carb or new cam?

[66gt350]

That is the decision that I am now facing with my fastback. Trying to tune efi is starting to drive me to excessive drinking. I just can't seem to get it dialed in. I'm running the Ford Motorsport E303 cam, which is notorious for running to rich with the stock computer and ending up with the dreaded idle surge. I've got it so I don't stall out at stop signs and red lights. But it still isn't right. Sometimes when I start the car, it is running really lean. The wideband AFR is about 20:1. And then other times when I first start it, it is running very rich, and the AFR is read about 11:1...and it is starting to surge.

I'm almost to the point of yanking the efi and going back to a carb. But I don't want to lose the fuel economy I'm getting. Before I did the swap, the E303 did good with the ole holley. Or should I start looking for a better cam that doesn't have the issues that this one does? This is really driving me nuts (more than I already am!!)

Anymore, I'm not looking at making this a 12 second car, again. I just want to make it more drivable and keep it my daily driver.

Sorry for the rant...time to get back to the homebrew.....

 

[66benchcoupe]

I think your problem is the BBK intake - don't like the design, runners are too long. I'll bet the car would run better with a stock intake off an Explorer or a Mustang. If you already have an intake and carb then bolt it on and see what happens!

Robert

 

[66gt350]

I gave up the bbk intake a while ago, because of the oil issue. That intake is basically unbaffled. I was burning oil like it was going outta style. I am now running the Holley systemmax ii with an accufab throttle body. The car runs the same with both intakes.

Sent from my DROID RAZR using Tapatalk 2

 

[66benchcoupe]

There's something not right with the EFI system. Have you had anyone look at it? I'm no expert, but I 've been told there are right ways and wrong ways to fool the stock computer (is that what you have?) with different MAFs and Injector sizing for larger than stock cams. I've also heard that fuel pressure needs to be regulated properly. Maybe someone here who is EFI savvy can help if you post all the parts in your combo?

Robert

 

[66gt350]

I'm fooling the computer the proper way. I've gone up to bigger injectors and mass air meter. I've used a tweecer and put in the correct values. I've actually used both 24 and 30 lb injectors with the same results. I've got an adjustable pressure regulator and fuel pressure gauge under the hood, and that is set to what the injectors like.

Here's my entire combo:

302 -- .030 over
E303 cam
forged flat top pistons
Trick flow twisted wedge heads
Holley SystemMax II intake
accufab 70 mm throttle body
30 lb injectors with matching pro-m mass air meter
tko five speed and 3:50 rear gears

I'm getting at my wits end.

 

[stangg]

Do you have a bone stock A9L/A9P that you could try? I have a 331, E303, forged flat tops 9.4:1 CR, AFR 165, Ford Cobra Intake (port matched) Pro Products 70MM throttle body, Ford 30# injectors, Stock regulator with 5/16" lines (~38-39 PSI), stock A9L, matching Ford mass air meter, T5 / 3:27 rear gears(8.8). When I first got it together I had the hunting idle issue and realized the air idle control valve ports on china made Cobra intake didn't line up all that well, so I had to "port" it somewhat. The hunting went away after I fixed that.

I've since added a 1" phenolic spacer to the intake (already had it)... When I put the plumbing together for the MAF and air filter, I wanted to hide the MAF wiring by reclocking it. That caused it to go flat on hard full throttle, and also a little hunting. I think I've got it back where it needs to be and I'm wondering if the MAF clocking might be part of the issue with yours.

Is your fan shrouded? I've heard sometimes the air coming off the end of the fan blades can upset the MAF readings if the air filter is too close.

Lastly, I think the difference between the A9L and A9P (for automatic) is that the P has a different program specifically for slowing / stopping. Since you have a manual trans, that shouldn't be an issue, but I'm wondering if maybe you've got a worn out pulse generator on the tranmission... perhaps it's sending a bad signal to the EEC causing the wrong tune for slowing / stopping... Just throwing the idea out there. I have no idea how critical it is for a manual. My understanding is A9P works for manual or auto trans, but A9L is manual only as it will have the stalling issue if used with an automatic. I'm sure you know a lot of this already...