Knocking from the back of the car - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

George-CZ · 05-05-2019, 08:58 AM

Certainly someone has already registered it.
The car stands on place, the engine running and suddenly somewhere around the axle .... knock, knock, knock, knock.
And then quiet again.
Car rides normally - all right.

What is this..?

Strydes · 05-05-2019, 09:06 AM

happened to me too. Sounds like someone is knocking to get my attention.. I look back and no one is there. Fuel pump???

George-CZ · 05-05-2019, 09:27 AM

Quote:

Originally Posted by Strydes

happened to me too. Sounds like someone is knocking to get my attention.. I look back and no one is there. Fuel pump???

Yes, exactly.
I stood behind the car when it knocked.
But I don't know where it was from.

redcoats1976 · 05-05-2019, 09:37 AM

missing any kids or wife.maybe they are trying to get out...

Camaro2ss2010 · 05-05-2019, 09:44 AM

I hear this from time to time. Haven’t been able to locate the source yet. It happens so fast.

TheFlyingBananaSS · 05-05-2019, 09:46 AM

Problem solved- ex-wife in trunk!

KillboyPowerhead · 05-05-2019, 09:53 AM

Do you only hear the knocks after a cold start, and a few minutes after running/driving? I hear this too; I'm on my second Camaro and the exact same thing happens, so I guess it's supposed to happen. The knocking happens after a certain amount of time every time, whether the car is idling or moving. I also figured it was the fuel pump.

George-CZ · 05-05-2019, 11:17 AM

Quote:

Originally Posted by KillboyPowerhead

Do you only hear the knocks after a cold start, and a few minutes after running/driving? I hear this too; I'm on my second Camaro and the exact same thing happens, so I guess it's supposed to happen. The knocking happens after a certain amount of time every time, whether the car is idling or moving. I also figured it was the fuel pump.

Yes ... It's only after a cold start.
A few minutes after turning the key.

You mean a fuel pump?
Fuel pump sounds buzzing.
This sound is knocking...

InFiD3ViL · 05-05-2019, 01:42 PM

This is supposed to happen. It is a distinctive tap-tap-tap-tap-tap

It freaked me out the first time I heard it. It sounds like someone is knocking on the trunk.

It has to do with the evap system.

Strydes · 05-05-2019, 02:02 PM

Yes happens when just start up start to move just a little and knock knock knock.. I turn my head back to look every time... Scares me

George-CZ · 05-05-2019, 02:15 PM

Quote:

Originally Posted by InFiD3ViL

This is supposed to happen. It is a distinctive tap-tap-tap-tap-tap

It freaked me out the first time I heard it. It sounds like someone is knocking on the trunk.

It has to do with the evap system.

System Evap?
That I hear first.
What and why is this please?

Reaper85 · 05-05-2019, 02:56 PM

Never heard this before........I'll take a listen the next time I cold start it.

xstuntman · 05-05-2019, 03:11 PM

That dead hooker isn't as dead as you though.

InFiD3ViL · 05-05-2019, 05:34 PM

Quote:

Originally Posted by George-CZ

System Evap?
That I hear first.
What and why is this please?

Per forum member Russell James:

"PCM clicks it, seals the tank, then applies engine vacuum, click it to seal off that vacuum, and a few seconds later checks the pressure sensor to see if it is maintaining a vacuum. Then clicks and releases the vacuum.

Leave your gas cap loose, and if it fails two of those tests in a row, it'll turn on your check engine light."

05-05-2019, 08:58 AM	#1
George-CZ Drives: 2010 2SS LS3 and 1978 STROKER 383 Join Date: Feb 2018 Location: Czech Republic Posts: 1,592	Knocking from the back of the car Certainly someone has already registered it. The car stands on place, the engine running and suddenly somewhere around the axle .... knock, knock, knock, knock. And then quiet again. Car rides normally - all right. What is this..?

05-05-2019, 09:06 AM	#2
Strydes Drives: 2010 inferno orange 2SS 6spd Join Date: Apr 2012 Location: Michigan Posts: 35 View My Garage	happened to me too. Sounds like someone is knocking to get my attention.. I look back and no one is there. Fuel pump??? __________________ roto fab cai bbk full length headers High flow cats 411rwhp/411trq engine pulled/ oil pump fail 525 crate engine installed 391 gear installed 226/236 110 cam tuned by full throttle speed 443@6000rpm /420trq@4900rpm

05-05-2019, 09:46 AM	#6
TheFlyingBananaSS Evil Genius of Chevrolet Drives: 2017 Z06, 2019 XTS, 2013 SS Join Date: Feb 2017 Location: New York Posts: 3,260	Problem solved- ex-wife in trunk! __________________ GPI SS2 VVT cam, ECS Novi 1500 supercharger, Corsa Extreme, Detroit Speed and BMR suspension, Circle D triple disc, Melling oil pump, LS2 chain tensioner, ATI 10% UD, DSX E85 kit, High Energy coils, BTR springs, LS2 Lifter trays, Titanium retainers, hardened push rods, FIC 1000 injectors, ZL1 pump, Mighty Mouse catch can, AEM gauges, Tial BOV, Richmond 3.91 gears, Custom gauge bezels, Speed Engineering headers, Stainless Works HF cats, DSX Aux pump, 710rwhp on E85.

05-05-2019, 09:53 AM	#7
KillboyPowerhead Drives: 2015 Z/22 Join Date: Aug 2015 Location: Ontario, Canada Posts: 931	Do you only hear the knocks after a cold start, and a few minutes after running/driving? I hear this too; I'm on my second Camaro and the exact same thing happens, so I guess it's supposed to happen. The knocking happens after a certain amount of time every time, whether the car is idling or moving. I also figured it was the fuel pump. __________________ Overkill/Self Tuned; Mace Camshafts; K&N Typhoon Cold Air Intake; Ported 80mm Throttle Body/Intake Manifolds/Manifold Spacer; Solo Performance High-Flow Cats, Cat-back Exhaust; Vitesse Motorsports Throttle Controller; Elite Engineering E2 Catch Can; BC Racing BR Coilovers; JPSS Delrin Radius Rod Bushing Inserts, Sway Bars; Pegasus Aluminum Rear Cradle Bushings, Camber/Caster Plates; Z/28 Toe Links, Trailing Arms, Upper Control Arm Bushings, Rear Shock Mounts

05-05-2019, 01:42 PM	#9
InFiD3ViL Drives: 2010 CGM 2SS/RS LS3 Swapped A6 Join Date: Sep 2016 Location: Spring Hill, FL Posts: 4,570	This is supposed to happen. It is a distinctive tap-tap-tap-tap-tap It freaked me out the first time I heard it. It sounds like someone is knocking on the trunk. It has to do with the evap system. __________________ 2010 CGM Camaro 2SS LS3 Swapped A6 - GPI LS3 SS1 .647/.638, (224/237, 112 +4, 7º overlap) on CamMotion 8620 core, BTR Platinum .660" Dual Spring kit w/titanium retainers, CHE bronze trunnion upgrade, stock heads milled @ .015, Melling HV 10296 oil pump, TSP 1-7/8" long tube headers (W/Catless Off-road Pipes), Corsa Xtreme 3" Catback, GPI Ported/Rod Mod Intake, Stage 2 Ported Throttle Body, Vararam OTR CAI, Mike Norris Gen 2 catch can + GM 1LE clean side separator, 160º thermostat - Megan Racing adjustable coilovers (lowered 1.75"), MRR M017 10/11" wheels-Tuned by Ryan @ GPI

05-05-2019, 09:37 AM	#4
redcoats1976 Drives: LT W/2LT,blue metallic Join Date: Jul 2016 Location: central florida Posts: 4,916	missing any kids or wife.maybe they are trying to get out...

05-05-2019, 09:44 AM	#5
Camaro2ss2010 Drives: 2010 Camaro 2SSRS M6 Join Date: Jan 2019 Location: Alabama Posts: 1,249	I hear this from time to time. Haven’t been able to locate the source yet. It happens so fast.

05-05-2019, 02:02 PM	#10
Strydes Drives: 2010 inferno orange 2SS 6spd Join Date: Apr 2012 Location: Michigan Posts: 35 View My Garage	Yes happens when just start up start to move just a little and knock knock knock.. I turn my head back to look every time... Scares me __________________ roto fab cai bbk full length headers High flow cats 411rwhp/411trq engine pulled/ oil pump fail 525 crate engine installed 391 gear installed 226/236 110 cam tuned by full throttle speed 443@6000rpm /420trq@4900rpm

05-05-2019, 02:56 PM	#12
Reaper85 Drives: 2013 2SS/RS Join Date: Nov 2015 Location: Barrie, Ontario Posts: 598	Never heard this before........I'll take a listen the next time I cold start it.

05-05-2019, 03:11 PM	#13
xstuntman Drives: 2012 Victory Red LFX Join Date: Dec 2012 Location: west central Texas Posts: 1,310	That dead hooker isn't as dead as you though. __________________ 2018 SS wheels, red Heritage grille, actual driving lights, ZL1 strut tower brace, GM Performance billet aluminum fuel door, front grille Bowtie delete, painted red rotors and calipers, 1/4 window American Flags, splash guards, AEM dry panel air filter.