Ok. Sometimes when my car is idling there is this thumping noise like something is hitting the bottom of the car.Its up front like right under the dash. I dont think its a knock from the engine, and if it was wouldnt i get a code. I dont think its related to the new work, i have heard this noise before, not as pronounced but i think its becuase of the lopeir cam im noticeing it more. at first i thought maybe it was the cat on the passenger side or the header. Had it idling up on a lift and nothing was moving but it doesnt do it all the time so it still could be that. could the clutch, flywheel, throw out bearing cuase this noise. im thinking it could be related to the vibration.
Thumping noise.
07stanggt
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One more thing. I had a guy's car a few months ago that sounded like a slight knocking in the botom end. It ended up being an EGR leak at the manifold that just echoed up through the engine bay and sounded like something terrible- Long shot but something to check...
Well the motors mounts were just changed again with the bmr k member. its comes with its own. i had just put prothane bullet motor mounts on in FEB and it was doing this before the k member. The trans mount is something to look at though. it does feel like is right there under your feet.
A rod bearing noise or for that matter a engine bearing noise gives a distinct sound. And if you drive your car hard it probably wouldn't make it 20 miles with a bad rod. Keep in mind everything that rotates vibrates. And anything that touches something vibrating also vibrates. Pull off your FEAD (your front accessory drive belt) on a cold engine to rule out engine accessories. Try to isolate it to an area. Get under your car and shake everything. Maybe something is loose. Try tapping your exhaust/oilpan/trans with a rubber mallet to see if anything is rattling. It basically could be anything rotating or anything touching something rotating. When it does it try pressing in the clutch to see if it changes the noise. Another easy check is crank endplay (I have seen a few 4.6l 3 valve with excessive crank endplay). Anything over 0.010" is going to cause problems.
I don't know the reason behind it but some of the thrust bearings are faulty. If you could post a sound clip or video I could probably point you in the right direction. Hope this helps you.
I don't know the reason behind it but some of the thrust bearings are faulty. If you could post a sound clip or video I could probably point you in the right direction. Hope this helps you.
Well the motor mounts were just changed again with the bmr k member. it comes with its own. i had just put prothane motor mounts on in FEB and it was doing this before the k member. The trans mount is something to look at though. it does feel like is right there under your feet.
Well long story short i have steeda under drive pulleys I have a rotaitonal vibration that seems like the engine is out of balance when driveing on the highway. Its not the rear we rebuilt that tuesday, its not the driveshaft becuase its done it through two driveshafts. So im going to put my stock pulleys back on saturday to see if they are cuase this vibration on the highway. I just didnt want to give up that 7 hp for tomorrow night
I agree a rod on this engine would not have lasted the way i drive the car. I did beat on the cats with a rubber mallet and the passenger side cat had something moveing around in it that sounded like marbles but after a few taps i went away. There is soemthig lose in there though. I have emission in nov and then im probably putting o/r legs on there.
thanks for the help.
Your catalyst is probably falling apart. High octane fuel+agressive tunes+ time = catalyst overtemp which cause the catalyst to melt and fall apart (providing they are not gutted 
). I have seen this ALOT!!!. This can cause vibration/noise. You might not meet those emissions in nov if it is the catalyst failing.
). I have seen this ALOT!!!. This can cause vibration/noise. You might not meet those emissions in nov if it is the catalyst failing.
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thats one good thing about Alberta. No emmision checks
but i will say that the first time i really noticed this rotational vibration is when i had cams, kooks headers and motor mounts put on in feb. So they were brand new then and unless the cats were bad outta the box, which is possible i dont think thats it. What my theory is now, (that i have rebuilt, replaced and or checked everything else) about the vibration on the highway was that maybe it was the UD's, maybe i just didnt notice it until the motor mounts went on, the stock motor mounts were just hiding it. The ud's i put on probably in december. and i remember things feeling different, but it just felt like maybe the engine was spinning up different, which is to be expected with ud's. thats all i can think of now or a flywheel. this knocking, maybe its connected i dont know.
Yeah, we build all the cars here in Detroit, but we sure as hell don't check them for emissions
I was asking if a bad rod or something else knocking in the rotating assembly with throw a check engine light? I thought it would, or is this dumb ass cel just as useless as it always was.
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Mechanical defects such as a knock would not normally throw a cel. If the knock was in the engine the knock sensors should pull timing. Some guys turn of the knock sensors in extreme cases were the cam is aggressive. I don't believe this is the case in your situation. If the knock is intermittant I doubt it is a rod or bearing problem. Being that you can feel it through the floor board I would be leaning toward the exhaust/headers hitting some where.
With the engine off, rock the engine back and forth by hand and see if you can duplicate the noise.
With the engine off, rock the engine back and forth by hand and see if you can duplicate the noise.
Actually you can get a check engine light with a rod bearing concern. I have seen this before. Your computer monitors your CKP (crankshaft position sensor). From this signal it determines a misfire if your crank slows down or speeds up across a certain cylinder. I have seen a few with the CEL on and misfire codes. This happens because the rod bearing being gone creates play which creates a delay mechanically which shows up a a lengthened wavelength on the applicable bad cylinder. It has narrowed it down to which cylinder is knocking a few times for me . Makes life way easier when diagnosing.
. Makes life way easier when diagnosing.
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No kidding..That's pretty cool. I guess you could also monitor the CKP wavelength if it wasn't throwing a CEL and figure it out that way as well.Actually you can get a check engine light with a rod bearing concern. I have seen this before. Your computer monitors your CKP (crankshaft position sensor). From this signal it determines a misfire if your crank slows down or speeds up across a certain cylinder. I have seen a few with the CEL on and misfire codes. This happens because the rod bearing being gone creates play which creates a delay mechanically which shows up a a lengthened wavelength on the applicable bad cylinder. It has narrowed it down to which cylinder is knocking a few times for me
Thats what i didnt know whether the knock sensor would give a cel, i would think that i would after it pulled timeing at least if the knock was still there. anyway i dont think this is a rod. My knock sensor isnt turned off, nothing is turned off including the rear 02s. didnt want to do any of that. I just have the VCT limited to 20 degrees and the comp phaser limiters installed.
Didnt want to change my pulleys yesterday becuase the dealer didnt have the crank bolt in. It wont be there until monday. I already reused that bolt once and cant do it again.
But after messing with it some more the thumping at idle in nuetral will go away when i push in the clutch? does this narrow it down to the clutch/flywheel or could it still be the pulley.
But after messing with it some more the thumping at idle in nuetral will go away when i push in the clutch? does this narrow it down to the clutch/flywheel or could it still be the pulley.
Yea me either. And i was thinking yesterday, regarding the vibration, if it was the pulley why wouldnt i feel the vibration when im in nuetral and just hold the rpms at like 2600 rpms like it is when im doing 75 on the highway. The only problem is it seems damn near impossible to hold the rpms steady and if they are changing i wouldnt really be able to notice that vibration anyway. ****ing electronic throttle, whoever thought of that can kiss my ass. makes launches hard for me too.
The other issue is that, if im on the highway, and getting the wahwahwah sound and push in the clutch and let the car coast, no vibration. Im leaning more towards the flywheel as the cuase of both sounds. The only reason i ask is i though maybe that its still the pulley and doesnt do it becuase there is no load on the engine at those rpms with the clutch in.
My car is really perfect if i could just get rid of these two problems. it runs perfect, it handles great. I know after friday night that on my nittos i can probably run a 12.4. thats bad ass on street tires for the street. Im probably going to change the frpp springs for something with the same drop but a softer spring becuase it bounces on the highway a little and then this car would be spot on in every sense.
The other issue is that, if im on the highway, and getting the wahwahwah sound and push in the clutch and let the car coast, no vibration. Im leaning more towards the flywheel as the cuase of both sounds. The only reason i ask is i though maybe that its still the pulley and doesnt do it becuase there is no load on the engine at those rpms with the clutch in.
My car is really perfect if i could just get rid of these two problems. it runs perfect, it handles great. I know after friday night that on my nittos i can probably run a 12.4. thats bad ass on street tires for the street. Im probably going to change the frpp springs for something with the same drop but a softer spring becuase it bounces on the highway a little and then this car would be spot on in every sense.
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...change your limit to 18
and I have faith in you that you'll do et better than 12.421 - 40 of 45 Posts
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