2005 Prius P0301 misfire

First good move, don't trust the dealer's diagnosis, just take it under advisement. I've worked for GM 20yrs., and I can tell you , 10 mechanics will give you 10 different diagnosis , and that's not including the service manager's two cents. Glad to hear you nailed it right out, that could of been a major dealer expense when they finally figured it out.

 

Did just as you said, put everything back together and now there's a massive gas leak right where the fuel line enters the "fuel rail"....so now what Kemosabe? This "child" listened to you and could've burned up his car due to not having DETAILED directions/information. Am taking it to a mechanic who'll probably charge more to fix/replace the f'd up fuel rail than if I'd just had them do the injectors....couldn't have cost too much. Heck a child could do it...

 

When I purchased my car about a year ago it had a po301 misfire. I did the easy stuff first. New plugs and swapping ignition coils around did not make a difference. So then I moved to the injectors. I did the ohms check and all were in spec. So at this point I figured it must a dirty injector. I started doing injector cleaner treatments to the gas. This yielded positive but random results. I would go through periods where the CEL would go off for 4-5 drive cycles then come back ON. Then it would go off again. I had this issue all summer.
So I finally figured I just needed to replace the injector. I bought a brand new injector from rockauto for $32.00 (wholesale closeout). The replacement took about 20 minutes mostly because I'm slow and cautious. It was very easy to do but you do need to be cautious and finesse the injectors back into their positions. The rail must seat properly onto the two plastic spacers otherwise the injectors could leak. Once everything was back together. I did the start up test. Voila! This is like a new car, nice and smooth on start up. The CEL finally cleared the po301 code and is now off for good I hope.

 

I've been sitting on a p0301 error code for 2 months after my battery rebuild. I ran the car for a few miles back when the traction battery went dead. This created carbon build up. After fixing the battery, I kept getting a persistent P0301 error code. I had done the same swaps and new spark plugs as Bryce. I also used a few injector cleaners, but did little to improve my situation. Same cylinder threw the code and hard initial starts.

I had resigned myself to replacing the fuel injectors, but decided to open the fuel injectors and look before buying the parts. Upon opening up the fuel rail and removing the injectors, I could see carbon build up on the tip of the injectors. I used my carberator and air intake cleaner and sprayed into the holes left by the removed injectors. The cleaner was made of toluene, acetone and methanol. As it was soaking, I cleaned up all the injectors. I then reassembled the fuel injectors and tried to start the engine. I had massive leaks and shut everything down and all sorts of trouble codes thrown(I believe this is what happened to Northcoaster). I had cut 3 of the 4 upper injector o-rings. I also had to disconnect the battery to clear the codes.

I picked up the o-rings and replaced the o-rings. This time I assembled the injectors into the fuel rail first and then guided the other ends into the engine. Tightened everything up. No leak, but had a weird rhythmic revving upon start up. This stayed for about 4 starts. I decide to reassemble the air intake. couple of starts more and the rhythmic revs disappeared (probably the computer having to relearn everything). No more codes thrown. It has only been a day, but
it looks good. No codes thrown and car starts smooth. I think the carbon build up was the source of my problems and created a large blockage in front of my injector. I hope the cleaning is all that I need, but I am prepared to replace it if the injector continues to leak.

Also, few things to do before you open the fuel rail. Buy the o-rings at a minimum. Only costs a few bucks and it saves time especially if you tear them up. It is easy to do if you put the injectors in the engine and try to put the fuel rail onto the installed injectors. I didnt expect to see so much carbon. I assumed my injector was just leaky. It is a good thing to see the situation before buying parts and guessing at what you need. It is easy as changing the spark plug, but just take care to not cut the o-rings.

I'll post more next week if I need to do more work. Seems successful, I'm getting 44mpg up from 35 for the 1st day of driving. Will keep a close eye on next few tanks.

 

Did you not read this bit?....."making sure the O rings are in place, use a little wd40 if it helps to re-install it and replace everything in the same order". You probably split the O ring and that is all, 40 cents worth, stop your whining. I think you'll find they were very detailed instruction, but no worries, thanks anyway, glad I could be of help. If you are that hopeless with a spanner in your hand then best leave it to the qualified people.

 

Bruce,

Can you post photos? I followed your instructions, but was unable to gain enough space to move the fuel rail enough, on my 2007 Prius, to get the injectors out to replace all of them. Ended up putting it all back together, without changing them. Did a quick leak check and all seems ok, but really wanted to swap these out.

 

Tommymommy, did you have something to add to the quote?

 

No, my internet connection is running slow and it decided I was done posting before I even started.

Do you have more info on changing out the injectors? I don't want to break anything. At this point, I have a solid fuel line, with little to no give, coming in to my fuel rail. It is making it difficult to move the rail back far enough to access the injectors.

 

Wow that was weird, your completed original post just came through.

To help with your question, when I addressed my PO301 problem, I only changed the cylinder 1 injector. Fortunately, it is the easiest injector to remove. Had it been cylinder 4, it would have been a problem. Frankly I don't understand why Toyota put that finger over the right side end of the injector line. It doesn't do anything if I remember correctly. The fuel rail has its own retaining bolts. I'd have to go look at to verify, but I would consider cutting the finger off if it serves no other function.

It's been about a year and no Codes since.

 

It would up have been nice if Toyota used a braided, flexible fuel line coming into th fuel rail. I have room to get to cylinders 1, maybe 2, but 3 & 4 are a no go.

 

Yeah I know, that stupid finger from the rocker cover limits fuel line movement.

 

If necessary, remove the cylinder head cover to free up the fuel rail. Then you can inspect the valve train and measure valve clearances while you are in there.

(Photos taken on my 2001 several years ago when I removed the valve cover to look around.)

 

Yup. You have to remove the 10mm bolt attaching the fuel line to the block to have any chance at aligning the injectors right when you put them back in. If you remove the two hoses going down to the throttle, AND if you use a ratcheting 10mm box wrench, you'll be able to remove the SOB. Yeah, the hook... if I wasn't scared of creating sparks and blowing myself and the car to smithereens I'd have cut the darn thing off!

 

Move plugs and coils, clear codes, retest. If misfire didn't move try moving injectors. Then compression test. Then leak test w dye and black light. Then pressurize cooling sys w plugs out and crank motor. Watch for spray. Observe lower coolant level. Loosen pressure cap. If problem gone coolant leak is cause. If still nothing look for leaking intake gasket w starting fluid and fire extinguisher as failsafe. Look for bad connectors to coils. Continuity test wires. Use signal tracer.