and it ran perfect again..

Obviously I'll take it get the check engine diagnosed, but any idea what would make it change between perfect and missing like this? Fuel Pump?

Help me please smart people, just trying to squeeze 6 months out of this thing without emptying an already empty wallet.

Thanks

 

[RomaniGypsy]

Gen 2 (2007) Sienna Minivan, about 250K miles. Been a great car, used for 500 mile trips to family homestead multiple times per year since purchase. About 3 years ago, engine had problems when starting and felt like it was severely missing, replaced a few coils and been fine since, although hardly used anymore.

Started using again recently, on a 1000 mile trip - everything perfect. After I got to destination, parked it and let it sit for a couple of hours, started it up and engine was missing badly, and check engine light blinking. Parked it (said some curse words and some prayers), and didn't drive it until a couple of days later - but then everything was perfect again. A couple of days later, started it it and it wouldn't start. Engine turned over and it sounded like it was getting good fuel, but just wouldn't kick on. Didn't want to kill battery so waited a couple of hours and then it started fine, so headed home (on a prayer). Drove 1000 miles perfect over a couple of days, no problems. After I got home, drove it a couple of errands, and still perfect.

Today, when returning from an errand (drove it about 10 miles or so), I started it, but engine was missing and check engine light blinks again. Just gunned it and made it home (again praying). Waited about 30 minutes and started it up and it ran perfect again..

Obviously I'll take it get the check engine diagnosed, but any idea what would make it change between perfect and missing like this? Fuel Pump?

Help me please smart people, just trying to squeeze 6 months out of this thing without emptying an already empty wallet.

Thanks

Hook up an OBD-II tester and figure out what your codes are.

I had this happen once in my '08 Sienna and I got a bunch of codes for misfires. 5 of 6 individual cylinder misfires and then a code for random misfires.

But it only happened to me once. When I lit it up again, it was fine. I bought a bottle of Techron, on the advice of my mechanic, and put in some fresh gas. 27,000 miles later, it has not happened again. So, for me it was probably bad gas.

My guess is that once the sensors detect misfires, they send the engine into some kind of "limp mode" that runs, but not well. After all, if [whatever] were -constantly- causing misfires, then it would never happen that the engine would run fine after a restart.

Maybe there's a near-clog in your fuel line? I'd look at what you were doing when the engine started missing. Was it under heavy throttle each time? That would cause misfires if there were an almost complete clog in the line. With low fuel demand, what little could get through the clog would be fine, but under heavy throttle, it'd need more than the pump could force through the clog.

 

[BillG]

If you're going to get it diagnosed, advice is probably not useful. I will say that sitting kills cars. Mice take up residence and chew through wire insulation, creating intermittent shorts. Batteries lose charge and battery cables get internal corrosion which can cause all sorts of gremlins. Fuel gels up and clogs filters and injectors. Vacuum lines degrade and leak or the previously mentioned mice, chew them up to make nest. The air filter is another great nesting spot and you can get pieces of filter (or other mouse-nest components) into the throttle body when you run the vehicle. And, yes, your fuel pump can get "sticky" from moisture in your fuel and create running/starting issues.

 

[cedenker]

Hook up an OBD-II tester and figure out what your codes are.

I had this happen once in my '08 Sienna and I got a bunch of codes for misfires. 5 of 6 individual cylinder misfires and then a code for random misfires.

But it only happened to me once. When I lit it up again, it was fine. I bought a bottle of Techron, on the advice of my mechanic, and put in some fresh gas. 27,000 miles later, it has not happened again. So, for me it was probably bad gas.

My guess is that once the sensors detect misfires, they send the engine into some kind of "limp mode" that runs, but not well. After all, if [whatever] were -constantly- causing misfires, then it would never happen that the engine would run fine after a restart.

Maybe there's a near-clog in your fuel line? I'd look at what you were doing when the engine started missing. Was it under heavy throttle each time? That would cause misfires if there were an almost complete clog in the line. With low fuel demand, what little could get through the clog would be fine, but under heavy throttle, it'd need more than the pump could force through the clog.

In each case the problem was always immediately after starting engine. Your idea about the "limp mode" is pretty much a perfect description. I'll try the Techron solution - I don't think I have bad gas, but certainly wouldn't hurt to clean the injectors. Thanks!

 

[cedenker]

If you're going to get it diagnosed, advice is probably not useful. I will say that sitting kills cars. Mice take up residence and chew through wire insulation, creating intermittent shorts. Batteries lose charge and battery cables get internal corrosion which can cause all sorts of gremlins. Fuel gels up and clogs filters and injectors. Vacuum lines degrade and leak or the previously mentioned mice, chew them up to make nest. The air filter is another great nesting spot and you can get pieces of filter (or other mouse-nest components) into the throttle body when you run the vehicle. And, yes, your fuel pump can get "sticky" from moisture in your fuel and create running/starting issues.

Easiest thing is to try a fuel injector cleaner. I remember when I had some coils replaced they were at the "end of the line" (coils 7 and 8 if I remember). I was thinking maybe there was a problem with fuel pressure getting to the last few coils. But the problem happened rarely enough could never prove it.

Thanks for the info!

 

[BillG]

Easiest thing is to try a fuel injector cleaner. I remember when I had some coils replaced they were at the "end of the line" (coils 7 and 8 if I remember). I was thinking maybe there was a problem with fuel pressure getting to the last few coils. But the problem happened rarely enough could never prove it.

Thanks for the info!

It certainly shouldn't hurt anything. That said, some people swear by "cleaners" and "boosters" and whatnot but every study (done by someone who isn't profiting from the sale) says that they don't actually do anything. If your area is anything like mine (good mechanics are 2-3 weeks out for appointments), I would still call and make an appointment. You can always cancel, if the cleaner works and solves your problems. As a second free option... When you go to the parts store to buy the cleaner, have them throw a scan tool on your car to tell you any current or pending codes.

 

[Acepedro45]

You need the codes from your check engine light before you start asking the internet for diagnostic help.