I got gremlins

Sounds like the regulator is iffy. The pressure should increase as soon as the vacuum drops. There shouldn't be any lag time.

Shouldn't drop more than 5 psi at idle.


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Both of mine also have a slight lag when you lay into the pedal. My personal rule of thumb is that pressure should never go below 30 PSIG, period.

E.g., on the '94: it's at 33 PSIG at idle and drops to about 30 for a second or less if you stab the throttle, and then it soars to 39 PSIG.

when you crack the throttle, the pressure should go up a little bit because the vacuum is decreased. however, the pressure will go down a bit sometimes, because of the increased injector pulse width. which of these effects will take over the other, differs from car to car.

if you set it to 38 psi with the vac off, then it should drop to 32 with the vac on, at idle. at least that has been my personal experience.

Supaman said:

Ok when my car is at idle the fuel pressure is 36 with the vac in. When I press the throttle it drops to 30-32psi through out the RPM band. Any RPM after2500 it goes up to 36-40 psi. Is this how it suppose to work. Is there a problem with my fuel pressure regulator? Thanks again guys for bearing with me.

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Something is not quite right IMHO. The pressure should not go below the vac-line-on idle-setting but for a second at any point ever (which is generally during tip-in). The fact that you dip and stay below the vac-line-on idle-setting suggests an issue to me. And you're not quite seeing the WOT pressure you probably should, given that your idle setting is at 36 PSIG.

I'd note that I don't see this as a reason for your miss however.

Good luck.

The cylinder balance test should have ruled out a bad injector or bad injector wiring.

On a plus note, you have multiple brains, which has to help with diagnostics.

Good luck.

i'm not trying to go over ground you may have already covered but you might remove your ACT and ECT sensors and clean the connections as well as the sensors themselves. i had an ECT sensor throw my A/F into the 15:1 range on the dyno once but this was at WOT and not where u seem to be having problems. also just for laughs switch out your MAF with an old one or a buddies (as long as its cal. the same) and see if that make a diff. also clean the MAFS connection while your at it.

also i just thought that maybe it could be the computer or the VREF signal to it. someone who knows more about that could have some input. good luck and hope u figure it out.

i'm starting to wonder if it has something to do with the EGR system besides the actual EGR valve. possibly the EVR or other associated EGR control type pieces?

EVR is on the backside of the passenger side strut tower. it controls the vaccum signal to the EGR valve. did u get any Engine Running codes when u dumped codes? i have gotten several codes that only the ER will dump not KOEO, that showed me problems with the EGR and related smog systems

here:

with engine codes, what you describe would be a "45"
but with the air bag system, you have a code "4" and "5"

Maybe its a problem with your catalytic converters or the cat sensors. I've heard that clogged or malfunctioning cats can lead to sluggish acceleration under load through the mid-rpm range.

Supaman said:

Could a bad injector cause a problem like this and cause a miss like feeling? This problems has fried my brains. Is there any way to test injectors? How hard is it to remove?

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As recommeded by HISSIN50:

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

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.dalidesign.com/hbook/eectest.html for more descriptive help
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

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 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 $33.

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.