BigE

iTrader: (2)

I was scanning my car and a friend's car this weekend (both relatively stock) and noticed a few degrees of knock retard on both. I got as much as 4° under WOT. His peaked above 8° and it happened under part throttle (we never took his over 60% TPS). My car has a lid, K&N, pro 5.0, p&p TB and a GMMG. His is an 01 with lid, B&B triflo, lowered, p&p TB and SFC's. He drives his VERY gently (no, really; the car has seen WOT maybe 5 times in it's life). I thought he might be getting KR from his subframes hitting as the suspension flexed. I dunno about mine. My exhaust is kind of close so I'll check to see if it's hitting. But has anyone seen KR on a stock car when nothing was actually wrong?

Just trying to get a feel for the sensitivity of the stock knock sensors...

Thanks

2002_Z28_Six_Speed

iTrader: (19)

I have regularly monitored a 96 Grand AM, 02 Cavalier, 01 Suburban, 03 Express with 8.1L, and 02 Camaro.

Anyways, when monitoring these motors they very rarely EVER exhibited KR. When they did it was always less than 4.

I would say there is something wrong if you are seeing that kind of (8 degrees) of KR. I can't say how damaging it would be as you don't see much operating time at 60% TPS.

RW99

Your car, being a '98, will likely show some false knock. His car, on the other hand, really shouldn't... especially when not at WOT.

Why not fill up your cars with some good race gas and repeat your data acquisition? False KR will still be there, while real knock should disappear, or at least diminish.

BigE

iTrader: (2)

In looking at the data, my car seems to follow that trend, Six_Speed. During a 15 minute trip with TPS from 0 to 100%, my car exibited KR twice, both at WOT. The first time was almost 4° while the second was less than 1°. His on the other hand, showed several times and under part throttle. I remember one time with his being in a turn over some uneven pavement so it may be a simple fix for him.

I don't know if he'd be okay with race gas, but I'd put it in mine. I think a local speed shop sells low high-octane gas (ie. above 93 pump, but not 116) that is O2 friendly. I may try to snag some.

It seems the consensus is that a very small amount of KR is considered normal, but not desirable and only at WOT.

Thanks for the replies.

robertbartsch

I heard here that rattles and shakes from the chassis do not impact the KR sensors as they are designed to pick up a very specific frequency that occurs during engine detonation....

...there is some discussion of this topic on the "internal engine" forum which talks about using LS1 knock sensors on LS2 motors....

Acetone will reduce knock. Try a few ounces in each tank of your store bought corn gas. You can buy acetone at Home Depo.

I've been using it recently and it really smooths things out.... I'm on my 8th tank and will continue using it.... it improves mileage too!

...ever since they started putting corn based alcohal in the gas here in NY, my car ran poorly..... with the acetone, it runs soooo much better...

I would pull the plugs out of both cars.... while your at it, replace the plug wires, in both cars too. Don't use platinum plugs. Our cars like NGK plugs...

...the short answer is neither car should be having that kind of KR unless it is 115 degrees in the shade and your running **** gas going up a steep hill in 5th gear with 6 people in the car and your towing a 40 foot twin-screw cabin cruiser.

If you guys have carbon build up which you will see on the plugs, consider a sea foam treatment.... do a search on this in the internal engine forum...

Patman

For once I'm actually going to agree with Robert Bartsch on something. I agree that the platinum plugs should be swapped out for NGK coppers.

When I had my C5 dyno tuned in completely stock form, it showed 7 degrees of knock retard, running 94 octane gas too!!! I pulled a plug and it looked like crap, even with only 32k on it. The stock platinum plugs are junk, I found most of the platinum missing and the gaps were obviously then way too high. I swapped in a fresh set of NGK coppers and immediately the next run showed no knock retard at all!

98NBMZ

iTrader: (6)

Your 98 most likely has the first design Knock Sensors in it. There was an issue with the first design sensor. Cars with the first design will run with a constant 4* KR. It is a relatively simple fix....just go to the dealership and get the second design sensor and the wiring harness (pigtail harness). I recently put new knock sensors in my car...I went with the sensors for an 02 Z06.

2002_Z28_Six_Speed

iTrader: (19)

Yes, the knock sensors are supposed to only look for a very special frequency which the block vibrates at during engine knock. I think it is around 6.4 k hertz.

Slowhawk

iTrader: (12)

Also check your MA.Seams like K+N's come with too much oil and can coat the MA wires with oil which give's the engine a false reading/lower load table which can cause KR.

The car should have no KR at all when it's tuned in.

LANDONZ

iTrader: (23)

if your mass air has oil on it..which im sure mine does after having my K&N installed for a year cleaning it every three months..how would I go about getting the oil off of it?

CamTom12

iTrader: (1)

Electronic parts cleaner. You can get it at pepboys, autozone, etc

98Z28CobraKiller

iTrader: (17)

Go SD and disconnect that ****

brad8266

iTrader: (23)

or just get rid of the KN, they have no real effect on HP and you have to oil them and **** your MAF up. I still use a stock paper filter.