Replaced a lot of things. Still knocking :(

[whiteMaro]

I've have a pinging/knocking issues with my 98 A4. Using 87 it knocks a lot. using 91 its not as bad but still knocks under load. Today I replaced the plugs, wires, Injectors, fuel filter, and Air filter. Its been a long day and the damn knock is still there. I did notice that the engine runs almost knock free when its cold but once It hits peak temp (180-210) its back to knocking.

Any more ideas of what it could be? I'm tired and done for today but I'd like to have this issue solved before I go back to work on Tue.

Thanks

[bigbrian442]

Re: Replaced a lot of things. Still knocking :(

Knowing when It knocks would be helpful here. Under load as in WOT or as your cruising at highway speeds. Have you changed the two knock sensors? Highway cruise knock can be cause by a non functioning EGR valve.

[whiteMaro]

Re: Replaced a lot of things. Still knocking :(

It knocks at any speed under load. I could get it up to 65mph knock free if I just lightly touched the gas and had an on-ramp 5 miles long. It will knock in any gear and any RPM above 2K. I can cruse at 65mph without much problem but if I come up to a slight incline or give it a little gas to increase speed it knocks and the RPM's jump slightly and fall back down.

All the plugs I pulled looks fine. No sign of running lean or hot.

[bigbrian442]

Re: Replaced a lot of things. Still knocking :(

Are you sure it's spark knock and not a mechanical problem? If your sure it's spark knock, I would start with replacing the knock sensors.

[whiteMaro]

Re: Replaced a lot of things. Still knocking :(

Are you sure it's spark knock and not a mechanical problem? If your sure it's spark knock, I would start with replacing the knock sensors.

Thanks Brian.

Yeah the engine runs fine when revved in park/neutral. Higher oct fuel helps the problem. Would the knock sensors go bad and not throw a SES light?

[bigbrian442]

Re: Replaced a lot of things. Still knocking :(

Any sensor can go bad and not throw the SES light. Sometimes they will sometimes they will not. At any rate the knock sensor should see the knock and pull back the timing. Do you know if your car has had a tune flashed into the PCM?

[whiteMaro]

Re: Replaced a lot of things. Still knocking :(

Any sensor can go bad and not throw the SES light. Sometimes they will sometimes they will not. At any rate the knock sensor should see the knock and pull back the timing. Do you know if your car has had a tune flashed into the PCM?

No tune. I am the original owner. None of my local shops carry the sensor so I had to order them. I'll just have to go easy on my car until next weekend.

Any other ideas on what else it could be? Would cleaning the MAF help in any way?

[bigbrian442]

Re: Replaced a lot of things. Still knocking :(

The EGR not working or being clogged would be a candidate. But even then the knock sensor should read the knock and retard the timing to stop it.

[whiteMaro]

Re: Replaced a lot of things. Still knocking :(

BRIAN, YOU KICK ARES!!!!!!!!!!!!!! If you were closer I'd buy you a few rounds.

Swapped out the driver side KS and went for a drive. The first mile had a few knocks and shudders but I kept driving and after mile 2 my engine was 100% knock free! I didn't realize how much power I had lost the past month.

One last question. The engine has 2 knock sensors, is this for redundancy or are both need together to function? I replaced one and my car is working but does that mean both were bad or just the drivers side KS?

[bigbrian442]

Re: Replaced a lot of things. Still knocking :(

It needs both. I would have to say they were both bad. They are supposed to pick up knock from the bank of the engine they are on.