So I put regular 87 octane in the tank and the engine knocks real bad when I depress the gas at low rpm. I put 93 octane in the tank and there is no knocking at all, whatsoever.

I hate spending the extra money on a car that is supposed to use 87 and run normal without knocking...suggestions on the fix? I've never had this issue before. Actually, I did on my rents vehicle and it was the EGR valve.

It's been doing this for about a year and I've been just getting by with putting extra buck in the tank. Help me out experts.

Thanks,
Shred.

[Edited on November 25, 2008 at 4:35 PM. Reason : Oh DuHuh, 1992 lincoln town car, 4.6 V8 ]

11/25/2008 4:35:04 PM

those engines are bad for carbon buildup. do a sea foam treatment and it should cure it. what you're hearing is predetonation (spark knock).

11/25/2008 4:44:02 PM

Should I do that and swap out the spark plugs? engine has 240,000 miles on it, but still runs like a champ.

11/25/2008 4:48:12 PM

yeah, wouldn't be a bad idea. especially if they've been in there that long. plug wires, cap, rotor also.

11/25/2008 4:51:14 PM

Quote :

"cap, rotor also. "

really?

[Edited on November 25, 2008 at 5:25 PM. Reason : really]

11/25/2008 5:24:40 PM

Thanks

11/25/2008 7:32:19 PM

your car has coil packs not a distributor

11/25/2008 9:20:01 PM

Not a bad idea to fog 'er out with a pint of SeaFoam.

Definitely not a bad idea to replace plugs. I usually don't fuck with the wires unless there's an obvious breakdown and one or more is arcing to ground.

If they ohm out ok with a multimeter, and you have no apparent misfire issues, then I say fuck the wires...unless they just look shitty.

And, BTW...if you don't want to or lack the skill, I can do it for a reasonable price.

11/25/2008 10:12:15 PM

11/26/2008 1:38:22 AM

Quote :

"your car has coil packs not a distributor"

WRONG as usual you stupid mother fucker. a handful of the early 2nd gen. town cars still had a distributor, though it does not have any affect over ignition timing as a conventional one does. i will concede it's more likely he has the two 4 point coil packs, in which case just only the plug wires might be worth replacing.

however, the main point is that yet again you fail. please go away, you only serve to confuse people that need help.

11/26/2008 3:58:47 AM

Those engines are terrible about buildup if not flogged on a regular basis. You might need to pull the egr and upper plenum and scrape out the egr passage.

11/26/2008 8:40:51 AM

^^ you say the timing was not adjustable yet the motor had a distributor. Did the distributor not have a reluctor inside for a crank position sensor? How did that work? Or was the crank position sensor on the pulley like most modern cars?

11/26/2008 10:26:46 AM

Thanks for the help.

11/26/2008 11:50:29 AM

I need to do this on my parents' 97 Crown Vic as well, it's doing the same thing under load (going uphill and whatnot). Even though that car only has ~55k miles on it.

Which may be part of the problem, now that I think about it...spends most of its life in town and probably never sees anything past half throttle except on the rare occasions I drive it if I'm back home.

11/26/2008 12:25:33 PM

Does the knocking do any damage? I'm just curious because it hasn't affected the performance of my car it's just annoying hearing that sound.

11/26/2008 1:54:47 PM

it can definitely destroy bearings with a quickness--it's not really something i'd ignore personally

11/26/2008 2:01:19 PM

^^^^^ignition advance/retard was controlled by a cam/crank position sensor. same as dodge magnum truck engines.

11/26/2008 3:02:37 PM

Quote :

"a handful of the early 2nd gen. town cars still had a distributor,"

is it a romeo fa1e block or not though. thats the question here

[Edited on November 26, 2008 at 6:44 PM. Reason : lol]

11/26/2008 6:38:20 PM