My car is acting very f'd up!!!!!!!!!!!!!!!!!!!

[Ahriman]

its like this: first gear is fine, second gear ok till you give it about 40% throttle, and then the car falls flat on its face, feels like i hit a damn wall, then it recovers when i let off the gas, can go all the way through the rpm's if i stay below about 40% throttle though does the same thing in third. its fine as long as i drive slow, but like i said, if i try to open her up even just a little, BAM, she feels like the motor cuts off, and then recovers when you let off the gas, and its like a violent cut off(like what MGM once described as feeling like you hit a wall!).

now heres the wierd part, it did this about 8 times without throwing a code, then i parked her and came inside for a while to take a test online(for school). went back down there to take it for a spin to see if it was still doing it. first time i put her in 2nd and opend her up BAM, hits a the invisable wall, but this time she gave me some codes.... P0103 Mass Air Flow (MAF) Sensor Circuit High Frequency ECM ; P0300 Engine Misfire Detected ECM ; P0507 Idle Speed High ECM. I pulled over, cleard the codes, and then she was fine, couldnt duplicate the invisible wall no matter how hard i pushed her.

any ideas guys? anybody ever have somthing like this happen? similar code combos maybe?

[nightmistwalker]

mine has done that twice to me ,had the dealership run it thru and they said nothing showed up,,strange but it only does it once in awhile

[ptparker]

If RaceRelated (or whoever did your tune) did not set the MAF fail frequency to at least 12000, at most 14000, and you pegged your MAF
When this happens the car will revert to a speed density tune. The stock VE table is sort of crappy and just good for limping around. The problem may come back when you peg out your MAF.

[Ahriman]

Originally Posted by ptparker

If RaceRelated (or whoever did your tune) did not set the MAF fail frequency to at least 12000, at most 14000, and you pegged your MAF
When this happens the car will revert to a speed density tune. The stock VE table is sort of crappy and just good for limping around. The problem may come back when you peg out your MAF.

hmmm... i see. car is running good thismorning

[ptparker]

Originally Posted by Ahriman

hmmm... i see. car is running good thismorning

Don't redline it when it is cold(er) out. Until you get that MAF setting looked at, your don't want to peg out your MAF at WOT. A friend of mine blew up his Lightning on a cold night by pegging out his MAF (Shot the number 7 and 8 connecting rods out of the side of the block). I am not saying it will happen to you, as we have a failsafe MAP/SD tune (the Fords don't). But, in even with a failsafe, you don't want it to happen again. It leans the motor out.

[TheWastedYears]

Check your K&N for water, and make sure the pipes haven't separated.

[korax123]

I think he is talking about when just driving normal the car will "buck" between gears when shifting. My car does this also and I hate it. If I give her like 40% throttle and shift @ 4-5k when the motor is warm the car "BUCKS" real bad but you can still shift and keep on moving.

Anyone know why?

[Ahriman]

Originally Posted by korax123

I think he is talking about when just driving normal the car will "buck" between gears when shifting. My car does this also and I hate it. If I give her like 40% throttle and shift @ 4-5k when the motor is warm the car "BUCKS" real bad but you can still shift and keep on moving.

Anyone know why?

no mine was happening right after the shift, like right at the beggining of the gear, if i went above say 30-40% throttle, it would "buck" very fucking hard, but if i let off the gas/press the clutch it would recover. and as long as i stayed below the 30-40% throttle i could climb all they way through the gear without it happening.

[TheWastedYears]

Sounds exactly like water in the intake.

As for general bucking after a shift... I attribute a lot of that to engine mounts. Mine does that quite a bit on the stock mounts, and didn't do it at all w/ the BWoody mounts.

[korax123]

Originally Posted by TheWastedYears

Sounds exactly like water in the intake.

As for general bucking after a shift... I attribute a lot of that to engine mounts. Mine does that quite a bit on the stock mounts, and didn't do it at all w/ the BWoody mounts.

Nah it's more like the engine is cutting in and out. Doesn't do it much at all when it's warmer outside. Just mostly when it's cold out.