how do you know?
TECH Apprentice
Joined: Feb 2002
Posts: 363
Likes: 0
From: tega cay, SC
Re: how do you know? you'll hear something that sounds like marbles in the motor at WOT. also you can autotap to find out. if you have ur pcm reprogrammed then you pry also have your knock sensors tuned down so they don't pick up false knock.
TECH Fanatic
Joined: Nov 2001
Posts: 1,975
Likes: 2
From: SW Florida
Re: how do you know? Easy ...
First of all, the only way you will know that you are getting timing retard is to use ATAP. It will tell you how many degrees you are getting.
If you are getting a lot of knock retard from the knock sensors, you need to find out if it's because of actual detonation (knock sensors correctly doing there job) or "false knock" from maybe the valvetrain or banging exhaust pipes, etc.
Pour in a couple of gallons of 100 octane no-lead race gas to an almost empty tank. Run the car until the race gas is completely dispersed thoughout the fuel system. Make a WOT run and check to see if ATAP shows knock retard. If it still shows the same amount of KR as you had while using pump gas, then you have false knock. If not, you were getting the previous knock retard due to detonation. Unless your car is running lots of boost, or running [extremely lean] it should never get KR on 100 octane no-lead race gas.
Ron,
First of all, the only way you will know that you are getting timing retard is to use ATAP. It will tell you how many degrees you are getting.
If you are getting a lot of knock retard from the knock sensors, you need to find out if it's because of actual detonation (knock sensors correctly doing there job) or "false knock" from maybe the valvetrain or banging exhaust pipes, etc.
Pour in a couple of gallons of 100 octane no-lead race gas to an almost empty tank. Run the car until the race gas is completely dispersed thoughout the fuel system. Make a WOT run and check to see if ATAP shows knock retard. If it still shows the same amount of KR as you had while using pump gas, then you have false knock. If not, you were getting the previous knock retard due to detonation. Unless your car is running lots of boost, or running [extremely lean] it should never get KR on 100 octane no-lead race gas.
Ron,
Re: how do you know? banging xhaust WILL do it. My duals were bangin on my DSloop, and that dayum thing drove me nuts. only under hard accels. I go to the track and only run a 13.2-13.3 when before the bangin DSloop I run 12.8. Car feels sluggish on take off, about half track, no more knock and zip off i go.
Re: how do you know? You mean the brace that runs underneath the tranny and has 4 bolts? Not sure how to remedy that one. Mine has been off and I only got minimal knock a few times on decel while in gear say about 5K. It was the exhaust that caused it, kinda sounded like a backfire of some sort, pretty loud.