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Discussion Starter #1 (Edited)
Does anyone have any advice on a 2005 ZX3, Duratec 2.0, MTX (160k miles) that shakes/rattles a bit more than it should at idle with engine fan/AC on? The car runs fine and settles at about 700 RPM at idle and 725 at idle with AC on. Other than the vibrations at idle with the engine fan and AC on, it runs well and feels smooth when driving at higher RPM. Even at 700 RPM when not too hot, it idles smoothly. I only feel the vibrations at stops. I guess this was a problem the previous owner tried to fix because the idle adjustment screw on the original throttle body was adjusted (I can see the screw is non-adjustable and glued).
With various repairs I have done the following that may be pertinent to my situation:
  • replaced throttle body with good condition used TB (gently cleaned)
  • replaced IAC valve
  • cleaned MAF sensor
  • replaced fuel injectors, spark plugs and fuel rail sensor
  • replaced TPS sensor
  • replaced motor mounts (After market [cheap] and now OEM)
  • replaced belt tensioner (tried a gently used after market and now OEM – OEM may be slightly worse)
  • replaced fuel filter
  • replaced AC compressor, and
  • replaced air filter housing with a cone filter.
I have disconnected the IACV at idle and the engine starts to die. I have not changed the belt as it seems in good condition, BUT I did notice that it seemed a little stretched because it is much easier to get this belt on than the other Foci in the family. Let me know if that $35 belt could make a difference as I am thinking about changing it anyway (I don't know how old it is).

Recently, I cleaned the TB a bit to see if I could get the car to idle a little higher than 700-725 RPM but this did not help (only difference is that higher RPM now hang a little longer at stops).

I’ve been underneath the car and turned on AC and see that there is slight increase in belt tensioner movement and noticeable additional shake in the transmission. I also see that the exhaust manifold shielding rattles a bit. The engine/AC fan unit was not noticeably vibrating more than the tranny.

Any ideas out there on what to try or if I can increase idle?
 

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Discussion Starter #2 (Edited)
I will add that these repairs were done in the past 12-18 months on a cheap project car for my son and I to work/learn on. The car was in bad shape when we got it but we love it now. It is my son's car and his solution is to turn up the volume!
 

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Discussion Starter #4
I was thinking mounts, then belt tensioner, then AC compressor and those pretty much all got replaced with other issues over time. After all the updated parts mentioned above, it seems like the tranny is vibing the most at idle with AC or engine fans so I changed the after market driver side mount with with an OEM. The pricier OEM looked identical but had slightly spongier rubber which resulted in the same or worse issue (pretty much no change). The passenger side mount is a new OEM and the torque (dogbone) is a poly but there was little if any vibration diff after installing the poly dogbone.

Is the car idling too low to begin with (700-725)? I dont know the spec but I did see other Duratec 2.0 Focus idle higher (they are ATX though).
 

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Basically my 2005 ZX4 SE 5-speed did what your does. I replaced the passenger side mount with a new Ford unit and the problem was gone. That was over 3 years ago.

Have you ever replaced the coils? Have you tested the coils to see that they are all contributing?

Paul
 

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The idle speed is electronically controlled and you cannot change it other than by rewriting the operating software to change it. You are dead on on the rpm on a not brand new engine, or 700-750 rpm. The pass side mount has the most effect on vibration but a solid rear dogbone can do it too.
 

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Discussion Starter #7 (Edited)
Paul1958: Great, thanks! I did not see or feel any indications of cracked or aging coils and I have tested the coils in the past (admittedly, I had a new tester and it was my first time). However, the current coils on this car don't have any print on the tops like my other Foci so it just occurred to me that they may be aftermarket (?). I will try newer OEM Foci coils (I picked up a bunch during 50%-off days at the junk yard so I don't have anything to loose). I have not thought of them in a while and almost forgot I had them in a box (somewhere).

AMC49: 700-750 RPM ... I'm a little disappointed that the idle should not be more like 800 RPM but I will try newer coils to see if I can at least get it closer to 750ish rather than the 725 with AC and engine fans engaged. The belt seems easier to get on than my other Foci - do you think a new, and tighter belt could help? I don't see any cracks in the belt and it is not noisy but there is definitely a little more movement in new belt tensioner when AC is on.
 

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Paul1958: Great, thanks! I did not see or feel any indications of cracked or aging coils and I have tested the coils in the past (admittedly, I had a new tester and it was my first time). However, the current coils on this car don't have any print on the tops like my other Foci so it just occurred to me that they may be aftermarket (?). I will try newer OEM Foci coils (I picked up a bunch during 50%-off days at the junk yard so I don't have anything to loose). I have not thought of them in a while and almost forgot I had them in a box (somewhere).
I would still do a cylinder contribution test BEFORE I changed them. Start the engine noting the vbration level. Disconnect the signal wire to one coil at a time and note the difference - which should be significant if that coil is firing and the cylinder is contributing. If there is no significant difference that that cylinder is dead and not contributing.

Good luck
Paul
 

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Discussion Starter #9
Okay, I did not understand what you meant by cylinder contribution at first but I did that based on your instruction and I have ruled out bad coils.

Back to evaluating the shakes/rattle – it is more or a rattle when the A/C is on. There is a little more vibration with A/C on but the most noticeable symptom is a knocking/rattling noise heard mostly in the cabin. I got under the car again and with A/C on and poked around with a pry bar to figure out where the rattling was coming from. As best I could tell, the rattling/knocking was coming from above and behind the transmission. With car cold, I found the exhaust manifold shielding loose and noted missing fasteners on the shielding around the alternator. I installed a nut and bolt for one missing fastener but there are a few other missing fastener points where I can see or feel a hole in the shielding but cannot figure out how it attaches. I have not found any schematics or parts to see how these attach. I will keep working on it.
 

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Have this same issue with a 2003 Zetec...AC on at idle it shakes...have not replaced the pass side mount.
 

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Discussion Starter #11
05 ZX3 Duratec 2.0. - First picture with the red arrow pointing to bit of heat shielding - is that bit of shielding in the correct place or should it be tucked into the side of the alt? Second picture is just for other side for reference. The 07 Focus 2.0 has a slightly different exhaust manifold or header shielding.

The heat shielding is missing at least 4 fasteners. I cannot get a nut and bolt in most of those spots so will try Ace Hardware for bolts that can screw in. I don't know how lucky I will be finding the right size so let me know if you have recommends or fastener part numbers to secure the shielding. Thanks
 

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Discussion Starter #12
It is ridiculous that after working on this car as much as I have over the past 15 months, I just noticed the alternator was missing a bolt! Also, one of the nuts on the stud was a little loose. After getting a bolt in and tightening, the vibration with A/C on has come down.

I did find a pic on Ebay of how the manifold shield is supposed look and all the bolts on the upper section (excluding the top two bolts) were missing. I bent back what I could and got 4 bolts back in. I cannot get three of the bolts back in because the back side was too mangled. Zero knocking/rattle noises now. I got the heat shield bolts from a newer Focus in the junkyard and was just lucky to find it because the manifold shielding and catalytic converters are usually gone.
 
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