mild detonation... with 87 octane and 10deg advance???

Foxfan88

My Grandpa has great wood.

Sep 13, 2004

2,487

4

0

Miami, Ok

Nov 20, 2005

#1

• Nov 20, 2005

• #1

ok i usually put 89 octane in my car. no detonation, by the last week i have put some 87 in. I run (what i hope is) 10 degrees advance. and sometimes, like say going up a hill or anything other common spark knock scenario, i will hear some slight detonation.

this motor is stock 137k motor, the motor seems to be a tad weak. could some carbon buldup contribute to this??? or is gas really crappy now or something??

 

DMAN302

My mom says thanks for the pearl necklace.

Nov 8, 2003

2,120

2

59

windsor, Canada

Nov 20, 2005

#2

• Nov 20, 2005

• #2

You hope it's 10Deg???? how exactly did you set the timing if you think it's 10? you need to confirm your timing..while you at it check your balancer for any wabble..it may be spun and timing possibly off due to that. Remember any wabble in the balancer is more than a bad thing and must be replaced ASAP.

 

srothfuss

Last night I stabbed the same guy 7 times in a row

Oct 17, 2004

1,796

3

0

Woodward Ave.

Nov 20, 2005

#3

• Nov 20, 2005

• #3

Regardless of your timing setup.. Carbon buildup inside the combution chambers heats up (with the engine) and pre-detonates your air/fuel mixture under loaded conditions like that. The reason that 89 octane doesn't give you those problems is because the higher the octane the harder it is to ignite the gas...

Advancing your timing (and still running 87) will only make things worse.

Retarding your timing will help (but kill more performace)

 

Skoobie

Damn...Tyler65's hot!

May 25, 2003

655

0

17

Vancouver, WA

Nov 20, 2005

#4

• Nov 20, 2005

• #4

Agreed, check your balancer for wabble. Mine bounced around like a fish out of water. Turns out I had my timing advanced 6 deg farther then it acutally was due to the outer section spinning, causing the marker to be inacturate. That aside you can do major damage to your crank if you let something like that go

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

34

129

Nov 20, 2005

#5

• Nov 20, 2005

• #5

Dont rule out a bad tank of gas either - you mentioned this happened after filling it up.

Good luck.

 

Foxfan88

My Grandpa has great wood.

Sep 13, 2004

2,487

4

0

Miami, Ok

Nov 20, 2005

#6

• Nov 20, 2005

• #6

yeah started happening with this tank of 87

oh and the "i hope" part was because i have the cheapy autozone timing light. i am pretty sure its 10 degs, because i took it to votech and checked with a GOOD snap on timing light and it was at 10 so the cheap light works good.

and the balancer has a SLIGHT wobble.
what causes a balancer to go bad anyway???
and i happen to have a spare balancer off the longblock i am rebuilding. Think i should swap the one out for the one from the longblock. It should be good and when i get my motor done i am pulling my motor and all the parts i need is coming from my current motor.

so lets get this straight.... the balancer should have ABSOLUTLY NO WOBLE AT ALL?

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

34

129

Nov 21, 2005

#7

• Nov 21, 2005

• #7

Foxfan88 said:

and the balancer has a SLIGHT wobble.
what causes a balancer to go bad anyway???
and i happen to have a spare balancer off the longblock i am rebuilding. Think i should swap the one out for the one from the longblock. It should be good and when i get my motor done i am pulling my motor and all the parts i need is coming from my current motor.

so lets get this straight.... the balancer should have ABSOLUTLY NO WOBLE AT ALL?

Click to expand...

The balancer can be deceiving because of the shape of the outer ring. It can almost be hypnotizing when looking at it, while idling.

There is an elastomer sandwiched between the inner and outer ring on the balancer. As that elastomer starts to take a poo (age, sustained high RPM blasts, tons of power spooling it up quick, etc) it starts to let the rings separate. So the outer ring can slide orbitally, and your timing marks are off. Or it can shift backwards (this is pretty common - what mine did). It is like someone hit one half of the outer ring with a hammer. So it will have excessive run-out. WIth the car off, I like to simply get my nose up to it and inspect the rubber and rings. You can see the relationship of the inner and outer ring pretty well.

Good luck.

 

Foxfan88

My Grandpa has great wood.

Sep 13, 2004

2,487

4

0

Miami, Ok

Nov 21, 2005

#8

• Nov 21, 2005

• #8

i took it off today. The rubber was starting to dry out and crack, the spare one i had was much much better.

at idle it still looke like it wobbled some. But i watched it when revving up and it was pretty straight..... so. i guess thats it.

 

DMAN302

My mom says thanks for the pearl necklace.

Nov 8, 2003

2,120

2

59

windsor, Canada

Nov 21, 2005

#9

• Nov 21, 2005

• #9

The vibration in a balancer will reduce the life of the crank bearings...I would spend the money on a new unit and when the motor is ready to be balanced you can use the balancer known to be good.

 

Skoobie

Damn...Tyler65's hot!

May 25, 2003

655

0

17

Vancouver, WA

Nov 21, 2005

#10

• Nov 21, 2005

• #10

After I replaced my balancer I had no wobble at all I would think about getting a new unit...

 

M

misl302

Member

Apr 29, 2003

40

0

7

WI

Nov 22, 2005

#11

• Nov 22, 2005

• #11

Regarding the possibility of carbon build-up, I think I've heard of a chemical (maybe household) that maybe can be poured into the spark plug hole to disolve the carbon. Hmm...maybe that was a dream.

 

srothfuss

Last night I stabbed the same guy 7 times in a row

Oct 17, 2004

1,796

3

0

Woodward Ave.

Nov 22, 2005

#12

• Nov 22, 2005

• #12

You can use "Sea Foam" sucked in through vacuum lines to clean out all of the carbon buildup in the engine. Becareful though, once you remove the carbon, you typically burn / leak more oil if the engine was neglected.

 

T

tjm73

Founding Member

Aug 3, 2000

2,418

2

48

Rush, NY

Nov 22, 2005

#13

• Nov 22, 2005

• #13

When were the O2 sensors replaced last? They can contribute to this kind of problem too.

 

Foxfan88

My Grandpa has great wood.

Sep 13, 2004

2,487

4

0

Miami, Ok

Nov 22, 2005

#14

• Nov 22, 2005

• #14

o2s havent been on there since i have had the car, too lazy to dish out 80$ to get them.....

 

DMAN302

My mom says thanks for the pearl necklace.

Nov 8, 2003

2,120

2

59

windsor, Canada

Nov 22, 2005

#15

• Nov 22, 2005

• #15

Well no 02 sensors are definately an issue you need to fix...that explains alot of the issues your having.

 

T

tjm73

Founding Member

Aug 3, 2000

2,418

2

48

Rush, NY

Nov 22, 2005

#16

• Nov 22, 2005

• #16

Foxfan88 said:

o2s havent been on there since i have had the car, too lazy to dish out 80$ to get them.....

Click to expand...

Without O2 sensors your computer is guessing at what ammount of fuel to use to get the correct A/F ratio. Combine that with any other sensors or systems not working 100% plus any mods you've made and it all adds up to poor performance and the detonotation you are fighting.

 

E

emagdnim

Active Member

Feb 5, 2003

391

15

28

Nov 22, 2005

#17

• Nov 22, 2005

• #17

Man get the o2 sensors your running in open loop all the time.

 

RacEoHolic330

I like to dress like a pretty girl

15 Year Member

Mar 4, 2003

4,014

1,698

203

Allentown, PA

Nov 22, 2005

#18

• Nov 22, 2005

• #18

Foxfan88 said:

o2s havent been on there since i have had the car, too lazy to dish out 80$ to get them.....

Click to expand...

hmmm.. no wonder your car takes its good ol' time getting down the 1/4 mile

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

34

129

Nov 22, 2005

#19

• Nov 22, 2005

• #19

I agree. If you had O2 issues alone, it should run a little rich (defaults into tabling). But if other sensors are giving poor input, that creates an issue.