hit 3rd gear today and i got KNOCK 19.5 and engine surging

[keith theriot]

first and second i had no problems , wow but when i hit third ouch. so i parked it.

 

[Amelio]

Hopefully you lifted real fast....unfortunately by when you see that on the SM master it happend last week.......you got a power logger?

 

[keith theriot]

yeah i lifted, just a scan master , i am gonna hook up the fuel gauge to it tomorrow and check the plugs

 

[Amelio]

what boost were you at? I see you have alky double check your system to make sure it did not turn off.....Also did it happen just after a shift or were you in 3rd for a sec when you saw that number?

 

[keith theriot]

i am running 20 psi , alky was working thru 1 & 2 , and it happened after the shift, as soon as it hit third gear my boost gauge went down to about 17 and went back up to 20 but it was surging

 

[TNTSNBS]

sounds like you lifted the head and perhaps popped a HG, hopefully thats not the case, let us know what you find out..

 

[turbo nasty]

What number was the alky set on?
Did you see 19.5 or recalled it?

 

[keith theriot]

alky set on 6 , i seen 15 and recall 19

 

[turbo nasty]

Well crap....yeah check the fuel psi. Not sure on the HA cars but the 86 and 87s have the fuel pump prim lead that can energize the fuel pump and you can use shop air to at least test the rising rate without driving. Doesnt rule out that the circuit is working when driving but does test that the fuel psi reg can raise fuel psi.

How much gas in the tank?
I have seen bad boost gauges to?

Give me a ring if you like

 

[keith theriot]

i need another boost gauge because mine is only for 20 and i may be going over at first boost , tank is 3/4 , when i got home i pulled the vac line from the fuel pressure reg. and the idle didnt change

 

[turbo nasty]

Smart move on the gauge. Did your seal the open vac line when pulled it off the reg?

 

[blackgn1]

I saw 15 degrees of knock one time. Saw the knock. Lifted. Blew both headgaskets in seconds.

 

[keith theriot]

yeah the vac line was working,

 

[bison]

Knock retard and detonation are two different things. You could have either or and not have it be displayed. If you are under 450hp a little detonation wont usually hurt it. Once you start making power beyond that the detonation will do more and more damage. If youre over 600hp and you actually hear detonation your engine is junk. KR is just what the computer has pulled and may not have been detonation at all. If the car is fine if you roll on it in 3rd and shows KR when it shifts its likely not detonation.

 

[kidglok]

the knock sensor can interpret any noise in a certain frequency as "knock" and pull timing.

Bison, can the sudden pull of that much timing cause the engine to surge?

 

[turb0buick57]

I would check your vac lines especially to the map, and your scanmaster numbers at idle again. I got similiar knock as your describing and lifted, found the vac line to the map had blew off disabling alky.

 

[bison]

the knock sensor can interpret any noise in a certain frequency as "knock" and pull timing.

Bison, can the sudden pull of that much timing cause the engine to surge?

20* retard would likely cause 175hp loss. It would feel like half the engine shut off

 

[turboclam]

Pull the valve covers and look for out of the ordinary, like a broken valve spring, bent push rod, snapped rocker arm shaft.

 

[Amelio]

20* retard would likely cause 175hp loss. It would feel like half the engine shut off

I have felt that.....on the other engine I had I got real bad tire spin causing my exhaust to bounce aroud setting off the knock sensor....I believe I saw 15 degrees flash up and the car fell on its face just about it did feel like it lost 100hp!!!

 

[keith theriot]

ok change the boost gauge, i am not going over 20psi. changed fuel filter , checked fuel pressure, pulled plugs they looked perfect, went test and still surge and knock but i am not hearing knock, when i am just cruising in third gear or overdrive it feels like i would have a miss fire, so i have to keep digging