Knocking only on medium acceleration - Mustang Evolution

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Old 03-24-2016, 11:16 AM   #1
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Knocking only on medium acceleration

I have a knocking noise that occurs only on medium acceleration in 1st through 4th gears, cannot hear it on fifth. No unusual noises in clutch and I can rev the engine in neutral and get no knock. I can hold it at 4,000 rpm in neutral and no noise. This is where a bad rod bearing would usually rattle. I do get the usual for oil pump rattle when starting it first thing in the morning. Drained the transmission and no metal in oil so I doubt the problem is there. No codes but the baro reading is 28.5 consistently even when the actual baro pressure is 30.1. The knocking does not sound like pinging so I do not thing i is timing related. I bought this car used and do not know the history. Is there any way to tell if it has been programmed and if so what can I do about it? How hard is it to put bearings in one of these in the car?
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Old 03-25-2016, 12:58 PM   #2
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49 views and no ideas?
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Old 03-25-2016, 01:12 PM   #3
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Cam phasers possibly?
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Old 03-25-2016, 03:25 PM   #4
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I know there can be a problem with the phasers at idle but will they make noise at speed also and only at load? There is no noise when no load, even wound up to 3500. They are also not making any noise at idle.
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Old 03-25-2016, 09:12 PM   #5
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Yes. You would likely hear it at idle.

How about the exhaust system? Could it be an exhaust leak that you are hearing?
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Old 03-26-2016, 07:16 AM   #6
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Well it is not in the pipes from the center connection back, i had it running on a lift and felt all around them. I cannot hear anything on a hard rev in neutral. That does not mean it cannot be a manifold leak under load. I guess I will have to get it back on the lift and go over the whole exhaust with a mirror and look for marks. I get the impression that these motors are not known for rod bearings going bad? That would be a good thing to know. I ordered a test kit from Blackstone labs and I will be getting the oil analyzed as soon as I get the kit. That will tell me for sure if it is a bearing. I hate the drive by wire throttle! You cannot rev the motor from under the hood, what a pain.
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Old 03-26-2016, 11:31 AM   #7
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Get a cheap stethoscope and work your way around the motor...you can also use a long screw driver......or some type of metal rod.
Don't know if you car is an automatic or stick............if it's an automatic put it in drive, put the parking brake on and apply throttle.........if it's truly a rod or main bearing you should hear the knock.
If it's an automatic it could be the converter....put it on the lift and use the stethoscope.......if it were the exhaust system and you are hearing a knocking it should be leaving a witness mark somewhere.
As for having a tune...the only way you are going to find out is with a tuner plugged into the OBD port.
What does the oil look like, any fine metal shavings........have you changed the oil since you purchased the car............if you were to change the oil and filter cut the filter in half and look for metal in the filter.........it doesn't have to be a lot........if you can see anything shinny in the oil you may have an issue...just a few suggestions.
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Old 03-26-2016, 12:26 PM   #8
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If the S197 5 speed manual is direct input to output in 5th then the reason you don't hear anything in 5th might be a bad bearing on the intermediate shaft. This might also make the noise worse with warm transmission oil.

That baro stuck at 28.5 is interesting, maybe just the default but not good if ECU needs this for adjusting fuel injection
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Old 03-26-2016, 12:45 PM   #9
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Bad Cam Phasers makes your car sound like it needs oil all the time...even at idle. Had mine replaced recently. Have you looked at your pulley's while the car is idling to see if maybe the Harmonic Balancer might be bad or the tensioner pulley ? Have you checked your Transmission Mounts & Made sure the bolts on the drive shaft didn't vibrate loose?
I'm not convinced it's in the motor because of it only doing it at medium acceleration. If it is in the motor it sure could be the balancer.
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Old 03-29-2016, 03:21 AM   #10
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My 2010 gt does the same thing from around 3000 Rpm and up its been doing that for for around 6 months. I don't know what's wrong with mine either. I personally thinks it's the phasers but my knock isn't getting any worse so I don't worry about it. So I would check the phasers.
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Old 03-29-2016, 07:09 AM   #11
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I went out yesterday morning and it was exceptionally quiet, no leaf blowers, mowers or gunfire. (I live on the firing ranges of a military base) I cruised slowly in 1st with the door open and I could hear a slight metallic tapping that sounded vaguely like a rocker arm. Now remember I am old school and not real familiar with the modular engines but might I have a bad rocker arm? I have read where the pivot can go bad on them. When I hit the gas there was no change in pitch of the noise at all, it stayed the same which eliminate the rod bearing as a noise. At least when it is cold.I am thinking that when I am in the car and with the Borla exhaust the noise may become more harmonic and sound like a rod.
Ideas? What exactly does a bad rocker or lifter in one these sound like when it is bad?
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Old 03-31-2016, 12:05 PM   #12
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Quote:
Originally Posted by Rickf1985 View Post
<snip> What exactly does a bad rocker or lifter in one these sound like when it is bad?
The 4.6 engine has a wear issue for the rocker's roller pin that shows up at high mileage depending on oil quality. If really bad then soft metallic click all the time.

The Coyote 5.0 is different design with smaller & lighter valve train parts. The lifters in either engine can stick cold for a few seconds after starting and make a light clicking noise. If the lifter is collapsed then the noise is louder and never goes away. Quality oil and longer trips to get oil hot help prevent all of this
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