cylinder 1 misfiring during warm-up

I have a 2009 Prius that I purchased 6 months ago and have been really happy with it until the last couple of months. As the weather is getting colder appears I have a misfiring problem on start-up

I have had this problem now for a little while and have been trying to get it understood before paying $$ at the dealer for "maybe" solutions.

It started as the weather got colder. Intermittently the check engine light would come on. Then after a few days would go off.

I have considered water in the line: fuel injection cleaner/antifreeze
I have considered bad gas in the tank: problem persists several fuel tanks later

I have recently purchased a trouble code reader/diagnostic that plugs into my laptop.
Trouble code is p0301. Cylinder 1 misfire.

I have taken it in to the shop.
They tried:
>>moving the ignitor coil from cylinder 1 to cylinder 4,
>>and also tried moving the spark plug from cylinder 1 to cylinder 2.
>>performed compression test. Ok
The dealer suggests replacing the injector line for $1400+.( They did this with warm engine. They have not diagnosed cold engine yet. That is new, read more,...)

I still have 5K kilometers left on the power-train warranty. If it is power-train I would like it resolved before warranty expires.

Now. Some new info as of yesterday:
Up till now I was not using the diagnostic monitor real time. but that started yesterday,...

Last night when I got home from work while the engine was still warm I connected the diagnostic monitor and went for a drive. Every few minutes I would pull over and refresh the cylinder misfiring data. I had hardly any misfires across all the cylinders at all. Maybe 1 or 2, here or there over the span of a 10 minute warm engine ride. Up and down hilly terrain. Nothing that came close to triggering the p0301 trouble code.

I parked the car outside and let it rest overnight.

So this morning I got into the car to drop off kids and go to to work. I once again connected the OBD scanner. In the first five minutes of driving the car to drop off the kids, cylinder 1 misfired about 1000 times. The other cylinders were random 1 or 2 misfires over that time. I then continued off to work. Over the next 10 minutes while the engine was warming up the 1st cylinder would misfire, but the misfire rate was decreasing as the car got warmer. After about 10 minutes down to about 100/misfires per minute. After 15 minutes (give or take), misfires were down to a negligible number. After 20 mins or so, Driving up a 1/4 mile hill with good throttle, still no misfire.

When I arrived at work. I powered down, and powered up the car several times (ran a couple of minutes each time). In each case there was little to no engine misfire on cylinder 1.

After work I will be doing another ride home and monitoring the same way. I figure I will have a lot of misfires on the first few minutes on that cylinder and then it will slowly subside. So goes my theory anyway.

So I was wondering if anyone has had a previous experience like this or if there are ideas for a solution to get better performance out of cylinder 1.

PS. I cleared the codes, and even with all the misfires this morning at warm-up it was not enough to trigger the check engine light. It did trigger the Pending trouble code though.

Thanks in advance
Joey

 

The evening drive proved to be similar to the morning. Many misfires ~700 in first 10 minutes, then down to about 100 for the next 10 minutes. After 30 mins misfires were < 5.

Stopping the car and letting it rest for a few minutes then restarting. I get misfires < 100 (over 5 minutes)

After doing some google research I thought I would look into the throttle housing clean project.
http://hiwaay.net/~bzwilson/prius/pri_throttle.html

I have included a couple of pictures of my throttle body. It can use a cleaning, but the more interesting part is the that the air filter box was improperly mounted. Does that must affect air flow sensing? Any insight as to what it may cause.

I have removed and installed the air filter module correctly.

So in the back of my mind I am going. I bought it from the dealer (after some 300 point check-up). No-one has been under the hood since purchase, then I take the vehicle in for the Check engine Light. Was it like this since I bought it?? (300 point check-up failure), or did the technician improperly install it last week when they were doing their investigation.

Pic 1)Is the rubber seal impeding the flow, or will the prius compensate?




Pic 2) Basically the same
View attachment 44409

Also, I read up on the net about possible intake manifold leak. Can anyone explain how to test?? spray what/where to see if the rpms go up? I have the scanner diagnostic. How to keep the engine turned on to do the spray?

Thanks in advance
Joey

 

Hi All,

Haven't been in under the hood in a long time so am taking it slow.

>Faulty plug in number 1 (will try this weekend )
>Moisture in number 1 igniter hole (top of spark plug) (igniter was dry when I checked this morning)
>Faulty igniter.(will try tonight)

I moved the igniter during my break, will test on the way home.(noob question: igniter and coil same thing?)
>spark plugs over the the weekend.

Also have rescheduled the car to go to the dealer next week. Hope I find something concrete by then.

Also will be doing MAF clean, and Throttle body clean. Then start swapping parts.

Will let everyone know how it progresses.

Thanks for all the input so far.

Regards
Joey

 

Summary:
Tried:
>Moisture in number 1 igniter hole
(igniter was dry when I checked this morning)
>Faulty igniter.
(-switched #1, and #2 igniter coil. Did not help )
>MAF clean
(removed MAF and spray cleaned it with MAF cleaner and reinstalled. Did not help)

Todo: (tomorrow)
-switch #1, and #2 spark plug
-Throttle body clean
-does it make sense to switch the injector? Is there a procedure somewhere?

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I paid the shop ~$80. And they gave me Toyota branded "fuel injector cleaner and antifreeze"

I think I confused igniter and injector regarding the dealer. They swapped the ignitor and spark plug. After consulting with Toyota Canada they recommended changing the fuel rail $1400. The dealer is a well established Toyota Dealership in my area that sold me a lease return. I figure the labor for the switching the injector is similar to the labor for switching the fuel rail?

I took a quick look at the injector swapping and it does look a little intimidating.

Regards
Joey

 

Hi;

Just looked at the dealer's invoice:
"swapped plug to #2"
"swapped coil to #4"
"performed compression test. OK"
Toyota Technical Assistance: suggested replace fuel rail or possibly bad fuel

Regards
Joey

 

I don't mind taking a stab at it. I can buy a new injector at the dealer today I figure.

my guess on the steps.
1) disconnect ground (disconnecting battery, reconnecting steps?)
2) disconnect relay, remove air box
3) valve cover (will I need new gasket)
4) release gas pressure ( how?)
5) remove rail to get at injectors
6) replace injector, and revers steps to put it back together

Is that over simplified? ( any gotchas?)

Regards
Joey

 

I have removed the back seat.

at 7:21 in the video I can see the access there is a grey plate that seems to be glued to the floor. Do I have to lift that to get at the plug? how?

Regards
Joey

 

Thanks for the advice so far.
Steps 1 and 2 are complete. Can't go any further without having injector and replacement gasket in hand.

Will check in later.

Bummer. They don't stock the parts, need to wait a day. Takes me into the weekdays. Need the car then.
Will see about getting it replaced at the dealership.

Thanks for all the help so far. I will post back after the injector has been replaced.

Regards
Joey