Mystery knocking noise - 03 Mach - 2003-04 Mach 1 Registry Owners Club

kingbri1 · 01-16-2014, 05:03 PM

Hello. 2003 Mach 1 -17,000 miles. I have a mystery knocking noise that is clearly coming from the underside of the vehicle ... mid frame. Here it is. The video is upside down for some reason but the knocking is clearly audible.

http://s931.photobucket.com/user/kin...4_503.mp4.html

any ideas? Has BBK Longtubes / BBX catted X / Flowmasters.

any help is appreciated. I've checked all exhaust connections and o2 sensors - everything snug and secure. It does throw "Cat converter inefficient" codes

Thanks!

not a gt · 01-16-2014, 05:24 PM

Have you hit or scrapped the undercarriage? How are Flowmasters designed, did something break INSIDE the muffler? When you give it throttle does the sound change or get faster??

kingbri1 · 01-16-2014, 05:29 PM

I've scraped the tubes a couple times but nothing that I thought was severe. When giving throttle it does seem to get faster but not louder. Unsure what flowmasters they are since the previous owner had them installed.. can't wait to get rid of them..

not a gt · 01-16-2014, 05:35 PM

IDK, while it is running I would get like a broom stick and kinda push along the exhaust system from headers back and see if you can isolate somehow, just an idea.

bris09 · 01-16-2014, 06:23 PM

If it is deffinitely not coming from the engine, I would guess that the inside of one of the cats has broken apart. Does it ever go away or sound like something is rattling?

kingbri1 · 01-16-2014, 07:14 PM

The cats were my prime suspect. When the engine is cold it doesn't do it as bad. When the engine is nice and warm it then sounds like the video

Sent from my XT907 using Tapatalk

not a gt · 01-16-2014, 07:16 PM

Hit 'em with the brrom stick with car off and you should hear something rattle

What is wild is the sound actually has a cadence to it, like pulsing with the exhuast gases. Hope you find it, do you need cats in San Antonio?

kingbri1 · 01-16-2014, 07:43 PM

Nope. No emissions testing here.. Yea there's a definite rhythm to it

Sent from my XT907 using Tapatalk

03DSG · 01-18-2014, 09:59 AM

Dumb question but if you push in your clutch does it go away? I had a throwout bearing go bad and it sounded a lot like that.

kingbri1 · 02-01-2014, 05:00 PM

Installed an Off Road H today... Problem resolved. Was definitely a cat.

03DSG · 02-02-2014, 08:30 PM

Good to see it was not the motor just a cheap fix.

not a gt · 02-02-2014, 08:34 PM

Quote:

Originally Posted by kingbri1

Installed an Off Road H today... Problem resolved. Was definitely a cat.

Great, fixed the problem AND freed up some ponies..win/win!!

bris09 · 02-02-2014, 10:59 PM

Glad to hear that. They were my first thought but it was hard to tell as the video didn't have the same sound you hear in person when the cats break apart.

kingbri1 · 02-03-2014, 07:56 AM

Yes... win/win is right... thanks for all the help and advice! M1R is where it's at!

drcozcaz · 07-31-2014, 01:42 PM

Did you have this problem?
My 2003 Mach 1 4.6l, DOHC, Has BBK Longtubes / BBK catted X / Flowmasters, Denso O2's, K&N filter, SCT tune. When I got my car the right side cat was burned out with just rattling pieces inside. I replaced the Cats with BBK Cats but again after about 6000 miles, the right cat again is starting to make noise. I got the O2 error code after a 500 mile drive. The mechanic tapped on the cat and you can hear the rattling pieces inside. Does anyone know why the right side cat would be burning out??

Also, I had a noise at the back of the engine that a mechanic found to be the flywheel hitting the cover plate. He said he bent it away with a screw driver and the noise was gone.

4a7191a · 08-03-2014, 05:34 PM

Had the same problem , went catless. Lol. Problem solved.

Lonestar77777 · 08-04-2014, 12:34 AM

Turn the radio up loader or replace the exhaust system. Sounds like an old plymount with a bad rod.

LS

01-16-2014, 05:03 PM	#1
kingbri1 Mach Master Join Date: Mar 2010 Location: SW, Ohio Posts: 116	Mystery knocking noise - 03 Mach Hello. 2003 Mach 1 -17,000 miles. I have a mystery knocking noise that is clearly coming from the underside of the vehicle ... mid frame. Here it is. The video is upside down for some reason but the knocking is clearly audible. http://s931.photobucket.com/user/kin...4_503.mp4.html any ideas? Has BBK Longtubes / BBX catted X / Flowmasters. any help is appreciated. I've checked all exhaust connections and o2 sensors - everything snug and secure. It does throw "Cat converter inefficient" codes Thanks! __________________ 2003 OW Mach 1 Magnaflow CB Steeda Tri-Ax JLT Intake Scott Hoag Signed!

01-16-2014, 05:24 PM	#2
not a gt Registered User Join Date: Mar 2007 Location: Waaayy out in the country,leave your GPS at home! Posts: 4,825	Re: Mystery knocking noise - 03 Mach Have you hit or scrapped the undercarriage? How are Flowmasters designed, did something break INSIDE the muffler? When you give it throttle does the sound change or get faster?? __________________ 2003 DSG Mach 1-03 Cobra Term/T56 swap: 2.3L Whipple,3.37 Upper,4 lb.lower, ID 1000 injectors,LCD cooling mod,Billetflow idlers,200A Alt,oil cooler delete with MMR adapter plate,MM oil filter kit,FrozenBoost Heat Exchanger Flowtech L.T., Maganaflow O/R X with Magnapacks, FRRP D.S.,T-56 with 26 spline input shaft and anti venom mod with reverse lockout box, FR steel flywheel,Spec Stage 3+,Moser 31 spline axles,FR 3.73 gear Tuned by B.Kurgan 601Hp/558/Tq

01-16-2014, 05:29 PM	#3
kingbri1 Mach Master Join Date: Mar 2010 Location: SW, Ohio Posts: 116	Re: Mystery knocking noise - 03 Mach I've scraped the tubes a couple times but nothing that I thought was severe. When giving throttle it does seem to get faster but not louder. Unsure what flowmasters they are since the previous owner had them installed.. can't wait to get rid of them.. __________________ 2003 OW Mach 1 Magnaflow CB Steeda Tri-Ax JLT Intake Scott Hoag Signed!

01-16-2014, 05:35 PM	#4
not a gt Registered User Join Date: Mar 2007 Location: Waaayy out in the country,leave your GPS at home! Posts: 4,825	Re: Mystery knocking noise - 03 Mach IDK, while it is running I would get like a broom stick and kinda push along the exhaust system from headers back and see if you can isolate somehow, just an idea. __________________ 2003 DSG Mach 1-03 Cobra Term/T56 swap: 2.3L Whipple,3.37 Upper,4 lb.lower, ID 1000 injectors,LCD cooling mod,Billetflow idlers,200A Alt,oil cooler delete with MMR adapter plate,MM oil filter kit,FrozenBoost Heat Exchanger Flowtech L.T., Maganaflow O/R X with Magnapacks, FRRP D.S.,T-56 with 26 spline input shaft and anti venom mod with reverse lockout box, FR steel flywheel,Spec Stage 3+,Moser 31 spline axles,FR 3.73 gear Tuned by B.Kurgan 601Hp/558/Tq

01-16-2014, 06:23 PM	#5
bris09 Registered User Join Date: Oct 2004 Location: Middletown, PA Posts: 3,992	Re: Mystery knocking noise - 03 Mach If it is deffinitely not coming from the engine, I would guess that the inside of one of the cats has broken apart. Does it ever go away or sound like something is rattling? __________________ Brian 04 Azure Mach 1 Mods: Enough to not be the slowest, but nowhere near enough to be the fastest. 17 Fusion Sport Now faster than the Mach 96 Laser Red Cobra Vert For those days you just wanna cruise with the top down 89 Shelby CSX Still rocking the VNT and Fiberides.

01-16-2014, 07:14 PM	#6
kingbri1 Mach Master Join Date: Mar 2010 Location: SW, Ohio Posts: 116	The cats were my prime suspect. When the engine is cold it doesn't do it as bad. When the engine is nice and warm it then sounds like the video Sent from my XT907 using Tapatalk __________________ 2003 OW Mach 1 Magnaflow CB Steeda Tri-Ax JLT Intake Scott Hoag Signed!

01-16-2014, 07:16 PM	#7
not a gt Registered User Join Date: Mar 2007 Location: Waaayy out in the country,leave your GPS at home! Posts: 4,825	Re: Mystery knocking noise - 03 Mach Hit 'em with the brrom stick with car off and you should hear something rattle What is wild is the sound actually has a cadence to it, like pulsing with the exhuast gases. Hope you find it, do you need cats in San Antonio? __________________ 2003 DSG Mach 1-03 Cobra Term/T56 swap: 2.3L Whipple,3.37 Upper,4 lb.lower, ID 1000 injectors,LCD cooling mod,Billetflow idlers,200A Alt,oil cooler delete with MMR adapter plate,MM oil filter kit,FrozenBoost Heat Exchanger Flowtech L.T., Maganaflow O/R X with Magnapacks, FRRP D.S.,T-56 with 26 spline input shaft and anti venom mod with reverse lockout box, FR steel flywheel,Spec Stage 3+,Moser 31 spline axles,FR 3.73 gear Tuned by B.Kurgan 601Hp/558/Tq

01-16-2014, 07:43 PM	#8
kingbri1 Mach Master Join Date: Mar 2010 Location: SW, Ohio Posts: 116	Nope. No emissions testing here.. Yea there's a definite rhythm to it Sent from my XT907 using Tapatalk __________________ 2003 OW Mach 1 Magnaflow CB Steeda Tri-Ax JLT Intake Scott Hoag Signed!

01-18-2014, 09:59 AM	#9
03DSG Registered User Join Date: Oct 2003 Location: Gulf Coast, Swiming in a sea of................ Posts: 133	Re: Mystery knocking noise - 03 Mach Dumb question but if you push in your clutch does it go away? I had a throwout bearing go bad and it sounded a lot like that. __________________ Comp 106060s, Tmhutch PSR, ARH 1-3/4"Longtubes & 3" X, Magnaflow cat back, Lightning MAF, 39lb injectors, "R" Pulley's, ATI Balancer, Jlt Intake, Roy's 3/8" Phenolic spacer, Aluminum Drive shaft, Fidanza Flywheel, Cobra clutch, 4:10's, SCT-Murillo tune, FTB drag rotors, Enkei RPF1 wheels, and lots of suspension work.

02-01-2014, 05:00 PM	#10
kingbri1 Mach Master Join Date: Mar 2010 Location: SW, Ohio Posts: 116	Re: Mystery knocking noise - 03 Mach Installed an Off Road H today... Problem resolved. Was definitely a cat. __________________ 2003 OW Mach 1 Magnaflow CB Steeda Tri-Ax JLT Intake Scott Hoag Signed!

02-02-2014, 08:30 PM	#11
03DSG Registered User Join Date: Oct 2003 Location: Gulf Coast, Swiming in a sea of................ Posts: 133	Re: Mystery knocking noise - 03 Mach Good to see it was not the motor just a cheap fix. __________________ Comp 106060s, Tmhutch PSR, ARH 1-3/4"Longtubes & 3" X, Magnaflow cat back, Lightning MAF, 39lb injectors, "R" Pulley's, ATI Balancer, Jlt Intake, Roy's 3/8" Phenolic spacer, Aluminum Drive shaft, Fidanza Flywheel, Cobra clutch, 4:10's, SCT-Murillo tune, FTB drag rotors, Enkei RPF1 wheels, and lots of suspension work.

02-02-2014, 10:59 PM	#13
bris09 Registered User Join Date: Oct 2004 Location: Middletown, PA Posts: 3,992	Re: Mystery knocking noise - 03 Mach Glad to hear that. They were my first thought but it was hard to tell as the video didn't have the same sound you hear in person when the cats break apart. __________________ Brian 04 Azure Mach 1 Mods: Enough to not be the slowest, but nowhere near enough to be the fastest. 17 Fusion Sport Now faster than the Mach 96 Laser Red Cobra Vert For those days you just wanna cruise with the top down 89 Shelby CSX Still rocking the VNT and Fiberides.

02-03-2014, 07:56 AM	#14
kingbri1 Mach Master Join Date: Mar 2010 Location: SW, Ohio Posts: 116	Re: Mystery knocking noise - 03 Mach Yes... win/win is right... thanks for all the help and advice! M1R is where it's at! __________________ 2003 OW Mach 1 Magnaflow CB Steeda Tri-Ax JLT Intake Scott Hoag Signed!

07-31-2014, 01:42 PM	#15
drcozcaz Registered User Join Date: Nov 2011 Location: trafford, PA Posts: 5	Re: Mystery knocking noise - 03 Mach Did you have this problem? My 2003 Mach 1 4.6l, DOHC, Has BBK Longtubes / BBK catted X / Flowmasters, Denso O2's, K&N filter, SCT tune. When I got my car the right side cat was burned out with just rattling pieces inside. I replaced the Cats with BBK Cats but again after about 6000 miles, the right cat again is starting to make noise. I got the O2 error code after a 500 mile drive. The mechanic tapped on the cat and you can hear the rattling pieces inside. Does anyone know why the right side cat would be burning out?? Also, I had a noise at the back of the engine that a mechanic found to be the flywheel hitting the cover plate. He said he bent it away with a screw driver and the noise was gone.

08-03-2014, 05:34 PM	#16
4a7191a Registered User Join Date: Jun 2004 Location: beaumont texas Posts: 1,344	Re: Mystery knocking noise - 03 Mach Had the same problem , went catless. Lol. Problem solved. __________________ 2004white mach1 2001 svt lightning 2011 Mitsubishi Evo X 1999 F250 7.3L

08-04-2014, 12:34 AM	#17
Lonestar77777 Guest Join Date: Jan 2012 Location: Tomball TX Posts: 415	Re: Mystery knocking noise - 03 Mach Turn the radio up loader or replace the exhaust system. Sounds like an old plymount with a bad rod. LS

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