1995 F-150 4x4 XLT 5.8l 160XXX - New engine mounts, distributor, rotor, plugs, wires, MAP, intake O2 and TPS sensors, EGR, IAC, plus many more. View my last thread for background issues and repairs/replacements if you want.

So I just solved my previous issue of a rough driving truck. I removed the passenger head, did repairs, put it back together and the truck drives great. Now it’s throwing codes:

KOEO:
126, 128, 172, 212, 327, 334
KOER:
126, 172, 334, 411

I sprayed starter fluid all around the intake manifold and around vacuum lines and no change at all in RPMs. I had replaced every single vacuum line and ran them according to diagrams I found on here. It all seems fine. All sensors, solenoids, etc have been replaced. The only issue I know I have is my engine temp sensor stopped working after the repair (new one in the mail) and I suspect my upstream 02 sensor may be bad (also in the mail) but that thing is seized to hell and back so that’ll be some effort.

But, I don’t understand why I’m getting a lot of these codes when these parts are all new; maybe 10 miles on them since installed. I did do a diagnostic check on the IAC sensor and it passed, resistance and volts are within spec.

Thoughts?

 

Did you test any of those new sensors? There are two parts to KOEO tests and Stored Code display. Were any of the "KOEO" codes you listed from Stored Codes? Did you clear the Stored Codes after replacing any sensor?

What color is the Ignition Control Module (ICM) installed on the truck? It should be a Motorcraft black version for your model year truck. This is related to your Code 212.

Code 327 and 334...is there a vacuum supply to the EVR and EGR valve? Did you measure the actual EGR Valve Position (EVP) sensor voltage?

Code 172..do you have any exhaust leaks upstream of the O2 sensor?

 

I only tested the IAC (OK) and the EGR (it’s new, removed vacuum to test rudimentarily and RPMs changed, so the plunger isn’t seized).

I unplugged the battery yesterday to reset and checked codes. It threw KOEO 173, 212 & 334. KOER codes were the same as today. Today I took it for a .5 hr drive until CEL came on. Checked codes (new codes added) and made this post.

The ICM is a black CCM style. It had a grey in previously which was changed to black per this forum.

There is strong vacuum to the EGR. I am unfamiliar with the EVR or what it is, I get no info online about that.

I am horrible with electric so I’m not sure exactly which wires need probing on the EGR, I get a voltage reading two different ways: 2.6v - 4v - Increases voltage when RPMs increase. 2.3v - 1.2v. Voltage decreases when RPMs increase.

The tube that collects exhaust gas back to the engine downstream from the O2 sensor had a large hole in it that was repaired. I used to have a large leak at the flange where the exhaust manifold mates with the exhaust piping that has also been repaired. I can feel air moving at speed at the rear passenger side of the engine bay but cannot detect where it is coming from. I do not think head cover gasket (new) and cannot feel air near that general area. It’s back a bit more and down further. Hard to tell when that engine is hot. It could be exhaust gasket, but that is also new and torqued properly with zero issues.

 

Code 212 is a Stored Code, not KOEO. That's why I pointed out previously there are two parts to the KOEO display. The first is anything flagged as out of range during the KOEO tests. There is a short flash, some code readers interpret that as Code 10, then any Stored Codes are displayed. It is important to know when a code is flashed out because the definition can change for codes that are KOEO AND Stored as well as KOER. Code 173 is a KOER or Stored Code. Code 334 can be displayed in all three.


Is the replacement black ICM a Motorcraft brand? If not, many of the aftermarket ICMs these days are black but are not compatible with the Computer Controlled Dwell (CCD) ignition on the 1994 and up F-series trucks.


There should be no vacuum applied to the EGR valve at idle.


EGR Vacuum Regulator (EVR)



You need to measure the EGR output signal (EVP sensor) with one meter lead. The other should be referenced to the Signal Return wire. They key should be in the Run position.


For reference: EGR Valve Position sensor (EVP)



EVP output at KOEO or KOER should be between 0.24 to 0.67 VDC. In theory the signal output should be the same KOEO or KOER. If the output rises KOER versus KOEO that implies vacuum is getting applied by a faulty EGR Valve Regulator (EVR). If there is any vacuum applied to the EGR valve at idle that will be the most likely cause of Code 334.


That is the air injection system. No exhaust gas is pumped to the converters, it's fresh air.


Could also be the air injection pipe that runs between both cylinder heads in the rear on the engine.

 

The diagram of the EVR (I had been calling it EVP) changed things. I realized from that web link that I had the vacuum lines going to it incorrectly swapped.

I had been working off this diagram which matches everything in my engine bay and I did not know which part of the Tetris-style ‘L’ shape for the vacuum lines at the EVP, TAB and TAD solenoids was “top” and “bottom” so I assumed “top” on the page was “top” of the solenoid, which seems to not be the case: in the vacuum diagram the “bottom” yellow line from EVR goes to the EGR, and in the website this is marked as the “top” vacuum connection.

So, I swapped all my lines. Now, the bottom vacuum plug on all the 3 solenoids are getting main vacuum.

I started the truck and it idled beautifully, smoother than ever before. No shake in the slightest. Then after about a minute or two of running it died and will not start. It cranks strong. Fuel pressure is 35 psi and codes are: 111, 10, 212, 334.

I feel we’re narrowing this down as I learn more about this vacuum and EGR system.

I do not know the brand of the ICM, there is no brand name on the face, only this info: REPF542701 - 2020/07/10 - 0005. Seems to simply be a model # and date of manufacture. If I remove it, maybe a make name underneath?

Also, I replaced the air injection pipes that connect the heads, there was a large rust hole in it. All of that system back there was re-connected or replaced while I had all the top end guts removed.

I had to make my vacuum lines work, based off the diagram plus making other connections that aren’t listed on the diagram. Used a lot of wye fittings to branch off of things. Here is my own drawing of my setup:

https://i.imgur.com/XbTZ1CI.jpg

I probably got something wrong here. I may take a video and link it here to walkthrough everything in hopes to explain and simplify.

edit:

Video of vacuum setup:

https://youtu.be/XUY5jZJ6E34

 

Hard to say who the manufacturer of the ICM may be. The last few we have seen that came in a Motorcraft box were not branded on the part. I caution you to never trust the color of the ICM anymore since we have seen several examples of black aftermarket ICMs that trigger Code 212 and other driveability issues. At the very least check the circuit between ICM Pin 4 and PCM Pin 4 to verify the IDM signal path is good between the ICM and PCM (computer). If that is verified good then you most likely have a counterfeit black ICM.

1994 and up CCD Ignition

 

I began by referencing this site. I wasn’t getting spark from the coil. I got to step 6: I put a sharpened length of copper wire into the LH spot of the coil and hooked it up to my test light. When the engine cranked the test light lit and the engine started. Who knows. I’ve turned it off and on multiple times and it starts fine now. Faulty wire?

Now, the engine idles at ~1500 rpm. It drops down to 1000 when in gear. If I press on the accelerator at idle it revs up to 2000 and stays there for a little while before slowly dropping back down to 1500.

It has a new TPS sensor installed. I probed the TPS and got 5.0v no matter the RPMs.

KOER - 412, 172, 411

 

Poor connection to the coil is more likely and very common.


Looks like a vacuum leak


What wire are you probing and what are you using for a ground reference? Did you test this TPS before?


411, 412 are related to the air injection system (Thermactor). Code 172 indicates a lean condition...may be related to the high idle/vacuum leak.

 

I made a mistake. I just tested the signal wire and grounded to battery negative. It read 0.8v closed throttle and 4.5 WOT. So its working correctly.

I sprayed starter fluid everywhere around the intake manifold and vacuum lines and heard no jump in RPMs. I guess I need to do more reading about how to find a vacuum leak.

 

I did the propane method to test for vacuum leaks. Used a long hose attached to the small tank. Went everywhere around the intake manifold multiple times, around every vacuum line, not the slightest change to RPMs.

 

The propane or carb cleaner test on these EFI trucks is usually inconclusive. Too many vacuum lines, visible and hidden, vacuum reservoirs and the huge upper intake make finding vacuum leaks frustrating.

If the truck is still idling high verify the throttle is fully closed. If it is then another quick test is cap off all of the vacuum lines except the MAP sensor and fuel pressure regulator. Start the engine.

If the idle drops down then you know the leak is external to the engine. If the idle remains high the leak is on the engine.