Can spark knock go undetected by our cars?

I took my car to the mechanic because it was acting odd (I'm not gonna explain that further, because it is the same problem I had before and I don't think repeating myself would help...) and he was hearing a knock/ping which he labeled as spark knock, but the ses light isn't coming on.

So my question(s) is/are: Can spark knock go undetected by our cars? And can someone explain what spark knock is, in terms of its knock-ed-ness (How it differs from other 'knocks')?

Any help is always greatly appreciated.

1993 z28 - stock

Edit while typing: I finished typing this and talked to my dad about spark knock, so now I know what it is, and what causes it. But, I still would like to know whether it can go undetected. (I didn't change the post to reflect this because I'm teh-lazy, lol.)

Any help...appreciated.

 

does your engine shake and idle rough?

 

To make it short. Spark knock or ping occurs when the fuel mixture explodes instead of burning smoothly, and excessive spark knock can cause serious engine damage. The engine has one or more knock sensors tuned to pick up the pinging sound. The info is given to the computer, which in turn retards the spark until the pinging stops. The computer will then advance the spark until pinging starts, and then backs off again to stop it. The idea is keep the spark advance at the optimal spot for best efficiency while preventing engine damage.

The computer does not light the MIL lite because this is how the engine is designed to operate. However; a scan tool will show the amount of spark retard commanded in response to spark knock, and then you can decide if you want to remedy the situation.

Spark knock could be caused by low octane fuel, carbon build up and/or hot spots in the combustion chamber, too much compression, too much spark advance, and other various reasons. There is a limit on how much retarding the spark will help, especially if there are mechanical reasons for the pinging.

 

Spartan: Yes, yes it does. That was my original problem (The one I wasn't going to repeat. lol)

pete: We are pretty sure we know what caused it (after all this time), I'll post that thought in awhile, but I have to eat my pizza now. mmm pizza....lol.

 

kuz my car idles rough, sometimes it doesnt sound like it wants to start but it starts and the engine shakes more than it should according to my grandpa who says i may have a plug out. The shop manager at work says it may be an ignition problem but none of the ford techs have the ***** to get into a coil ignition.

 

Spartan: Same here! (Spark plugs have build up on them - more on that below.)

Anyway, I've finished my pizza and can now tell you what we believe the cause/probable solution is (for my particular problem).

Probable problem: Driving like a grandma. It sounds strange, but the shop I took it to has seen this before, and says the most likely problem is that I'm not driving it hard enough.

To give you an idea of my driving: I NEVER get above 2000 rpms, besides the one time per fill up (if that)that I go WOT. Through town (25-35 mph), country roads (55 mph), highway (70 mph), I never drive the car above 2000 rpms. I do this to save money on gas (65% city, 30% country, 5% highway = 20-21 mpg ), and to try to keep my car in good shape.

Unfortunately, it would seem this has been my downfall. The shop owner/senior mechanic, as well as an employee who also owns a camaro told me that it is actually very common for this to happen with gm's 350's when they aren't driven like they are suupposed to be driven. If you don't wind the car out every once in awhile, carbon builds up (There's the spark knock culprit ) and the car can act like it is.

Probable solution: Drive the car like it's meant to be driven! I have been given a 'prescription' to go out and drive the car on the highway, as well as do a few 'WOT' runs upto 3000, 4000, and 5000 rpms, followed by a full-blown, let the car shift as high as it can run. It's just a little bit strange to have a mechanic tell you that you aren't driving your car hard enough, ya know? lol.

This means that tonight I get to spend a little bit of quality time with my car!


So Spartan, do you drive like me...like a grandma? [8D]

P.S. I also have to run seafoam, which I've wanted to for a month now, but My dad didn't know what it was and didn't trust it. I now have to do it on order from our mechanic!

Seafoam ftmfw! lol.

 

Give it the Italian tune up. Drive with the engine running around 4500-5000 RPM for about 1/2 hour. Keep it in a gear that will give a safe speed. That should burn all the carbon out of the combustion chamber.

 

Things I did in my car quality time:

WOTs: 0-25, 0-35, 0-45, 0-55, 20-75
'Italian tune up(s) (Not quite half an hour each, but close to 10 min each.): 2200-2400 rpms, 3500-3800 rpms, 4500-5000 rpms
Spurts of speed at all sorts of rpms, driving at different speeds in OD, D, 2, and 1.

I think I covered all the bases, and I think I'm gonna do it again tomorrow night, and really put it through its paces. I didn't want to get on it too hard, but I forced myself to.

Man, with the way I drive I should be driving a 4-banger station wagon. lol.

 

well... considering the fact that i recently got arrested for doing donuts... i guess you could say i drive like an insane grandma... But no i drive on the freeway alot (anywhere between 60-120mph)do 5mph over the speedlimiton the highway. I had my plugs and wires changed (from the looks of things for the first time since 1994) back in november(?) they could just be old how many miles should plugs n wires be changed? kuz my car had like 124xxx when i picked it up and now it has 127,700.

 

I don't think wires are meant to ever need replacement, but things do go wrong.

For plugs, I've heard anywhere from every oil change, to every 60000 miles.