Plug/injector Issue.

Discussion in '1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-' started by bentley429isBAC, Aug 10, 2014.

  1. Anyone ever pull the plugs to find 1 look brand new? No heat on the strap at all. The other 7 look good. Have a few street hits on them and about 100 miles. SBF cylinder 5. It is holley efi, crank sensor only. Cylinder has spark also. I pulled the injector plug off of #5 and there was very little change in idle. Pulled it off of #6 and there was a very noticeable difference. Put the #5 injector plug on the #6 injector, back to normal. Could it be the injector isn't completely flowing the correct fuel or any fuel for that matter? Went over all the wiring, made sure it was all correct back to the ecu. Car starts fine, idles good and feels strong so I am kind of confused whats going on. All cylinders have good compression. Last time I changed the plugs they were all pretty even for the most part. With a temp gun 1" from the head all cylinders were 380-480 degrees at idle except for the clean plug. That one was 200. Already removed all the injectors to get them checked out.
  2. I haven't done it myself, but you should be able to check the log to see the fuel flow for each injector. We had to do something similar to confirm that my engine was getting fuel when it wouldn't fire.
  3. Will look into it. It's just odd I didn't notice a change. Sounds the same and I swear its got the same power. Happy I decided to pull them and take a look, thing was pretty dialed previously. Sound to you like the injector just isn't spraying properly or at all? Thats pretty much all I can think of. Took the air hose to the inlet side to blow out whatever was in there, all blackish dirty fuel. Sending them all out anyways, been in the car 3 years probably time.
  4. Was the plug completely clean? Or just much cleaner than the other ones? If it was just a little cleaner, I'd suspect a semi-clogged injector.
  5. Completely clean. Could of returned it to advance. I cut the threads off and there is almost no fuel on the porcilen to mention. The strap def was lighting off though. Used the noid light and all was good there. Car is way to loud to hear if its pulsing. Guessing the injector managed to quit same time I changed the plugs last. Just can't understand how it doesn't feel like its down on power and idles normal.
  6. PM bg00gt on the bullet, he does an injector service for cheap and will be able to tell you if one is bad.
  7. Cylinder balance test: use this to find dead or weak cylinders:

    Revised 25 March 2012 to add necessity allowing the KOEO tests to finish before starting the engine and the need for a properly functioning IAB/IAC to run the cylinder balance test.

    The computer has a cylinder balance test that helps locate cylinders with low power output. You’ll need to dump the codes out of the computer and make sure that you have the A/C off, clutch depressed to the floor and the transmission in neutral. Fail to do this and you can’t do the engine running dump codes test that allows you to do the cylinder balance test.

    Here's the way 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. You watch the flashing test lamp or Check Engine Light and count the flashes.

    Be sure to turn off the A/C clutch depressed to the floor, and put the transmission in neutral when dumping the codes. Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.

    Here's how 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. You watch the flashing test lamp or Check Engine Light and count the flashes.



    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.


    The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

    89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.


    The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

    WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

    What to expect:
    You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and drivability problems

    Some 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.

    Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off, clutch depressed to the floor and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

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

    Cylinder balance test

    If you have idle or IAC/IAB problems and the engine will not idle on its own without mechanically adjusting the base idle speed above 625-750 RPM, this test will fail with random cylinders pointed out every time it runs. The IAC/IAB must be capable of controlling the engine speed to run in the 1400-1600 RPM range. Playing with the base idle speed by adjusting it upwards will not work, the computer has to be able to control the engine speed using the IAC/IAB.

    Warm the car's engine up to normal operating temperature. Use a jumper wire or paper clip to put the computer into test mode. Let it finish the Key On Engine Off (KOEO) code dump. Start the engine and let it go through the normal diagnostic tests, then quickly press the throttle to the floor. Remember to keep the clutch pedal (5 speed) depressed to the floor during the test. 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/loan. 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 with a plastic screwdriver handle between the throttle butterfly and the throttle housing. 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.

    I generally use a big screwdriver handle stuck in the TB between the butterfly and the TB to prop the throttle open. The plastic is soft enough that it won't damage anything and won't get sucked down the intake either.

    A battery charger (not the trickle type) is a good thing to have if you haven't driven the car lately or if you have any doubts about the battery's health. Connect it up while you are cranking the engine and it will help keep the starter cranking at a consistent speed from the first cylinder tested to the last cylinder.

    See the link to my site for details on how to build your own blow down type compression tester.
  8. Thank Jeff. Pmed him. He is out of town for a week so I will send them and he's going to do them when he gets back. Probably should be done anyways. Hopefully it didn't hurt the cylinder, just can't understand how I didn't notice a loss of power. Compared logs from earlier this year and the passes are nearly identical.
  9. Did you do a compression check yet?
  10. Yeah was the first thing I did. All holes the same.
  11. Thats good, if thats the case i wouldnt be too worried about it. I dont think you can detonate a hole without fuel.
  12. Agreed thats the way I am looking at it.