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audible rattling from 2k onward only under light acceleration please help

LILIKE16ST

Senior Member
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#1
as the title states I've been experiencing rattling that starts around 2k on up mostly in the 2-3k range and only happens under very light throttle once I put the throttle down more or go WOT it stops this is also causing false knock on cylinder number 3 when this happens which pulls timing. it does it bad sometimes on the highway because the conditions are perfect for this to happen as the rpm are right in that range and throttle is very light as well. My ap only shows knock during these specific conditions and only on cylinder 3. I am running a stratified e30 flash with a revision and no I don't think it's the fuel my e85 tested 90% and the fuel qualify is amazing overall and I'm getting positive corrections on all other cylinders even during these instances. as I stated once I go heavier on the throttle or WOT it's business as usual there is no knock detected and I don't hear anything rattling or pecking and the car runs great. if I drive easy and keep rpm below 2k or so I don't have issues either and I don't have issues with this even in that rpm range unless I'm very light on the throttle. I been running this tune for months with no issues until the last few weeks so no I don't believe it is tune related either. I can't imagine there is engine damage because it runs fine when hard on the throttle which does not seem like it would be the case if there was engine damage. I recently changed the oil and changed the trans fluid to motul 300 I checked the ngk plugs I put on 5k ago and all seems well there no issues to speak of. I am running out of ideas. I checked my rmm and noticed it wasn't as tight as it should be but I tightened it up and it did not fix the issue. Any help would be greatly appreciated it's driving me crazy and I'm running out if ideas and it's a real downer. it makes me not enjoy my car nearly as much as I once did. it doesn't really make much noise idling but it has made the pecking sound before at idle (tune has my idle set to 1000 for rmm vib purposes) but it is mostly in the situations I described and usually cannot be heard at idle. I can hear it when I Rev the car up past 2k when in neutral or with the clutch pressed it makes no difference but it only does it if I am very easy on the throttle while easing the rpms into that range. I'm stumped any help would be appreciated
 


DAPR

Member
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Charlottesville
#2
Pull the plugs and post a picture of what they look like. I'm also in VA and have plenty of experience if you need a hand.
 


OP
LILIKE16ST

LILIKE16ST

Senior Member
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Thread Starter #5
I have the plugs pulled still I installed the stock 47k mile plugs just for testing but there was no change plugs look fine to me but I'm no expert. it pecks at idle sometimes and sometimes it doesn't and it mostly does it when fully warmed up..when car isn't at operating temp yet it doesn't peck at idle far as I can tell thus far. it does do it when the engine isn't loaded just revving weather it's in neutral or with the clutch pressed it makes no difference. car seems to run fine outside of this. it's really irritating me. where in VA are you? I'm in southwestern va. it sounds terrible when it does this...it's loud enough to cause false knock but it's only on number 3 for whatever reason. it pulls timing and shows bad knock during these accurances but as soon as I get into the throttle more and the rattling/pecking stops it goes back to the normal positive corrections like the rest of the cylinders always see. I took a few logs of this in case my tuner or anyone else wanted to look at it and try to see from the logs. I made it do what it does on the log then matted the throttle in which case you can see it no longer shows knock even in that rpm range. it's real strange and it's got me bumfuzled. any help is greatly appreciated thanks for the response

p.s. I looked at that thread it us similar to what I'm experiencing however this noise comes from the engine bay area when the hood is popped it sounds like it's coming from the valve cover but it's hard to pinpoint exactly I have not gotten to try to hear it from under the car yet I'm going to try that this weekend and look around some more.
 


OP
LILIKE16ST

LILIKE16ST

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Thread Starter #7
I will snap that pic and try to get me uploaded asap thanks for the help...anyone else? I am in southwest VA about 30-40 miles from the TN boarder. I know where Charlottesville is I went there couple years back to visit my wife's cousin when he was working up there. nice place there
 


OP
LILIKE16ST

LILIKE16ST

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Thread Starter #8
it's pecking and rattling significantly worse now and it's doing it more frequently and it don't really stop after I start matting the throttle like it did even up to 4k and beyond I have another log I took just cruising on the highway 70 mph it was doing it pretty bad...I'm starting to think it's engine damage at this point I just don't understand what could have caused damage car has always ran great always had the best and good fuel too. it's just frustrating
 


OP
LILIKE16ST

LILIKE16ST

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Thread Starter #9
car just turned over 52k I've owned it since April of 2016 bought new with 50 miles on the clock. car has never given me any trouble and never had any issues at all until now
 


koozy

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#10
have you checked the Depo charge pipe? The bracket has cracked for a few people. This could cause rattling. Did your RMM need or have a spacer included? Missing the spacer could cause rattles. For testing purposes you can put back the OE charge pipe and RMM. Aftermarket parts should always be suspected as many don't meet OE mfg./design/usage standards.
 


OP
LILIKE16ST

LILIKE16ST

Senior Member
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Thread Starter #11
have you checked the Depo charge pipe? The bracket has cracked for a few people. This could cause rattling. Did your RMM need or have a spacer included? Missing the spacer could cause rattles. For testing purposes you can put back the OE charge pipe and RMM. Aftermarket parts should always be suspected as many don't meet OE mfg./design/usage standards.
I did suspect the rmm could be the culprit however it was installed for a few months before this issue started but I guess it could have progressively gotten worse if that is the issue. my bracket broke off completely on my charge pipe and I had some issues with it popping off this was a separate issue the bracket is still bolted to the side of the trans it's just broken clean across the weld where it's welded onto the pipe. I'm just frustrated at this point. I'm going to swap them out tomorrow and see what happens.

this knock or rattle has gotten pretty bad of late and it's almost bad enough even with a slight Rev at idle it's hard for me to imagine either of these things causing a rattle that bad in that situation with exception of maybe the motor mount
 


Plainrt

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#12
I have had stock charge pipe rub on crossmember and make noise similar to what you describe.
 


LilPartyBox

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NYC
#13
I had similar sound. I also thought it was the rmm. Even went back to stock. I eventually discovered it was a dirty air filter. Unexpected I know but after I cleaned and lubed it car was happy again.

Sent from my SM-G950U using Tapatalk
 


Messages
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Location
Metro Detroit
#16
Hate to go there but I suspect that you may have a cracked cylinder or a head gasket failure. It's a common issue on these engines when running larger turbos without a block that hasn't been modified for a deck plate. The cylinders can start walking around and sooner or later it either cracks or the head gasket starts to leak. I reading all the blown engine threads I have an impression that cylinder number 3 is a "weak link" but that could be simply result in my having read between the lines too much. One way to get a better grasp on what is going on is to take a look at all 4 cylinders with a bore scope and see if number 3 looks worse. BTW, bore scopes are now dirt cheap and easy to find on ebay or amazon.

As for what happens when you get too much water in a cylinder, the increase in available volume for combustion is reduced and Knock is what happens. In addition most times you'll also have oil leaking into the combustion space and that will also trigger detonation. Eventually it will burn a hole in the piston and then you have a totaled engine.
 




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