i need real tech help, fuel issues maybe more.

[nitrous_bob]

ok heres the deal, my first trip to the track w/ this car was dissapointing. the car has 4.10's , et street rad's, long tubes, mac prochamber, mac 2 1/2" catback, 50/50's, and thats about it. but my old car similar setup went 13.20's @ 102 NA and 12.50's @109 on 75 shot , heres what the '93 did

1.8 60 foots
14.00 @ 97 NA
13.20 @ 105 on the 80 shot

afterwards, i started checking it out, found out the maf was from '91 t-bird, cal'd for 32 or 36 lb. inj.

i fig'd "cool thats it" replaced w/ a stocker (i still have 19's) and thought i felt a big diff

went to the track on friday and times did NOT improve much at all, only about a tenth

so here are my questions, w/ the maf cal'd for 30's was i phat or lean ?

w/ the stocker maf on, why am i still slow, it seems like there should be a big diff from running w/ the wrong cal'd inj, not just a tenth ?

why did i not melt anything (plugs were beautiful) if i was in fact super lean running the 30 lb. maf sensor and spraying it ?

fuel pressure at idle (vac on ) is about 35

i am going to do a compression test, and check fp at load

other than that...i'm lost , any help is appreciated

 

[nitrous_bob]

bump....where you at jrichter ?

 

[ls1beater4eva]

whats your timing at, and whats your fuel pressure vac off ? i would just chesk your tps allso i have had that make a world of difference if some other stuff is off to .

 

[jrichker]

Do the diagnostic thing first...
Dump the codes and see what the computer says is wrong…

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 Walmart.

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.

Cylinder balance test:
Warm the car's engine up to normal operating temperature. Use a jumper wire or paper clip to put the computer into test mode. Start the engine and let it go through the normal diagnostic tests, then quickly press the throttle to the floor. The engine RPM should exceed 2500 RPM's for a brief second. The engine RPM's will increase to about 1450-1600 RPM and hold steady. The engine will shut off power to each injector, one at a time. When it has sequenced through all 8 injectors, it will flash 9 for everything OK, or the number of the failing cylinder such as 2 for cylinder #2. Quickly pressing the throttle again up to 2500 RPM’s will cause the test to re-run with smaller qualifying figures. Do it a third time, and if the same cylinder shows up, the cylinder is weak and isn’t putting out power like it should. See the Chilton’s Shop manual for the complete test procedure


Do a compression test on all the cylinders.
Take special note of any cylinder that shows up as weak in the cylinder balance test. Low compression on one of these cylinders rules out the injectors as being the most likely cause of the problem. Look at cylinders that fail the cylinder balance test but have good compression. These cylinders either have a bad injector, bad spark plug or spark plug wire. Move the wire and then the spark plug to another cylinder and run the cylinder balance test again. If it follows the moved wire or spark plug, you have found the problem. If the same cylinder fails the test again, the injector is bad. If different cylinders fail the cylinder balance test, you have ignition problems or wiring problems in the 10 pin black & white electrical connectors located by the EGR.

How to do a compression test:
Only use a compression tester with a screw in adapter for the spark plug hole. The other type leaks too much to get an accurate reading. Your local auto parts store may have a compression tester to rent. If you do mechanic work on your own car on a regular basis, it would be a good tool to add to your collection.

With the engine warmed up, remove all spark plugs and prop the throttle wide open, crank the engine until it the gage reading stops increasing. On a cold engine, it will be hard to tell what's good & what's not. Some of the recent posts have numbers ranging from 140-170 psi. If the compression is low, squirt some oil in the cylinder and do it again – if it comes up, the rings are worn. There should be no more than 10% difference between cylinders. Use a blow down leak test (puts compressed air inside cylinders) on cylinders that have more than 10% difference.

Post codes & fix them.