ardorseed

This is my first time posting; I’m definitely a novice and appreciate all advice (no matter how obvious it may seem to be). I purchased a 2005 Mustang Premium with a load of aftermarket parts installed including a Vortech supercharger, Snow performance meth injection system (which has been disconnected), upgraded clutch, etc. It was sold to me as a 550 to 600 HP car with about 52,000 miles (only 15,000 miles since the rebuild).

Anyway, it was my first high HP car, so I didn’t notice the sluggishness until other mustang fans were able to drive it. I took it to a specialist where we noticed the horsepower (on a dyno) was very low for the car with all the parts (around 315, which is basically stock for the 4.6L V8 on the 05s). The only problem was, it wouldn’t always start.

The engine would fire and spike between 1.5 and 2K on the tach, and then it would die. The only way to get it started was to floor it before (or immediately after) starting it. For some reason, it appears to be getting flooded after I drive it for 40+ minutes and let it sit for 3+ days without starting it up in-between.

Any ideas?

jpplaw

That is a tune problem. I would suggest getting a real tune from someone who knows what they are doing, even an email tune from a recognized tuner (Brenspeed, Bama, etc.) will be better than what it sounds like you have now.

Dino Dino Bambino

If the inside of the supercharger was coated in oil, there's a good chance the inside of the throttle body is also coated so you might wanna clean it thoroughly. While you're there, you can also clean the MAF sensor.

jpplaw

Also, generally if you flood these 3v's to the point where you have to floor it to shut off the injectors to get it started, your spark plugs are now toast.

ardorseed

I'll try to get to each of them here:

Tuning: I had it professionally tuned at a shop I'm confident with. They switched the tune after it dynoed so that it opens up the air flow on startup. This helped, but it still gets too flooded if I leave it for more than 2 or 3 days. Any specific suggestions I could bring to the tuning shop? I'm sure they'd be happy to made an edit and email me the new file.

Throttle Body: this was cleaned out when we cleaned out the blower parts, it did have some oil in there if I recall. As for the MAF, I have a MAFia extender that probably came with the supercharger that's on there now. I'd be happy to clean it, is there any way to check whether the sensor is working correctly? Should I replace the throttle body?

Spark plugs: these were replaced a number of times, and yes, they were very black when we pulled them out. I've replaced them 2 times and cleaned them, too, since these issues started. I'm fine with replacing them again, but of course want to try and get the root problem fixed beforehand.

jpplaw

Your shop tuner has the MAF transfer function messed up - the tune is telling the ECM that way too much air is entering the engine than really is, that is why it adds so much extra fuel and floods. In the tune, the tuner through programming, tells the ECM how much air is entering the engine at 30 points over the MAF sensor voltage/AD Count curve. "Opening airflow up" at start-up only tells the PCM to add more fuel. A tune cannot add more air, if you tell it more air is entering, then the PCM adds fuel; if you tell it less air is entering, then it adds less fuel - fuel is the only actual variable. Getting the MAF Transfer right is 95% of all tuning "magic". The injector values could be off as well. Seriously, a lot of people can tune, but only a few can tune really well.

Clean the MAF sensor with dedicated CRC MAF cleaner. As far as working correctly, MAF sensors either work or not, there's no in-between, except for when they are dirty. The MAFia could also be out of whack. Have you tried starting it without the MAfia? Have you tried starting it with the MAF disconnected? I would dispense with the MAFia and get a real upgraded sensor set-up.

What spark plugs are you using?

JimC

I wonder if the proper sized injectors are in the car? That could lead to flooding.

cruisin5268d

ardorseed, I *highly* encourage you to change your username to something that does not include a full e-mail address. That's just asking for spam and dangerous e-mails.

ardorseed

The injectors are the FMS 601b injectors, are those the correct size? The spark plugs should be Automate HT0s. Interestingly, when we first replaced them about 3 months ago, 4 of them were Ford Racing, and the other 4 were stock.

I'll clean the sensor, and will update this post with my progress. If it still has this issue after cleaning it, I'll try a new tune, and if that still doesn't work, I'll look into switching out the sensor and/or shutting the MAFia off. I imagine this will take a while (each test requires leaving it for a few days), but I'm excited about trying everything out.

Thanks again for all the help, this is a great resource.

Simon1

This above is good advice. MAFs either work perfectly or not at all. If they are dirty, then they cause drivability issues. I know this from personal expereince.

A lot of people can tune cars to make great HP, but few can or will take the time to make sure the drivability of the tune is spot on.

Another possability is having a leaky injector. Which I doubt. A good mechanic would be able to diagnose if it's leaking fuel while sitting.

Get the tune figured out. Don't be confident in a shop's claimed tuning ability without seeing a prior track record of success on vehicle identical to yours. When these cars first came out, all of the old tuners thought they were awesome at tuning and blew stuff up. Just becuase you could tune and 03 Cobra, doesn't mean you can tune an S197.