fuel pressure

65 seems a bit high to me....but maby it's right. also I weighed my 88 GT with no power options or A/C....3/4 tank of gas and nothing removed (tire and jack still in) and it was 2300...I would guess a coupe in stock form would be around 3K

coupecop said:

I would like to know how high you should have your fuel pressure because i have IT at 65 and the gauge is in the fuel line not on the regulator. also does any one know the weight of a coupe.

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with the vac line attached it should be 36-39psi. coupes weigh any where from 3100-3250 depending on options.

39 pounds for a stock motor, but closer to 42 for your setup.

At WOT, the air/fuel ratio is a function of fuel pressure, RPM, airflow through the MAF (mass air cars only) and the TPS. The O2 sensors don't have any control input into the computer's program at WOT.

Therefore you can use the SOP meter...

Get one of your buddies to ride along with you. Find a level stretch of road where you can do some testing. Watch for the wind speed and direction, it can have a definite impact on your test results.

Don't choose a speed range that will make you shift gears, the shift quality & speed will affect your results. Use 2nd or 3rd gear and do a run from 2000 RPM to 5800 RPM. Call out the RPM as it increases and have you buddy record it and the elapsed time. If you have one of those cheap digital watches like I do, a stop watch is built in.

Start the fuel pressure at 36 PSI, vacuum off and make a run. Turn it up to 37 and make another. Be sure to reconnect the vacuum every time you set the pressure. Keep turning up the pressure and making runs until you notice a drop off in time. If your bud was careful to record the results, you'll have a nice chart to use to find the optimum pressure.

Thats a good idea. I just used the SOP meter

It sound like you might need some larger injectors. With the combo you have, you should at least step up to 24# injectors if not larger.

Two things:

1.) 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 about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $35.


2.) Swap the C&L MAF for another 24 lb calibrated MAF. The C&L MAFs work good for some people and don't for others. The sample tube approach C&L uses is a shotgun approach to hit a small window in the air/fuel ratio range.

Do you recomend the Pro-M brand of MAF sensors?