So my Toyota Corolla has had a slight habit of rumbling a little when starting up, usually on the first time I start it for a day. The car shakes more than usual, I think it's coming from the front, aka the engine. Today, I started it up twice not too long after each other. The first time, it rumbled as usual, and the second time you could distinctly hear the engine making a sound a bit louder and a slight rumbling.

The performance and drivability of the car has not been affected whatsoever.

Any ideas as to what is going on? I don't like the rumbling.

Does your car also rev for no apparent reason (even without touching the gas pedal)? It might be something to do with the radiator as I've experienced a similar thing with my old Civic.

Nope, no revs for any reason other than the normal ones. The car's pretty new, 2007, which worries me a bit.

sounds like misfires. check your coil packs.

My check engine and Maint. Req'd lights have not yet gone on. In fact, the car itself is showing no problems.

I don't exactly know where those packs are or what sign I'm supposed to be looking for (dust, grime, blackening), so should I bring it to a dealer?

It can be many things, more information is needed. But does it just shake a lot? and does it shake constantly? or does it shake for a bit then calms down then shake again?

Just on start-up, usually the first start-up of the day or if I haven't used the Corolla in a while.

While the engine is igniting, the car's chassis rumbles and shakes a bit, considerably more than what I'm used to. Moments after ignition, it stops. It does not shake again during the drive, or when I am turning off the engine.

Is there any squeaking on startup along with the shaking? Something may be up with the belts. I'm not gonna say engine mounts, otherwise you'd be dealing with the rumbling more often.

What car do you own, year, and milege?

I have never heard any squeaking on starting up with it.


2007 Toyota Corolla. It has about 44,000 miles.

That's the same Corolla I have. What's your idle like at startup, or just idle in general? Does it dip below 400rpm and jump back over 400rpm while rumbling?

I get 800 RPM general idle. I'll check my start up, I know it jumps to about 2200 RPM then it settles back down, but I'll take a look tomorrow morning when I go to school.

Oh wait my last car was 400rpm.... actually my Corolla idles higher at about 900rpm. Though my car jumps up to 1800rpm before settling down.

I should be more specific, I meant when at idle while rumbling does the rev needle bounce a little?

I'll be quick, but there three things i'm thinking of:

1. Idle Air Control valve/motor. Could be gummed up with carbon deposits or even oil (from PCV blow-by). Carb cleaner spray usually cleans this up well. Not likely to happen on a such a low miles car, but possible.

2. Motor oil. If the motor oil has been in there for a while, it can sometimes cause the hydraulic lifters to tick. This doesn't cause rumbling, but motor oil can also affect how smooth the engine runs and idles when starting up.

3. Mounts. Very unlike this should fail at your low miles. Obviously it can cause vibrations when they get worn or down right fail.

Clean your throttle body.

The needle doesn't move. Upon starting up, the needle will jump to 1.9-2k and then hover at 1.2k, until I shift it into reverse and back it out. When I brake then, the needle will be at 800 RPM, and driving resumes.

It didn't rumble today.

Probably some carbon build up in one of the 2 places. EGR or IAC.

I'm not sure if having carbon build up in the EGR would actually cause idle issues.

EGR is basically exhaust gases being piped back into the intake. This supposedly reduces NOx, and cools down the combustion chamber (When running hot). Under normal circumstances, EGR is just a emissions control device, and the car can do without it. Luckily my current car doesn't have a EGR, which (when i've taken apart the throttle body and intake) keeps things very clean inside. Even if the EGR was complete clogged up (which I have seen before), the IAC and throttle body is responsible for engine idle, not EGR.


A thottle body cleaning is good to do, but i'm not sure how you would do it safely on a electronic throttle body which the previous generation (as the originial poster has) Corolla has. If the carb cleaner seeps into the motor or even to the throttle position sensor, it can ruin those parts. This is something that a service manual could tell you how to do. I hope it doesn't turn out to be a Dealer-only job (for cleaning the throttle body).


Speaking of the Dealership, sometimes they do have software upgrades for the car's computer. Toyota doesn't really announce this, but they do upgrade the car computer's software if there is a upgrade availabe and the car is having issues that the upgrade is supposed to fix. The dealer can look up if there is a upgrade available by calling them up and giving them your VIN number and ask what the upgrade fixes or enhances.

I'll take a look @ the 2nd thing. The ECU in the Corolla was just changed for a new one not even 2 months ago, so there shouldn't be any problems with that.

It could be the ECU The robots are taking OVER!

I'd be pretty disapppointed in Toyota if it was really the ECU. The dealer's already changed it out twice due to it failing.