Knocking??!
Thread Starter
Pro
Joined: Dec 2000
Posts: 534
Likes: 32
From: Farmington NY
Knocking??!
My car idles okay, searches a little bit but is okay. When I drive it there are not problems either, the issue I have is, if I step on it when going 15-20 mph it seems to be knocking horribly. Sounds like marbles rolling around in it!! I'm not much of a mechanic so I'm wondering what I should be looking at to correct this?? I removed and replaced the injectors this winter so I'm up to most any task with the assistance of the Forum! Where should I start? I have an 85 with no modifications other than a C Marcho chip, dynomax ultra flow exhaust and K&N filter. Did a little minor porting on the plenum when I had it apart this winter (also have an AFPR with pressure at 40 psi) What should I be looking at? Thanks for whatever help you can offer. :confused: :confused:
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Re: Knocking??! (Gregory VanLare)
I've never "heard" ping though the AutoXray has shown some knock counts at high RPM.
Your knock sensor or ESC module may not be doing it's job. Any codes?
Also verify base timing and TPS setting are at factory spec, especially with an aftermarket chip.
Your knock sensor or ESC module may not be doing it's job. Any codes?
Also verify base timing and TPS setting are at factory spec, especially with an aftermarket chip.
Thread Starter
Pro
Joined: Dec 2000
Posts: 534
Likes: 32
From: Farmington NY
Re: Knocking??! (Gregory VanLare)
I don't have any codes. I don't have an oem ignition control module, last year, mine wasn't advancing (I had someone do a scan) so I picked one up from Autozone. Could that be the problem? The knock sensor was replaced a year and a half ago. Would it be worthwhile for me to pick up an Auto Xray? I've seen the ezlink for $169. My concern is, I can get all of the values but don't know how to interpret them!! My service manual doesn't offer that info!
Burning Brakes
Joined: Aug 2001
Posts: 1,238
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From: walled lake MI
Re: Knocking??! (Gregory VanLare)
knocking would be a high pitched, really quick, tic tic tic. if it is the problem, it should happen under most high load conditions, irrespective of speed.
if it sounds more like rattling, (and if you have no codes) it might, just might be an exhaust leak or resonance. i wonder if your exhaust system has double-walled tubing. i have just read that it is possible for the welds to get loose and cause rattle. i would also suspect some kind of resonance if it only happens in a narrow RPM range, and not correlated with load.
another remote possibility (if it is knock) is that your knock sensors are not torqued in right. the ECM only looks at the sensors' resistance to generate codes. a good sensor that is not properly installed may not trigger codes, but might not be doing its job.
btw, lack of spark advance will actually inhibit knock.
good luck tracking it down!!!
[Modified by tempest, 10:27 PM 5/9/2002]
if it sounds more like rattling, (and if you have no codes) it might, just might be an exhaust leak or resonance. i wonder if your exhaust system has double-walled tubing. i have just read that it is possible for the welds to get loose and cause rattle. i would also suspect some kind of resonance if it only happens in a narrow RPM range, and not correlated with load.
another remote possibility (if it is knock) is that your knock sensors are not torqued in right. the ECM only looks at the sensors' resistance to generate codes. a good sensor that is not properly installed may not trigger codes, but might not be doing its job.
btw, lack of spark advance will actually inhibit knock.
good luck tracking it down!!!
[Modified by tempest, 10:27 PM 5/9/2002]
