H/C/I swap and car runs like crap!

[KcMstang]

Don't know if anyone remembers but I was suffering a pretty constant miss and just plain running like crap problem. I did everything I could without tearing into the motor and nothing seemed to fix it. I finally decided to tear into the motor and see what I could find. I found my lifters had really seen better days so I picked up some new ones and my timing chain had lots of play in it so I also replaced. I went ahead and took off the stock heads and replaced with GT40p and pulled the stock cam to throw in an e303. I already had the cobra upper/lower intakes so I thought that would be a pretty good basic setup for now on the cheap. I cranked the car up for the first time and it sounded healthy with that cam in there, really got me excited. Then after getting the timing and fuel pressure set it was time for the first test drive. I took it down the street and right away it starts acting up again. Now I'm at a total lost and ready to take the car to the crusher. The other night I decided to spend a little more time w/ the car and rev the motor while watching the fuel pressure guage. I found at idle the guage read 38psi and then when I revved the motor it would drop quickly to about 20psi and slowly rise back to 28-30psi. It is the stock fuel pump in there so I went away an order a 190lph fuel pump because I didn't think it should be that low with the motor around 4k+ rpms. Is that normal or was it good to order a new fuel pump. I need the bigger fuel pump won't hurt regardless just trying to figure out if it could be my problem with the car running like crap.

BTW - there is NO check engine light on!

 

[jrichker]

Fuel pressure is checked with the vacuum line disconnected from the fuel pressure regulator and capped . At ilde, you should see 38-41 PSI.

Dump the codes and see what the computer says is wrong…Codes may be present in the computer even if the Check Engine light isn’t on.

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is less than $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see http://www.midwayautosupply.com/p-7208-equus-digital-ford-code-reader-3145.aspx– It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is

 

[KcMstang]

Can you use explorer type (skinny) 19# injectors in these cars? A friend of mine let me throw them on with a stock MAF to see if that was my problem because I did have 24# injectors and not sure what that MAF was calibrated for...

 

[jrichker]

The Explorer 19 lb injectors will work fine, that is what I am running.

Only aftermarket MAF’s are calibrated to the injector size. The injector size on all Ford computers is part of the computer program. Since it is not easy or cheap to change the computer program, the aftermarket MAF manufactures modify the MAF to lie to the computer. The MAF modification tricks the computer into changing the amount of fuel the injectors get.

All the Ford OEM MAF’s are calibrated to match the computer. Do not swap MAF sensors between different model computers or different types of housings. If you do, you are sure to be out of calibration

 

[KcMstang]

So I couldn't swap stock FORD MAFs from an A9L and A9P computers?

That might be my problem because the car is running horrible no matter what the rpm range is and I actually got it running good on the old 24# and MAF I was using but thought some of my problem might have been too big of injectors for what I was running.