#3 spark plug chalky black... and misses

[merc91]

its just the #3 spark plug thats chalky black like its running rich, and your can feel it missing at lower RPM's, and up in the high revs you don't notice the miss in that cylinder. distributer is a year old and plug wires are a few months, all good pieces too, checked the contacts in the cap and it all looks good.

I am suspecting a leaky injector causing it to run rich... And at high revs i don't notice the miss so much because of the increased demand for fuel vs the missing at low revs when its getting way more fuel than it needs? I did have 1 of the 19lb injectors before the build that was sticking before i cleaned it out, so i wouldn't be surprised if that was the culprit.

is thier any way of testing this injector out while its in the car to see if its stuck open? Or will i have to take off the plenum and just swap the injector.

[86VickyLX]

its just the #3 spark plug thats chalky black like its running rich, and your can feel it missing at lower RPM's, and up in the high revs you don't notice the miss in that cylinder. distributer is a year old and plug wires are a few months, all good pieces too, checked the contacts in the cap and it all looks good.

I am suspecting a leaky injector causing it to run rich... And at high revs i don't notice the miss so much because of the increased demand for fuel vs the missing at low revs when its getting way more fuel than it needs? I did have 1 of the 19lb injectors before the build that was sticking before i cleaned it out, so i wouldn't be surprised if that was the culprit.

is thier any way of testing this injector out while its in the car to see if its stuck open? Or will i have to take off the plenum and just swap the injector.
Could do a fuel pressure test.
Could also do a cylinder balance test with the computer...
You know how to run a self test right?

[86VickyLX]

After the Engine ID code (light flashes 1/2 the amount of cylinders in the engine) You can step on the brake pedal and rotate the steering wheel. As for the dynamic response check, the SEFI cars such as our cars, and the mustangs, do not have a dynamic response check. Instead, we have the ability to do a cylinder/injector balance test, which will numerically kill each injector to check for a drop in engine RPM. To do the balance test, the regular running test should have already been completed. That means, the light isn't flashing any more codes/repeating any codes. After the light has stopped flashing, step on the gas slightly, and then take your foot off of it. The idle of the engine should increase. It is now in cylinder balance test mode. Do not do anything to change the engine rpm or it will stop the test. It will go through each injector. You will notice that the engine will appear to run rough during this test. This is normal as one cylinder is being killed each time. After it has shut off each injector, the idle will return down to normal, or close to normal, and flash a code at you.
The corresponding codes to the cylinder balance test are as follows:
*--------------------10 (Cyl 1 has failed)
**-------------------20 (Cyl 2 has failed)
***------------------30 (Cyl 3 has failed)
****-----------------40 (Cyl 4 has failed)
*****----------------50 (Cyl 5 has failed)
******---------------60 (Cyl 6 has failed)
*******--------------70 (Cyl 7 has failed)
********-------------80 (Cyl 8 has failed)
*********------------90 (All Cylinders pass!)
*********..*********--------99 (Engine has not learned to idle)

[johnunit]

Swap the injector and see if the symptom follows the injector. If you put it on cylinder 1 (for example) and cylinder one then gets the issue, you have an injector issue.

[86VickyLX]

Swap the injector and see if the symptom follows the injector. If you put it on cylinder 1 (for example) and cylinder one then gets the issue, you have an injector issue.
He just wants to check it without taking it all apart...
but this is a good idea too.

[johnunit]

ah, yeah. forgot how much more involved pulling an injector is on an EFI 5.0 than the 4cyl cars where most of my EFI experience is.

[mrltd]

unplug the injector and see what happens

[merc91]

she's burried way under the plenum with my heter hose tucked in thier also so i'll have to take the plenum off anyways to unplug the harness. I know its just #3 running rich and the electrical ignition all seems ok so that pretty much just leaves the injector i'm thinking.

I had no idea about the self test thanks, i'll check it out and run the test on my mustang A9P computer and see if anything turns up.

[1990LTD]

http://i.ehow.com/images/a07/9a/2j/test-injectors-1991-civic-200X200.jpg

[86VickyLX]

she's burried way under the plenum with my heter hose tucked in thier also so i'll have to take the plenum off anyways to unplug the harness. I know its just #3 running rich and the electrical ignition all seems ok so that pretty much just leaves the injector i'm thinking.

I had no idea about the self test thanks, i'll check it out and run the test on my mustang A9P computer and see if anything turns up.
good luck!

[marquisman]

it may be worth it to go to crappy tire and grabe one of them 40dollar ford code readers, for OBDI. i had one before i got my more expensive scanner. it will do cylinder blance tests.

[86VickyLX]

it may be worth it to go to crappy tire and grabe one of them 40dollar ford code readers, for OBDI. i had one before i got my more expensive scanner. it will do cylinder blance tests.
Yeah, but a wire grounding the pigtail and a check engine light will do it for cheaper. Granted it takes longer, but it's free :D

[gadget73]

The only kind of code reader I'd buy is one with a digital display. A lot of the cheap ones either have an LED that you count the blinks on, or a beeper that you count the tones on. Its exactly the same as grounding the wire, only it costs more.

[marquisman]

the one i was talking about has the digital display. and it come with the book that lists all codes. was the best 40bucks i spent, when i got into EFI panthers

[pantera77]

http://www.thedieselstop.com/faq/9497faq/maint/vra/images/a11519a.gif
FTW

[marquisman]

this is the one i got. i also have a scanner that does everything till 08

http://i.ebayimg.com/20/!CCUB5i!BGk~$(KGrHqYOKjwEzlJ-MbOJBNKs0s)gSg~~0_12.JPG

[87gtVIC]

http://www.thedieselstop.com/faq/9497faq/maint/vra/images/a11519a.gif
FTW

Agreed.

I have a star II tester.

[merc91]

well, i ran the self test and got codes 95 and 31. 95 is from not hooking up the vss wire to my new ecu which from what i understand is fine. but the 31 was for my EGR so i swapped it our for a spare i had and the motor idles and runs allot smoother and no engine light flashing for today. Substancially more power also.

#3 got a new plug and wire swap and its still chalky black and the other plugs are light tan so looks like its time to throw in a new injector.

[gadget73]

You'll get a little off-idle hesitation with no vss input, but you should actually have vss wiring to the ECM connector on a 91. Possible the stock vss wire lands on a different pin though.

[86VickyLX]

You'll get a little off-idle hesitation with no vss input, but you should actually have vss wiring to the ECM connector on a 91. Possible the stock vss wire lands on a different pin though.
Wire for the VSS is in the same spot between the Mass Air and speed density models. My check engine light flashes at me too. It flashes that code too... Hmm, might have to look into that for myself.