Prius Vibration - 2003

Get the engine to idle Prius base idle Does it still vibrate? If you then unplug one coil at the time, is the effect same on every one? I’m pretty sure it’s not. Then you will find the problem cylinder (the one with no or least effect).

After finding problem cylinder you can make sure it’s not coil problem by switching two around. Then you can measure or look at wiring to that coil and fuel injector for that cylinder. Then you can change or swap around fuel injectors but you will probably need new O-rings for that.

 

Does it vibrate at neutral? At neutral transaxle is (electrically) off. To get it to idle at neutral (only true idle) you need to do the steps on the link.

 

Miss-fire sources:

• ignition - you've already ruled that out assuming no connector issues
• fuel injectors - not ruled out (Chapman is local expert)
• manifold air or PVC hose leak - not ruled out, various tests
• failed or failing valve - not likely, they tend to fail hard
• failing throttle plate position - sticky, connector, or encoder

The video doesn't work, no engine noise. To make the engine run, hit "MAX AC".

A failed O{2} sensor means the fuel-trim mechanism could have failed. This means the engine is using the default table built into the car and likely a very rich mixture. Do you take photos of the original plugs that might show carbon build-up?

BTW, the cited article is not terribly accurate about how the Prius ignition timing works. But it sounds like the last spark plug change fixed that particular car.

Bob Wilson

 

That means its engine related. Maybe you could make better video? Running in neutral? From under the hood? Try to test ignition coil unplugging again in neutral. If it’s not in one cylinder it can’t (almost) be ignition or fuel injector related.

 

Good to know you are not using a Prius-aware scanner.

So is this an auction Prius you are trying to return to service? Understand I am sympathetic to the goal but a Prius is not a regular car. It takes new skills and a scanner that knows how to read the Prius ECUs.

Have you measured the cylinder pressures?

Bob Wilson

 

I fully understand. Sometimes we've had auction cars show up. You've got history this this ride and it makes sense to make sure it is not something trivial.

I take it no evidence of bubbles in the radiator or loss of coolant (i.e., head gasket II?)

Chapman is the injector expert. He may have some ideas but I would be interested in knowing if they all 'sound alike':
Mechanic's Stethoscope
You might be able to identify a specific cylinder not firing correctly.

I would suggest swapping injectors but Chapman has reported the "O" rings often rot out and this can lead to another problem.

For grins, test the throttle plate with the car 'off' to make sure there is no evidence of sticky plate.

Don't rule out the mass-flow sensor being dirty. Again this like the O{2} sensor, it can lead to fuel mixture issues.

How are the short and long-term trim doing? Are they moving or 'fixed.' IF the old plugs were not gunked or sooted up, the fuel trim would be the next thing to look at.

If you don't mind, clear the codes and start it up to get the current codes again? I know Snap-on has a good reputation but I tend to favor scanners I've had 'hands on.' Still this sounds like an engine-only issue so the Snap-on should cover the parts we're most interested in. I'll see what Vol. 1 says as the ambiguity group for the codes.​

Bob Wilson

 

I think you should really do the coil unplugging test again. Most of the stuff that peoples in this topic are suspecting should be seen in that test. Just do it in neutral. If you last did it in park transaxle can help or even completely spin the engine so might be impossible to see anything. If you have done it in neutral and are completely sure about it then we can rule out many things and concentrate on the things that are left.

 

I'm not sure that was me, but I think I might remember somebody else saying that in one of our injector threads. Toyota definitely does recommend using new O rings (injector tops, into the fuel rail) and rubber seals (injector bottoms, into the cylinder head) whenever the injectors are removed and replaced. They can be purchased separately. (I recommend having extra O rings on hand for anyone who hasn't installed the injectors before, because as another PC member found out, there's some advice in the shop manual that seems strangely touchy-feely, but if you shrug it off you wind up with smashed O rings and bent injectors and fuel spraying out, instead of a successful job.)

But before going there, I remember at least two, maybe three, recent threads, all this winter, where members' fuel filler pipes have rusted through just above the right rear wheel where salt water gets thrown up, and the water has gone in and diluted the fuel, most noticeably after driving in wet weather.

-Chap

 

I did put it this topic also that you will probably need new O-rings to install fuel injector. If fuel filler neck leaks you would have check engine for evap leak.

 

Oil in the intake is normal for Atkinson cycle engine. Did you do the coil unplug test in neutral? Fuel trim numbers appear to be normal in idle (neutral) and under load (brake and accelerator in drive)?