miss at wot

[mystcobra04]

have a bit of a problem, at wot i get a bad miss, at normal operations it runs fine. i can slowly acc with out any miss but soon as i hammer it it misses. i havn't lost any fuel mileage and seem to run good until wot. i have mod with 2.9 pulley, Itune, cai and cat back this summer and it been running great. any help on this ????

 

[LeKiD]

Plug gap ?

 

[mystcobra04]

going to be checking this weekend plug and coil. your thoughts on fuel filter or jets plugged.

 

[Posi]

Change the plugs first and gap them around .032" to .034" of an inch. It's the cheapest route and the easiest.

 

[mystcobra04]

thank all, will do post back on finding.

 

[quik cobra]

Sounds exactly like my car but my car is throwing the po175 code.

 

[highcompression]

Datalog voltage as well. Alternator could be getting weak. My Ford Racing Aluminator alt solved ALL my alternator issues. It's a 130a vs stock 110a and puts out way more appropriate amps @idle and mid RPM's. Much better ramp up rate then stock (and some other "high amp") too. Seems to be a nice piece for a mildly modded "stockish" car that doesn't spin it to the moon: 6500+). From what I can see on the outside, looks like ford made some changes since 03 ? They're a all new unit, no reman crap and have outlasted every other I've used (I've ran about every kind you can name between me and my buddies over the years. I dissect them after failure too, I'll leave it at that) on this car and others. Hopefully I didn't just jinx myself by praising my alt (and luck ?) lol .... .....

 

[highcompression]

Like others have mentioned as well, change/check plugs and or gap. Might be a fuel delivery issue, could be a weak COP, mechanical ? .... Start with the easy stuff first: plugs and datalog voltage.

 

[Jensanity]

I've dealt with this all too much lately.
*First time - water in spark plug hole after using too much water in engine bay while cleaning
*Second time- failed coil pack from the water from the first time.
*Third time- not necessarily a misfire, but there was definitely a hesitation and my a/f was lean and this was caused by either a weakened alternator or overspinning my alternator causing high heat and inadequate voltage I'm assuming. Either way my fuel pumps were not getting the power supply they required and my car ran like piss at WOT because of it.

The car ran fine at idle and cruising, but anytime I would go half throttle or more a misfire or hesitation would happen in each of these three situations.

 

[mystcobra04]

Hay all, thanks for the information, plugs were the issue. but reading some of the posts I'm wondering am i going to have problems with alterntor with the down size of the pully from stock to 2.8 on the blower, just a thought.

 

[greenflash00]

I had a problem similar to this last year once it turned cold out but only happened in high rpm. Tuner said it was spark blowout. Cooler denser air = more boost. Sure enough when it warmed up it was gone. Glad you got it figured out!

 

[93stang5.0]

I been having similar issues myself. I have noticed a slight miss at WOT and A/F does go lean some. My plugs are gapped at .028" and I datalog the voltage and did see a drop in the volts. Alternator does have a 3.2 pulley with a 4lb lower. Should I consider replacing the alternator??

 

[cobra=trouble]

Nevermind I just say u fixed it