truckhead302

EEC codes:
332- Insufficient EGR flow
452- insufficient input from VSS to PCM
542- fuel pump circuit open- PCM to motor ground

I failed emissions on Texas state inspection because of high NOx output. Would any of these codes being fixed correct the high NOx output and allow me to pass inspection? I know EGR has to do with emissions, I just don't know what to do to fix the codes. I replaced ALL sensors including EGR, VSS, and also my PCM an more all about a year and a half ago. I appreciate any help and tips.

sdmartin65

The initial problem I'm sure is a vacuum leak somewhere. A vac leak will set the 332 code but for some reason will also set the 542 code. If it is a bad enough leak it also throws a purge canister code. A faulty egr will indeed increase the nox reading. Properly working egr keeps cylinder temps low, increases mpg ect. It's really an integral part of the fuel system as designed on these trucks. Sorry to go on, look for a vacuum leak to pass IM test.

truckhead302

Should the light go off by itself when the problem is corrected or will I have to clear the codes somehow? Since it's EEC and not obd1 or 2 I have no idea how to clear them because I know a code reader won't do it.

Just call me Sean

iTrader: (1)

Disconnect the battery for a few minutes to clear codes.

Warlockk

The EGR isnt a complicated system. We have written several walk through on how to check it. I would recommend picking up a shop manual so you can follow it step by step. Methodically is the way to do the EGR. Here's a run down. The EGR sends exhaust gas back into the cylinders during low demand warm cruise. Meaning the you are cruising alone the highway not accelerating. Because you don't need power the EGR turns on. This does several things. First it displaces air fuel coming in so you don't use as much gas. Second because it won't burn it decreases cylinder temps. That means the ecu can advance the timing to burn the mixture and cut the fuel to run leaner without detonation. Again saving fuel and cutting emissions. Finally heat is required to create NOx. Because the cylinder is now cooler you create less NOx.
The system is made up of a source vacuum line from the intake. This should have vacuum all the time and no leaks. That connects to a vacuum solenoid controlled by the ecu. This should switch. You can jump the power to switch it manually and make sure it turns the vacuum on and off and doesn't leak. The lines runs to the EGR valve. That line needs to not leak. The valve should switch open and closed when vacuum is applied and released. If it doesn't move its broken or stuck. The diaphragm in there is prone to breaking. Finally the valve and tube can get clogged with carbon. You can clean it but if you go to the trouble of taking it off you may as well replace it.

452 is the signal from the speed sensor. Its on the rear differential. Check for a broken wire or a bad sensor.

542 is saying that the wire that turns your fuel pump on from the ecu is bad. It switches the ground on and off. I've never heard of that being caused by a vacuum leak but maybe. Check the ground wire to the fuel pumps. It should be open the switch to ground when you turn the key on then open again after a few seconds.

Finally as mentioned clear the codes by pulling the battery for a minuet. Then drive the truck for a bit and see if any codes come back.

A few tips for passing emissions. First make sure the codes are clear. It may take a while for the test cycle to complete and reset the code so give it a week of driving. Cats work best when they are hot. So make sure your air system ( smog pump) is connected and get the engine good and hot right before the test. A mechanic can check to make sure that your cats are working by checking the o2 sensor outputs. Or you can measure the temp before and after the cat. If it is working it will be much hotter after the cat. Also I couldn't hurt to run some seafoam and some of that emissions test pass fluid through the engine before you go test again. I don't know how Texas is but here in California if you fail twice they mark you as a gross polluter and you have to go to a special test only station. Its pita so find out before you go. It might be worth it to have it checked before you go test.

dixie460

Yes it is... EEC stands for Electronic Engine Control, and for these trucks there are 2 variations.

EEC-IV is OBD1. You can read and clear codes with a jumper wire or buy an Equus 3145 code reader to do it the easy way. Like this one:

EEC-V is OBD2. Reading codes requires a code reader, but they can still be erased by disconnecting the battery for a little while.

You didn't say what year your truck was, but if it's an F150 older than model year 96, or an OBS F250 or larger, then it's EEC-IV/OBD1.

truckhead302

It is EEC-IV
I used a jump wire to get the codes. It's a 93'. I just wasn't sure as to getting the codes off once I've corrected them. I'll mess around with it and try the suggestions and let y'all know how it goes. I appreciate it!

truckhead302

Can't find any vacuum leaks, and VSS and all surrounding wires are in perfect physical condition. I can't find my ground wire for my fuel pumps though. I know there is one, but I've looked all along the frame and around the fuel tanks. All I can find are electrical wires for the pumps themselves. Also if I had a bad VSS or a broken wire leading to it, wouldn't my speedometer not be working? Anyways, any more ideas? Or maybe I forgot something?

truckhead302

Oh I did forget something! How exactly can I use a jump wire to activate the vacuum and make sure the lines do not leak for the EGR? Thanks

Warlockk

The vss doesn't control the speedometer. There at 3 wires running to the pumps. 1 power from the relay 1 signal to the fuel gauge and 1 running to the ecu. The one going to the ecu is your primary concern. To activate the solenoid you need to find power and ground leads. You can Google search a schematic or figure them out with a meter. Just make sure you have power and ground to the solenoid and turn it on and off. Make sure it switches and holds vacuum. You will want a vacuum pump and a vacuum gauge. It will make testing much easier. You can borrow them at Autozone.