FAQ: What is spark knock? What is KR (knock retard)?

Sometimes what we used to do on the 4G63 engines in our eclipses/talons/laser, was take the knock sensor out and put some Teflon tape on the treads then re-install. This would "deafen" the knock senor alittle bit and reduce false knock. never heard of it being done on these cars though.

96_Juggernaut wrote:

Sometimes what we used to do on the 4G63 engines in our eclipses/talons/laser, was take the knock sensor out and put some Teflon tape on the treads then re-install. This would "deafen" the knock senor alittle bit and reduce false knock. never heard of it being done on these cars though.

Yeah.... not crazy about that idea.

Thanks, tho.

Can anyone confirm it's a tunable variable with a tuning suite?

I think you can adjust (decrease) the amount of retard per degree of knock, effectively raising the noise floor. If not with DHP than with Tiny Tuner. I would never do this, though. The ZZP article sites a single instance after a built transmission was installed, and after the KR signal was analyzed on a scope.

An OEM engine/trans with bolt-on mods shouldn't generate false KR unless something is bumping the trans case, like the crossover pipe. They make a false KR dynamat kit for this. I would assume your KR is real until you can reproduce a similar graph to #4 when the engine is not in boost/under load.

I haven't and wouldn't do this on a street car. I have no problem believing my knock sensor. If you have mechanical parts making contact address that first. As stated - that guy was having issues with mechanical noise after a transmission rebuild, which is not normal. I can only assume something is _very_ loose inside the trans.

I see KR with a sudden throttle increase, then it immediately goes away as RPMs raise. Then im WOT with 0 KR.

If I can just get that initial KR to go away, I'd be a happy camper!

That is normal from my experience, the computer needs to see knock before it can correct it.

charlieRobinson wrote:

I see KR with a sudden throttle increase, then it immediately goes away as RPMs raise.

Do you have scans to go along with this? What conditions, exactly? From a stop? From highway speed? Every time you nail the throttle or only in certain gears/certain conditions?
Could be the moments needed to unlock the TCC and downshift? What if you hold in 2nd gear at 45 and punch it?

charlieRobinson wrote:

If I can just get that initial KR to go away, I'd be a happy camper!

What are you tuning with?

Have you ever done the "BBV Mod"?

Is that so? So i should always except to see knock retardation when I stomp the gas?

that's normal?

charlieRobinson wrote:

Is that so? So i should always except to see knock retardation when I stomp the gas?

that's normal?

BONE STOCK 3800's have KR. They all do. Every single one of them. It's programmed into the factory tune with torque reduction and all that crap. Why do you think that with the KR that you do have, your car hasn't exploded yet??? It won't. It was made that way. If you want to go faster, we tune and mod to get rid of it. Your response is exactly why I hate talking about KR. People read the thread and about how bad it is. Their cars were running fine until they go out and buy a scanner and see normal KR....they freak out for no reason. The whole "KR" fear is ridiculous IMO. Unless there's a serious problem to where the engine can't function as it should and knocks like crazy (bad gas as an example), it's fine. Tuning is the only way to get rid of it.

I tried to tune yours....didn't work cause of the '99 thing. Get it tuned.....and yes, you will see that KR every single time you stomp the throttle, then it disappears. That's how the factory programmed the PCM.

You'll need a tuner to do this, but the way I'd check for false KR is to program a less advanced timing table in place of the OEM version. There are different ways of doing this. You can just replacing the stock timing values, or you can actually wire a stepped potentiometer to your IAT sensor wire, rewrite your IAT table in 1º steps, then control your timing on the fly with the happy knob.

Being able to adjust your timing in steps from from hot to less-hot should make all your true KR drop to zero. Any leftover false KR (caused by mechanical whatever) should then be revealed.

Re: seeing the flash KR every time you step on the gas - it can be tuned out. Your car won't make peak power, but you can have a zero KR car if you tune for it, and still have more power. This is always the case even with N/A cars. The closer you are to the verge of detonation, the more power that's made. The difference is, on boosted engines, detonation is more likely to chip pistons, so tuning for zero KR makes sense in some situations. Track racing is one good example. You'd think tuning for max power is the goal, but reliability is a real concern. I'd rather race a 95% reliable engine with 80% power than an 80% reliable engine with 95% power.

Scott, i'm not 'worried' about the KR. I just want the power it's robbing from me!

AA, good idea on tuning the timing down to see if i still see KR. That should be a perfect clue if I still have KR after if it's false knock, right?

Like I said, I only see KR when I jump on the throttle real quick. Once I let off and then ease into it instead, my KR is 0! WOT is 0 KR!

It's just that initial pedal to the metal that spikes my KR.

It's not horrendous, just annoying!

Im stuck on what Scott told me before about fuel ramping. That the stock PCM ramps fueling until you hit WOT.

Can I be pretty sure its just my fueling tune?

Could it be noise or something else related to the traction control causing the KR also? Does it happen regardless of whether the TC is on or off?

charlie get the dynamat for between engine and tranny thing. it causes a lot of false knock

Tuner. Tuner tuner? Tuner tuner tuner tuner, tuner tuner tuner.  

charlieRobinson wrote:

Scott, i'm not 'worried' about the KR. I just want the power it's robbing from me!

You have 0 KR at full throttle. It's not robbing any power from you. It's protecting itself during the fast change in airflow. Nothing to see here. It's totally normal. Move along.

Once you have started tuning it's something you can work on, but seriously don't worry about it until then.

Do you guys lower the value for the temperature it takes for the KR sensors to activate?

Any harm in dropping it from 158 to 100?

And what do you have your min RPM and min MAP set at for KR detection?

There's no reason not to set KR sensor activate temp to -40ºF.

RPM and MAP should be okay stock.

Why do you suppose GM set it relatively high?

No idea. It's always been a mystery. I believe the Regal GS and Pontiac GTP have lower KR activation temps. But, one or both of those cars will throw a code if a 160º t-stat is used, whereas the Riv will not. I agree with the 160º t-stat code - running these isn't the best idea for a year-round daily driver.

I did multiple scans with both Torque and DHP and received 0 knock all the way up to the top of 2nd gear (~85mph) and everywhere in between (cruising at city and highway speeds). Does this seem okay for what I was running (3.5", 3" DP, glasspacks, FWI, 180*, and AL104s)? I saw at most 10 psi of boost. I'm going to go back and scan some more today now that I have my 3.4" on. If a knock sensor was bad wouldn't it throw a check engine light? I was reading that you can test them with a multimeter but I don't know what values to look for. Are there any other tests I could do to make sure that they are working properly?

if you see no KR with your mods, stock timing, and a 3.4" pulley, you have a freak Riv. Congratulations.

I just scanned with my 3.4 and still none. I think somethings wrong here.

It isn't impossible to have 0 KR. I know the feeling - had a hard time getting any after I cleaned the fuel injectors. Try a run just past 2nd gear, so it shifts into 3rd and hold it for a sec or two. That's where you'll likely see it. Be safe - log and playback; don't monitor real time.

Plug in your scanner, turn the car "on", not running. Start your scan. Take a hammer and tap the block near the knock sensors. You should see some slight blips.

If you're actually knocking, you can hear the knock. It's a slight "ting, ti-ting, ting" sound under boost.

I've never heard of a code being thrown for a bad KR sensor, nor have I heard of a sensor going bad.

AA wrote:

Plug in your scanner, turn the car "on", not running. Start your scan. Take a hammer and tap the block near the knock sensors. You should see some slight blips.

I like this option. Where are the sensors at?

Low middle of each side of the engine, nearest to cyls 3 and 4. One sensor in front, one in back.

You can see one near the starter in this pic: