I was trying to clean IACV, but it had a stripped screw and didn't have time to do it. Since I have a small window of availability to work on it when the engine isn't hot, because I'm always on the go with work and kids. In the mean time I did a seafoam through the throttle body and that helped quite a bit and I was able to narrow the misfires to 2,4, and 5. Replaced those ignition coils yesterday and it was running like new and it felt great. I have also recently replaced EGR valve, spark plugs, took off intake manifold and cleaned out all the carbon that clogged up egr ports. Took off throttle body and cleaned it. It was running like new again!! No vibration and I could barley even tell the engine was running it was soo quiet. However, when it was in park the idle would jump up and down from 1 to 1.5. When it was in drive no jumping. (I'll attach the video) Drove it to work and it was fine, and on the way home from work CEL came back on saying there was a P0131. I cleared CEL to see if came back. Took kids out last night and on the way home I hear a noise and it starts over heating. Pretty sure it's the belt tensioner, and I had started to hear a noise from the tensioner a couple days ago, but it went away and now a P0420 code. I've been able to fix everything else, but the belt tensioner I'm not sure I can do. It didn't throw a belt, but made a lot of noise. Would I have to replace the whole system with water pump and everything or just the belt tensioner itself part # 231081at autozone.

 

 

 

ignore the codes for right now, IS the ac/alt belt tensioner working correctly- its the top one you can see against the ac belt- engine running with hood open, rev engine to 2500 and let off, tensioner should maintain a steady rate/pressure, not jump around like its not holding tension any more~
If it were really bad, the alt could be momentarily stopped causing false codes, or more likely a loose belt will cause low volts and false codes

Why do you think its the timing belt tensioner? if that wasn't replaced with the wp and belt job it can fail, smart to replace all tensioners when doing that job

If the tbelt tensioner fails you will know right away - the engine will stop running = forever!

 

Please describe overheating event- more than 1 time? more than 3/4 up the gauge?REDLINE? Should NEVER go beyond its normal 1-2 lines below half
Can be as simple as dirt between the rads or thermostat or fan sensor A failure

total miles on car?- wp replaced before at ?? miles, coolant fresh- less than 5 years old
Coolant level is good in rad, and in res bottle too? CK'D COLD OF COURSE!!!!

 

verify: you installed the correct NGK = $8 each spark plugs?