2004 mustang hesitation

ThirdgenTa

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Girlfriends Mach 1 with 80,000 miles on it seems to hesitate/stumble when she accelerates at 30mph. Her coworker who races mustangs said bad gas but she has put amother whole tank in and it hasn't changed. Where should I start? I thought about the fuel filter since it has never been done.
 

greasy

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Check air filter, clean MAF, check plugs........if that does not work move to the fuel filter. Fuel filter should be done regardless with that many miles.
 

wombat

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Check air filter, clean MAF (don't forget to plug it back in!), check plugs........if that does not work move to the fuel filter. Fuel filter should be done regardless with that many miles.
Fixed that for ya! :bigthumb:
 

ThirdgenTa

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Check air filter, clean MAF, check plugs........if that does not work move to the fuel filter. Fuel filter should be done regardless with that many miles.
I know I cleaned the air filter at this time last year. It was pretty filthy. I'll do the maf. How hard are plugs to do in these cars?
 

RedBeard

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I know I cleaned the air filter at this time last year. It was pretty filthy. I'll do the maf. How hard are plugs to do in these cars?
10 minutes, stupid easy to do. And def replace the fuel filter if that hasn't been done before.
 

greasy

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I know I cleaned the air filter at this time last year. It was pretty filthy. I'll do the maf. How hard are plugs to do in these cars?

Not hard at all, a spark plug socket and 12" extension should be all that is needed. The only kind of pain will be the passenger side because you have to remove the intake piping to access the plugs.
 

ThirdgenTa

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Does the engine need to be cold? Also how important is it to use a air compressor to clean around the plug and do I absolutely need a torque wrench?
 

greasy

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Does the engine need to be cold? Also how important is it to use a air compressor to clean around the plug and do I absolutely need a torque wrench?

It does not need to be cold, but be very careful if it is warm as they are aluminum heads. If the car is daily driven and the engine bay is dirty I would have compressed air or shop vac ready. The COP (Coil On Plug) should seal the spark plug on the head well, but better to be safe than sorry. I think the plugs only need to be torqued to around 11 ft lbs, I never use one on the Cobra. When tightening with a 3/8" ratchet I just get them snug while holding the head of the ratchet (not the handle).
 

ThirdgenTa

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This guy at the auto parts store said that the plugs are probably going to break off in the head
 

greasy

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This guy at the auto parts store said that the plugs are probably going to break off in the head

Why would they do that? :rofl:

Take any advice that comes from an auto parts store guy with a grain of salt. I think less than 1% I have heard from from those guys has been relevant and 99% has been complete bullshit.
 

RedBeard

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This guy at the auto parts store said that the plugs are probably going to break off in the head
Lol. They're retarded. It's a 2004 so it'll have the 9 thread spark plug heads and not the 4 thread like on the early 03s. You'll be fine.

Remove the intake tube, 2 10mm headed bolt for the COP covers on each side and your standard spark plug socket with a 9-12" extension is all you'll need. Spark plug changes on 4Vs are VERY easy.
 

RedBeard

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Get a set of quality NGK plugs as well. And if you do the fuel filter get a motorcraft filter.
 

ThirdgenTa

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Tried doing the first one and there is a lot of resistance. I barely turned it and it didn't get looser so I am hoping it's not stripped... now to get the socket out of the head so I can get it to my friends house
 

VenomousDSG

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This guy at the auto parts store said that the plugs are probably going to break off in the head
Dafaq....... Was guy at the autoparts store smoking crack?

NGK TR6 plugs, fuel filter if haven't done before, clean MAF and IAC, and filter clean and you will be fine. You said you're having a lot of resistance taking the plugs off, have they EVER been changed?
 

ThirdgenTa

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Dafaq....... Was guy at the autoparts store smoking crack?

NGK TR6 plugs, fuel filter if haven't done before, clean MAF and IAC, and filter clean and you will be fine. You said you're having a lot of resistance taking the plugs off, have they EVER been changed?
Well he said he's had a few mustangs.. but he also said that it needed 2 piece spark plugs..
I'm not sure if the plugs have been changed. She bought it from a dealership with things done to it from the previous owner. As far as I know it just has exhaust, no cats. Also has a cai. Had 20,000 on it when she bought it
 

VenomousDSG

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Well he said he's had a few mustangs.. but he also said that it needed 2 piece spark plugs..
I'm not sure if the plugs have been changed. She bought it from a dealership with things done to it from the previous owner. As far as I know it just has exhaust, no cats. Also has a cai. Had 20,000 on it when she bought it
Get a set of NGK TR6 plugs, gap at .032. Replace/clean other things mentioned.

If problem still remains, it's more than likely an air/fuel problem given it's modded. If you don't know the history on it, or if it's even had a tune before, i probably will lean towards that. These 4vs usually require a tune even with basic cold air kits and exhaust, otherwise it will run like shit.
 

ThirdgenTa

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So I brought it to my friends house. Engine was hot. They came out like butter. All 8 done in 20 minutes. My friend said the old plugs looked just fine. Well when I left I got on it at 40mph and the wheels broke loose and gained traction and then shifted into second and broke loose again. Definitely has more power than before. I thought the hesitation was gone but noticed if I just barely hit the gas it will start hesitating and if I hit it more it will go away. So the hesitation isn't completely gone but goes away a lot easier. Before it would do it for a good 5 seconds and just not have much power. I still have to do the fuel filter and clean the maf.
Thanks for the help btw
 

blakbearddelite

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If none of that works, you might need to check the coil-on-plugs or coil packs....whatever they're called. I had a nasty misfire on my 2V that turned out to be a bad coil or three. The thing that sucks about the coils is finding the culprit. I just decided to replace all 8. Car ran perfect after that.
 

Grabber

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Not sure if it has been said. Could be your throttle body. I suspect that or your MAF. If the MAF is dirty or wet, your car will hesitate, idle funny and surge. Just use some compressed air on the MAF to give it a clean and check your throttle body. Is the blade sticking or feel like it has a lot of play if you try moving it?
 

ThirdgenTa

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Damnit. Did the plugs, replaced the fuel filter, cleaned the MAF, IAC and the air filter and it is still doing it.
 

greasy

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Like Blackbeard said, could be an issue with the COP's then.
 

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