Aftermath of EGR Cooler Cleaning Project

Just clean the MAF sensor and whatever else you got soaked with some throttle body cleaner spray and blow it off with compressed air if you have it and then a little less PSI of compressed air to blow out the spaces where those devices attached to the intake and or throttle body to make sure all of that is dry and try again usually just sitting and cleaning fluid doesn't hurt these things The goes thru shop tanking . That's a different story but just at the house and cleaning fluids and so on You should be able to rinse it re-clean it with throttle body cleaner blow it off set it down to additionally drip drain or dry if anything has gotten in any of the ways or voids of the device and try it again this happened on my generation 3 both of them a couple of times doing similar and I had access to junkyard vehicles and had plenty of the sensors that are in the throttle body area still have them in the tool box after cleaning and doing whatever all of the originals worked fine and netted no codes.

 

You’ve presented the info well; should be getting helpful responses.

Try recleaning the MAF sensor with the proper cleaner? CRC Mass Air Flow Sensor Cleaner is one.

You had the intake manifold off, and throttle body separated?

What’s the miles on it? Did P0301 just show after the EGR cleaning? It often pertains to head gasket failure at cylinder one.

 

It's easy to forget to connect something, or not connect it all the way. Tripple check everything.
Clean the sensors with MAF/MAP sensor cleaner and let them air dry for a 5-10 minutes.

Also check that you didn't pinch the intake manifold gasket or didn't tighten a bolt/nut enough.

Clear the codes and start the engine. I forgot to connect the MAP sensor I think it is, on the top
back on the intake manifold, it ran rough, and got the check engine light. I cleared the code but
it didn't go away until I drove the car a few miles.

 

Most of the codes you have listed there are shown as 'permanent'. That means the car simply saw those conditions at one time, and has remembered seeing them. The permanent codes will go away after a certain amount of driving without those conditions recurring. You don't have to do anything about them.

If at any point you happened to turn the car ON before you had plugged those items back in after doing the work, that would explain those permanent codes. (The intake air temperature and mass airflow sensor are combined in the same item; that's just one plug.)

That leaves only this one code shown as actually current:

The only true part of that description is the first nine words. P0301 indicates that cylinder #1 isn't firing properly. That can be because there's not enough fuel in the mixture, or because there's too much fuel in the mixture, or because the mixture isn't getting compressed enough, or because the spark plug isn't making a good enough spark at the right time, or because something foreign like water or coolant is getting in the mixture, or because too much recirculated exhaust is getting in the mixture. So, misfire codes leave diagnostic work for the human to do.

 

Did you disconnect the 12 volt for this work. In my experience this'll cause a short term surge in rpm at start-up, for the first 30 seconds or so, once engine's running. Just one such pulse, not repeating, IIRC. This'll be for the next 2~3 start ups: I suspect it's recalibrating something.

Yeah with 237K miles, if this is the first EGR cleaning, it'd be a miracle gen 3 if it didn't have a failing head gasket. And there's P0301. But I suppose I'm jumping to conclusions...

How long have you had it, since what miles?

 

I don't think so, but if all else fails. As others have said, maybe something disconnected/pinched. How did the EGR look, say the cooler interior?

That borders on eerie.

That too. I wonder if it's the original engine: until partway through model year 2014 gen 3's had "low-tension" piston rings, likely Toyota trying to up the mpg. Whatever the reason, that piston/ring combo has proven very prone to runaway oil consumption. Someone might have replace the engine, or swapped in a short block. But then sell it?? Typically high mileage gen 3's are for sale for a reason.

 

It will only clear the codes, which you can do with a proper code reader.
You need to check everything first and make sure all is correct. ( See post #4)
Clear the codes, start the car and see/hear/feel how the engine runs.
If you wish to disconnect the negative cable of the battery for 30 minutes, up to you.

It is much easier to check that everything is connected correctly and bolted correctly.
Then trouble shoot. If the map sensor is not correctly plugged in, replacing a good one
with another (hopefully) good one, and not connecting it correctly, will not resolve the problem.
And drive you crazy.

 

Double check that ALL the vacuum hoses are connected properly.
Also, check to make sure that the air inlet assembly was put back correctly.

 

Repair Manual info:

 

I’ll have a look tomorrow.

just being librarian btw; someone more knowledgeable will hopefully weigh in regarding your questions.

 

As it happens, there is only one resistance test shown in the document Mendel shared, and that test is a test of the IAT sensor (terminal THA to E2). The other three pins—the ones uninvolved in that test—are the ones to the MAF sensor proper.

The manual doesn't give you any simple multimeter test of the MAF sensor, because it isn't the kind of circuit you can test that way. Too much going on inside it. You can see the test they give for the MAF functionality is to use Techstream and look at what reading the ECM is getting from the sensor.



Now, getting back to that resistance test of the IAT sensor that you did conduct, are you positive the 1.68Ω reading you've given wasn't 1.68kΩ? 1.68kΩ I could believe, at your 75℉ reported temperature, per the graph in the manual.

 

If I had to put money on this, I'd go with a vacuum line not connected, or improperly tightened throttle body bolts causing a vacuum leak.

SM-G781V ?