[96CobraSC]

Ok well i recently bought this car, and you can see in my signature that there has many mods. Before the engine recived the forged internals, 42 lb injectors, 255 lph in tank fuel pump, and a 14# SC pulley the car was dyno tuned at 440 RWHP.

Well I bought the car when there was only 500 miles on the rebuilt engine and 9500 on the car. I drove the car for another 1000 or so miles to complete the break in time (still running non synthetic for about 750 miles)

So i decided after I changed the oil at 1500 miles to rev her out a little just to see how she feels. Before this the car was never over 3500 rpm. I pull out of my street and drive for about 5 mins to warm her up then decide to get on it a little. For one, there was no more pull in the car then my 97 superchaged gt(even slower) and that car puts about 275-300 RWHP. Not just was it slow, but THICK black smoke came from the tail pipes after 4500 rpm. (extra Fuel ??, was not oil didnt have a hint of blue)

Now i know the car is running rich, but even so, would the performance be hurt this much?

also:

1)the check engine light came on about 100 miles after buying the car( bad O2 sensors?) - the guy told me they came on and off for him w/ the high flow cats.

2) the only tuning difference that was made durring the rebuild was the correct tube for 42 lb injectors in the MAF.

3)And the FMU disk was changed from a 12:1 to a 4:1...

4)There is no fuel pressure regulator on the car, he said it was installed right after the rebuild, but it started leaking so he just put the stock one on. (the car reads 38 psi fuel pressure @ idel)

now he also gave me a paper for air flow rating that should be burned into the hypertech chip. The tunings on it now are for the stock car with the the vortech kit with an 8# pulley.



now i want to get the car dyno tuned, but it seems to me that it is going to be more then just that. PLease any suggestions for what to do and what it can be would be great!!

[97Red248A]

Sounds like the charger is messed up, and like you said, you're running entirely too rich. You may want to do a compression test as well.

JMO.

[alcoholic]

If I'm reading step 3 correctly, you're running at a 4:1 A/F ratio??? If that is correct, this is your problem, I can't beleive the car is even running if that's the case. 12:1 is safe, if you were trying to lean it out, you went the wrong way.

[96CobraSC]

well it still is making good boost on the gauge, and it sounds great. No rattel. My friend has a 95 cobra with a vortech on it and his charger sounds no where as nice as this one. I dont think that is the problem though. The super charger does have about 8000 miles on it though. Never raced.

But the power is deffintily not there, sounds like a deseil truck please guys help my baby soo she can run like she should...


and can runing rich really hurt performance a lot. I dont mean 30-40 hp. This car should have at least 480RWHP and it feels like it have about 275

thanks again for any help.

[96CobraSC]

The fuel managment units disk was changed from a 12:1 disk to a 4:1... I think it has only to do with the injector size. Not positve though

i think the number has to do with how much it has to increase the fuel pressure. so a 12:1 would give you a higher psi reading.

[97Red248A]

42 lb injectors still seem to be too much, even with the charger.

[alcoholic]

I'm not familiar with what you're talking about but I know that the Mass Air meter sends a voltage to the EEC or the FMU if you have one, which tells the injectors how far to open. Your fuel pressure is regulated by a regulator so that is always fairly constant. Your A/F ratio changes across your power band, so you may be correctly tuned at certain RPM and not at others. Hope this helps.

[96CobraSC]

The 42 lb injectors should not be to big for this aplication, I have seen them run with 50 lb injectors with similar set ups. The FMU is only a mechanica device that increases fuel pressure. It does not get voltage reading.

"The FMU is downstream (after) of the stock regulator. As boost pressure begins to rise, the FMU starts restricting the flow of fuel returning to the gas tank. Like a garden hose, if the flow is restricted, the pressure increases. "

If there is anyone that has experiance with the supercharged DOHC engine, i would love your input.

all advise is much appretiated though.

thanx,

excuse my spelling...

[GTRaptor]

For one i think that YES you are running way TOO rich and that can foul the plugs and decrease the power that much.

Your setup has several "flaws" for one, you need to get rid of the FMU and need to have a chip custom made for your car.
I have seen this many times, stock kit works ok, then the user adds smaller pulley, larger injectors and MAF, and presto..less hp.

The most likely problem then is tunning.
But check the compression too, dont discard a blown ring or valve seal.

Also inspect those plugs, i bet you they are wet.

Dont "experiment" have that chip burned and remove the FMU completely, you dont need it.

[96CobraSC]

thanks gt,

thats what i was looking to do, but I was not sure if there was anything else I had to do when I remove the FMU. I was talking to SHM, and they didnt say to remove the FMU. THey said its going to need the extra fuel to run the 14# boost with out detination. I know I run 93 octane w/ bottle of octane boost and it doesnt ping at all. I hope this is true when the FMU is removed and i have the chip custom tuned.

[GTRaptor]

SHM is full of crap, the FMU is not needed.
As a safety you can have an adjustable FPR to increase the fuel pressure a bit if needed.

BTW the 42 lb injectors are just fine for that kind of power.