Diagnosis Help

The fuel pressure is supposed to be checked with the vacuum line disconnected from the fuel pressure regulator. When you remove the vacuum line, make sure that there is no gas in it. If there is, that is the source of your code 42/92.

Code 42 & 92 (running) System rich - Fuel control or (memory) System was rich for 15 seconds or more (no HO2S switching) - Fuel control. Look for leaking injectors, fuel pressure too high, cylinder(s) not firing due to bad ignition.

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.

Code 19 - Engine off - No Vehicle Power (pins 37 + 57) or bad PCM VPWR Diagnosis. This is a wiring problem that is from a bad ECC power relay, bad connection, bad fuse link or a bad computer. The ECC relay is located on top of the computer under the passenger side kick panel. Pull the connector off any fuel injector and measure the voltage on the red wire: if its 12 volts or better, the ECC relay is OK. If the ECC relay is OK, pull the kick panel off and measure the voltage at pins 37 & 57. If it is 12 volts or more, then the computer's diagnostic firmware has taken a dump and is defective.

Engine running - Erratic idle during test (reset throttle & retest) - Idle Set Procedures

under part throttle and also has moderate bucking at cruise. Rock steady 700 rpm idle, and WOT seems fine.

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My 1993 coupe is doing the same thing. If I’m cruising along below 2k rpm I can feel a slight , but repetitive hesitation , feels like a misfire, or as if the vehicle is not getting the proper fuel at low throttle.
I watched the tach tonight and did not notice any drop in RPM but I could feel the car bucking ever slightly.
If I hit the gas I can not feel any hesitation or bucking.
Other than the bucking my engine should be in superb condition with only 78 k pampered miles.
Let me know if you get your problem figured out
I changed my plugs and fuel filter to no avail..

I would take a look at your PIP (it might simply be on the outs). Excessive run-out (bad dizzy bushing) can indirectly cause some issues with it too.
If you have a spare dizzy (or a buddy with a known good one), you can swap it and see if it helps.

Good luck.

After searching possible causes I just tried the “pop hood in the dark method” WOW what a light show.
I saw what appeared to be hundreds of tiny holes in my plug cables, and some were arching onto nearby metal.
I guess I will buy new cables , I’m sure it cant hurt

I would also check your TPS after you have checked the stuff mentioned above to make sure the voltage increase sweep is smooth while manipulating the throttle (.98v at idle throttle to ~4.5 at WOT should be normal). You would be amazed at how fast an O2 sensor can go bad. (wire laying on header, existing rich condition fouling it, etc)

Gunnerm1 said:

After searching possible causes I just tried the “pop hood in the dark method” WOW what a light show.
I saw what appeared to be hundreds of tiny holes in my plug cables, and some were arching onto nearby metal.
I guess I will buy new cables , I’m sure it cant hurt

Click to expand...

LOL
a real eye opener.......I did the same when i first got my car a few years back. After i put the new plugs and wires on it was a whole new car......I couldnt believe the power i had been missing

Having the same problem, replaced TFI and FPR. I need to look at the Fuel pressure but if it were bogging due to that shouldn't it throw two lean codes in memory? I would change plugs and wires but there is no arcing and Im pretty sure thats not it.

The only reason that I think my 02 is bad is because it only throws codes on one side. Since yours is throwing codes for both sides, I would think that it is a vaccum leak or something. Or also your plugs arn't always firing resulting in unburnt fuel-rich condition.