Knocking on cold start

Good morning,

Yes, there is a TSB on the noise, and I attached it at the bottom for you.

If you are under 70,000 in miles, it would be a warranty item.

Let us know if you have any other questions.

Roy

Hello, I just wanted to add to the concern you are experiencing. The knocking sound you hear is because a cylinder is misfiring. I would also recommend that you get the vehicle nice and hot from normal driving and let it sit overnight. In the morning remove all four spark plugs and inspect inside the bore for coolant. If there is evidence of coolant, then that's your cold start misfire causing that sound. You will also notice the expansion tank for the coolant getting low depending on how much of a leak there is.

I have done a few cylinder head gaskets for this particular concern. The intake manifold bulleting was updated. I believe it to include a misfire under load. The EGR passages are small holes and get plugged up causing a lean misfire to the adjacent cylinder. That would be my first step to inspect before spending money on the intake manifold. Please update us with that information.

I will clean the EGR first, inspect the plugs and then do the intake. thanks

Sounds like a plan.

Roy

It turned out it is doing even if the car is warm, most of the takeoffs...unless you hit the gas hard. Any instructions on how to remove the EGR for cleaning? will remove plugs before.

First verify that is the EGR. Disconnect the electrical connector to the EGR. If the problem goes away, then there is an updated, I take an EGR pipe for the repair. If it still misfires with it disconnected under load, then you could have a bad coil or spark plug. Let us know what happens with the first test when you unplug the EGR. Posted a picture of the connector.

Unplugged it Nd the shaking is down 89% and only lasted a second. Turned it off and on again several times and it's even less shaking. Everything looks original, doesn't look like anyone has ever removed the EGR pipe.

Why does the intake need to be updated? Can't i remove and clean it and do the same with pipe? What about the cooler is it possible it is clogged up as well?

Removed plug looks great, no water inside bore, and no loss in coolant. Cleaned the EGR pipe, was not clogged up but dirty, sprayed inside the EGR itself as well as much as i can reach as its going to be pain removing the cooler assembly. Also, there is some build up inside the intake, sprayed there as well. Put all together and started it, the knock was drastically reduced.

The cooler only has coolant running through it. I wouldn't worry about anything behind that going to the exhaust. If you remove the intake manifold, you will see the small EGR passages where the gases will flow. If they are plugged up, then the manifold and EGR pipe need to be replaced.

You can try to clean it but usually that carbon is pretty packed on there, that is why they had us just replace the manifold. To be honest I never had to replace one. It has been the head gasket failing causing that misfire on cold start. There is also a software update you can have done to see if it helps with the knocking sound and P0300.

I'll replace the intake with the updated one and change PCV, pipe i can clean the heck out of it. I'll see after. I had many friends with Prius that had the same issue but no head gasket symptoms, still drivable, only happens in the morning.

Sounds like a plan.

Keep us updated on the result.

Roy

Forgot to attach pictures, one of the cylinders and a plug.

Replaced intake with one from Lexus, as well as PCV. The first time started excellently, the second time great, driving it around great. Parked it and was cleaning it and started the sound again, not as bad and not as long then it smoothed out. Have misfire pending cylinder 1, it was there before. Removed plug and coil and switched them to 2, will see what it does, started fine now. It may be randomly now, where before it was every time abd it was doing it while driving where it misfires and i lose a lot of power. Cleaned erg pipe too. Am thinking erg valve maybe clogged up.

Only driven it around the block though.

Can you post a video of it when it is knocking? I just feel like you are just installing parts on your vehicle. Also, I feel like you did not understand what to look for on the intake before replacing it? It seems like you are on the right track with the coils.

A misfire will slow the crank down and cause the rattle/knocking noise. A bad coil, spark plug, or injector can cause that. An engine mechanical fault can cause that also. If you post a video at least we can try to verify if the sound is due to a misfire or something separate from the misfire codes, you already have.

But if the intake did not need to be replaced then why did i have all that build up plus the pooling in the intake? Replacing it plus cleaning the EGR helped 86%. I do understand what you say but mechanical observation is a must to tix before i differ into what seems like more than one issue. Like i said before, i was t even able to drive it as it was misfiring very gas pedal touch and had very little power and the knocking sound was so bad and so obvious and every time, so the intake was an issue. There may be a bad plug or a coil as well, but a bad coil would not just do that only at start up, it would it mainly while warm and several tokes while running, which isn't happening. I feel it's the EGR. I'll try to take a video but it is not doing it as much as i wanted, only once yesterday while I was parked and running while being cleaned. It's the same sound they all have ct and Prius.

Thank you for the update. The pooling in the intake, do you mean the oil build up? Every CT has some oil in there from it taking in PCV fumes back in. As for the coil. I had a tech looking at a CT doing the same thing. Cold start rattle/knock.

We went in with a bore scope to look for coolant and it was dry. He orders an intake manifold and EGR pipe because of the bulletin without reading what the conditions for replacement should be. He installs it and the same cold start sound. He got lucky that in one of those starts the engine kept rattling around and we were able to look at the misfire counting up. We checked the coil, and it had no spark.

This business can throw curve balls at you at times. Will we ever see that condition again? I don't think so, but you may just be experiencing that yourself right now. If you swapped coils and plugs around and the misfire follows it, then you have already solved the issue.

My thing is if it's a plug or coil why does it only do it on start up for 3 seconds? I am going to let it do it a few times then read the codes again. For right now it's still cyliner 1 misfire pending.

And I am sure cylinder 1 is one closest to the passenger side.

And now no matter how many times i hit the gas it won't do it, it's mostly when cold but random and not as bad as before.

Can you go to MODE 6 data and look at the misfire monitor counter stored? It keeps a record of misfires there. Let's see if by you moving the coil over if the misfiring is following it.

I'll check the misfire codes when i get home. here is a video of it:

Can't find a mode 6. when the car started the misfire on cylinder 1 went up to 49 then back to zero, on other cylinders was around 2.

Now smooth again and not showing misfires. Very strange.

Here.

Also removed EGR connector and didn't do it so i have driven it like those 10 miles all okay. I will check when cold if the misfire is there.

Thank you for the update. Will check in the morning for your results.

Started it on a cold day today still with the EGR disconnected, no knocking at all.

The EGR doesn't do anything on start up or idle. If it were stuck open it would cause a hard start and really rough idling to the point of wanting to stall out. I did not hear any of those conditions in your videos. Can you read the ECM calibration number and post it on here? I want to see if there is an updated calibration. I can only check for USA/Canada market. I am not sure where you are and if this will help us, but it is worth a try.

How do you read the ECM calibration number? I am in the US.

Try to go into ECU information.

These?

It starts with 376. I posted the old and new calibration numbers for the year models. You may need to go on the generic side to read it. Also make sure it is the ECM module. That looks like maybe the hybrid module your looking at?

Nowhere to be found, used two different scanners.

Here is what the bulletin explains:

Vibration/Tapping and/or Misfire After Cold Soak

Service
Category Engine/Hybrid System

Engine Control

Market USA

Section

Applicability

Introduction

Some 2013 – 2016 model year CT 200h vehicles may exhibit a vibration due to a rough idle and/or tapping noise from the HV transaxle after cold soak. The check engine light may also illuminate with Diagnostic Trouble Codes (DTCs) P0300, P0301, P0302, P0303, or P0304 (Random/Multiple Cylinder Misfire Detected). The Engine Control Module/ECM (SAE Term: Powertrain Control Module/PCM) logic has been modified to reduce the possibility of this condition occurring.

This would be the only other solution left to have completed and that is to have the Engine Control Module reflashed with the latest calibration if it is not current.

I see. I'll take it to Lexus to see if they can scan it.

Please let us know if your vehicle needed the update and if it helped.

I will. I made an appointment. It always makes me wonder how the heck an update can resolve such issues, i had a car that needed a transmission update to get it to be as smooth as silk when it comes to shifting.

That seems like where we are heading. Some of the newer vehicles have over the air software updates to avoid having the customer take it into the dealership.