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Cracked Intake Manifolds

NoVaGT

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Mustang folks;

It appears as if Ford has an issue with the S550 Coyote intake manifolds cracking. My car is currently at the dealership having it's IM replaced, and evidently the part number is new/revised. I have requested to see the failed IM, so hopefully I can get a pic of what broke at 8400 miles. Evidently there is a runner where a valve is, and it cracks there.

The symptoms are low-RPM misfires that feel like subtle bucking/surging. Mine occurred between 1500RPM and 2100RPM, and it annoyed the every living shit out of me. The engine pulled like a train once past 2100RPMs, but was dog-guano at low revs when just cruising. It's most noticeable in 5th and 6th gears, just cruising along. If I cruised for 20 minutes on the freeway in that RPM range, I'd get a CEL, misfire codes, and have to do a crank position sensor re-learn.

I've perused the "Issues, Repairs, Warranty, TSB, Recalls" sub-forum, and found thread after thread that had similar symptoms to my car, and I think it's fair to think that the symptoms may be different from one car to another. The RPMs the misfires occur at might change, for instance, based on the severity of the crack,

Anyways, if anyone has bucking/surging, misfire CELs, your IM might be the issue.
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usgiorgi

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Yup, I had this issue. I think I commented in your other thread. They replaced my IM. I've read that the dealers give some the run around with doing spark plugs first and then coils. My symptoms were being down on power a little, stutter between 1500-2100rpm, and codes p0300 and p0308.
 
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NoVaGT

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Yup, I had this issue. I think I commented in your other thread. They replaced my IM. I've read that the dealers give some the run around with doing spark plugs first and then coils. My symptoms were being down on power a little, stutter between 1500-2100rpm, and codes p0300 and p0308.
That's it. Exactly. Same RPMs, same codes.

To be fair, I don't think it's the dealer doing the run-around thing. I think the techs get Ford H.Q. engineering involved, and there is a step-by-step elimination process they go through.

I will say that in my situation the techs seemed to know exactly what was wrong, and went straight to the I.M., and got it replaced. My advisor said he's seen 6 cracked Mustang S550 I.M.s in the last 2 years he's worked there. Multiply that by the number of advisors working there, (probably 6 or 8), and that's a lot of cracked I.M.s
 

Grim12

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Have them swap it out to a GT350 or Cobrajet!
 
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Is there any experiences of this happening to the GT350 IM's or is it only affecting the GT IM's?
 

THE_AHJ

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sub'd,

I had this issue on my 98GT and it SUCKED. My concern is that I did the PP2 install myself, if this creeps up what are the chances Ford gives me the finger to replace this because I didn't have an ASE certified shop do the install on the PP2?
 

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I had this issue on my 98GT and it SUCKED. My concern is that I did the PP2 install myself, if this creeps up what are the chances Ford gives me the finger to replace this because I didn't have an ASE certified shop do the install on the PP2?
The safest bet would be to revert to stock, but chances are they wont blame the mods unless the crack was where the throttle body connects haha.
 

THE_AHJ

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Well I guess if the issue does come up and this f*cker cracks (praying it doesn't) then I'll go back to stock and reflash stock tune and take it in...man I really hope it doesn't happen to me AGAIN.

Pretty much the codes are the indicators of a cracked manifold right?
 

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usgiorgi

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Well I guess if the issue does come up and this f*cker cracks (praying it doesn't) then I'll go back to stock and reflash stock tune and take it in...man I really hope it doesn't happen to me AGAIN.

Pretty much the codes are the indicators of a cracked manifold right?
I felt the stutter well before the codes showed up. (At least the CEL wasn't there).

All of a sudden, one day I started feeling a misfire like stutter. I tried to convince myself that it was in my head, until I realized it was definitely real. In any gear between 1500 and 2100rpm it would stutter on light throttle.

I was sure it'd be a spark plug or a coil, but then the codes showed up about a week later. I took it to the dealer and after a day, they replaced my IM.
 

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Great. What iis with Ford and their intake manifolds? Had the same thing happen on my 96 GT. When it cracked it sprayed coolant all over engine. Had to get all the plug wires and plugs replaced as well. Of course it was out of warranty when it broke.
 

THE_AHJ

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Great. What iis with Ford and their intake manifolds? Had the same thing happen on my 96 GT. When it cracked it sprayed coolant all over engine. Had to get all the plug wires and plugs replaced as well. Of course it was out of warranty when it broke.
It was part of a recall, shouldn't have anything to do with warranty. Mine was a 98, the part cracked in 2005 right at the thermostat coolant everywhere as well. I did the swap myself thinking nothing of it and then down the road I got a recall letter from Ford to bring it in for repair. I told them I had it done and that I bought the part myself. It was like $200.00 or something for the part, did the install myself but didn't tell Ford and they cut me a check for $700.00 to cover labor cost. Fast forward to 2017, recently sold the car for $1800.00 with that replaced manifold still intact and almost 300K miles on the car...still ran great. But it is a bitch when something like that goes, my bro had a 96 and that manifold thermostat housing was aluminum and not plastic like the 98 smh.
 

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Ive got a leftover stock intake and tb only 3k miles for sale, pm me,
i will send you pics!
 

newkidnik

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I have some subtle bucking in the rpm range, but no CELs. I suspect mine may be from the intake, but I don't believe it does it at 1500-2000 rpm in 5th or 6th. It's worse when cold. Might be OK for now. We'll see. '16 with about 7500 miles.
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