[MrGearHed]

Hey guys, im semi new to the forum and i had a question.

I just bought a black on black 2003 Mach 1 and i love it.
Mods include CAI, 90mm MAF, Bassani X with Magnapacks and a tune.
It was tuned with a diablo on a dyno. The previous owner just modified a couple parameters of the diablo tune. He added 2 degrees of timing from 2k-4k rpm and 2.5 from 4k-7k and upped the fuel pressure by 2lbs. He said it put down 300whp with the added timing and fuel, All the math works out that it should. This car is immaculate, the only problem is that if im cruisin around town in higher gears at anything below 1800ish rpm, if i get in the throttle more than a little it misfires, idk if its a ping, or if its just loadin up on fuel, but i ran 93 octane with a mean octane booster that raises 16 gallons 6 points lol, and it still did it. It is worse when its hot out, thats why it points to a ping. It still runs great, moves out, just bothers me when i wanna just cruise at a lower rpm. I was wondering it anyone else had a Mach with this issue and if theres a timing/fuel adjustment i can make that would help. It has new spark plugs and about 73000 miles on it.

Any suggestions would help, i just want this car to last forever and haul ass, so someone throw me some knowledge

Thanks

[War]

well I don't own a mach 1, and i never tuned my car, but i'll tell you right now...

Sounds like a coilpack, and mine did it for a good 30-50 miles before it finally threw a code. I'd say change your sparkplugs first, if it still does it, the culprit is one of those coils

I didnt see the *new sparkplug* what kind of material, we talking about motorcraft nickel tips or copper?

[BMR Tech]

Sounds like a "Coil On Plug" (what most call a coilpack)

Or it is spark knocking.

Is it throwing codes? My advice is to get it on a dyno, and have it dyno tuned....then datalog it on the street.

If you are unable to get it to a dyno and get it tuned.....datalog some of the live parameters on the Diablosport Predator.

Datalog the spark adavance....and see what it does around the time when the issue happens. You will see it drastically change when the "knock happens, assuming your knock sensors are working properly.

Datalog the 02 sensors too.... When an 02 sensor is bad....you will have hesitations at low rpm under load.

Also, does the cold air intake go into the fenderwell, or is the filter under the hood? If it is in the fenderwell, switch to an underhood system.

Good look and keep us posted!

[MrGearHed]

The sparkplugs were just replaced, motocraft original equipment and its never thrown a code, and I've driven it about 2000 miles, I really don't think its a coil pack, the car only has 72000 miles on it, I think its too much fuel at low rpm, loading up and flooding sort of, I'm gonna consult a friend of mine whose got about 50 mustangs including an 03 cobra and see what his suggestion is

[justang1999]

sounds like a coil to me as well. the coil might still be good you should pull all the coils out and inspect the rubber boot to make sure it does not have any split or cracks. if so you can just replace the boot for about 8-10 dollars.

[BMR Tech]

Datalog it. STFT/LTFT - Spark Advance - 02's.

I find it hard to believe it is "loading up"....unless a kindergartner put the tune in it....or there is something else majorly wrong.

I am firm in believing it is:

COP issue
Pre-Ignition/Spark Knock
02 Sensor

Was the air filter recently cleaned? You might want to pull the mass air meter off and clean the MAF wires.

You say it has a 90mm MAF? Is it a lightning MAF? Ask the previous owner if it was tuned correctly for that MAF. Transfer Functions etc.

[Mach Boy]

I had a similar problem at the same RPM under any load and it was part of my wiring harness that had went bad. Fast forward to this year I had a similar feeling under heavy load at a high RPM and it was bad COPs.

[MrGearHed]

It seems COPS are the major verdict here, it will do the same miss in high tons sometines too if I'm in the throttle, and sometimes as i take off from a stop at low low rpms, the o2 sensors look like theyve been replaced recently, any suggestions on where to buy Cops and what brand to get, oem, aftermarket?

Thanks for the help guys

[MrGearHed]

Ok so my problem has developed, the misfire basically happens under load, its bad at low rpm and its intermittent in the higher rpms, like if i pull through 2nd or 3rd it will misfire a couple times throughout the rpm range and you can feel the power suffer when it does, i think its gonna be MAF or COPS, what do you guys think i should do first, new cops? It also doesnt misfire nearly as bad when its cold outside, it still does, but its much worse in hotter temperature, idk if that really helps narrow it down, most things run better in the cold lol. Im more concerned about it being a ping or small detonation, i dont want to cause bad damage to my engine by not fixing this problem fast enough, i really do think its a coil issue, im going to clean the maf and filter and see what that does, then ill do coils. Any feedback is appreciated.