Moderate Knock , loss of power and less MPG

car : toyota echo 2001 , M/T , 125000 Miles

Hi there i will appreciate some advice and help if possible on this matter.

i notice a remarkable “ping” “Knock” sound on my car + plus a decreaced fuel efficency at about 25% + considerable lose of power at about 20% . i start to feel this simptons after my car was serviced about 3 weeks ago

some of the items included on the scheduled maintance where

-replaced air filter,shock struts,mount struts,Accesory belt and serpentine belt, oil change (in wich i switch from 5w-30 to 20W-50),coolant change,tie rod ends replaced , rack ends replaced and thats it.

i am thinking that maybe the air filter is not a good one and is obstructing the air supply to the engine or maybe the oil is to thick for the car (take into consideration that i swith to 20w-50 cause the temperature range where i am is about 75.2-92.0 F all year)

another thing could be the gas quality i usually use premiun gas on my car since where i am the octane rating for premiun is 95 ron and regular 91 ron so if i use regular i will be at 86 AKi wich is 4 octanes lower than the recoomended by the car , but even whith premiun fuel i am having the problem

the spark plugs have about 20K miles and i am discarding that posibility since they are denso Iridium sparks so they should last at least 10K miles more , i have no check engine lights on and all the emessions on the car are ok , i have just make the annual emession test for it.

any advice here will be realy appreciated

Jorge,Is 20w-50 one of the approved oils for your car? Thats my thinking on the mileage decrease,as for the reduction in performance,nothing yet.

Very difficult to diagnose on the web. Could be a rattle (loose heat shield etc.), preignition, detonation, and so on.

Probably not the air filter, even if it is clogged.

Gas could be the problem, however the car’s knock sensor should make knock barely audible (inaudible to untrained ears). If the problem goes away when you fill up with premium fuel, then that is probably the problem.

Clogged fuel injectors? Valvetrain noise? Who knows. Try the better gas and let us know.

Why do you switch from 5W-30 to 20W-50??? Does your owner’s manual recommend that? Whether or not that is causing the problem, I think it is a bad idea.

After you put the proper oil in your car (ASAP!!!), see if the engine behaves normally. If the problem persists, try a tank or two of high octane gas to see if the knocking goes away. If it does go away with high octane gas, you have a problem with premature detonation. It could be a bad EGR valve or one of many other things, but testing with high octane gas will tell you if premature detination is an issue.

Premature detonation is what happens when the octane of the air/fuel mixture is too low and compression from the cylinders detonates the mixture before the spark plugs fire. It can harm your vehicle, so get it addressed ASAP after you replace your oil.

no 20W - 50 is not a recommend oil for my car the recommended is 5w-30 , however and answering to Whitey i change to 20w - 50 because my car was designed for the US , but as my temperatures are much higher i tought that maybe a 30 weight oil will not protect the engine in the afternoon when temperatures can reach 92F this is the first time i am doing but i will go back to 5w-30 as fuel consumption is increasing like crazy.
whitey just today i have to fill the tank so i will fill it with premiun you have a good point on your comment there thank you very much
basically i have a ping or knock when i start from a standing position (and only for a second or so ) and when i change from 1st to 2nd gear
after that i dont have more knocks (except if i step on teh gas abruptly) “for example i am driving at 40 miles steady and suddenly i step on the gas abruply then i have poor aceleration + knocking”, i am driving on the 3-4 K RPM range cause below that is very hard to accelerate the car so basically i have to accelerate more to reach the speed i desire , before that i was able to get the speed i am used to drive at about 2.5 -3k RPM
i will come back with results
thanks a lot

i change to 20w - 50 because my car was designed for the US , but as my temperatures are much higher i tought that maybe a 30 weight oil will not protect the engine in the afternoon when temperatures can reach 92F

No. Use the recommended oil. 92? is well within what Detroit expects. Heavier oil can cause additional wear and other problems. Stick with what the owner’s manual list.

I would not wait until the next scheduled oil change to go back to the manual’s recommended oil.

The 20W50 oil is totally unnecessary, and may explain some of the decrease in fuel mileage. 90F is not too hot for 5W30 oil, and I suggest you switch back.

I have to wonder about the struts, tie rod ends, and rack ends. Was a wheel alignment done? If not, you need one. This could also affect mileage.

The knock and loss of power are more difficult to explain. This car should not need premium fuel, since it is designed to run on regular. I’m wondering if the ignition timing is incorrect. I don’t think the 20W50 oil can make this much difference all by itself.

Pinging…Lack of power…lower MPG…Anyone check the timing yet???

(take into consideration that i swith to 20w-50 cause the temperature range where i am is about 75.2-92.0 F all year)

Bad logic, your engine operates a hundreds of degrees. Go back to the recommended oil as soon as possible.

Ok i have some news

  1. i fill the tank with premiun Fuel yesterday so far i have drive 150 miles and i was able to sense no more ping or knock around >25 miles also i can feel a little better accelaration however is too early to get into a conclusion i will test the behavior with 2 more fills
    as far as the timing i am not sure if this car autoadjust the timing as is distributorless
    i am waiting for the oil to cooldown to change it i have purchase alredy a 5w-30 oil and lets see what happens thanks for the comments
    someone told me that maybe the gas station i have fill the last 2 tanks is mixing the gas with something else to sell it cheaper or is just bad quality gas - however if everything is ok with texaco premiun fuel i will switch to texaco regular gas and see the results

Use the oil recommended for your car. 'Nuff said.
Go back to the octane recommended for your car.

Pinging problems are caused by preignition, actualy a secondn wavefront but I’ll skip the dissertation. The causes of this besides using an octane rating below that recommended are too hot a cylinder temp (typically caused by too lean a mix), malfunction of the exhaust gas recirculation (EGR) system, or ignition too far advanced. While your knock sensor, a “tuned” piezoelectric or piezoresistive shock sensor, should send a signal to the ECU to back off the timing to compensate, the Echo is not a high compression engine and has no boost, so preignition should not be a chronic problem.

The aforementioned problems should all trigger fault codes in your onboard diagnostic system that should be stored in your computer. Have you had the computer checked for stored codes?

the oil has been change to 5w-30
power of the car has been restored with premiun fuel, if i use regular fuel i have ping and knock everywhere
one thing i notice is a nasty rotten egg odor from the car when i am driving at around 70-75 MPH
can this be related to the problem?
still having several problem with fuel economy ,32MPG vs 39MPG(normal )

Jorge,That sulpher smell (rotten egg)is from either a mixture problem(various ways for this to happen)or failing cats. some whould say a dead cat (get the joke)?

I doubt fuel is the issue here. Premium fuel will only treat the symptom. Keep in mind I only recommended using it as a diagnostic tool.

Take the car to a mechanic for a proper diagnosis. Tell her/him you are experiencing premature detonation that seems to go away with high octane gas and that you need a proper diagnosis.

Is this car driven mostly in the city, short trips? Seems that way with all the suspension work.

It could be carbon deposits causing the ping. Could also be an old sticky thermostat making it run a little too hot.

20w-50 is way too thick for that motor. I could see it sapping some power