Juddering when accelerating

Wild guess, but how about reading the code(s) behind the CEL?
Autozone, other chain service stations, Midas, etc, will read codes for free. However, they are not using Techstream, so many codes are often not read correctly or at all.

Teachstream is software written for Toyota, to read the Toyota family (Lexus, Toyota, Scion, Daihatsu (JDM)), to read ALL codes. Hacked copies available at Amazon/eBay, $25-$35. Laptop required; ideally Windows 32bit (XP or 7), and on a spare junker laptop. Many posts on install help on the Internet; do a search.

 

Seems like a lot of attention was paid to the EGR system. Was it badly clogged? How about the EGR "cooler", the rectangular component with the coolant hoses, between the EGR valve and the exhaust manifoltd: it was replaced with the valve?

 

Someone here said you can get an idea of the cooler's condition, degree of blocking, by removing the valve and looking into the cooler. Here's some info on removal and torque values, might be helpful.

 

Welcome!

What work has been done to your Prius? PCV valve? Over here we have what is called top tier gasoline which has a high level of detergents. What type of gas do you buy? Ever use any fuel injector cleaner?

What did the egr pipe look like when cleaned? Egr valve have a lot of deposits? Have any lights on the dash before you blocked the egr? Does your Prius consume any oil?

Lots of possibilities, but I have cleaned the intake and egr system front to back and found carbon deposits plugging the intake inlets from the egr system. I did this when our 2010 had about 120 k miles and up over 142 k miles currently. Was able to remove early symptoms of what you are describing.

Keep us posted.

 

Do you have tools and inclined to do any work yourself? Given you blocked the egr and still got the same result, IMO the inlets from the egr system are clogged. The pipe being clean is a good sign, but the inlets from the egr into the intake manifold are probably restricting air flow.

If you can, work on cleaning the intake manifold and if not done, change the PCV valve while the intake manifold is off ( it is a lot easier). Throttle body as well while everything is apart. It took me a little over 2 hours from start to finish for the intake system, if you are inclined and have the proper tools.

 

Could it be a dead spot in the throttle position sensor that just decided to manifest itself now? That would be more suspect if the throttle body had undergone an "extensive" cleaning where cleaning fluid and deposits were driven into the sensor. Such a cleaning has not happened though. I confess, I know nothing about a Prius EGR system, whether these things are still vacuum operated or not. If it it vacuum operated, then it could be a leak in the vacuum diaphragm. Taking guesses at other possibilities here.

 

I planned my work and did change the gaskets out. I assume the factory torqued them to spec and when I pulled them out, the gaskets showed no signs of compression. So they could be reused, or for $35 and a little planning you can have new ones installed. I used a nylon brush and toothbrush for the manifold inlets. I did spray some Pb blaster on the plastic manifold to help cut some of the deposits then let it thoroughly dry before reinstall otherwise you'll have the volatile cleaner creating havoc upon startup.

I also did the egr cooler. If you are going to add that to the list of work, plan for more than a day and an extra set of hands helps a lot. If you are doing the cooler, plan on draining the engine coolant and replace the coolant with the Toyota super long life pink fluid.If you follow factory service recommendations for maintenance, at 150k miles, you are due to replace it anyway as well as the inverter coolant.

Good luck next weekend and keep us posted.

 

I want to be sure I understand the problem:
You get shudder/rattling around 18-23 mph
You replaced EGR valve and no change
You blocked EGR valve, and problem went away

If this is so, then I think your EGR valve is good and your intake manifold is clogged. Removal isn't very difficult with mechanical skills. Far less complex than a head gasket.

You should replace the gaskets if possible and use a torque wrench to properly retighten the bolts. But basically you get the thing out and soak it in solvent and use nylon brushes to clear out all of the channels.

I can't say that's 100% certain it will work, but it seems very likely to me.

 

Here's some info on removal/install of the intake manifold:

 

Throttle body:

 

Thought I'd mention that when you clean the throttle body, it is normal to find oil pooled as you gaze past the open butterfly valve and into the throttle body. You don't need to clean that oil out as it is a result of the Atkinson cycle and it will quickly accumulate there again if you clean it out.

 

take out plugs and check for hairline crack if you cant see get a new set

 

What does Toyota actually do when they perform the new service action? -- the one with the extended warranty. I believe it mostly to do with the start up rattle, I have the exact same condition as the OP and mine strata at 150k now at 158k ... get a slight pulse as he does. It does not feel like an electrical misfire ... goes away under hard throttle or after about 20mph.

I occasionally get the startup rattle -- very infrequent. I actually had it a bit more when new.

 

And finally what was the problem? Throttle body or something else?

 

I'd go with inlet manifold as other have suggested, just had similar problem cured with a quick clean of manifold. Got to say I was a little skeptical at first but it made a huge difference to the car, Bout an hour and a half to do and cost nowt to do it

Posted via the PriusChat mobile app.