Need help ASAP. I'm sick of dealing with this car.

[Black2003Vert]

Caution.This snake bites

Black2003Vert's Avatar

Join Date: May 2006
Location: San Antonio
Car: 2003 Mustang Cobra
Posts: 82
Trader Rating: (0)

Problem first happened when I was racing my cousin and I hit 140 mph. Started shaking and loss power. Came home and pulled plugs. Burned off tip of plug.Happened again a few months later. Time for retune.Cold air, C&L pipe, throttle body/plenum, off road h, exhaust, ported blower, upper 2.8, lower 4 lb, heat exchanger, tune. The problem was happeing so I went and had retuned. Motor was very lean. They richened up and motor would hesitate/miss at 4 k.They said I needed new coilpacks. I ordered the GMS coilpacks. I waited three weeks for them to come in but didnt drive vehicle. Couple of days before they came in I noticed the motor knocked for a couple of minutes when I started it.Put the GMS coilpacks in and no change. Had motor checked and knocking was from melted pistons. Pulled motor, rebuilt, bored thirty over, added longtubes and cooling mod. Drove around on new motor for brake in. Was told to get it into boost a lil bit to set rings.Other night got on highway and once I shifted to fourth, slowly boosted and motor began to shake exactly like it did before the motor started knocking.

Any one know?

 

[TERMIN8TR]

who is tuning that car?

 

[Black2003Vert]

It was tuned by Murillo motorsports. The problem occured before the last tune. Tune didnt help and they misdiagnosed the problem. They said I probaly have a bad coil pack. I ordered the GMS coilpacks but motor started knocking before they came in. Rebuilt motor and of course problem is still there because it was never corected since I dont know what is causing the damn problem.

 

[The Gixxer]

ok

a knocking sound ? hmm yea I was going to say it sounded like you messed up your egine... I have heard of a few cobra's doing those woot pull's and blowing there engine's.... but then you said you rebuilt it.... check to see if it is your compressor for your a/c.... I know when my parent's monte started to knock we came to found out was the compresser for their a/c.... not cheap either it was like $600 for a new compressor... of course we replaced it ourselves...

 

[Black2003Vert]

Its not knocking now, its hesitating at around 3500 - 4000 k. It just hesitates and go's no where.

 

[shoand03cobra]

Vacum leak!!

 

[redfiresvtsnake]

+1, check for a vacuum leak.

 

[Tom's_03SVT]

get a better tuner too...

heard of a few others having issues with Murillo Motorsports.

Do a search.

 

[Black2003Vert]

I know its not a vacuum leak. It did this before the motor was pulled and now after the motor was reinstalled. I am gett'n tuned by a different person but I was hoping I could have this problem fixed before the tune so my a** isnt raped on repairs.

 

[SlowSVT]

Sounds like your tuner is the root to all your problems. I can't see how melting electrodes is from bad coil packs. A/F ratio's or ignition timing is what burns pistons and plugs.

Did you upgrade your fuel system before all this? I didn't see anything on your post related to fuel system mods.

 

[Snakebite2k3]

good luck man

 

[zincsvtcobra]

Just curious but what plugs are you running and at what gap?

 

[Posi]

Find another tuner and get their opinion! That's a shame man and I hope you get it fixed.

 

[Fuerza]

How many miles on your new motor? I'd start with your engine builder first. Get a compression and leakdown test.

 

[Fuerza]

Also what all was done on your engine rebuild? You mentioned burned pistons but was anything done to the heads for the rebuild?

 

[RealBadDude]

Sounds like your tuner is the root to all your problems. I can't see how melting electrodes is from bad coil packs. A/F ratio's or ignition timing is what burns pistons and plugs.

Did you upgrade your fuel system before all this? I didn't see anything on your post related to fuel system mods.

+1 on fuel system... with all your mods it may keep up under low rpm and low boost, but under WOT when fuel demand is at it's highest it could be cutting out.

Do you have a fuel pressure gauge and a wide band O2? with all those mods i would invest in one. it could save you the cost of another motor.

 

[1bad03snake]

Try PSI in Webster(10 minutes south of Houston)

 

[SlowSVT]

but under WOT when fuel demand is at it's highest it could be cutting out.

........and BOOM!

 

[Cobrabuddy]

The problem should be obvious to a tuner... Sounds like you're not getting enough fuel or something, going lean, and melting parts... You said you had them rebuild the motor, broke it in, then got into some boost... Did you not tune it before doing that????

Prob shouldn't be in boost when you have no idea what type of base line you're running... A wideband and fuel pressure gauge would prob be a good idea... Or again, just a tuner who knows what they're doing.

If the car isn't getting the fuel it needs during a 4th gear rip and you're way lean, it's just game over!

 

[younggun04]

I melted a piston pretty much the same way as you did. got my ported blower on and supporting mods etc... got it back home was taking a friend out for a drive and the car started to hesitate at about 4500 rpm. the next day tick tick tick. took it to ford melted piston due to a poor tune to lean and too high of timing. needed a new engine. for some reason ford still warrantied it! picking the car up tomorrow with a brand new engine and my warranty expires on august 19th! man i got lucky. But it sounds like it's your tune. take your car somewhere else and never look back.