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-   -   missing while accelerating and rough starting... (http://mustangforums.com/forum/4-6l-1996-2004-modular-mustang/712450-missing-while-accelerating-and-rough-starting.html)

Maddsajin 08-01-2014 11:44 PM

missing while accelerating and rough starting...
 
i have a 2003 gt 4.6l 2v. has 205k miles on it... little high.. well here goes, i figured i would post this to help other people out with similar problems...

i have a startup problem with the closed loop cold start. it idles really rough. you can actually see my hood vibrating like crazy... when i put my computer on it during the closed loop cycle it flickers the o2 sensor failure. bank1 sensor1. thats the passenger side front o2 sensor. thats my first problem..

also when under moderate acceleration up to 5k rpms, it builds up a hesitation..
says cylinder 2 is misfiring.. i have new coils on 1-5 and 4-8. oem motocraft..

here is what i have replaced.. the list........
4 coil overs
all sparks plugs motorcraft copper core single spark
oil change - oil filter
clutch 11" king cobra stage 2
all brake rotors and pads
trany fluid
water pump

and its got a cold air intake and flowmaster h-pipe exhuast... i love the sound..

i have been fixing serveral air leaks on the topside. i have a NEW IAC but when i put it on it stalled the engine like 10 times in a 5 mile trip... but i contributed that to not resetting my KAM with the battery when i fixed a major air leak...

i have a new o2 sensor on order. it will be at my house on next tuesday. so im wondering is there anything i am missing or is the o2 sensor all i need to replace to fix both of these problems??

any advise will help..

thanks!

dawson1112 08-02-2014 04:23 AM

Try swapping out #2 cop with one of the new ones you bought and see if the misfire moves with it. If the misfire follows that #2 cop then you know you need to replace it.

If the misfire remains on the #2 cylinder after swapping the cop then it could be fuel related, possibly a sticky/leaky injector.

since you have an 02 sensor coming for it I would say that should take care of your first issue. If it doesn't then you need to look at the wiring to that sensor.

Maddsajin 08-02-2014 04:05 PM

Quote:

Originally Posted by dawson1112 (Post 8414403)
Try swapping out #2 cop with one of the new ones you bought and see if the misfire moves with it. If the misfire follows that #2 cop then you know you need to replace it.

If the misfire remains on the #2 cylinder after swapping the cop then it could be fuel related, possibly a sticky/leaky injector.

since you have an 02 sensor coming for it I would say that should take care of your first issue. If it doesn't then you need to look at the wiring to that sensor.

awesome i will try swapping the cop today... ill reset the mill light "still on cause th o2 fault at the engine start" so that way i can track and see if it follows..

also i have been looking at these COP's on ebay... there made from PROMINENT AUTO PARTS.. they guarantee them for 1 year with free returns.. they say there going to the SEMA show... that gotta be good if there going to the sema show... there on sale right now 50$ for the set of 8... for 50$ im thinking to try them out"free returns"...

wow didnt think it would show up like this ... just copied the link to the page... this is not a advertisement.. just trying to link what im looking at.. tell me what you think of these coil overs...


thanks! i will let you know

dawson1112 08-02-2014 04:30 PM

Quote:

Originally Posted by Maddsajin (Post 8414509)
also i have been looking at these COP's on ebay... there made from PROMINENT AUTO PARTS.. they guarantee them for 1 year with free returns.. they say there going to the SEMA show... that gotta be good if there going to the sema show... there on sale right now 50$ for the set of 8... for 50$ im thinking to try them out"free returns"...



DG 508 C1454 FD503T Complete Set of 8 New Ignition Coils for Ford 4 6L 5 4L V8 | eBay

I think they are Chinese junk , and might last for a year if your lucky.

Maddsajin 08-06-2014 09:34 PM

Quote:

Originally Posted by dawson1112 (Post 8414403)
Try swapping out #2 cop with one of the new ones you bought and see if the misfire moves with it. If the misfire follows that #2 cop then you know you need to replace it.

If the misfire remains on the #2 cylinder after swapping the cop then it could be fuel related, possibly a sticky/leaky injector.

since you have an 02 sensor coming for it I would say that should take care of your first issue. If it doesn't then you need to look at the wiring to that sensor.

ok i got the o2 sensor in and put it in last night... that fixed the rough starting idle... LTFT 0% both banks and STFT go from -3% to +3% on both banks... perfect readings now...

on another note i dont have much funding right now, so i went with the cheep chinese COP's. i bought 2 COP's for 14$... i couldnt resist... i got another code thrown today checked it, and it was only cylinder#2.. so i changed the COP with the chinese one.. bingo!!! no more miss.. i went to the store just to take a drive and WOT purrrrrfect... i just hope the chinese COP's last for a while.. the COP that was on cyl#2 was original with the date code of 2002... so for now my baby is fixed... just FYI the chinese ones really look very well made but we will see...

my next torment is my idle fluctuates, i already have a new IAC but havent put it on yet... when i put it on before when it was running badly it stalled my motor like crazy... so my next question is should i replace the IAC with the new one and also reset the KAM with the battery... or what do you think?

thanks for all the advise and please let me know...

dawson1112 08-06-2014 09:55 PM

If you already have a new IAC for it then you don't have any thing to loose by trying it.

You can usually clean them though and that takes care of the problem. Clean the MAF while your at it.

Maddsajin 08-06-2014 10:06 PM

Quote:

Originally Posted by dawson1112 (Post 8415748)
If you already have a new IAC for it then you don't have any thing to loose by trying it.

You can usually clean them though and that takes care of the problem. Clean the MAF while your at it.

i have made a home-made "sonic" cleaner... C.L.R. and a sander strapped to a clear container... it works way better then a QUE-TIP.. but i think the IAC is on its last leg because i can hear a ton of gurgling from the intake, which its from the old IAC.. i know its from the IAC because i can disconnect the sensor and the gurgling stops, then before it stalls out i plug it back in and the gurgling comes back...

do you think i should reset the cpu when i install the new IAC...?


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