Hi guys I’m new here and fairly new to working on vehicles. I have a ‘93 f150 5.0 that’s giving me a headache.

It’s throwing a code 33 which is the EGR but I have replaced the EGR itself, the sensor, and the solenoid. I also checked the vacuum line and it’s not clogged or anything but the code won’t go away.

Upon looking up symptoms of a bad EGR, sputtering and missing are common and what I experience at times. It doesn’t always happen but when it does it idles poorly at lights and sputters at the beginning of a new gear. Not sure what else to check or if these issues are even related so any advice would be greatly appreciated.

 

The EGR valve is controlled by the EVR solinoid, which is controlled by the computer. If there's an cracked hose or bad wire, the. EVR solinoid won't be able to move the EGR valve.
These trucks are going on 30 years old and all the nylon vacuum hoses are as brittle as pretzel sticks. I bet there's still a vacuum leak in the system.

There's a few things to look at.
make sure the EGR valve is working. You can pull off the EGR vacuum hose from the EVP solinoid and use a handheld vacuum pump on it to see if the diaphragm moves. The vacuum pump will also tell you if the line has a leak.
You can also test the solinoid with 2 lengths of wires by disconnecting the electrical plug from the EVP solinoid and touch the 12v and ground (power from the battery terminals) to the terminals in the EVP solinoid. It doesn't matter what polarity is. If it clicks, it's should be good. More scientific method, you can pull a vacuum on one side of the valve and hold it there; then touch the 12v and ground wires to the solinoid. If the vacuum drops to zero, the valve is definitely good.
The good news is that these trucks are pretty simple to diagnose and repair compared to today standard; the computer just looks for voltage on/off or resistance changes: our computers don't monitor the change to the engine behavior. Invest in a small toolbox with a multi meter, a vacuum pump/gauge, a fuel pressure gauge, and some wires with alligator clips and you can diagnose and fix alot of common problems with these trucks. Don't fall into the temptation of 'this part is broken, I'll just remove it and cut the wires and vacuum lines.' Fix it right and it'll last for another 30 years.

 

How are you running the Key On Engine Off (KOEO) tests/Stored Code display and Key On Engine Running (KOER) tests?

Code 33, if you really are getting two digit codes, is a Stored or KOER code. If it is a code in Continuous Memory you have to clear the CM codes or drive the truck through 40 drive cycles after replacing any parts. If it is a KOER code I would suspect it will also be in CM so you would see it as a CM and KOER code.

 

Thank you for your feedback. I definitely fell down the rabbit hole of putting new parts in with hopes of it fixing the code. I checked the EGR hose for any leaks and I believe it’s good. As far as the EGR, the solenoid, and the sensor goes, all of that has been replaced. The sputtering issue happened on my way to work this morning (a 10 minute drive). It’s when it shifts into a gear and doesn’t idle very well at lights. However, I drove it yesterday for an hour and no issues at all. I’ll look into checking the fuel pump next.

 

Rla2005- the codes I got were 33 and a low idle code (don’t remember the #) using the KOER method. I attempted to delete the codes by removing the negative battery cable for 15-20 minutes and the light still popped on.

 

You moved on to the engine running test because you are getting a system pass from the engine off test?

 

Yes sir, I don’t have the book in front of me but the two codes I got were only available through the KEOR method.

 

Assuming you got System Pass Code 11 for the KOEO tests and Stored Code display, stored codes are now wiped since you removed a battery cable, Code 33 is now an active code since it displayed in the KOER tests. Manual testing is required to see if the EGR valve is opening with vacuum applied and the EVP sensor output values are valid. If those two are good then you have to trace out the vacuum supply and verify the EGR Valve Regulator (EVR) is good.

 

I’ll work on checking the parts of the EGR system but I replaced all the components other than the hoses. I tested the EGR vacuum line and it was good. Could the pipe that connects to the EGR be clogged? When I was changing the EGR it was pretty dirty inside

 

A clogged EGR tube will not trigger a Code 33. On this vintage vehicle the EGR valve feedback is position based. There os no way for the computer to measure actual EGR flow. With all of the new parts hard telling if any of them are good without testing each one. Yes, part quality has taken a steep dive in the negative direction these days which makes shotgun part removal very dangerous to your wallet thickness.

 

So, being exhausted from throwing parts at it, I ended up taking it to a mechanic to figure it all out. The EGR code was thrown due to one of the parts not having an o-ring; the poor idle and sputtering ended up being a bad ignition coil boot. So $100 later all is good, thank you guys for your help