Knock retard gurus, please step inside

I'm getting desperate here.

I get between 12-15* of knock retard during WOT (70%+ TPS) above 3,000 PRM WITH or WITHOUT the blower. I have disabled low octane retard along with burst knock. Last weekend I ran 110 leaded mixed 60/40 with 92 octane in the car (no cats) and still got the same KR. I've gone over every inch of my exhaust and "fixed" anything that could be close enough to hit anything. The plugs and wires are new and the valve covers have never been off the car.

I have many many logs from Datamaster if anyone wants to see them. I have plenty of fuel and plenty of spark.

TTT

Do you have a lt4 knock modual?....Thats alot of knock your getting, Something is setting it off pretty good. Odviousely, its false knock, most likely your valvestrain is setting it off, if you have lt1 edit you can limit the amount of timing your computer takes out when it hears this faulse knock.

Originally posted by MEAN LT1
Do you have a lt4 knock modual?....Thats alot of knock your getting, Something is setting it off pretty good. Odviousely, its false knock, most likely your valvestrain is setting it off, if you have lt1 edit you can limit the amount of timing your computer takes out when it hears this faulse knock.

I've tried LT1 and LT4 KMs. The LT4 KM showed 3* less but the sampling data wasn't perfect.

I don't want to adjust the KS in Tunercat. When/if my motor does detonate, I want it to pull as much timing as it needs.

Thanks for the reply.

What? Nobody likes a challenge? :eek: :D

Do you guys need more info? :confused:

Not sure about your KR but if you ran leaded fuel you can kiss your O2's goodbye. I tried this last year and after 2 sets of O2's i gave up on leaded race gas and low lead Aviation fuel. If you getting that much retard even with that high an octane fuel, you may have to disable knock retard. Then you will have to trust your tune, so make sure its plenty rich. What do you mean you have plenty of spark? if your running to much advance then you may have found your problem

Originally posted by SMOKNZ
Not sure about your KR but if you ran leaded fuel you can kiss your O2's goodbye. I tried this last year and after 2 sets of O2's i gave up on leaded race gas and low lead Aviation fuel. If you getting that much retard even with that high an octane fuel, you may have to disable knock retard. Then you will have to trust your tune, so make sure its plenty rich. What do you mean you have plenty of spark? if your running to much advance then you may have found your problem

I've run 5 gallons of leaded fuel through my motor twice. Neither time did it affect my O2s. The second time, the fuel was diluted with 92 octane from the pump.

I meant that the car wasn't 'missing' and I have proper fuel delivery.

I replaced the KS yesterday. No change. :(

I may be way off regarding this, but isn't it possible to get detonation from too much fuel? I agree though, something sounds odd and maybe some wideband time would be worth your money to help get it dialed in.
I had a tuning glitch and it ended up being something as simple as my O2 sensor wire (passenger side) burning against the damned header. Once it was fixed, the car died of course. Why? The ignition FUSE had come loose. It didn't blow, there was just no contact. I double checked everything, bought a new ignition module, swapped coils, wires, etc and must have pulled the fuse 2-3 times just to be sure. I towed it to a local dealer and was seriously ticked at their $200.00 bill to reseat the thing. Lesson learned, I double check the dumbest things now. Either way, good luck and I hope my rambling isn't too far off topic.

Tech, that's a lot of KR and that must feel like your car hit a wall when it kicks in... if I were you I would first try to reduce spark advance in the midrange and see what happens... Then try putting a desensitizer on the knock sensor because it is obviously fake knock. Other than that I have no clue.

I shouldn't have to retard timing (stock tables) and I don't want to desensitize the KS. I want the motor to last.

Thanks for the suggestions.

High RPM and high TPS. What could it be?

I was getting the same retard, turns out the connector on the sensor was ruined by the headers. Anyone know where I can get a shorter sensor ? connector?

Where was the connector screwed up? The gray piece doesn't seem to be burnt or damaged and the section of wire that I can see looks fine.

The connector was off compleatly. It was heat distorted like it had been laying on the primary. My headers are not designed for a ks. They are racing headers. I am looking to run the ks anyway. I was implying that perhaps your ks is not working or that the wire is not delivering a compleate circut.

I had a problem with my KR spiking.

I found out that I had a bad connection for my coolant sensor. Previously a stripped blower belt had cut the wires for the sensor and it had been repaired BUT it appears that it also caused the wire to strip elsewhere and become exposed to shorting.

My clue came after I started seeing the coolant temp results from datamaster jumping all over the place.

Originally posted by 97TA-WS6-Con
I had a problem with my KR spiking.

I found out that I had a bad connection for my coolant sensor. Previously a stripped blower belt had cut the wires for the sensor and it had been repaired BUT it appears that it also caused the wire to strip elsewhere and become exposed to shorting.

My clue came after I started seeing the coolant temp results from datamaster jumping all over the place.

I'll pull the wire out of the harness and check the connection at the PCM. Thanks guys.

Any other suggestions?

Tech, in my opinion you can't add a supercharger on a car that is not supercharged and expect to use the stock timing tables. They were meant for stock, not a blower. Although it would make sense theoretically that the stock timing tables would work, in reality I don't think it would. Plus, you have tried a lot of things except changing the timing, I think its worth a try right. :D

As mentioned in my first post, this is with and without the blower. I have a ramair hood so I'll have to do is pull the belt and slap on my air box.

I left my new KS in the block and hooked my old one up to the harness (zip tied and taped to the starter). I got ZERO knock retard. The KS is picking up something from the block that 110 leaded fuel didn't fix. I heard very mild ticking which could have just been your standard stamped rocker arms. I'm waiting for it to cool down.

High RPM, high TPS, no audible noise, KS does not pick up knock if unless it's screwed into the block. My spark plug wires come from the top of the valve cover and come no closer to the KS than the stock wires. There is no miss and no arching. What could it be? :confused:

my bad, forgot

Just reduced timing on 80+ KPA and 3000+ RPM (where I was getting knock) by 10%. Same knock retard.

Unlike I thought before, I don't think it is based upon RPM or MAP. I can put it in high gear going up a hill which produces high MAP values but no retard. Similarly, I can rap out 1st or 2nd very smoothly and get no KR. At low RPMs I can bury the throttle and make the car jump all over the place without any KR.

Any suggestions?

What kind of ignition box u runnin? Maybe it has gone bad or something. I remember reading a post a while back about a guy that had knocking problems that he could not get rid of and once he swapped the box it was fine. Of course you would have to have had the same box before the blower which is unlikely... Just another thought...

I've tried it with a 6A and just the opti. I've also had two different coils on the car.

I just noticed that my right 02 mV are always higher when I get spark retard. The difference isn't really that significant, but the right is always richer.

I searched the board and found a thread where Injuneer told someone to test the KS circuit. I've got 4V+ coming from the wire and 3900 ohm resistance through the sensor. Everything checked out. :(

I guess I stumped the gurus... Normally I would be happy, but my car still runs like ass. :)

I have some kind of feeling it is something completely unrelated... it must be something real dumb but not that obvious. Do any other readings other than o2 mv's look off??? Have you tried new o2's??? That's someting I gotta do soon too and I think you need them even more because of that leaded race gas. Sorry man.

The O2s are fine. They are just as responsive as before the gas. I replaced them last summer when I had KR and there was no change.

The only thing I noticed is one side is always a little richer than the other. The difference isn't significant, but the right is always richer.

This one sounds very tough to chase down. After reading all of the posts the one thing that became obvious to me is it generally happens to you at about the same amount of vibration....which is either caused by a certain amount of load or RPM. Obviously false since it's below 100 KPA and it doesn't happen when you pull hard in high gear or 1st/2nd (especially since 110 octane didn't get rid of it either).

I had a bad false retard problem with mine (and still do mysteriously once in awhile....only occasionally now thank God) .....and it turned out to be the sensor itself. When my tuner went to remove it it spun around rather than unthreading from the block....it had become loose within it's own housing, you could shake it and feel it vibrate some, so ....it was actually knocking within itself, setting itself off :rolleyes: ....that's obviously not your problem though.

Since it's happening to you at the same load most of the time it's obviously a vibration of some sort that is very hard to track down. You can really never be sure of the exhaust as close as most systems come to our cars. Have you checked the A/C lines? They can clang around a bit and set things off. Even though it's ovbiously coming from the block from what you said about tying it to the starter ....it could be the block picks up these vibrations better than the starter. Any chance of header gasket leak?

Thanks for reading up on my continuing ATI install nightmare.

As I mentioned, the blower is bypassed but still bolted on the car. Someone from the LT1edit mailing list suggested that the mister nozzle for my P600B might be hitting something or that I might have a loose motor mount.

While I was under there I saw that this wasn't the case, but that the blower was actually butted up against the block. I pushed and pryed but couldn't move the blower. I assume the vibration of the motor could cause a bit of noise. The part of the blower which is touching the block is just below the water pump and on the discharge side of the impeller (near where Procharger is stamped). Is this a common thing?

At idle, I've tapped on my header and head with a long screwdriver and found that you had to hit it pretty hard to increase the knock count. I realize that the KS responds to frequency rather than volume, but I couldn't set the thing off without banging the sh*t out of it. For something to vibrate/bang hard enough for the KS to pull 10*, shouldn't I be able to hear it?

Is it normal to get some KR while free reving the motor?

Thanks guys. Your help is very much appreciated.

Reving the motor = no load = false knock too ....I've had this too. Isn't this $hit fun to track down .....

Originally posted by canbaufo
Reving the motor = no load = false knock too ....I've had this too. Isn't this $hit fun to track down .....

It's funny. I started losing my hair shortly after I bought the blower. :D

Jason,
I looked at the datamaster logs that you sent and e-mailed you back, but just thought I'd share what I found.

Your knock does not START at high rpm OR high map. 90% of the retard you see is in fuel trim cell 11, with rpm's at about 2800, map at about 65-70. Also throttle is between 1/4 and 1/3 (going by TPS %). Eventually you might get to a higher rpm or tps, but that is not where the knock starts.

Some of this is false knock and some of it is real.
If I were you I would track down the false knock and pull some timing out based on where the knock first starts in the logs and go from there.

Not sure what else to tell you, but I wish I could help more. :(

Originally posted by Dan K
Jason,
I looked at the datamaster logs that you sent and e-mailed you back, but just thought I'd share what I found.

Your knock does not START at high rpm OR high map. 90% of the retard you see is in fuel trim cell 11, with rpm's at about 2800, map at about 65-70. Also throttle is between 1/4 and 1/3 (going by TPS %). Eventually you might get to a higher rpm or tps, but that is not where the knock starts.

Some of this is false knock and some of it is real.
If I were you I would track down the false knock and pull some timing out based on where the knock first starts in the logs and go from there.

Not sure what else to tell you, but I wish I could help more. :(

According to the logs which I sent (the most recent I have at work), that may be the case. While driving I can bury the throttle and everything is fine until I hit 3k RPMs and BOOM a large spike. I get peak KR around this area. I've pulled timing from 3000+ PRM and higher MAP values (can't remember the exact number) without any change.

How did you determine which knock is real and false? I assumed running race fuel would rule out false knock since I still got very similar KR.

I appreciate the help!

The only thing I can add is to actually remove and reseat the knock sensor into the block, using as accurate a torque wrench as you can. I have seen a few cases where it was just a little too tight, and this caused it to be too "sensitive", setting off prematurely.

-Ernest
95 Z

Thanks Ernest. I have replaced my KS and was sure to torque to 14 ftlbs.

Originally posted by Tech
While driving I can bury the throttle and everything is fine until I hit 3k RPMs and BOOM a large spike. I get peak KR around this area. I've pulled timing from 3000+ PRM and higher MAP values (can't remember the exact number) without any change.

You're saying "bury the throttle"....I don't see TPS get above 1.X volts ever. Nor does TPS% get much over 35ish. Have you checked that the TPS goes from the .65v closed at idle that you have to 4.25+ volts at wot? Does it go up linearly?

Again, the knock retard is coming in before 3000rpm...usually starts right at 2700rpm and about 60-70map.

Check the TPS though....

Originally posted by Dan K
You're saying "bury the throttle"....I don't see TPS get above 1.X volts ever. Nor does TPS% get much over 35ish. Have you checked that the TPS goes from the .65v closed at idle that you have to 4.25+ volts at wot? Does it go up linearly?

Again, the knock retard is coming in before 3000rpm...usually starts right at 2700rpm and about 60-70map.

Check the TPS though....

I'll check the TPS, thanks.

The reason why you didn't see 100% TPS is because the car had the blower on it and it hadn't been tuned. Like I mentioned, those were the only files I had at work. I'll gladly send you some updated ones tomorrow.

Sure, send me whatever you want. I'll help as much as I can. :)