[iH8myCorolla]

Hey everyone,

my 09 Corolla S has recently had a "knocking" or "rattling" issue when accelerating after the car has warmed up. This noise does not occur until the engine is near being completely warmed up. It's most noticeable (or only happens) at low speeds and between 1300-2200 RPM. The only changes I have done recently are get a new alternator (3rd one on this car in the last 60k miles, previous one lasted like 1-2yrs), 4 new all-season tires last month (along with 2 new TPMS sensors that I'm sure they screwed up while putting new tires on), and changed the oil about 3-4k miles ago. I took it to a mechanic near me (that also did the alternator, tires, and TPMS) and they said the noise is coming from inside the engine, so it could be the timing chain or vvti stuff. They will need to take apart the engine and keep the car for about a week, giving me an estimate of minimum $1000.

Now a little bit about this mechanic, let's call them Rob Dumerel:
I've had issues with this mechanic in the past. I took it to them when one of my cylinders was misfiring, and gave them the error codes and explained everything. Check engine light was on so they could definitely pull the codes, especially if I was using a Bluetooth OBDII adapter with my phone. I get a call saying they need to clean the throttle body for $130. Not sure how an error code specific to cylinder C means throttle body, but I digress. I said go ahead and do it because they're the mechanic and they know better, so they did. When I picked up the car, I didn't even get out of the parking lot before I experienced another misfire and check engine light coming back on. Did research on the engine code, went to Autozone and bought a new spark plug, replaced it myself for $80 and got a $130 store credit at the mechanic. This is just one of the many stories my family has.

Back to the main point. I can't be without my car for a week, and definitely don't want to spend over $1000 as a current full-time student. I've read online that it might be the MAF, and others are saying VVTi or timing chain. One is much much more expensive than the other.

Here's what I've done so far:

• check for loose paneling
• mechanic said my oil levels were fine
• check the throttle body for any carbon buildup
• I always use unleaded (87) gas
• I might need more coolant

What I'm tempted to try:

• higher octane gas
• clean the MAF
• put factory air intake back on
• re-calibrate throttle body

So if anyone has any idea or tips as to what it could be, please help me figure it out. I can post a video that has audio of the noise, but it's much different in person.

Edit: specified my model, S. I also have a Weapon-R Short-Ram intake that has worked fine for the past few years.

 

[LeanBurn]

If you have been suspicious of this so called "Rob Dumerel" before, why in the world would you take it back to he/them let alone seek a diagnosis? Many similar stories as a result of dealing with "Rob Dumerel" would almost look like you are a glutton for punishment...but that just my take.

When was your last oil change? So the noise does not occur while the vehicle is stationary with the engine running at those RPM's?

 

[iH8myCorolla]

When was your last oil change? So the noise does not occur while the vehicle is stationary with the engine running at those RPM's?

My last oil change was about 3-4k miles ago, using full synthetic 5W-20 as labeled on the oil cap. This only happens when the car is moving, I have been unable to replicate it while my car is stationary, no matter the RPM.

It is currently in the low 20's/high teens where I am. We recently had a fairly big snow as well. The snow happened on Friday, this issue started Monday night. I drove it over that weekend just fine.

 

[LeanBurn]

If it only occurs while moving, I can't see it being the engine. It has to be in the running gear/chassis.

I would try thawing your vehicle out completely in a heated garage to rewind the chassis and running gear to pre-snow conditions. If it goes away it would be the cheapest fix ever.

...and I would never ever take it back to that mechanic again...regardless.

 

[iH8myCorolla]

Yes, it would be, and I would be so happy! What do you think about putting a higher octane fuel in? I have always ran on 87, but the research fuel for this car was 91. I did quite a bit of research and saw the knocking might be related to combustion or air/fuel mixture, which leads me to MAF and fuel type. I might also try changing the oil and cleaning the MAF. Would you recommend I use 5W-20 or 5W-30?

 

[LeanBurn]

Higher octane couldn't hurt I guess. Neither can an oil change to a slightly heavier weight like a 5w30.

These are the oddities:

-It occurred seemingly overnight.

- The knocking occurring in only an ~1000rpm range is very strange. From what I understand, VVTi is somewhat largely ECU/throttle controlled not so much RPM dependent like VTEC.

-It only occurs when the engine has warmed up. When everything is warmed up the combustion process should be optimized, spark and fuel should be at their best. Instead this is where it is "triggered".

Did you drive it hard over the weekend? I wonder if the VVTi mechanism is stuck? If it is the timing would be too advanced for the lower RPM but be more OK for processing at slightly higher. This could result in some knocking I suppose if everything (engine load, engine temperatures etc)

Can you feel the VVTi engaging if you go WOT? For my car I have decent power from 1500-3000-ish but then I can feel a rush of power from 3500 to near red line.

 

[iH8myCorolla]

I put in 89 octane last night (had about 1/4 tank of 87 remaining), and that doesn't seem to have helped at all yet. I reset my throttle body, and I also cleaned my MAF using a CRC cleaning spray from Autozone. Here's the link to a video of my dash when the issue occurs. You should also be able to hear it.

The car for sure feels sluggish when accelerating. Very, very sluggish, no matter how hot or cold the engine is. Once it hits around 3k RPM, then it feels sorta normal. I have an aftermarket Weapon-R short-ram CAI, but I've never had an issue with it.

 

[LeanBurn]

Its tough to tell without hearing any other RPMs as it gives no context. Does it sound like this in real life?

 

[iH8myCorolla]

Its tough to tell without hearing any other RPMs as it gives no context. Does it sound like this in real life?

Nooooo nothing like that, and thank God! I'm unable to hear it while stationary, whether in park or neutral at any RPM. I'll try to record some more audio when I get home later tonight at different RPMs and speeds.

 

[bsmiley]

I'm still wondering how replacing a spark plug at Autozone costs $80... did you replace the coil too?
The video sounded like the engine was reving at 4k rpm but the tach never went above 2k.... hard to tell what noise youre experiencing.

 

[SuperchargedMR2]

!. Never use this mechanic again. Find a better asap.

2. I agree that it sounds like the transmission or running gear if you can't make it happen while still.

3. How does a spark plug cost $80? I paid less for 4 of them.

4. Higher octane will make no difference except cost you money.

5. I would use 0w-20 full synthetic anyway as that is the preferred oil weight for our car.

 

[omar.bari]

Yes, it would be, and I would be so happy! What do you think about putting a higher octane fuel in? I have always ran on 87, but the research fuel for this car was 91. I did quite a bit of research and saw the knocking might be related to combustion or air/fuel mixture, which leads me to MAF and fuel type. I might also try changing the oil and cleaning the MAF. Would you recommend I use 5W-20 or 5W-30?

Hi ,

Did you happen to find the problem and the fix? I have the same problem in my corolla for over 2 years now

 

[Mgeorge]

My Corolla was knocking when the head gasket was on its way out. It would do it at low to mid rpm when under load, and premium gas didn’t help. You can do a compression or leak down test to check the condition of your head gasket.