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Old 06-16-2014, 04:36 PM   #1
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Misfiring no codes

Hey a little input would be nice,, I've got a 99 4.6 gt and the damn thing is missing when I stab the pedal, its not consistant, its not throwing codes and it varys in degree.

the plugs are pretty fresh, the intake was replaced and nothing appears visibly wrong or broken, I have replaced the MAS and TPS and no change. My buddy hooked it up on his expensive *** scanner and it reported multiple cylinders misfiring,, like most of them. Thats why we went after the MAS, but nothing,,

any suggestions?

thanks, Dave
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Old 06-16-2014, 05:19 PM   #2
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COPs, fuel filter?

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Old 06-16-2014, 05:41 PM   #3
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The fuel pump was also recently replaced, I am assuming its good, the COP'S? who knows
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Old 06-16-2014, 07:10 PM   #4
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Fuel pump and filter are different though. Try putting a new fuel filter on they are like $12 for Motorcraft

Also if you are unsure about Cops might be a shot replacing the springs and boots. There a lot you can buy for like $30

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Old 06-16-2014, 07:27 PM   #5
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I didn't realize the 99 had an external ff, I will do that and the spring kit idea i have considered,
I had a similar situation with 07 GSXR,, a few shops tried to diag it after i did and finally it was figured out to be a bad injector, I'm wondering if this ain't the same thing, ever hear of multiple injectors going out at the same time?
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Old 06-16-2014, 11:42 PM   #6
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So i just ordered a set of accel coils, i'll let you know how that works out FOS
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Old 06-17-2014, 09:03 AM   #7
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Startron is a great fuel additive that will clean injectors. I have used it often on my wife's van.
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Old 06-17-2014, 10:37 AM   #8
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Beware any aftermarket coils such as the Accels or MSD or whatever. They have proven time and again to burn no hotter than OEM and reliability is not at the same level. I hope you get lucky with them but your best bet is the OEM at $40 a pop. Or you can do what another poster said and buy the $30 boot and spring kit. If the actual COP itself is not cracked or corroded or otherwise ****ed then it should be fine with a cheap rebuild.
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Old 06-17-2014, 10:39 AM   #9
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Aftermarket coils are a waste of money. And have been proven to hurt performance

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Old 07-03-2014, 10:19 PM   #10
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anyone had any experience with the 24lb fuel injectors??? do you need to do anything else when you put these in?
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Old 07-08-2014, 09:08 PM   #11
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Quote:
Originally Posted by davidr_1961 View Post
So i just ordered a set of accel coils, i'll let you know how that works out FOS

I have accel coils I've haven't had any problems and it seems to make my car fire up better than it did with the oem


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Old 07-09-2014, 07:14 AM   #12
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Same problem I have with my 2001 slight miss
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Old 07-09-2014, 11:09 AM   #13
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I have the same problem, no engine light comes on but still misfiring between 30-50 mph


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Old 07-09-2014, 12:16 PM   #14
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anyone had any experience with the 24lb fuel injectors??? do you need to do anything else when you put these in?
You'll need a tune so that the engine doesn't run rich.
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Old 07-09-2014, 02:55 PM   #15
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I had a couple of coils go bad intermittently. They would idle rough but smooth out until 45 to 55. I just bought 2 new coils and started swapping them out until the problem went away. No codes either.


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Old 07-09-2014, 04:36 PM   #16
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Just went through this one with my 2003 GT automatic. It would misfire under steadily increasing throttle around 35-50mph or so. If I stepped down hard it would go away. At first I thought it was the TCC failing to release because it felt like a TC shudder.

Since the car has about 100k miles on it, I replaced the boots and springs with the United kit from Rock Auto.
Also replaced all plugs, which looked good, with NGK.
No change although I did seem to feel more power from the NGK vs the copper Motorcraft's I usually use.
Put back stock tune. No change. I use Bama 91P or 87P BTW. Never a problem.
Bought one Motorcraft coil and picked the easiest one to swap, drivers side front.
Bingo! All fixed.
At least until it rained a few days later and the car acted up. First time it ever did that just during rain. Previously with the original coil in the weather didn't matter.

Anyway, this time around I hooked up my SCT3, laptop and Livelink.
First time using this program so I got all the latest drivers and SCT (actually SF3) updates.

Data logged for 10 minutes and really tried to aggravate the problem. Fortunately the car cooperated and was stumbling bad.

The LiveLink showed Cylinder 3 logging about 150 misfires in 10 minutes. Others were zero except for Cylinder 6 which had 1 misfire.

Bottom line is I replaced Cylinder 3 COP and the car has been fine since, about a week.

BTW I had done all the nromal stuff first. Clean MAF, IAC, check connections etc.

Our cars are aging and even if the COP looks fine, it may not be and the classic symptom from what I experienced and am reading is a stumbling at light to increasing throttle at about 35-50 MPH.

Buy one or two coils and keep moving them around, keeping track until the problem goes away. Or, buy an entire new set because if they are all the same age it's only a matter of time before the others start getting sick.
I'll cross that bridge when I come to it lol !
Good luck!
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Old 07-09-2014, 10:58 PM   #17
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Quote:
Originally Posted by vert03 View Post
Just went through this one with my 2003 GT automatic. It would misfire under steadily increasing throttle around 35-50mph or so. If I stepped down hard it would go away. At first I thought it was the TCC failing to release because it felt like a TC shudder.

Since the car has about 100k miles on it, I replaced the boots and springs with the United kit from Rock Auto.
Also replaced all plugs, which looked good, with NGK.
No change although I did seem to feel more power from the NGK vs the copper Motorcraft's I usually use.
Put back stock tune. No change. I use Bama 91P or 87P BTW. Never a problem.
Bought one Motorcraft coil and picked the easiest one to swap, drivers side front.
Bingo! All fixed.
At least until it rained a few days later and the car acted up. First time it ever did that just during rain. Previously with the original coil in the weather didn't matter.

Anyway, this time around I hooked up my SCT3, laptop and Livelink.
First time using this program so I got all the latest drivers and SCT (actually SF3) updates.

Data logged for 10 minutes and really tried to aggravate the problem. Fortunately the car cooperated and was stumbling bad.

The LiveLink showed Cylinder 3 logging about 150 misfires in 10 minutes. Others were zero except for Cylinder 6 which had 1 misfire.

Bottom line is I replaced Cylinder 3 COP and the car has been fine since, about a week.

BTW I had done all the nromal stuff first. Clean MAF, IAC, check connections etc.

Our cars are aging and even if the COP looks fine, it may not be and the classic symptom from what I experienced and am reading is a stumbling at light to increasing throttle at about 35-50 MPH.

Buy one or two coils and keep moving them around, keeping track until the problem goes away. Or, buy an entire new set because if they are all the same age it's only a matter of time before the others start getting sick.
I'll cross that bridge when I come to it lol !
Good luck!

yeah my buddy has suggested the same thing, replace them all! i'm in california man, thats a 400 dollar deal, there are other things going on with the car that just have me leary of doing this. When I changed the oil for the first time 2 weeks ago it was as silvery as you could imagine a nightmare to be. when I bought the car about 2k miles ago it had been given a fresh oil change and I had no reason to be concerned, thats changed. I am about to change it again now that about 1000 miles have been put on since oil change and see what it looks like. if its silver again I'm thinking this misfire is going to be the least of my problems, I too suspect TCC or some other flukey thing causing the misfire and somehow tied to the metal in the oil pan.

its such a bummer, the body and pain on this car is very clean, very clean, the interior is ALMOST perfect, but it runs like ****
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Old 07-09-2014, 11:04 PM   #18
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BTW, two modis scanners have told us its multiple misfires, so whatever the problem is its affecting 4 holes or more my friend Varun wants more time to diag it so i'm going to let him have the car for a day or two
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Old 07-10-2014, 12:27 AM   #19
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If you see silver in the pan that is not good at all. The sell may have changed the oil to hide a internal problem like a spun bearing or bad piston rings. Do a compression test first. Easy to do and cheap. That will tell you a lot about the condition of the engine. You could get a junkyard engine for cheap and replace the motor if you have to.


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Old 07-20-2014, 02:08 PM   #20
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Ok, so I broke down and picked up all 8 coils and plugs (Motorcraft) on Ebay, got them to my door for 334, just couldn't pass it up, so i put them in today and went for a 20mi test drive and it seems to have solved the problem.. the car runs nice and smooth, no misfiring at all so far. 1 plug had a messed up wear pattern on it and the other 7 looked good. all 4 coils on L side of motor burned the grease on the plugs and smelled like a burnt electrical component would smell.
NOW its time to start the build !!!! Thanks for all the input guys, i appreciate it
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Old 07-21-2014, 07:31 AM   #21
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Glad you got it fixed! Happy building!
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