check engine light flashes over 55 mph

Ok so this is my first time on this forum (which rocks).
this is also my first Ford. I just got an 88 f150 Lariat 4x4 with a 300 I6 and 4spd manual transmission w/granny gear. The truck itself has about 135,000 miles, but I was told that the engine and trans were replaced 35,000 miles and ten years ago. (the guy used it to haul his boat occasionaly)

Getting to the point, while the truck was clean well kept, and mostly seems to run fine, when I get up around 55 or higher the CHECK ENGINE light flashes randomly but keeps doing so untill I slow down. I ran the self test and got codes 32 (EVP circuit below minimum voltage of 0.24 volts) and 67 (Neutral safety circuit failure). I don't know what either really means.

It runs about 2,500 rpm at 55 in 4th, but I don't get the light at similar rpm's in lower gears, although sometimes it flashes for a moment when the engine is working hard

I don't really know how serious this is or not, the truck seems pretty solid if a little slow to get up to speed, which I gather is typical. I've been babying the engine and havn't tried to take it over 65, but as this is a work truck I have to drive it on the highway under load regularly.

Any advice would be greatly appreciated. thanks

check for vaccum leaks. and for vaccum at the evp. if thats ok check voltage at the evp plug in should be 4 - 6 volts. if ok replace evp

Try resetting your computer by dsconnect your battery cables for 5 minutes. it wont hurt anything, except reset your radio presets.

Thanks for your help, MustangMike & Sumpn'Serious

The egv voltage and vaccum lines checked out okay. I havn't tried replacing the egv yet, will try that next.

Battery reset makes it stop for a while, but it just comes back.

I had it in the shop for some brake work so I had my mechanic check it out. He said that this is very common on older Fords, he could adjust it but it would just start acting up again. He told me it wasn't anything I needed to worry about. Does my mechanic know what he's talking about? Can anyone explain to me exactly what the egv does before I mess with it? I know it controls exaust gasses but that's really all I know. Another stupid question is, where is the egv located and what does it look like? I couldn't find a picture in my Chilton manual.


the flashing light sure is annoying.

Thanks again!

I'm not sure which style EGR you have in your truck but the 32 code has different meanings for each type, yet all are egr problems, which would certtainly cause those symptoms. www.fordfuelinjection.com list tests you can do to hopefully help you diagnose this further.

EVP is for vehicles equipped with EGR solenoid(s), with or without an EVP sensor

EVR is for vehicles equipped with an EGR Vacuum Regulator (EVR) and an EGR Valve Position (EVP) sensor

PFE is for vehicles with Pressure Feedback EGR (PFE) sensor and and an EGR Vacuum Regulator (EVR)

32:
EVP - EGR not responding properly during test - EVP
EVR - EVP signal is/was low - EVR
PFE - PFE shows low pressure, EGR not seating or memory, not seating intermittently - PFE

Cheers,
Popa Tim

Ok, I've done quite a bit of reading and am pretty sure you have the EVR system.
The EVR is the EGR Vacuum Regulator. it passes vaccum to the EGR.
The EVP is the EGR Valve Position Sensor. It passes the position data (EGR Open/Closed) back to the PCM.

To Test the EGR:
The EGR is normally closed at idle. Disconnect the hose and if there is vacuum present at idle then the problem is the EVR. Otherwise connect a hand vacuum pump to the EGR and it should open at 5inHg. If you remove the EVP you can confirm this visually.

To Test the EVP:
w/ key off, disconnect sensor harness, turn key on and measure the voltage between Vref and Sig rtn, it should read between 4 -6 volts. If it's not check the wiring. this is unlikely but it does happen.
Next turn the key off and connect an ohmeter to the EVP signal and to Vref, disconnect vacuum and connect a vacuum pump. As you increase vacuum the reading on the ohmeter should go from around 5500 ohms to 100 ohms @ full vacuum. If the EGR valve doesn't hold vacuum you have a bad EGR valve. If the resistance isn't in the range then the EVP is bad.
If you don't have a vacuum pump just undo the sensor from the housing and push the rod that sticks out the bottom to make sure that the sensor opperates in range. If it does not operate in range then the sensor is bad. other wise your EGR valve itself is bad.The wire colors are
EVP signal == Brown/light green
Vref = brown/white
Sig rtn == grey/red


To test the EVR:
Connect a vauum gauge to the output (EGR) side. There should be no vacuum at idle.
Activate the EVR by holding throttle up, about 6inHg should appear at the output side (and There should be more than 15inHg of vaccum on the input side. If not then you have a vacuum leak.)

I hope this helps!
Popa Tim