Knock Sensors Pulling Timing
Knock Sensors Pulling Timing This is on a procharged car so don't mind the nitrous talk... So I went out to re-tune the car today after adding a 2nd stage 50 shot on top of a 120 shot 1st stage (cold fusion plate). I am getting ready for a half mile event so I was doing 4th/5th gear pulls. Bottle pressure at 950psi and 4th pulls real clean, shift to 5th and its humming until about 5300 RPM when the computer pulls 3, 5, and then 10 degrees of timing. Shut it off, pull over, and then pull #8 plug. No signs of detonation so I put a new plug in and make another pull. This time it breaks up in 4th gear and I shut it down.
Setup is a forged 370 with ported 243 heads running 9.6:1 CR and a procharger at 11psi. These runs were on a 9 NGK plug running E67 gas (flexfuel) and 10.5 gas scale AFR. I locked the timing in at 14 degrees. I almost seems like there is too much heat buildup or the rings are too loose after the engine gets hot causing this to happen. I will post some plug pics later and I still need to pull the other 7 to see what they look like. Any help is appreciated.
Setup is a forged 370 with ported 243 heads running 9.6:1 CR and a procharger at 11psi. These runs were on a 9 NGK plug running E67 gas (flexfuel) and 10.5 gas scale AFR. I locked the timing in at 14 degrees. I almost seems like there is too much heat buildup or the rings are too loose after the engine gets hot causing this to happen. I will post some plug pics later and I still need to pull the other 7 to see what they look like. Any help is appreciated.
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
Knock sensors only detect noise...they do nothing else.
Any controlling actions are down to whatever the tuner/ecu has been told to do based on whatever noises they are hearing.
It's up to the tuner to ensure they are configured correctly and they only respond in such a manner to actual confirmed detonation.
Any controlling actions are down to whatever the tuner/ecu has been told to do based on whatever noises they are hearing.
It's up to the tuner to ensure they are configured correctly and they only respond in such a manner to actual confirmed detonation.
Knock sensors only detect noise...they do nothing else.
Any controlling actions are down to whatever the tuner/ecu has been told to do based on whatever noises they are hearing.
It's up to the tuner to ensure they are configured correctly and they only respond in such a manner to actual confirmed detonation.
Any controlling actions are down to whatever the tuner/ecu has been told to do based on whatever noises they are hearing.
It's up to the tuner to ensure they are configured correctly and they only respond in such a manner to actual confirmed detonation.
ive seen some vehicles ive tuned pull timing bc of something like exhaust or body rattling or hitting metal. I would check everything for any noise that could cause false knock.
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
Yeah but I would think the sensors would "hear" the knock on the 1st 4th gear pull as well. What would have changed between gears, between pulls? I am going to try more E and a colder plug to see if that buys anything. I am probably adding about 500HP onto the base engine power so a 9 plug may be too hot.
Knock sensors hear noise, not knock. Whatever then processes that signal tries to determine if there is knock within that noise. Between you, the tuner, the ecu etc it is up to you to tell the ecu how to filter out real knock from all other noises.
And what changes between 1st and 4th ? load of course. There is always more load against the engine in higher gears.
And there are guys well well north of 1000hp who dont need 9's, so that is unlikely. Most dont even use 8's
So no, all that needs done is it tuned correctly and the ecu configured so that it only responds to actual detonation. Not random noises that perhaps might sound like it.
If the ecu for whatever reason cannot be configured to do this, then that aspect needs dumbed down so it does nothing.
Which all comes down to the tuner doing their job and determining whether there is any actual detonation.
Sorry for the confusion but both pulls involved 4th gear. The pulls were just separated in time by about 5 minutes. The first pull got me into 5th gear before pulling timing while the second pull only lasted a a few seconds in 4th before timing was pulled. I still need to check the other plugs to see if there is an issue.
Trending Topics
So I pulled the rest of the plugs and 1, 3, 5 had signs of detonation. 1 was the worst followed by 3 then 5 that maybe had a few oil specks. The other complicating factor is that the engine is running about 1 full AFR point richer (11.3->10.3) than normal with or without nitrous. Going back through my logs this has been happening for a couple months. Only change is the new nitrous plate which could very well be unrelated. I switched in a new wideband, same thing, rich. Switched banks for the wideband, same thing. Any thoughts?
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo 9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
But you're asking if it is failing....but in what way is it failing ?
Is it not working, is it not holding pressure, is it leaking ? What is the mode of failure you're suggesting ?
Initially the thread was about possible detonation....then you mention the engine might be running richer ?
Richer from what, when ? etc etc
So how are you getting a failing FPR from this ?
Is it not working, is it not holding pressure, is it leaking ? What is the mode of failure you're suggesting ?
Initially the thread was about possible detonation....then you mention the engine might be running richer ?
Richer from what, when ? etc etc
So how are you getting a failing FPR from this ?
Detonation is real
Reviewed logs to find out has been running rich, not sure why
Started troubleshooting by moving the wideband around to see if it was a single injector or single bank issue. Its not.
The tune hasn't changed.
Can't think of any obvious reason for the car to be running rich other than the regulator failing.
Reviewed logs to find out has been running rich, not sure why
Started troubleshooting by moving the wideband around to see if it was a single injector or single bank issue. Its not.
The tune hasn't changed.
Can't think of any obvious reason for the car to be running rich other than the regulator failing.
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
It would be very unusual for a regulator to fail, and give too much pressure.
If the car ran well before...and is now detonating and too rich, that doesnt make any sense. It should be less likely to see detonation with that richer mixture
So something must be off on the tune. On those runs is it getting the timing you think it should be getting ? Have you any logs ?
Although in your first post, you suggest the vehicle has just been tuned ? So there is no previous data to compare to ?
When was the 11AFR and when was the 10AFR runs ? Is this before and after this retune or other ?
If the car ran well before...and is now detonating and too rich, that doesnt make any sense. It should be less likely to see detonation with that richer mixture
So something must be off on the tune. On those runs is it getting the timing you think it should be getting ? Have you any logs ?
Although in your first post, you suggest the vehicle has just been tuned ? So there is no previous data to compare to ?
When was the 11AFR and when was the 10AFR runs ? Is this before and after this retune or other ?
Yes, the only difference in tune was the 14 degrees of flat timing from 4000 RPM on. I tried it again with the previous tune which ramps to 18 degrees and the car is still rich. I logged the timing and it is ramping as it should. The "new" AFR is something that randomly showed up a couple months ago during which time the only change was swapping out from a 1 to 2 stage nitrous plate. Wasn't looking for AFR changes when logging a couple months ago but now that it is breaking up when spraying I looked at everything I could.
How are you just now realizing that it's been running rich? Do you not watch your wideband while driving? Also it sounds like you have logs but just noticed it was rich in the logs but how would you have not noticed it in the logs before? Just seems a little far fetched to me.
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
Verify all sensor readings are as expected. Compare like for like runs....and see if injector pulse widths are the same, yet yielding vastly different AFR's. That would give more indication of a problem than anything else
But it sounds here as if lots of changes have been made, and the end result is different running, which is surely to be expected ?
As toy where the detonation has appeared from...I'd be more concerned about that
But it sounds here as if lots of changes have been made, and the end result is different running, which is surely to be expected ?
As toy where the detonation has appeared from...I'd be more concerned about that