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#216926 - 12/10/11 10:25 PM 05 GT intermittent missing but no check engine light.
Caine808 Offline
Junior Member
Registered: 12/10/11
Posts: 5
Hello, I have been having the same problem with my 05 GP GT since I bought it 3 years ago and would like some help. Every once in awhile (around every 15-20 start-ups) the engine will idle fine but when I start to go it feels like the engine lacks power, at speeds of 20+ it will feel like it is missing (shuddering\jerking in the engine). Their is also a noticeable drop in the estimated MPG on my info screen but their has never been a check engine light that has come on at all. However, if I pull over and turn the car off and start it back up the problem vanishes. I have talked to 2 of my customers (I work at a bank) who are mechanics and they both have said it is most likely a sticking EGR valve or a coil pack that is fixing to go bad. I would just like a 3rd opinion before I drop it off to be fixed please.
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#216931 - 12/13/11 10:42 AM Re: 05 GT intermittent missing but no check engine light. [Re: Caine808]
FordMan77 Offline
Member
Registered: 10/26/07
Posts: 122
Loc: St. Louis
Have you had the plugs and wires changed? Also would recommend removing and cleaning the entire TB as these years are known to get build up on them and cause strange issues. Doubt the EGR has anything to do with a miss.

Clean the tips of the coil packs w/ a scotchbrite pad and put some dielectric grease on them.

Also wouldn't hurt to have the fuel filter replaced as well.
_________________________
These are highly engineered precision vehicles, the first step in diagnosing the problem is to strike the suspected offending part sharply and repeatedly with a blunt object, then re-test.
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#216932 - 12/13/11 02:26 PM Re: 05 GT intermittent missing but no check engine light. [Re: FordMan77]
Caine808 Offline
Junior Member
Registered: 12/10/11
Posts: 5
I had the plugs/wires replaced around 10k ago (AC Delco parts), cleaned the throttle body out extremely well (I did not remove it though) the last time I changed the air filter (around 4k ago). Neither of these helped the problem. I plan on changing all the coil packs this weekend and I will clean the terminals during the replacement and see how it goes. I am a bit confused about the fuel filter though, I was told that my car doesn't have one.


Edited by Caine808 (12/13/11 02:27 PM)
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#216933 - 12/13/11 04:20 PM Re: 05 GT intermittent missing but no check engine light. [Re: Caine808]
jjcom Offline
Member
Registered: 08/12/06
Posts: 464
Loc: USA
Those cars don't have a fuel filter, they've moved onto a giant screen in the fuel pump module. Since it clears after the car is restarted, I have to wonder if it's the throttle body. The coils on these cars don't normally go bad. I've seen them come in all original after 200k + miles. And when they do go bad, normally corrosion is present or it has a dead miss on that cylinder.
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#216935 - 12/13/11 04:27 PM Re: 05 GT intermittent missing but no check engine light. [Re: Caine808]
FordMan77 Offline
Member
Registered: 10/26/07
Posts: 122
Loc: St. Louis
Whoops, you're right. I forgot the newer ones didn't come w/ an external filter, yours is in-tank and is rated to last the lifetime of the pump.

Have you tried cleaning the MAF?
_________________________
These are highly engineered precision vehicles, the first step in diagnosing the problem is to strike the suspected offending part sharply and repeatedly with a blunt object, then re-test.
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#216936 - 12/13/11 05:45 PM Re: 05 GT intermittent missing but no check engine light. [Re: FordMan77]
Caine808 Offline
Junior Member
Registered: 12/10/11
Posts: 5
I cleaned the MAF with the spray that CRC makes (i think that was the brand name) when I replaced the air filter. Is their a way to diagnose if its the throttle body?
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#216938 - 12/13/11 10:55 PM Re: 05 GT intermittent missing but no check engine light. [Re: Caine808]
jjcom Offline
Member
Registered: 08/12/06
Posts: 464
Loc: USA
They will normally throw a code for correlation error with the throttle position and pedal position. It maybe a pending a code and not yet lit the SES light.
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#216939 - 12/14/11 10:20 AM Re: 05 GT intermittent missing but no check engine light. [Re: jjcom]
Caine808 Offline
Junior Member
Registered: 12/10/11
Posts: 5
Ok, I did go to autozone yesterday on my lunch break and had them hook it up to a scan tool (because it’s free) and there were no codes stored, im not sure if their tool is sensitive enough to pick up on a throttle body code though. Since im at it, I have also been having a transmission problem. A few months ago I had the Pressure Control Solenoid replaced because my car would shift hard and fast after reaching normal operating temp (it set me back by 700$). Now its shuddering/bumping in 3rd gear. It happens all the time (under hard or soft acceleration and when the engine/trans is cold or at normal operating temp). Could this be the new pressure solenoid acting up? Because if it is its still under warrantee. And I want to thank everyone for your help!
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#216940 - 12/14/11 02:45 PM Re: 05 GT intermittent missing but no check engine light. [Re: Caine808]
Caine808 Offline
Junior Member
Registered: 12/10/11
Posts: 5
I also wanted to add that the shuddering happens after it shifts into 3rd gear, not before. Im not sure if that makes a difference or not but i just wanted to be thorough.


Edited by Caine808 (12/14/11 02:46 PM)
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