Knock Options

[90GSX]

Well im experiencing knock and im not sure whats causing it. My car has been really doggy of late, so i hooked my logger back up to see what was going on. Well when i hit the gas, even just barely, it jumps up to 43 counts of knock, even when im not boosting yet, through every gear and cruising. I have replaced the knock sensor, and i do have lifter tick when i start up, that goes away after the car runs a couple seconds. I dont think my engine is knocking, im imagining if it were, it would definatly be audible. i did a boost leak test, and logged my car when i put my boost controller on (14psi) and everything was fine, so i guess i could do another and see if that could be causing it. The wierd thing is after i drive it for a while, the knock would just stop, and it would run fine again, then start reading knock, then stop. im kinda stumped on getting it to quit. any ideas? thanks

[smrtkd69]

run a quick resitance test on the injectors, im assuming stock 450's, might be time for replacement

[turbohcar]

Do old 450's usually go bad or is this a rare experience? I've got some knock while cruising but when I accelerate it goes away. I always attributed it to rich knock.

[asiankid91]

i am geting knock all the time to, i am runing 550 with a translator and it still wont stop knocking. when i am crusing i peg 43 counts but its weard if i rev it and bounce rev limter it all go away. i am thinking it just mite be rich knock. me and nc (nate) tuned it for like 2 hours and it ran fine its just when i first start it up and take off it runs so shity i just think its the cold weather

[90GSX]

The knock goes away when i let off the gas, but picks up again when i push it in. But it will go away after about 10 minutes of driving, then occasionally do it while im driving

[turbohcar]

Not yet. It's on my to-do list. Being that my low fuel trim is 94% and the rest are the lowest they can be 81% it must be taking as much fuel out as it can to compensate for an overly rich condition. I'll order the knock sensor on Monday.

[90GSX]

Yup

[natedogg]

The most common causes for phantom knock are:

Noisy lifters (may not actually be audible). Fix with 3rd gen lifters.
Ticking timing belt tensioner. Fix with new tensioner.
Bad knock sensor. Fix with new sensor.
Bad timing belt idler pulley or tensioner pulley. Fix with new pulley(s).
Bad balance belt pulley if you still have your balance shafts.
Low oil level.

[fastclipse82]

there was a similar post at gatewaydsm and this is why I told him:
ahhh, here goes. Check your cam angle sensor, knock sensor, lifters for tick, any loose bolts on the engine (especially the back), motor mounts (yes gabor, if theyre bad they can cause phantom knock) and ECU. If thats not it then check your fuel system and if you dont already have one, buy an EGT gauge and probe and watch what your temps are when you have high knock. Also, get it tuned. If the car is running good and there are no noticable knocking sounds coming from the engine then you most likely dont have real knock. 43 counts of real knock would be absofuckinglutely devistating to your engine and you'd have almost no power whatsoever. Odds are its phantom knock. Best way to tell, cruise with the rpms at 3500 in 3rd gear and punch it. If the knock stays low, its probably phantom knock (due to the ecu not seeing the knock while its in the lower rpm's, which is when the ecu is most sensitive to knock) The ECU reads real knock far more accurately at the higher rpms and ignores alot of the phantom knock. This is why you want to do everything possible before you get the knock elimator in your ECU (which is the final step). If you do have real knock and you get the knock eliminator then your ecu will ignore alot of the low rpm knock becuase it will be programmed not to read knock until 3200 rpm's which is when it becomes less sensitive. And if it is real knock then your screwed because your ECU will not pull timing at all and your engine is toast. phew. . .

[JMoushon]

I'd check base timing, make sure it is set correctly.

[turbohcar]

My base timing was set when the new headgasket was put on. If anything it's set too low. The timing belt tensioner was also changed then too. It does have the stock hydraulic lash adjusters and stock pulleys that came on the car though. Ordering knock sensor now....

[ncgalant]

I had a very similar problem. I didn't think the knock was real either. Turned out I had a bad injector or two and the knock was real.

[90GSX]

I wonder if it may be an injector because if i let off the gas, the knock immediatly goes away, then when i pick up the throttle it comes back and so on.

Oil level is fine, knock sensor is new, egt's run where they always been running, not exactly sure what "normal" is on it, but usually runs 1400-1500, depending on how fast im cruising.

[fastclipse82]

you have phantom knock. Like I said if the car runs even decently then its phantom knock. 43 counts of real knock would be absolutely devistating on any engine.