KNOCK, guage, sensor problem?

[84ttype]

Ever since I've installed caspers knock guage I have been noticing problems. Basically what happens is if I floor it from first gear, it always pings into the high yellow or red. If I hit it when I'm rolling in 2nd gear it "sometimes" goes high yellow or red once the boost hits(Its only at 7lbs right now too.) I'm not sure how audible the knock would be, But the engine doesn't even hiccup and sounds like its running perfect. I did check the knock sensor today and the wire was stretched pretty harshly so I gave it some slack but it didn't help the problem. I have the FPR set at 44lbs right now as well which is supossedly good for a 12 second run(its an Accufab unit from postons).

One thing I can think of is replacing the sensor(it is original after all) and checking the wiring. The only other thing I can think of is the motor shakes a little (NOS motormounts) I don't know if that would have an effect on the sensor (Measures vibration so maybe?). After that though I'm basically at a loss as to what to do. Can you guys help me out? (stats are in my sig.)

 

[BRAD_PADGETT]

I have the same gauge and most likely it is all false knock. When there is real knock the gauge will go up in sequence from green to yellow to red. When this happens you need to back off. I notice the same issues on my scanmaster as well. Constant increase in numbers is real knock. I have been tuning my alky kit and I will get false knock upon shifting where one light will go on. Any time the knock gauge goes up in order it's bad. Chime in anybody. Brad

 

[SLOW_85]

Ever since I've installed caspers knock guage I have been noticing problems. Basically what happens is if I floor it from first gear, it always pings into the high yellow or red. If I hit it when I'm rolling in 2nd gear it "sometimes" goes high yellow or red once the boost hits(Its only at 7lbs right now too.) I'm not sure how audible the knock would be, But the engine doesn't even hiccup and sounds like its running perfect. I did check the knock sensor today and the wire was stretched pretty harshly so I gave it some slack but it didn't help the problem. I have the FPR set at 44lbs right now as well which is supossedly good for a 12 second run(its an Accufab unit from postons).

One thing I can think of is replacing the sensor(it is original after all) and checking the wiring. The only other thing I can think of is the motor shakes a little (NOS motormounts) I don't know if that would have an effect on the sensor (Measures vibration so maybe?). After that though I'm basically at a loss as to what to do. Can you guys help me out? (stats are in my sig.)

If it's showing some lights, it's hearing something. Could be alot of causes for that. http://www.geocities.com/rad87gn/tech/knocklist.html
If your only running 7#'s boost, 44#'s is way to much fuel pressure.
Your not even running stock boost levels.

 

[Bat]

Less for Hot Air

Don't go by the rule for fuel pressure of the IC cars. These run and work much better on less.

 

[TurboBuickSix]

There is no "rule" for fuel pressure v.s. et or power etc.Every engine needs something different.The same 2 motors on the same boost level~ one may need 4 more psi fuel than the other for no apparent reason.What you need to do is hook up a good scan tool like turbolink or directscan and see what you have.The caspers gauge is to alert you to an issue that needs to be further investigated by more sophisticated diagnostic tools.If it's rich enough to knock you should smell a strong fuel smell at times.You need a scantool to see what the ecm is doing in order to get a better idea on your tune.Never go by exactly what works for someone else,it could be totally wrong for your car and work perfect for theirs.

 

[84ttype]

Ok, heres an update: I tossed my A/C heat shield because I noticed the lower valve cover bolt and the downpipe were hitting it. now the downpipe has about a half inch of room where it bends to go under the A/C and a little more than that by the lip on the firewall and by the heat shield under the car. the knock gauge no longer goes "straight" into the red but occasionally still progresses into the red quickly (fast enough that it hits red before I can let off the gas!). other times if I roll into it I'll get the third green or first yellow light. It doesn't seem to be running rich either. I was looking into getting a direct scan setup for my can anyway, so thats looking like a must. My neighbor who rebuilt the motor suggested also getting an alky kit to see if it is a true knock, so I'll probably do that as well. any other thoughts guys?

 

[84ttype]

Important update! while driving home tonight I drove through sprinklers and noticed that... when My wipers are set on high the knock sensor goes up one light each time the wipers make a sweep???? can anyone explain this????

 

[cool 84]

Important update! while driving home tonight I drove through sprinklers and noticed that... when My wipers are set on high the knock sensor goes up one light each time the wipers make a sweep???? can anyone explain this????

Sounds like false knock. Throw some racegas in there and if the knock remains exactly the same, it's false.

 

[Squid4life]

Important update! while driving home tonight I drove through sprinklers and noticed that... when My wipers are set on high the knock sensor goes up one light each time the wipers make a sweep???? can anyone explain this????

either the wiper linkage is hitting something, making it read false KR, or you need to try fixing a ground or two. Where did you ground the gauge? Have you checked the grounds on the back of the head?

 

[Jerryl]

.......... Have you checked the grounds on the back of the head?

Ground wires are at PS front on a Hot Air. :biggrin:
(I know you knew that)

 

[TurboBuickSix]

Important update! while driving home tonight I drove through sprinklers and noticed that... when My wipers are set on high the knock sensor goes up one light each time the wipers make a sweep???? can anyone explain this????

Electrical noise.Did you ever see those little metal capacitors with 1 orange wire coming out of it by the fuse box? If you can get one,or maybe there is one there already,they are very common.Some have a plug that goes to a fusebox ign or bat terminal and allows you to plug something on top sort of extending the plug out of the box a little.Plug your + into one of those and it will filter out this noise.I had this prob long ago on a 84 I had when I put the blinkers on with the KB KR detector,this was the fix.I could take a pic of one later if you don't know what I am talking about.

 

[Squid4life]

Ground wires are at PS front on a Hot Air. :biggrin:
(I know you knew that)

Do you also have a ground strap on the drivers rear head, going to the firewall? This is the one I meant to say, but I have been paralyzed from the neck up most days (new baby). :biggrin: