spark knock sound under any acceleration

[Steve Clark]

Hi! Longtime reader, infrequent poster.

I've got a 2001 Touring Ed. that has a spark knock under *any* degree of acceleration at *any* rpm. Dealer has changed plugs and reflashed the controller. I've been running premium octane rather than the regular that the manual recommends for close to three months now, I've used three bottles of Techron injector cleaner. I've driven it hard to try to burn out any carbon. No change.

Does anyone have any insight or a solution that I could try?

She's got 79k miles on her. Well out of warranty.

Thanks.

Steve

[MX-5]

You don't mention if the knock sensor was tested or replaced?

Was the timing retarded when the block was tapped on with a hammer.
A scanner will tell you the timing advance and knock sensor operation through the realtime datastream

[slartyblarfast]

Sounds like you might have a headgasket blown.If the gasket goes bad between cylinders it will knock like an sob under any kind of acceleration. The only way to find out is to do a compression test or a leak down test.Have'em check it.

[Steve Clark]

No, the knock sensor hasn't been checked yet. The service tech said it would *probably* throw a CEL if it malfunctioned, but I suspect you might be on the right track in your diagnosis. I may have to break down and buy a scanner. As technical as cars are today, it'd probably behoove me anyway for future repairs. Besides, I could keep checking for that P0402 on the Miata.

As for the head gasket, I have some doubts as the car runs like a champ. Wouldn't performance be degraded if the head gasket was leaking? I'm asking, not refuting.

Thanks for the responses, guys.

[BORICUA]

Have you checked this thread...

http://www.ptcruiserlinks.com/forum/...?TOPIC_ID=5796

I had a similar problem and got it solved, also have you done the ignition test to see if you got a error code.
Hoppefully this will help.

[Steve Clark]

Thanks, B-man. I don't have any sort of stumble or hesitation, but I just downloaded a bunch of info on reading codes w/o a scanner. My old Dodge Shadow had this feature too, but for some odd reason, I though Chrysler had discontinued it. Glad they haven't! I'll run 'em tonight and see if I get an error code.

The dealer replaced the plugs, but not the wires and I'm wondering if that isn't part of it. We'll see. Thanks.

-Steve

[MX-5]

quote:Originally posted by Steve Clark

I could keep checking for that P0402 on the Miata.

Here's the CEL info for your Miata concerns.
It's very popular.
http://www.miata.net/garage/egr.html

[Steve Clark]

Well, ran the built-in trouble code diagnostic-ator....nothing. Just the crystal-clear display of my mileage. Of course, I haven't had a CEL either so maybe that's why. RRRRRRR! Saturday, I'll crawl under it and check the knock sensor. Maybe it's loose or something.

MX-5 - thanks for the P0402 info. I've actually followed that exact procedure once or twice before. I think I may have to check the EGR valve itself. I'm told some carbon can build up in there. Or maybe it's a sensor issue. I'm not sure. I've been fighting/living with it for nearly two summers now. What year is your MX-5? What's your handle on Miataforum?

[MX-5]

Search for member #4700. I've been around there a long time.

[sotexpt]

MX-5 I wanted more info on your NO2 switch.
You can email me direct from my profile.
Scott