knock problems

[ajt86]

hey guys

i usualy tune alot of V8 trucks, im trying to help a friend with a 2002 buick regal 3.8 supercharged. heres his mod list.....

fenderwell intake
TOG headers
autolite 104 plugs
3.4 inch supercharger pulley
1.9 mod'd stock rockers

hes got 7* spark knock with the stock tune in it with that pulley, where do i start with his tune to try and get rid of his knock without pulling out all of the timing?

im hooking up my LC1 to it this weekend and doing some logs, just figured this is a popular combo and wonderd where i should be looking

[Russ K]

Every V6 that I've tuned has overly sensitive knock tables. I double the knock decay table & halve the knock attack table.

And verify the AFR with a wideband. I tune the 3800 SC to 11.5 AFR in PE. A 160*F thermostat will also help with the spark knock. And use at least 91 octane fuel.

Read here for more info:

http://www.hptuners.com/forum/showthread.php?t=8815

Russ Kemp

[Perforator]

Look at the afr spark table first. Depending on what afr he is commanding at wot it could add up to 6 degrees of timing. Nobody uses 160 degree thermostats anymore, stick with a 180. You could check out clubgp.com. There are a lot more 3800 enthusiast there.

[JerryH]

Christ, here we go again.
DO NOT SCREW WITH THE KNOCK SENSOR SENSITIVITY!
A proper tune will let you run incredible timing without KR, and raise MPG and performance without knock.

Telling someone who added headers, smaller pulley, 1.9 rockers to just turn down the knock table sensitivity, verify with a wideband (not not change anything, just verify it???), and go to a 160 degree T-stat (a jurrasic tuning method that was around before tuners becuase poeple did not know better, and the fact *IS* that it increases engine wear AND lowers MPG with *MAYBE* a 1/2 degree lowering in KR!) is not only BAD advice... for someone of your experience, it is almost inexcusable!

They've added mods that TREMENDOUSLY changed the amount of air going into the engine (pulley and rockers)... they TREMENDOUSLY changed the amoung of gases going out (headers).

1 - Whether you believe it or not, a VE tune should be the first thing done.

2 - Whether you believe it or not, a MAF tune should be done.

3 - Whether you believe it or not, a timing tune should be done.

4 - Whether you believe it or not, a tranny tune (shift points, TCC lock/unlock, etc...) should be done.

5 - Whether you believe it or not, a complete go through of the bin removing all instances of controlling RPM and speed limits via fuel should be done (you control limits via spark, not via leaning out the fueling to dangerous levels!)

6 - Then AND ONLY THEN, if they want to get more serious about tuning, THEN they go wideband and really dial things in... *if* they want to go to that level.

Sheesh! No wonder I rarely come here anymore! The misinformation and stubborness displayed means that no one advances in methodology and tuning effectiveness in YEARS because everyone thinks that there is only ONE way (the wrong way it seems, judging from the above) to tune cars around here.

Stock cars run around 2-4 degrees of KR from the factory, doing serious mods that drastically change the amount of air going in and going out means that it is normal for the KR to go up. I bet with JUST a good MAF tune that drops to stock or less levels or KR alone. The rest just makes the whole car better than stock in terms of KR.

If I had his car for an afternoon, I bet I could get that puppy to run 13's on a reworked bin that included modified 2005 GTP spark tables *and* 87 octane fuel with no more than 1-2 degrees of KR at most, and along with the performance boost, a nice 3-4 MPG increase on the highway.

[Russ K]

Jerry,

Hopefully a few more of my "misinformed" posts will prevent you from ever coming back. Your posts are of no help or value to anyone.

Russ Kemp

[g_am_er]

Hey Russ, I think I can speak for alot of us here when I say "I wish Russ would come "misinform" me." No really, please.
http://www.hptuners.com/forum/showthread.php?t=20033

[coachcrow56]

I have read posts and used advice from Russ K and Jerry H and my car runs just fine---learned a lot from both----why can't everybody just get along and do what is best for this forum!!!

[90 Regal GS]

Heh! *boxing anouncer voice* in this corner we have Jerry H weighing in at 3450 lbs capable of 150mph,Awsome gas mileage and tuning to remove kr! AND in this corner we have Russ K weing in at aprox 3000 lbs also capable of 150+mph and loves turning down the kr sensors BEFORE tuning! gentlemen are you ready? *DING* FIGHT!!


Russ I dont think anyone is trying to insult you when it comes to the 3800s but it has been proven by many you can remove most if not all of your kr with a good overall tune on most 3800s. As for messing with kr sensor settings I would say it is ok to mess with the recovery rate to get back to good timing faster but I would not mess with the attack rate much if any at all.

Is the stock kr settings a bit conservative? Probably yes. Gm designed it to last 100k miles+ without breaking. Most of us 3800 guys would like to keep it that way too and still be fast. And we have done that.

But I think to tell people to reduce the protective settings on a motor without trying to tune out the problem first is simply wrong on any car. (unless you have money to blow) I know I dont.

I mean it is like telling someone to turn off all the torque mgt for the transmission to get an extra 1/10th in the quarter. you might get a bit faster but at what cost to the transmission? replacing the trans every 30-50k?


As for the guy tuning the buick I would go with what Perf and Jerry have suggested. Oh and 160 tstats suck. Your buddies Buick is far from a race car. I am sure it is a daily driver more than anything else and should be tuned accordingly. Too many people try to tune for wot only and that is only 10% of the picture for most of us fwd family cars. Afr spark is a big one like Perferator said. If his pcm is commanding less than 12:1 afr wot, it could be trying to add a bunch of timing you cant use.

Performance and economy are absolutely possible with a 3800. And you absoutely don't have to mess with the kr sensor to do it. A 2002 bin is a much better bin than earlier years as well for tuning.
Will