missing under light throttle

$15 bucks when you need it is not expensive. Going to the dealer to diagnose and fix a problem at $120 hr is expensive.

 

True, the diagnosis for the issue was more a used car checkup since I had just purchased it than anything else. I had just specifically mentioned it as an issue I wanted to get looked at while they were at it. I think total it was just under $100 dollars for their 'diagnosis' and total car checkup plus state safety inspection. This is my first Prius, so I felt like being cautious. I do most car work myself, and although I'm a little anxious to work on a prius instead of my normal all combustion vehicle I'm up for it.

How does techinfo work, Do they have essentially any work detailed out or is it limited to what they want DIY'ers to do?

 

Patrick,

I didn't pull my EGR valve as my my carbon build-up was to the intake manifold side of the pipe and within the intake manifold itself, so I cannot comment as to the gasket used for it. The intake manifold gasket is of the o-ring type variety contained within in a channel of the IM. If undamaged, it seems fine to re-use. I torqued everything to factory spec and have had no issues at 10,000 miles. I doubt it's very expensive, though, and would buy one if I were actually planning the job. I ended up tearing mine apart on a Saturday evening after finding the "high torque, low rpm" thread. I just figured it was worth a look, and when I got it apart it became pretty clear it was going to be well worth the look. The throttle body uses a rubber o-ring style gasket, too.

Intake Manifold intake manifold gasket

I used CRC Brakleen, compressed air and a tooth brush and just went at it. I was initially nervous using brakleen on the "plastic" intake manifold but it was a non-issue. As usual, the brakleen did a great job.

Glad to see you bought a gen 3. Since I got mine, I've been thinking it would be great to somehow get you hanging around the gen 3 forum!

 

Morlince,

I just pulled the airbox, throttle body and the intake manifold in that order and went to town cleaning the ports and the EGR pipe. If you DIY-ed the plugs, I'd think you won't have any problem. Carefully pulI the 2 coolant lines from the throttle body and you'll only lose a splash of coolant. I'd at least check this out before you get into pulling the fuel rail and injectors. It's a bit of digging but it's not difficult. Certainly, if you can find factory manual directions for pulling the IM, go for it but it's not necessary. I can look around here for the torque specs if you like...

At 140k miles you were ready for plugs, but I'm not sure what to make of the misfire code. I guess the EGR port clogging could cause it, but I don't think I've read of anyone else with this issue having a related code. Will be interesting to see how you make out.

 

Thanks for the reply... Doesnt seem too bad after looking at it last night so that should work. Do you need to clamp the coolant lines or will you just lose what's in them at the disconnect and no more?

Yeah, if you have the torque specs handy that would be good, otherwise I can look into them a little as well.

From other reports I've read, this issue can cause a misfire code to flash, so I have hope.

 

21 ft-lbs - intake manifold
14 ft-lbs - throttle body

I did not clamp the coolant lines and only seemed to lose what was contained in the hose sections and TB. Added an ounce or 2 to bring the reservoir back to the full line and did not need to bleed.

Good luck and please post a results update.

 

So finally got around to this last night after I had to go into town to get something and it seemed I was always right at that point that the ICE would miss and knock. I had been putting this off until I had more time, but I couldn't stand it anymore after that. So I tore into it, took me just over two hours to complete. Really not too bad, just follow the parts until you get to what you need and then reverse it when you are done. I keep a portable table next to me while I'm working on cars and it really helps to lay out parts and their misc nuts and bolts in order as I go. Took some pics, sorry about the large size.

Here is the condition of the egr tube. Mostly all dry soot material. I blew it out and then used some throttle body cleaner to get the remainder. No picture of it clean, use your imagination. No DIY tube block installed, though i may think about it if this starts happening more frequently.



Here is the condition of the valves, the one on the right I have already partially cleaned. I did not get too deep into cleaning these as I was worried about damaging or clogging up the fuel injectors that are right on the top of the hole. It was mostly dry caked on mess, until i made the mistake of blasting a little throttle body cleaner in it and then it turned into a gummy nightmare.


Here they are clean.


The interior under my throttle body was oily and wet. I did not get a picture of it, but I did clean it out really well.

Lastly here are the heads in the intake manifold. This was after some light blowing through the egr line, so the ones on the right may be partially clear...


...but the ones on the left, WOW! These things were almost entirely clogged up down the line, not just at the top of the hole. I used the small flat head in the picture to get in and pull out as much of the thick oily gunk as possible then used some pipe cleaners, then sprayed through with some throttle body cleaner, then pipe cleaners some more until it was mostly clear. Sadly I do not have a after shot of those since at this point i was just wanting to be done.


I finished cleaning the intake manifold by blowing through the egr line with a compressor then spraying more tb cleaner through both ways until it was fairly clean.

I put it all together, found some misc rubber thing that I had no idea where it went and got worried until i realized it was out of a spark plug socket.

I usually run into the knocking issue on the way to work, and this morning I DID NOT HAVE ANY ISSUES AT ALL... WOOT!

Hopefully it lasts for a bit, cause that's a PITA to think about doing very often. For full info, my car does not seem to burn oil, and it has just over 140k miles on it. I am also in the USA as it seems like a lot of people were having this on UK models only.

Thanks all for any assistance, and I'll keep you guys updated with any MPG changes or if not when it happens again.

___________________________________________________
/\\/\\orlince

 

Morlince, thanks for this info. Again, this is after 140,000 miles: good to know.

So your dealership with their recommendation for new spark plugs and some injector cleaning, pretty much useless. Toyota should really step up to the plate on this.

 

Yeah, total rubbish. It seems as though this is starting to come to light more and they should have some service bulletins out that reference this. It would also be really easy if someone bought in a prius with high mileage that was having these issues, to just pull the EGR tube and check it out.... I mean really easy.

Yes, for my mileage, spark plugs were probably a needed item regardless, but I can only imagine what hell and money I would have went through if I took it back to them and had them figure this out and fix it. I'm just thankful I kept digging and found this thread.

So far so good on my end, I keep on hesitating when hitting the gas though from fear it's going to knock. I think I have PTSD from this.

_______________________________
/\\/\\orlince

 

My 2010 prius gen iii had low throttle misfire. It occurred first at highway speed under cruise control, going away when under higher load. Would also experience at low load or tip-out of accelerator under many conditions. It was unusual that when engine was cold, did not get misfire. After reading these posts, I removed EGR tube and intake manifold for inspection and found same plugged manifold EGR tube outlets. The only open EGR outlet was to cylinder #2 which was flagging the misfire code. I also disconnected throttle body from manifold to avoid removal of coolant lines. The main EGR tube molded into the manifold had a lot of dry material, looked like oxidized metal from exhaust system or rust. Made a nice pile on the newspaper. The cross tubes going to the cylinders were gunked up by which appears to be oil or fuel from cylinder head combined with the rust particles. I cleaned it out, replaced PCV valve since it was accessible (I do not think the original was bad though), reassembled and car runs very smoothly now. I think the car ran well during cold operation because EGR valve was commanded closed ... just guessing. Thanks to all for repair info.

 

First let me apologize for necro'ing an old thread, but it's relevant. The bit about it NOT happening when it's cold really puzzled my grizzled old mechanic.

This is something that truly puzzled my "hill country mechanic" (nearest true Toyota mechanic is 75 miles away). I had it to him first before breaking down & just sending it to Toyota when he reached the end of his rope. He said he'd never seen a misfire where it got WORSE as the engine warmed up, rather than the opposite.

The bit about the one that is UNclogged matches exactly with what the Toyota tech is saying...1,2 completely clogged, 3 mostly clogged...but it's cylinder 4 that's throwing a Misfire.

Quote from Toyota tech:
The technician said he pulled the intake off and checked the EGR for all 4. He said that one and 2 are completely clogged, 3 is half clogged and 4 is completely open. The misfire is due to too much fuel and not enough oxygen to ignite. He is letting the engine cool down so he can inspect the head for any leaks when he is done he is going to make another video explaining what else he has done and what the verified issue is.