Tuning help

[Slowhawk]

Looking for suggestions to help cure my knock problem.
The car get's KR had WOT.Up to 14 degree's suddenly.Part throttle there is none.I'm ussing a Scanmaster and A/F is around 780mv.BLM's are 139 at idle and 130 or so cruising.

Any suggestions?

Car setup:
009's,Street chip,hot wired 340L,front mount intercooler,T44,ATR headers,test pipe ATR 2 1/2 catback,ported intake,poly driver side motor mount.

Thanks

 

[strikeeagle]

You don't say what your boost is?

 

[Slowhawk]

Oop's sorry

15lbs on the gauge

 

[strikeeagle]

Have you been able to run 15 PSI with no knock using the same gas recently?

What has changed?

 

[Slowhawk]

The whole setup has changed since last summer.I had no scan tool then and you could hear knock.
Since then I did the intank,hotwire kit and 009's(from 36).Also installed the poly mount.I'm thinking of turning the boost back to 10psi and work my way up.The gas is Mobile 93.

 

[strikeeagle]

I will tell you this - today's pump gas is absolutely lousy. My GN has lots of bolt-ons that should make it better able to run more boost without knock, but not so, because it just hates pump gas. I have resorted to running 100 octane unleaded all the time - although at $3.49/gallon in 2002 and $4.49/gallon in 2003, it's more than my wallet can take. I'm definately going to get up off my azz and go to methanol in 2004.

Good luck chasing your problem. BTW, if you want to be sure it's octane related, try adding some 100, or even leaded race gas. Just keep an eye on your O2 sensor's health if you do the latter.

 

[Slowhawk]

I turned the boost back to 10-12 psi and the KR went to 7-9 degree's.
Is there a way to check timing with the Scanmaster?

I have fuel pressure set to 44psi (line off)..How high can I go?
How about Octain booster? Race gas is hard to get around here.

 

[strikeeagle]

Well, knock problems are a PITA.

First of all, is it real knock or false knock?

Let's say it's real knock. OK, is it octane related, A/F related, or something else?

Let's say it's A/F related (i.e. lean knock).

How's your fuel delivery system - pump, hot wire, AFPR, lines, hoses, filter?

I guess what I'm trying to say is even with crappy pump gas your car shouldn't have a bunch of octane related knock at 10-12 PSI.

Do you believe your O2 sensor? How are your O2 cross-counts?

 

[Slowhawk]

Right now I'm leaning towards false knock.A/F on my meter is at around 11-1 and .860 on the scanmaster.This was at 10lbs of boost.I get knock when it goes under boost.The fuel pressure does rise at this time.The 02 is new.

I installed a whole new exhaust including downpipe.It was very close to the frame and I did dent the pipe for more clearance(maybe a 1/2 inch of clearance).I will go over this before driving it again.
The car pulls incredable.In this 35 degree day it is spinning the tires at 55mph when it goes under boost.

I'm also leaning towards the chip.It might have too much timing in it.Can I check the timing with a Scan master?

 

[strikeeagle]

I'm not familiar with Scanmaster, so perhaps someone else can chime in.

Imagine how fast you'll go when your knock sensor isn't pulling out a bunch of timing.

Good luck hunting things down!!!

 

[Pronto]

Run your gas down then try 6 gals of Xylene homebrew (3 to 1 with mmo)with 10lbs of boost then keep raising it to see what happens. What street chip do you have?

 

[V6POWER]

Don't use more than 30% xylene. I put one gallon of xylene and four gallons of 93 (20%) in a five gallon can with 0.5 oz. of Marvel Mystery oil. This gives me about 98 octane.

 

[5ltretr]

doesnt anyone here think the BLM's of 139 is to high?

I would fix that first.

 

[Slowhawk]

Originally posted by 5ltretr
doesnt anyone here think the BLM's of 139 is to high?

I would fix that first.

What should they be at?? 120??

Also my idle speed is 1050rpm on the tack and Scan master.

I think I'll check out the vacuum setup and reset the throttle stop and voltage.

 

[Mightysix]

BLM'S should be at 128..... Your idle is alittle high. I would bring it down to 800 os so.

HTH, Mike

 

[5ltretr]

your IAC's should also be around 0-10 in park and under 30 in drive.

its weird on my car , in drive it sits at 29-30.

never less

 

[Slowhawk]

Thanks guy's

I'm going to check all this out tommorrow.Was hoping I could throw it all together and it would be fine I just need to spend some time fine tuning it now.

 

[5ltretr]

good luck !

you might want to try a different 009 chip.

post back if you find the problem.

 

[Slowhawk]

Ok,I did some more work with no positive results.

Turned set screw on tb to lower idle to 850rpm and reset TPS to .42v.
Added octain booster
Checked for vacuum leaks ect.

I still get 9 degree's of knock with 10lbs of boost.
Idle is unstable (choppy)but doesn't die.Vacuum at idle is 16-18 inches.
BLM's are 136 at idle and 110-130 at cruise.
IAC is 10-15 at idle.
WOT 02 voltage is .820-.860 tried leaner/richer with no change in KR

How can I get the BLM's down?

I'm leaning towards the KR is fake.I can feel a vibration on heavy throttle from under my seat-towards the rear of the car.I'm going to replace the tranny mount since my motor mounts before were toast.

Are tranny mounts known to go bad?

Thanks

 

[5ltretr]

fuel press?