Vibration at Low Speed after EGR cleaning

First I just want to thank everyone on this forum for all of the great resources. The resources on this site have helped me drastically improving the performance on my new used car.

I bought a 2012 with 107,250 miles. Upon purchasing it I knew that the suspension would need to fixed. That work has been done as well new tires, all new shocks, and a new steering rack.

shortly after getting the car back from the shop, I got misfire codes P303 and P304.

After purchasing the car I was able to get service records from the dealer, that at 105k the car had been brought to the dealer for a check engine light for code P0303. They did a head gasket test that says pass, and replaced all the spark plugs and ignition coil 3. Two thousand miles later it was back at the dealership again for a check engine light and running poorly. This time codes P0300 P0303 and P0304. They ran a compression test and recorded 1:160, 2:155, 3:155, 4:150. It says they removed the vehicle intake manifold and carbon cleaned vehicle. The next thing it says is recommend head gasket replacement.

In the time I have had the car since the issue occurred, I have cleaned the entire EGR system from the intake through the cooler, and replaced the EGR valve in the process. It was not bad. Valve likely didn’t need to be replaced but didn’t want to get into a situation where it was bad and had to wait for parts. The intake was relatively clean, not as clean as I got it thanks to this forum, but signatory not badly obstructed. There was a fair amount of carbon on the egr valve itself and the cooler was 80-90% clogged. I cleaned the throttle body and replaced the pcv valve at the same time.

this work improved the throttle response a bit, and I haven’t had these codes return in the thousand or so miles since I completed it.

I then did an oil change as I hadn’t had it done since I bought the car. Oil was perfect and didn’t need to be replaced. I also replaced the transmission fluid which was basically silver.

Through this whole process I’ve been monitoring the coolant level and it hasn’t dropped an inch.

I am still left with the original symptoms of a vibration between 20-40 mph, as it seems when the gas engine kicks on. It’s only during this speed band that I get the vibration. The work above has maybe slightly improved the situation. But I am still left with the vibration and rattle. I have never experienced the cold start rattle I have seen. I’m currently getting good gas mileage.

My only thought at this point is the transmission or the the damper plate.

Any assistance or insight would be greatly appreciated.

 

ASRDogman - I have not, I could clean those but something tells me it wont make a difference. I will try and report back.

Paladin55 - I did this initially before swapping the EGR with genuine new one. It made no difference either way. If I can get the car operating properly I will plan on changing it far more frequently. The intake manifold was pretty clean when I removed it. I then ran throttle body cleaner and brushes through all of the EGR ports, as well the main large section where they all connect. I kept doing it until the fluid came out clean and then power washed the whole manifold.

Grit - It certainly wasn't ideal. It likely was never changed before I replaced it.

Mendel Leisk - It sucks that I got stuck with it. I believe the car was traded in to a dealership, then auctioned, then I purchased it from a mom and pop dealer. I doubt the guy I purchased it from had any of the history. Unfortunately i'm basically into it for more then its worth, so I have no option but to drive it, or attempt to sell it fixed or not.

Tombukt - I will send you an email.

 

Just did the MAF sensor. No change.

 

Tombukt2 - thanks for the video. The noise sounds similar, but I can’t replicate it at idle. Only at slow acceleration, basically when the ICE turns on.

I'm likely going to just keep driving it to see if it gets worse and hopefully trips a code.

 

Tombukt2 - thanks for the video. The noise sounds similar, but I can’t replicate it at idle. Only at slow acceleration, basically when the ICE turns on.

I'm likely going to just keep driving it to see if it gets worse and hopefully trips a code.

 

I can also add that today I noticed that when the car was cold started this morning this issue did not occur. It drove fine through the speed and power band where the vibration would occur. Then once the engine was warmed up it came back. I hadn't previously noticed this as I usually start the car and let it warm up before heading out. I will continue to monitor. Still not getting cold start knocking.

I will note I started monitoring hybrid temps when I determined that the fan noise I was hearing in the cabin was not the AC. The hybrid battery was reaching 110 at times on the temp sensor 2 through the Dr.Prius App and if it got warmer the fan seemed to go into high speed mode. I doubt this is adding to the problem but I plan on cleaning the fan out next. What is the normal operating temperature of the hybrid battery?

At this point I am hoping that driving the more will present more of a problem.