Bubba1972

Long time reader, first time poster!

Three months ago, Ipurchased a2000 Mustang GT Convertible. It's completely stock. I really enjoy driving it, and am eager to invest some dollars into improving performance.

Now for the problems. Short on time and big on pollen in the local area (all the cars are green now), I filled up at the local gas station and ran it through a basic car wash (I can see the cringes from here). The next day, I noticed it running VERY rough -- expecially at lower RPMs and in 1st/2nd gear.In3rd-5th,it smooths out, that is until you try to accellerate.

Symptoms include jerky acceleration, rough idle, and wierd compression/popping noise at the exhaust (and a slight gas smell). Before long, "Service Engine Soon" light came on.

The next day, I took it to our local performance mustang garage. They called me the next day and said it was a crack in the intake manifold. The crack was letting antifreeze into the #8 plug well, which was now fouled. They replaced the manifold, plugs, etc. After more money than I care to admit, I picked her up and went home. The next day (today), same symptoms (although not as bad) and the service engine light is back on.

Did I screw something up by going through a simple car wash? Did I get bad gas? Is there something more evil lurking? I plan on taking her back to the shop on Monday...and advice from you experts would be much appreciated!

Thanks! Bubba.

breagles

Well I'm not sure but I would check with ford on the manifold recall I think it was for a limited time but if you had your manifold replaced and you have a receipt they will cut you a check for the cost of the repair . Did you change the plugs also ? I would . Also I'm thinking the popping noise and sputtering is from a weak fuel pump therefore causing detonation in the intake and causing it to crack from running lean . When you take it to the shop have them scan it while they are driving it and check the fuel pressure under a heavy load .If that is not it which I'm sure it is then check the coils . Good luck and hit me up and let me know what it is .

99roushgt

well this sounds like the common dirty IAC , take off the IAC and clean it out and hopefully that would fix the problem i do not have a pic of where its located but its on top of the manifold attatched to your upper intake plenum and looks like a little silver canister with a hose going to it.

Reed44

I have heard on here that the intakes will crack, so that is possible it did happen and was a problem. Since you dont have a CAI, it would be hard for water to get into the intake, but maybe your airfilter housing is not on all the way or is cracked and water got into it from the car wash? Pull the air filter out and see if it is dry. While you are doing that, clean the MAF sensor. How many miles are on your car? I am no expert but see if any of these has happened to your car.

breagles

only a lean fuel situation will crack an intake trust me check the fuel pressure .It's called detonation .

Bubba1972

Breagles, your posts are showing up as "awaiting approval". I look forward to reading what you have to say.

Thank you all for responding so quickly. I'll try out your suggestions before taking her back to the shop. I welcome any additional theories as to what is causing this issue.

Bubba

ShadowDrake

The intakes DO crack, the stock plastic ones crack because of the heat of the coolant vs the cool of the incoming air. If it does not have an aluminum coolant crossover in the front this is very possible.

Step 1: Go to AutoZone and get the code scanned for free, write down the number for the code (P-something) and the description of the code then come back here and post/PM it to me. This will help a lot in the diagnosis of the problem.

An IAC will NOT produce problems when underload as it is closed at part throttle and above... all it allows through is metered air. There is very likely a vacuum leak if the intake manifold was replaced, I wouldn't be surprised if they forgot to reconnect something, it happens to the best of us. You may also have a loose air connection after the MAF which could cause the same issues. A dirty MAF could cause issues as well. Your coil for the #8 cylinder (or others even) may have become damaged... there are too many possibilities to list until you get that code scanned and return with what the error says.

Bubba1972

ShadowDrake,

Thank you for the suggestion. I went to AutoZone, and the code is P0303. The printout read Cylinder misfire detected - Cylinder #3. Probable causes: 1. Igintion system fault - spark plugs, ingintion wires, 2. Vacuum leak, 3. Injector fault, 4. high/low fuel pressure.

Remember that the problem presented itself after filling up with gas. Is is possible that the cracked Intake Manifold (which caused antifreeze to pool in #8) was properly detected and fixed, but the bad gas caused #3 to foul as well? Could it be two mutually exclusive problems presenting the same way? After filling up with 89 octane gas, it seemed to smooth out a bit, but it's still obvious that it's missing (now we know in #3).

Maybe I'm way off thinking gas. I could do a plug change myself, but am worried that I'd be fixing the symptom rather than the cause.

96GT226410

Take the coil off of number 3 and put it on any other cylinder. See if the problem moves to whatever cylinder you move the number 3 coil to. If so, there's your answer. If not, check for spark and checkyour injector. If it's good, check for unplugged vacuum lines. Your problem is not an IAC. If you have a misfire, it's ignition, fuel, or exhaust related. Unless of course, you soaked some electrical compnents or it's wiring under the hood when washing it.

kenv

Could also be a bad MAF