Since I've owned my 2000 LS, I've burned premium gas 99.5% of the time. REcently, I put about a half a tank of regular in it. A few days later, I noticed a knocking noise in the engine. I've burned several tanks of premium since that, but, the knocking noise remains. Any ideas? Also, does anyone know a good way to remove the headlights so the inside of them can be cleaned. I've always had a fogging problem with them, but, don't want to pay the unreasonable amount of money they want to charge me to put in new headlights. Thanks so much!

bake the headlights at about 250 degrees for a few minutes. There are many posts covering this. They only caveat is that your headlights have to have the gray adhesive sealant if it is black you are out of luck.

Did you run the car hard when you pumped the regular fuel?


If anyone out there is considering using 87/89 octane please do not.

BTW :W to :V

I don't recall driving hard during this time (mostly around town). I should also say I believe I have a leaky valve gasket, also, as I do see dirty oil on/around the gasket covers. The check engine light has been coming on and off during this time (mostly staying on). Also, I'm still not sure how to get the headlights off? Thanks for your help.

justr seach the forums using the the terms fog and/or headlights. I would retype the how to but it has been done so many times already.

If you can get to an autozone ask them to read you computer for you. Post the code back here. I doubt the VC leak is causing the knock to occur. I ran 89 one time and it knocked like crazy fortuneately it did not continue to knock after I pumped 93 back in.

Sounds like your car tried to adjust to lower octane gas but couldn't pull enough spark out and therefore you started knocking.

However it will take a while to adjust back.

To speed up the 'adjust back' time - just disconnect your battery (remove the ground strap from the trunk with a 8mm socket) and let it sit for 5mins. Then plug it back in.

this should remove and 'memory' the PCM has about the gas and knock adjustment.

Sounds like your car tried to adjust to lower octane gas but couldn't pull enough spark out and therefore you started knocking.

However it will take a while to adjust back.

To speed up the 'adjust back' time - just disconnect your battery (remove the ground strap from the trunk with a 8mm socket) and let it sit for 5mins. Then plug it back in.

this should remove and 'memory' the PCM has about the gas and knock adjustment.

Thanks, that helped!!

Well, disconnecting the battery helped a little. However, there is still a knocking sound and the car idles like it's really straining. It runs smooth on the road, though. I took it to Autozone and it passed the diagnostics test with no codes returned at all. I've taken it to a couple of places to have the oil changed and they won't change the oil because of the knocking sound. Do you think it could be related to the timing chain?

Well, disconnecting the battery helped a little. However, there is still a knocking sound and the car idles like it's really straining. It runs smooth on the road, though.

Does this knocking sound happen while in the driveway? It might be a mechanical problem if it does.

pull the eec codes


I run 89 (10% eth.) all the time with no knocking

Does this knocking sound happen while in the driveway? It might be a mechanical problem if it does.

You can hear it when slowing down, cruising at very slow speed and while stopped at red lights, etc.

You can hear it when slowing down, cruising at very slow speed and while stopped at red lights, etc.

OK...that does not sound like spark knock/octane issue to me. My sport does this a little too, but I think it is an exhaust leak or EGR leak. When under decleration, timing is really kicked up in most tunes I have seen and you can hear the exhaust tick more at that point.

Always good to stay positive on these things. Bad bearings(bottome end) can be heard best when there is no negative load or positive load on the engine so you get slack. That can be hard to do, but that is usually how I try to see if I have a bearing problem. It is easier to moderate with a manual trans. Doing the oil change might be a good first step. A friend of mine had bad valve noise in his 318 and it was due to a bad oil filter. It's been over a year now and he has had no problems. Maybe you have a valve lash problem too. Use a long screwdriver that you can put up to your ear while you rest it on different places on the valve cover. That will help you pin-point valve train noises.

It would be nice if you could hook up an analog oil pressure gauge also.

Good luck,
Don

OK...that does not sound like spark knock/octane issue to me. My sport does this a little too, but I think it is an exhaust leak or EGR leak. When under decleration, timing is really kicked up in most tunes I have seen and you can hear the exhaust tick more at that point.

Always good to stay positive on these things. Bad bearings(bottome end) can be heard best when there is no negative load or positive load on the engine so you get slack. That can be hard to do, but that is usually how I try to see if I have a bearing problem. It is easier to moderate with a manual trans. Doing the oil change might be a good first step. A friend of mine had bad valve noise in his 318 and it was due to a bad oil filter. It's been over a year now and he has had no problems. Maybe you have a valve lash problem too. Use a long screwdriver that you can put up to your ear while you rest it on different places on the valve cover. That will help you pin-point valve train noises.



It would be nice if you could hook up an analog oil pressure gauge also.

Good luck,
Don

Thanks, Don!!!

. A friend of mine had bad valve noise in his 318 and it was due to a bad oil filter. It's been over a year now and he has had no problems.

Good luck,
Don

I just did an oil change at home and used a motorcraft filter. I had a bit of a knocking sound before. I would always hear it when stopped at a traffic light. I think it would go away when I put it in N or P. Well I noticede that is was not happening yesterday. The old filter was a fram. Any chance this is the reason the sound went away.

I just did an oil change at home and used a motorcraft filter. I had a bit of a knocking sound before. I would always hear it when stopped at a traffic light. I think it would go away when I put it in N or P. Well I noticede that is was not happening yesterday. The old filter was a fram. Any chance this is the reason the sound went away.

That would make it 3 people in a year that I know of that have had this problem with their Fram filter. Strange...