I have a 2002 Prius, 254k miles. Been getting a rough idle at startup for a few seconds then seems to clear out, go away. Check engine comes on sometimes: P0300. Sometimes I'll get P0301, P0302, P0304, but not always. I've replaced all the coils, and spark plugs, brand new MAF sensor, camshaft position sensor, crankshaft position sensor... No luck. Anybody have a similar issue or can point me in a better direction? I've noticed that the blue temperature icon is on in morning... Ambient temperature has been 70*F+... What temperature does the light go out? Only reason I bring it up is I've read the coolant sensor can be a culprit... Wondering if I should replace those as well... One on block, one on radiator/cooling fan. Thanks ahead of time for all your help.
If I remember right, my blue light goes out when coolant temperature reaches 50 celsius as shown on the ScanGauge. Hope this helps, -Chap
1. Did you install the correct NGK or Denso iridium spark plugs (as listed in the owner's manual)? If not, that should be done now. 2. Check the fuel line pressure (should be at least 43 psi at idle speed.) If this is low, remove the circuit opening relay and check the resistance across the switched contacts of the circuit opening relay, when the relay coil is energized using 12VDC. Replace the relay if the resistance is more than 0.5 ohms. If the fuel line pressure is low but the circuit opening relay is good, the fuel tank (which contains the fuel pump) needs to be replaced. 3. If the fuel line pressure is correct, maybe the fuel injectors are clogged and need to be replaced.
An attractive option to replacement, if you have the time to send them away, is reconditioning of the injectors, which I was able to have done at less than $20 per, in contrast to $120ish for a new injector. Providers of this service will usually give both before and after quantitative test results so you can see what was accomplished. In my case what I found out was the injectors were in very good shape to begin with and probably didn't need the work. The service provider also offered before-testing only for $7.50 per, and provides the results before returning the injectors, so I could have gone that route and authorized the full servicing only if they had needed it. The service manual does give procedures for testing the injectors yourself, but for me not having all the necessary equipment right at hand it seems quite reasonable to spend $30 not to have to futz with it, and get a nice detailed report from someone who does it all the time. An article where I learned about the service is here. -Chap
I checked again this morning with a Graham miniscanner and it was 49C when the light went out and the scanner flipped to 50C. Bob Wilson
Thanks for everyone's input. I'll have to watch the temp on my scan tool, 50C makes sense. Yes I used iridium plugs... All parts I purchased from local Toyota dealer... Didn't want to worry about aftermarket parts from an auto parts store. Fuel pressure... How do I, can I... check this on my own? I've heard of the fuel tank dilemma... I'll have to check the relay. Injectors... She is my daily driver, hate to put her down for a few days... I could just replace all the injectors, but its a chunk of change that may not be needed.
You might consider running a tank of 50/50, E85/E10. Sort of a home-made, injector cleaner. Bob Wilson
It seems like the only tedious bit is fabricating a tee connector with the right Toyota quick-connects on the ends so you can monitor the fuel pressure (you really want to see not just the static pressure the pump can build up, but what it drops to while the engine's running and injecting fuel). Somebody who didn't run a shop might not want to go to the trouble of building that to use it one time. It would be cool if somebody wanted to build one and make it the PriusChat Circulating Fuel Pressure Tee. We could just start a page on the PriusChat Wiki to keep track of who had it last. I had sort of the same idea in mind when I bought the M22x2.0 bottoming tap for chasing out the towing-eye threads in the front bumper in case your towing eye won't screw into it. (Nobody's asked me for it yet....) -Chap
