Engine engine knock...

engine knock...

2003 Corolla CE 5-spd with 40,000 miles. AEM CAI and Magnaflow resonator-back exhaust and custom ground kit are my mods.

So, lately I've noticed my engine knocks pretty bad under load anywhere from 1800-3000rpms. From 1/2 throttle to WOT at any rpm from 1800 to ~3000, I can hear some definite knocking. I never noticed it before the intake, but doesn't mean it wasn't there...maybe I just didn't pay attention. It may be knocking at rpms over 3000, but I don't think so. I can't really hear b/c the intake gets pretty loud above 3000.

Compression is 200psi on all 4 cylinders, i.e., there's no carbon build-up in the combustion chambers. The car runs great - great power and pretty smooth, although it idles pretty/low sometimes.

If it were knocking, would the knock sensor detect it and retard timing??

If the mixture were lean, shouldn't the O2 sensor pick it up and richen the mixture??

Any ideas?

Thanks,
Trav

Which gas brand and octane rating are you using? Have you tried 91octane? Is it pinging or really knocking? What's your elevation (above sea level)?

I've used mainly Exxon, but have used Chevron, BP and Conoco. Usually 87 octane, but sometimes use 89, and have also tried 93. Elevation above sea level here is about 1600 ft above sea level. Neither brand nor octane make a difference. It's just as bad with 93 as with 87.

I don't really know the difference between knock and ping. I can tell you, it's a light rattling noise. Nothing obnoxious and you really have to listen hard, but mainly b/c the intake and exhaust are so loud. If not for the intake and exhaust, it would be very noticeable.

I removed the spark plugs and opened the gap a tiny bit. They looked fine (ceramic insulator was white w/ no blistering or carbon build-up). The center and ground electrodes looked great....no problems there. The engine runs great with great power. Sometimes the idle pops down to ~5-600 and it idles real rough, but it's always done that.

Ideas??
Trav

Check for proper PCV valve operation... Pinching the hose between the valve and vaccum source should cause idle to drop slightly. You might want to have your base ignition timing seting and your MAP sensor output checked.
Some interesting info here on Toyota's ignition timing control; http://www.autoshop101.com/forms/h59.pdf
http://www.autoshop101.com/forms/h40.pdf

are you sure its engine knock? could be the CAI rattling and "tapping" something in your engine compartment.

Nope - definitely an audible ping. It's not the CAI rattling.

Here's what I don't get...

There are virtually no carbon deposits in the engine, so no hot spots. Spark plugs look great after 40,000 miles...good mixture, not overheated....no problems there.

If it were pre-ignition, then it would HAVE to be due to auto-ignition and there's no difference b/w running 87, 89, and 93 octane of different brands. A lean mixture MIGHT be plausible, but the O2 sensors would pick that up and the ECU would inject more fuel, right????

And if it's detonation or spark knock, then the knock sensor would pick it up and the ECU would retard timing. Plus, higher octane fuel would probably take care of this as well.

I pulled the EFI fuse to reset the computer today. Guess what? Still pings.

Could it just be the way the 1ZZ is designed? What yall think?

Thanks,
Trav

i have that same exact problem!!!!!!! i noticed it after i installed my intake. you could only hear it when your in the car. when you get out to check under the hood ill i could hear is the engine idoling. it sounds like a pinging noise. i too have used all gas types but i used to use hi octane without the intake and i never got that noise. if you fix it some how plezz tell me.... fedorlegacyGT is my screen name on aim

Ok, take it from someone that has lost a car to a thrown rod, You can't have Rod Knock. You would know exactly what it was. You would hear a LOUD TINGTINGTINGTING that would get faster the faster you drove. Also it would be SO loud that people would stop and stare at you when you go by, Also you would get a slight loss in power. I am just saying, don't worry too much, what you are discribing sounds more like something related to your intake, the RPMs you discribe are where the engine seems to have more movement, If you had Rod knock you would notice it on the opposite side of the RPM range, you would hear it from around 4k-redline. I say take a good look at your intake.

Yeah, ryan is still mistaking the normal, CAI amplified VSV valve ticking noise at idle... CorollaULEV is experiencing a light rattling noise under load at 1/2 throttle to WOT at any rpm from 1800 to ~3000. Is it really pinging caused by pre-ignition which should be reduced with higher octane or by knock sensor retarded ignition timing, or is it a mechanical noise or a loose CAI tube or other component rattling under vibration?

I suppose your question was for me. I'm 100% sure it's not a mechanical knock or anything rattling around. Not a hose b/c they've been checked and double and triple checked.

I've got some hardcore pre-ignition going on. I've cleaned the mass air sensor with electrical parts cleaner and wrapped the o-ring that seals it with teflon tape to create an air-tight seal. I've opened the gap a bit on the spark plugs. I've used Sea Foam through a vacuum line w/ engine running and also ran some through the gas tank. I've reset the ECU several times. I've driven calm and not-so-calm. I've re-grounded the engine and frame. I've ran every brand and grade of gas known to mankind. Nothing's helped.

Never had a CEL on. If the mixture was lean, the O2 sensor would cause the ECU to richen the mixture, right??

And if it were knocking (which it hardcore is) then the knock sensor would cause the ECU to delay timing, right? How could I check the knock sensor or ignition timing?? Do I have to remove the intake manifold to get to it?? How could I verify it's working??

Late,
Trav

I don't believe a lean condition could even cause such pinging.
The KS is bolted up high in the back of the head, close to the TB... According to Toyota; "The ECM is designed to filter out KNK signal voltages that it considers are outside of the engine 'detonation' range. Thus, a check of a knock control system by tapping on the engine close to the knock sensor may produce an output signal, but will not cause spark timing to retard. A check of the KNK signal pattern using the Diagnostic Tester Oscilloscope or lab scope may provide you the most diagnostic information."
Can you have it checked and test driven at Toyota dealer under warranty?...cause this is really not normal.

Every toyota I've ever driven makes a light rattling sound (coming from the engine) when climbing step inclines... My buddy was with me once and he heard it and said, "hey, can you hear that? Your engine is knocking." Then he proceeded to question me about my octane number. I replied, "yup, typical toyota noise." I come from a family that has gone through many toyotas: tacomas, camrys, corollas, siennas...they all make that sound. I dunno if that is the sound you guys are refering to...just thought I'd drop my observations. Good luck.

Yeah - the ECU will only retard timing if the knock occurs at a certain point in the combustion. It depends on WHEN the knock is happening (crank angle) as far as whether or not it will retard timing. Slight pinging is normal and healthy - best economy with slight ping. But I was getting some REALLY HEAVY detonation....

It probably was smart enough to know that retarding timing wouldn't have done any good.

Trav

i noticed a knocking sound while going thru the drive thru myself just yesterday... but when i got home and checked it was gone... probably something to do with the gas.