Engine knocking issue at low speed

[pwuser161228146379]

Asalamu alaikum,
I'm facing engine knocking issue in Axio 2007 at low speed accelerating between 1500 to 2000 rpm. Sometimes it is severe and sometimes it vanishes and knocking starts when the car reaches normal operating temperature, when the car is cold there is no knocking. Pick and fuel average is good, starting is also good and the car mostly knocks under load when going uphill or when the ac is on. What could be the issue? How to solve this problem?

[sardarg]

sir @pwuser161228146379 which engine oil grade you are using??
did knocking started after change of petrol pump ??

lastly please visit a workshop which can deep scan your vehicle, read out the codes and fix it by using new parts. do not attempt desi style hard reset to remove codes please. P0325 error is for knock sensor as per toyota code list.

[pwuser161228146379]

10W-30 grade. And no I'm using same petrol pump from many years. There is no check light or error code.

[pwuser161228146379]

@capsat @Xulfiqar @rajaatta @helper_learner Please guide.

[Xulfiqar]

First isolate if this knock is mechanical or is spark knock, mechanical knock like slapping chain or dancing tensioner is obvious. For spark knock, do you or your freinds or mechanics have another car with a similar MAF sensor? - swap it out and retest. A worn out MAF underreports air mass which causes less fuel input that causes marbly knock.

Dont drive too much with such knock. (assuming its spark knock) - it can really hammer on the big end bearings.

You can connect a nice scan tool to it and check the trim PIDs, if the trims swing wildly from a lot of positive to a lot of negative or vice versa - just off idle - you have a questionable MAF.

It can also be a bad AFR sensor, but it also induces other codes most of the times. Make sure its PID is stable.

[hash4u]

very nice points
changed plugs and knock in my passo vanished

[helper_learner]

Ws,

You are in rawalpindi right?

Visit @rajaatta or @dani_kk for scaning and diagnosis.

As told by sir @Xulfiqar driving like that can possibly damage engine.

[pwuser161228146379]

Update : I think that it is spark knock not mechanical knock. Yesterday I filled the tank with high octane fuel and drove the car 70 to 80 kms but the knock was as it is. Today I went to Sunny Automobiles located in Rawalpindi for injectors cleaning but they said that cleaning injectors will not solve the issue. This is piston slap which is common issue in 1NZ-FE engines and 20W-50 oil might reduce it. But I insisted them to clean the injectors, injectors were first tested on machine and they were working properly but still cleaned it with ultrasonic cleaner. After that cleaned the spark plugs with ultrasonic cleaner and the owner said that the spark plugs are not gapped properly which can also cause the engine to knock. Genuine iridium plugs were installed 3 years ago and only 40k kms is driven and I think that iridium plugs don't need any cleaning or setting of gap but I didn't said anything because I wanted to resolve the issue. After all this process we went for test drive the knock is still there but it is very very minor even I can't hear it properly.

[Hassan1991]

20w50 is too thick for this engine. Your car came with R1nz, which has no piston slapped as much as I know. You might be referring to injectors noise.

[Xulfiqar]

Did you check the MAF sensor for correct operation? Or you are you on the “juctor champi, pilugg and traatal sarviss bandwagon”?

[pwuser161228146379]

I also don't like traatal and pilugg sarviss but I wanted to resolve the issue so I didn't disturbed him. My scanner was not working properly, today I fixed it. I will check MAF sensor readings and share here. What are the normal readings for MAF sensor? Anywhere from 2 to 7 grams/second (g/s) at idle?

[Xulfiqar]

You need to plot the maf pid to see the response time of the maf at different rpm loads

A very rudimentary test is to see if the fuel trims move wildly when moving off.

Another culprit for marbly knock is a bad pcv, make sure thats in good shape too, the hose on those engines clog up.

[hamza.khalid962]

Hi, I am facing same spark knock issue at operating temperature when engine warmed up on toyota vitz 2006 2sz-fe engine, using 5w30 oil grade spark plugs maf sensor are in good shape I have tried high octane but still hearing knocking sound untill 60 Km/h and knocking vanishes after 60 Km/h.