2000 Corolla - Valve Pinging

[cj10]

This is a lingering problem. Car has about 180k miles. The main concern I have is the valve pinging. Here is what I observed:

1) engine light comes ON quite often under different conditions 1) when I'm accelerating at above 2000 RPM or 2) when I'm driving hard (accelerate and decelerate fast) at relative high speeds (about 70 mph) on the freeway. Trouble code is almost always P0171.

2) Pinging is profound when I first start in the morning when accelerating or going up on a hill. It goes away when I drive the car for a few minutes and throughout the day with use.

3) there is a hissing sound at the front of the engine. I can't locate the source. I changed the intake manifold gasket and tried to locate it using the old carburetor spray technique. hissing sound is quite loud when I'm driving up on a hill.

note I've tried to use fuel injector treatment combined with pure unleaded gasoline (no ethanol) but no success. I am using the middle octane at the pump.

Mahalo.

 

[carlile92]

Have you tried or checked the upstream o2 sensor and air flow sensor in the intake it also could be that valves need to be adjusted

 

[porschpow]

didn't know you had to adjust valves in these newer cars

 

[cj10]

I will check the o2 sensor and get back to you folks on my finding. Mahalo!0

 

[Donabed Kopoian]

Double check for a vacuum leak. I don't think it is the HO2S since you have pinging accompanied with the lean condition.

Causes could be:
1. Fuel Injector failure (poor pattern spray will cause pinging from double-ignition)
2. Vacuum leak (pinging from lean condition)
3. Stuck thermostat (engine overheating will cause pinging)

 

[cj10]

Thanks. Don't think it's #3. For #1 how can I test for that without actually pulling out the fuel injectors and inspecting for partially clog nozzles? On item #2 I can't find a vacuum leak. Did try the carburetor spray. Maybe I need to look harder. This weekend will check then o2 sensor and look hard for a vacuum leak.

 

[Donabed Kopoian]

No way to test without removing the injectors, unfortunately.

Try again, make sure you get every single hose, mating surface, and anything that uses vacuum. Brake booster is usually the usual suspect if none of the lines appear to be leaking, and another one to check is the vacuum reservoir canister (they are usually hidden behind the passenger-side fender, if you have a dent in that fender or ever been crashed there, I'd check that first).

 

[Scott O'Kashan]

cj10 - You can use the smoke test to pinpoint vacuum leaks. It's easy and effective.

Search YouTube.com, Keywords --> Scotty Kilmer, Smoke.

 

[Scott O'Kashan]

cj10 - Any updates for us?

 

[porschpow]

I didn't see it mentioned here, but timing chain tensioner?

I know with my car if I accel lightly and manitina it, it pings/chatters, however if I lay on the gas, it doesn't do it (creating tension lost by the tensioner)

I am changing mine tomorrow. I'll let you know how it goes

 

[Donabed Kopoian]

Bad tensioner would make a difference with acceleration and deceleration, not light throttle and wide open throttle. It also won't cause a lean condition.

You're better off tracing down that hiss first and finding out what is causing that before you look anywhere else (just curious, is the hiss coming from the air intake point? Because that is normal). And again, check the fuel injectors. Both a vacuum leak and poor injector spray will be more pronounced at idle and light throttle than they will be at wide open throttle.

 

[Scott O'Kashan]

cj10 - So how are you making out with this problem? Update?

 

[porschpow]

Guess, he is still working on it. I just changed my tensioner (PITA to unbolt) but it still has that pinging chattering noise when I apply light throttle btw 50-70mph. It would stop if i have a heavier foot on the throttle....weird???

 

[cj10]

aloha everyone. I did the smoke test and it's a negative. Check voltage change on first do sensor with changing rpm. Negative so could be the do sensor.

 

[Scott O'Kashan]

Guess, he is still working on it. I just changed my tensioner (PITA to unbolt) but it still has that pinging chattering noise when I apply light throttle btw 50-70mph. It would stop if i have a heavier foot on the throttle....weird???

Drive up a steep hill and accelerate briskly. If the pinging noise starts and then stops when you lift off the accelerator, that sounds like an ignition timing issue causing pre-ignition/detonation and this is a very serious condition. It can actually punch holes through the pistons.

Try using a tank of Premium fuel and see if the pinging goes away. If it does, you've just pinpointed why the pinging noise is occurring.

 

[porschpow]

the pinging won't happen if i accel briskly. it only happens just keeping light pressure on the accel (like keeping speed on the highway. Once I reap on the gas pedal, it goes away

 

[Scott O'Kashan]

Try that going uphill though. The engine needs to have a large load on it for the pinging/detonation noise to occur. On a straight and level road, that might not be enough load to cause the pinging/detonation even punching the gas.

Try a tank of Premium fuel and see if the pinging noise goes away. If it does, we might be able to fix that problem.