Well I sprayed starting fluid all around the injectors, vacuum hoses, intake manifold, and any other suspect areas....no affect to the motor so I believe I've eliminated leaks.

I received the fuel pressure gauge and it came one NPT cap/plug too short so I will have to go buy one today from the hardware store before I can check fuel pressure.

I replaced the PCV again and the EVAP. Both the motorcraft and duralast PCV are making a lot of noise (you can really hear the "shaking" component in the sensor). I don't know if this is an issue or if it's supposed to sound that way

I will try to replace the fuel filter today if the rain holds up, I started raining yesterday before I got a chance to change it. I did turn the throttle screw to see if it affected the rpm level and it did in fact drop the rpm. I am waiting to adjust the idle screw per the procedure you posted until I check my fuel pressure.

 

I took a look at the throttle plates, they seemed to look good in my opinion

 

Here is what it is doing at idle. Sorry, I should've turned the music down so you could hear the motor better

 

Looks like a fluctuation between 850-1000 rpm.
The fluctuation doesn't bother me, just the high Idle.

 

Yes the high idle is confusing the mess out of me. I performed the idle screw set procedures yesterday with little results. I followed the procedures, set the idle to 650 +/- 25 rpms with the IAC unplugged. After finishing the procedures (snapping/easing into the pedal, unplugging the battery for at least 5 minutes) and after reconnecting the IAC and battery, started it up....its sitting right at 750 rpm....why not the 650 I set it at? I'm going to perform the procedures again today, I don't believe I had the truck completely warm beforehand


So just a heads up to anyone following this thread, the Jegs Fuel Pressure Kit that I attached a link to previously in this thread DOES work with the 460 fuel rail. I got it installed yesterday after going to the hardware store and grabbing one more 1/8" NPT plug/cap (I believe the kit was supposed to come with one more, I may have just received one with a cap missing).


My fuel pressure reading on a cold motor were around 30-32 psi at idle and when I revved the motor it instantly jumps to around 38-40 psi.


Once the motor warmed up, the numbers changed to about 28-29 psi at idle and still about 38 psi when snapping the throttle. Do these numbers sound about right?


I have just noticed that my ignition coil seems to buzz for a few seconds after shutting off the motor, didn't do that before. Correct me if I'm wrong, but, don't my symptoms sound like they could be stemming from a worn/weak ignition coil?

 

Was that a repeatable & steady 750rpm, if so, an improvement no less from 850.
Are you using your Truck Tach, or another ?

It took me a few tries the first time I performed an Idle procedure to get the best result. Hardest part was holding the rpm for x-seconds.
Yeah, you want a fully warmed engine before adjusting.

Fuel pressure looks ok, and the FPR is working as the vacuum decreases with higher rpm. You may see the same 38psi when you disconnect the FPR vacuum line.

 

Not aware of any normal buzzing from an 88' Coil. Coils degrade over time, and you get what you pay for in quality.

You can check the spark jump and color of your spark. Auto parts sells a Spark-Gap checker.


"symptoms" - from time, as you progress, you need to revise your "symptoms", recheck your "Codes", etc... Seems you have achieved progress since post #1.

 

Yes 750 WAS pretty steady. Today while I've been driving it tho, it has been staying around the 850-1000 back and forth and hasn't dropped and stabilized hardly at all 😫

I'm using the truck's tach for all of my numbers

 

Well I ordered a MSD ignition coil, I've always thought they were a good brand.

That's my thought as well. I plan on resetting the idle today and after that I am going to check codes to see if anything else throws.

My thoughts on the ignition coil were: after I got power to the O2 heater, I was reading around 0.85V on the signal wire. Now from what I've learned, that's a little rich correct?. Couldn't that be caused by a failing ignition coil? Not getting enough spark power to fully combust the fuel/air causing it to read rich at the sensor, which in turn would lean out the fuel/air and become easier to ignite, and then cause the computer to throw more fuel? Could that not be a possible cause of the fluctuating idle? I may be getting a little ahead of myself but that was my whole thought process behind the ignition coil

 

Yeah, in theory, .85 is just into the rich zone.
What normally happens is a constant switching between Lean & Rich, you should see that on your O2 Signal wire, like the sign wave in a previous post.
If you have a constant .85, you have an issue.
Next time you are measuring, open up a vacuum line to see if it leans out briefly.

So, completely burning the fuel has been the goal of the EPA and subsequently under duress the auto industry, starting in California. This is why you see 2 spark plugs for each cylinder, more and more. Some California models had a "hotter" coil installed to burn more fuel.

If you had a weak spark (testable), you would have a loss of power, and lots of black smoke, as well. Also, potentially a 42 code.

 

The key term there is "were". Plenty of early failures posted in recent past.

You might get lucky or left stranded with no spark. Keep the old coil in the glovebox.

 

Well I checked the codes again yesterday, got all passing 11 codes (KOEO, CM, and KOER). I checked the voltage on the signal wire coming from the O2 sensor and found it to be idling around .75ish volts when the truck would idle normally (around 750-800 rpms) and then when I would start fluctuating rpms pretty bad, I had the sine wave signal that was oscillating back and forth between less than .1 volts (down to around 30-40 mV) and about 1.2 volts. It has really began to drive "hit or miss". I drove it down to my uncles house to pick up some chairs and warm the truck up and it seemed to run pretty good. I had to REALLY step on it to get it to stumble on the way there. On the way back from his house, it was stumbling like it has been.....I don't get it. It seems to drive different every time. Also seems to run better while its cold outside vs hot outside.


I forgot to pull a vacuum line to see if the O2 signal leaned out any. I should be receiving my new ignition coil today and hopefully will get a chance to swap it out. What I did notice was some REALLY questionable wiring leading to the ignition coil plug. Does anyone have a wiring diagram for the ignition coil? My plan is to wire in a new plug so I know I have good connections going to the ignition coil.


In regards to your comment about the black smoke stemming from a bad ignition coil, I have noticed that the tailpipe has become pretty black and have noticed more of a gassy smell than usual.


I will definitely be keeping the old ignition coil just in case, I had no idea MSD had kind of fallen off. Thanks for the heads up!

 

Random connector: single wire into connector, single wire coming out connecting to the ignition coil bracket


Ignition coil plug: Only two wires running into the plug, bare wire showing, and two butt connectors on one wire

I have uploaded a picture of the connector that plugs into the ignition coil. When I went to purchase a new connector from RockAuto, I noticed that all of the plugs for the truck had 3 wires coming off of the plug....my truck connector only has 2 coming off....I did notice, however, there is a ground wire coming from the same wire bundle as the 2 wires going into the ignition coil plug. The single ground wire runs out of the bundle, to a random connector (I cant get it unplugged either), and then a single wire runs from the other end of the connector to the metal "bracket" that the ignition coil mounts to. Could this ground wire be the missing wire from my plug?? Or did whoever messed with this wiring forget to connect a wire??

 

Your measured O2 voltage range indicates that your O2 sensor is working.

What point are you measuring the O2 voltage? EECM pin 29?

During your measurement, am I reading that the range is approx 0.1 ish to 1.2 ish ? and you are fluctuating the RPM from Idle to 2800 ?

 

I measured the voltages both at the sensor and at pin 29. Yes that is correct, the fluctuations were between less than 0.1 and 1.2 volts just at idle. When I revved it up to different points between 1800-2800 rpms, the voltage readings were all over the place each time. They never settled at any voltage or anything close to settling.