Hi All,

Preparing for 5 inches of snow this weekend and lo and behold my truck is throwing all sorts of codes and cant idle correctly nor get into gear. I pulled the following codes and was hoping you all could help me. I can also record a video of the flashes as this is my first time doing this test on this truck and I cant say I'm an expert.

Key on engine off: 116, 126, 114, and 121
Engine on test: 99, 81, 26

Any advice would be great I don't know where to start.

 

You will never get a mix of two AND three digit codes. It's two OR three. Your 1996 MY truck should display three digit codes for KOEO, CM and KOER tests/display.

Re-run the KOER tests.

These codes will usually appear if you did not warm up the engine/transmission before running the KOEO tests:
Code 114 (KOEO): ACT out of self test range 0.3 to 3.7 volts.
Code 116 (KOEO): ECT out of self test range 0.3 to 3.7 volts.

This code indicates a problem with the Throttle Position Sensor (TPS)
Code 121 (KOEO): Closed throttle TPS voltage higher or lower than expected.

This is the most likely reason the truck is not running well:
Code 126 (KOEO/CM/KOER): MAP sensor out of self test range 1.4 to 1.6 volts.

This sensor provides the most critical feedback to the computer. Ignore the reference to the output voltage, the signal is a variable frequency but still out of range. Verify the MAP sensor, located on the passenger side of the firewall near the HVAC blower case, is plugged in electrically and the vacuum hose to the manifold is still attached. If that is good then you most likely have a bad MAP sensor. Look for signs of water intrusion from a missing or damaged hood/cowl gasket.

 

Thank you sir!! will check as soon as I get home from work and update. Ill also put up a video of the flashes cause it seems that was the series I got. Like I said Im still learning so I truly appreciate your help.

 

Highly suggest you invest in a simple code reader like the Equus/Innova 3145. Counting flashes gets old in a hurry...

 

Will do! Ill pick one up from autozone when I pick up the MAP sensor. My ignition coil also makes a buzz after I shut the motor off. Do you think that it could also be the culprit?

 

It's not the coil making the buzzing/farting noise at shut down. It's most likely the EGR Valve Regulator (EVR)



It's a common issue that is not really an issue. Just annoying.

My old 1992 F350 w/5.8L engine did the same thing. I did notice the orientation was opposite of the photo I posted. Once I flipped it to match the photo the noise was gone. Your results may vary.

 

The inexpensive MAP might be useful as a diagnostic, but I've had terrible life from them. As in, 3 months or less.
I finally gave up on the 'lifetime warranty' version, and
grabbed 3 from the junkyard-
they all worked, and I now have 2 spares.

jus' my experience.

t

 

Well thanks everyone! Replacing the MAP got me back on the road. The TPS 121 code is still throwing the CEL but at least I don't have to watch flashing lights anymore thanks to the autozone reader. Definitely can feel the TPS issue when pulling off the throttle as well as a noticeably high idle. Dont have a cluster with a tach so I cant tell you exactly how high it is but its on the wanted parts list.

Any tips on trouble shooting the TPS? Should I just replace it?

 

only if it is bad and use motorcraft if at all possible,
Test the TPS with a volt meter to see what the voltage values are. Measure between the green wire and the black wire with the tps harness plugged in, and the key on, engine off(not running). Closed throttle should be no less 0.6V, and no more than 0.99V and then voltage should be 4.8-4.9V at full throttle.

note: remove your 2 air intake hoses from throttle body to have easy access to harness plug, you dont have to remove throttle body to do this check

Throttle Position Sensor Testing, Replacement and Adjustment | Full Size Ford Bronco Forum

 

Appreciate the response. I don't have a volt meter but I guess I should go get one. Pulled codes after going to the store this morning and it was throwing 122 and 126.

 

if you replaced your MAP sensor, seems like you have a vacuum leak in the hard plastic line going to it or the short rubber piece that connects the hard plastic line to MAP sensor is dry rotted, or at the vacuum tree on the upper intake, is dry rotted, if your still getting the fault(126) did you clear the codes before you test drove it, after replacing

 

I believe Code 126 can be present in the KOEO and KOER tests as well as Continuous Memory. I suspect the code is in CM therefore the best thing to do is clear the codes.

 

Correct it was a stored code. Tested again and it was gone. The 122 code persists and it causes the idle to be a bit funny. If I drive on the highway or do something that gets the RPM's up for a while it'll idle very high and almost run away when I put the clutch in or leave it in neutral. Itll go back low when i put it in gear but will go back to the extremely high idle when put back in neutral unless I restart the truck, then it idles fine.

 

Classic symptom of a bad TPS or bad connection in the TPS circuit.

As you drive the truck the computer is always looking for the lowest TPS output (ratch algorithm). With a "noisy" output the computer is falsely led to believe that lowest TPS signal value is a lower value than it actually should be. Shutting off the engine then restarting resets the baseline stored TPS value. As you drive, the cycle begins again.

My old 1992 F350 w/5.8L engine had similar symptoms, but the TPS tested good. However...the green corrosion in the TPS connector was another story and the root cause.

If you do end up replacing the TPS I HIGHLY suggest a Ford/Motorcraft brand. Aftermarket TPS sensors are well known to have short lives as well as trigger other issues because of poor quality. Do not fall prey to the "You have to adjust the TPS to a mythical value" conspiracy theory. Anything between 0.6 to 1.0 VDC at closed throttle is fine. As you are experiencing, the computer adjusts on the fly to compensate for the TPS output.

Some good reading about the Throttle Position Sensor (TPS)

 

As RLA2005 stated, stick with Motorcraft when replacing sensors or senders Whenever possible. This reduces a dominoe effect cause by junk parts from the part store or "SUPER DUPER" parts meant to enhance performance.

Rarely anyone here will advise against Motorcraft. Most here, including myself, have "been there, done that.." regarding aftermarket sensors or parts.