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Discussion Starter #1
I have an 01 v6 mustang with about 150000 miles. I noticed a few weeks ago a heavy mis during acceleration. Car cranks and idles perfectly. I have replaced spark plug and wires, checked resistance on ignition coil, checked MAF sensor. Figured it would be fuel related. Check fuel pressure today. Pressure at KOEO was less than 10 psi. At crank 32 psi, and after about 5 mins of idling, up to about 58 psi. Should my fuel pressure be the same at KOEO as with the engine running? Ant other suggestions are also appreciated. Only mods to the car is an off-road h-pipe, which I have O2 sensors plugged in with MIL eliminators.

thanks
 

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Well i am having the same problem. Not to sure what it is either. I have done the in line fuel filter, plugs, wires, and there is not no check engine light or codes showing from mechanic. Coil pack reads right with ohm tester. Fuel pressure is good when driving and the car is hesitating at acceleration.
 

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same issue, this helped

I had that same problem with my old Mustang at around 160,000. My automatic sixer had issues missing the punch during acceleration. I changed everything you mentioned including spark plugs, wires, etc. but I changed out the old coil for a screamin demon coil myself and also had the injectors cleaned professionally. Once both of those were done, my car ran just fine. Still a little sluggish, but I attributed that to age. Try looking into a new coil. They're cheap and easy to install. Got it from AM, and I just ordered another for my Mustang now cause the old car was totaled from a deer. The coil works wonders!
 

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also,

Have the exhaust checked. Sometimes the back pressure from the after market exhaust messes with the acceleration. This is usually found in newer Dodges i.e. Chargers, but it can also cause issues with Ford. No where near as common though.
 

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Im having almost the same problem mine stumbles when accelerating.:nono: it could the cats are clogged or There is a valve that lets a small amount of exhaust back into the engine and that might be getting stuck its called the EGR valve it could need to be replaced.

Try getting a trouble code reader and see if any codes get set off. Im going to replace my EGR ill let you know if it helps!:nogrinner
 

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Discussion Starter #8
Been lookin in to a new coil anyway. May go ahead and just change that out. The back pressure sounds like somethin to check into also. I done the exhaust only about a month or so ago due to a broke cat and this was a lot cheaper fix. But I don't remember noticing it before the aftermarket exhaust. Will keep u guys updated. Thanks for the help
 

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how do you know it misses.. does the check engine light flash? that indicates the computer senses a misfire is currently happening.. do you have any error codes from the computer? its important to know what the codes are exactly
 

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I recently had my car in for an oil change, and new E3 plugs with new Duralast wires, ended up getting a misfire and a rising heat gauge, the SCT helped a little. Got rid of the plugs and replaced with new Motorcraft ones, then my mechanic, while checking the misfire problem, noticed the coil was going bad and replaced that for free, cause they had one someone ordered but never got installed, then told me the Ford Mustang Coils go out about every 150000mi...

I recently had a new battery, a new alternator, said stuff above, and was going to have a new pulley but found that the part I thought was broken is actually designed the way it is, all done in the span of 2 months and all unfortunate for reasons starting with the car not holding a charge....
 

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Been lookin in to a new coil anyway. May go ahead and just change that out. The back pressure sounds like somethin to check into also. I done the exhaust only about a month or so ago due to a broke cat and this was a lot cheaper fix. But I don't remember noticing it before the aftermarket exhaust. Will keep u guys updated. Thanks for the help
on this, I had to replace a header cause of the stock one cracking and breaking clean off, the engine sounded sweet like that but the car just wouldn't "GO" like it used to... also with the story above I wrote, I forgot to add that I replaced the lower intake valve gaskets cause they blew out (mech said had nothing to do with the e3 plugs but it's a bit too coincidental they blew out just after installing the plugs...)
 

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Discussion Starter #12
how do you know it misses.. does the check engine light flash? that indicates the computer senses a misfire is currently happening.. do you have any error codes from the computer? its important to know what the codes are exactly
No check engine light and no codes. When I crank it up it runs perfect and rev motor to about 4000 rpm with no hesitation but when I go to drive and press the accelerator it jumps and misses like its not getting a spark or either not getting fuel. Once I get up to driving speed and set the cruise it runs fine
 

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i ended up going to ford and had them check my car they said that it was my coil pack. i had tested that before i brought the car to them and it tested fine for me. so i changed it myself and it fixed my problem. it was like 85 dollars for ford to hook up to car. and bought original part for 100
i had no check engine light on changed several sensors filters the whole nine yards spent well over 200 plus with injector cleaners and gas from test driving id say best bet is get ford to plug up for the 85 dollars and find what your problem is before ya nickle and dime yourself
 

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Discussion Starter #14
i ended up going to ford and had them check my car they said that it was my coil pack. i had tested that before i brought the car to them and it tested fine for me. so i changed it myself and it fixed my problem. it was like 85 dollars for ford to hook up to car. and bought original part for 100
i had no check engine light on changed several sensors filters the whole nine yards spent well over 200 plus with injector cleaners and gas from test driving id say best bet is get ford to plug up for the 85 dollars and find what your problem is before ya nickle and dime yourself
Yea I'm done nickel and diming. I can't afford to just keep buying new parts. Think im goin to take it in before too long.
 

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it sounds like the 150,000mi thing with the coil is about true huh?
 

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My '04, 3.8, had a slight miss for the 3 years that I've had it, until a couple of months ago when I found the fix. I could fix it for a few weeks by changing plugs, or wires, or coil, but it wouldn't last. After I changed out those parts, it would be improved, and each time I thought that I had the problem fixed, but each time it would return. The last time I went in for wires, I told the guy at the counter about my problems, and he had the cure. It seems that he also had a 3.8, along with a couple of more guys that worked there. The stock wires for the right bank run down from the coil, behind the rear of the engine, and then come up around the exhaust manifold. He sold me a different set where the right bank wires run straight across the intake and drop down to the plugs. They right side wires were about half the length of the originals. I don't know if it was the length, or if they were cross firing by running side by side for the longer length, but anyway my problem has been solved. It was the first time that I could light up the tires from standing start, since I've had the car.

As far as engine codes go, a couple of times it had thrown a fault for a cylinder misfire, always on the right side, but not necessarily the same cylinder. I was thinking of replacing the injectors until I found these new wires. It running so much better, I've changed my mind about trading it. Just my 2 cents, but it worked for me.

Nashcat
 

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i'm gonna guess you didn't reuse the factory stand-offs and wire looms to keep them from touching; if the wires touch anything metal, over time they will start to arc through the insulation and you'll have your misfire issue.
 

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i'm gonna guess you didn't reuse the factory stand-offs and wire looms to keep them from touching; if the wires touch anything metal, over time they will start to arc through the insulation and you'll have your misfire issue.
You know, at 60 years old, this isn't the first Mustang hood I've ever looked under. I actually used new stand-offs and wire separators when I installed new wires. The factory stand-off don't really hold up well, after they've been opened up, once or twice. But thanks for the advise anyway.

I miss my '65 Stang that I had in the 70's, that would run in the low 12's with a maxed out 289cid. But that was in the days of real gas and 13:1 pistons. I don't miss adjusting the points, but most of you wouldn't know about that.:bounce2:

John
 

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Discussion Starter #20
My '04, 3.8, had a slight miss for the 3 years that I've had it, until a couple of months ago when I found the fix. I could fix it for a few weeks by changing plugs, or wires, or coil, but it wouldn't last. After I changed out those parts, it would be improved, and each time I thought that I had the problem fixed, but each time it would return. The last time I went in for wires, I told the guy at the counter about my problems, and he had the cure. It seems that he also had a 3.8, along with a couple of more guys that worked there. The stock wires for the right bank run down from the coil, behind the rear of the engine, and then come up around the exhaust manifold. He sold me a different set where the right bank wires run straight across the intake and drop down to the plugs. They right side wires were about half the length of the originals. I don't know if it was the length, or if they were cross firing by running side by side for the longer length, but anyway my problem has been solved. It was the first time that I could light up the tires from standing start, since I've had the car.

As far as engine codes go, a couple of times it had thrown a fault for a cylinder misfire, always on the right side, but not necessarily the same cylinder. I was thinking of replacing the injectors until I found these new wires. It running so much better, I've changed my mind about trading it. Just my 2 cents, but it worked for me.

Nashcat
Were these wires made for the car or were they made for another car that they just happen to fit the 3.8? Do you remember the brand and where u got them? Thanks for the info.
 
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