My 2004 Prius is nearing 108K miles with no real problems so far. I have noted a slight decline in gas mileage, and I wonder with the mix of driving (half highway, half city/suburban) that we do whether we should get the engine looked at before the 150K recommended. Has anyone done this and found it to be helpful?
There are a number of items you should have had done at 100k miles that may affect how well the car runs: http://priuschat.com/forums/gen-ii-...70-what-services-you-need-what-you-don-t.html http://priuschat.com/forums/gen-ii-...-just-checking.html?highlight=checking+efusco
If you've noticed a decline in mpg, then you've got the usual list of things to check: wheel alignment, tire pressure, dragging parking brake. Also make sure your engine air filter is not excessively dirty and your engine oil level is not overfilled. If all those are good, then you might consider replacing the iridium spark plugs. I just did that on my 2004 w/98K miles. Engine seems to run a bit smoother. Note that the engine ECU will accept a fairly substantial misfire rate before logging a DTC. For example, the Toyota repair manual, regarding DTC P030x, indicates that the DTC will not be logged until the engine ECU counts 108+ misfires over 200 revolutions with engine RPM at 1,600. The four spark plugs will collectively fire 400x over 200 revolutions (100x each plug), so this means a ~25% misfire rate is deemed OK.
With respect to a slow. long term MPG reduction, wouldn't it also be SOP to check, and clean if necessary, the MAF sensor located below the intake air filter? Inquisitive minds want to know...
I took my 2012 Toyota Prius into Toyota for the 100k service maintenance check, was told I needed the spark plugs changed or a tune up . Had Carmax change the spark plugs/ tune, was told it would improve my gas mileage, but I’m getting far less gas mileage.. What gives?? What happened? What’s my next move?
You have tagged onto a thread in the Gen 2 forum, in case you didn't realise. Perhaps if you ask your question in the Gen 3 Maintenance and Troubleshooting forum, you will get better answers from owners who have the same generation as you. Not all information is applicable over the different generations.
