95 F150 Supercab 4x4 w/ 5.8l that I purchased from a rancher who needed a bigger truck to haul horses around. Check engine light has been on for some time (according to previous owner) without any real diagnosis. Haven't looked for the codes so far but had a local shop look at it to get it through the emissions check process required by Washington state.

During the local shops check they identified the EGR and a related device towards the back of the engine compartment. I replaced the EGR and the truck runs smoother but the check engine light comes on after the engine warms up. I plan on jumping the OBD connector to count CEL flashes later today.

Any ideas as to the other sensor/device that should be changed with the EGR?

 

Welcome to the site!

Suggest you're on the right path by checking codes. Can save a lot of money not buying unnecessary pieces-parts.

Not sure how much difference there is between our model years - but the three main compenents that I've had trouble with on my EGR system are the valve, the valve position sensor sitting on top of the valve, and the control solenoid sitting on the intake manifold towards the driver side rear.

Another consideration may be to inspect the vacuum lines for any cracks or failures. Not a big fan of the nylon / plastic tubing here.

I was getting a fault - something about the EGR valve not being in the correct position - traced the problem to the control solenoid that had a little foam filter that had plugged up. With my big mitts, in the course of trying to unsnap the cap of the solenoid to work on it - busted things up, so had to buy a new one from the dealership. Wasn't real painful - about $35 IIRC.

If you opt to change the position sensor on top of the valve - be sure to get the right color - I think the options are grey and white, and they don't mix.

 

Welcome to the site! Check for codes and post them here. We can go from there.

 

So far - besides the EGR valve did the basics - plugs, air filter, PCV valve. Today I decided to continue with the replacement of the distributor cap/rotor. Found a plug wire with no connector ... replaced the set. Truck runs a lot better.

Vacuum hoses look good but will continue to look at them as I move throughout the engine compartment.

However, the CEL still comes on after running for 10 minutes or so. The codes were read as (in order) 654, 654, 172, 334, 452, 172, 334, 452: used jumper wire and read the CEL flashes. Some of them repeated several times so I'm going to clear them and then run the truck to see what comes back.

Also, I do have some popping when under load/accelerating - sounds like a break in the passenger side exhaust manifold to header gasket. I realize that it may cause some 02 sensor mis-reading.

Other things that need work - prevous owner had a blow out that bent driver's rear quarter panel that also crimped/opened fuel filler pipe to rear tank. Looking at getting a flexible fuel hose to replace that section. Not sure if the lack of a good seal on that section is causing some sensor or PCM issues as well.

 

In my code readout list - there was a single "1" between the two 654 readings and then the repeats of the 172 334 452 sequence for continuous memory codes. These were all pulled using the KOEO procedures as I had read not to do any KOER codes until the KOEO codes were resolved.

 

Although it says not to do the KOER test until other issues are resolved, it doesn't matter. You can do the KOER test. I didn't do that writeup, I just copied it from somewhere else. I was going to edit it later to properly outline exactly how the test is done. Go ahead and do the KOER test also. I will list the codes you have now for you:

172- Oxygen sensor shows system always lean. I would think the EGR problem was the cause but should be gone now that you replaced it, unless there is a problem with the EGR solenoid. Your exhaust leak could also be the cause.
334- EGR closed voltage higher than expected. Again, I would think changing the EGR would have resolved this code unless the EGR solenoid is malfunctioning.
452- Insufficient input from vehicle speed sensor. Does your speedometer work? If it does, the computer may not be recieving the signal. This will affect the way the engine runs.
654- Manual lever position sensor not in park position. Was the transmission in park when you did the test? This is saying it wasn't, so it could be out of adjustment or not working at all. This also will affect how the engine runs, particularly the idle.

The proper KOER test procedure isn't written in the instructions, so I will try to get the instructions in there soon.

 

Speedometer works fine. Transmission was in park but will double check again after driving the truck around today - I want more than just a couple of minutes of idling to get the codes.

I figured the CM codes were more than likely associated with the EGR valve.

Will try and post new codes later this evening.

Appreciate the assistance.

 

Trying to find the leak in the exhaust on the passenger side. Tried looking with a mirror at the header to pipe connection to see if the gasket was leaking ... tight area to work in. I want to get this cleared up before I go too much farther just to eliminate that potential. Will update as I get past that issue.

Cleared the CM codes (172, 334 and 452) and will be driving the truck around for my "commute" to the local park and ride. Will examine codes in a few days.

 

Drove the truck about 40 miles on the freeway and side roads (35 mph). After warming up I noticed that on uphill climbs it knocks quite a bit and a little loss in power. Ran KOEO check and got the 654 (MLP) and then in the CM got 172.

As stated earlier I only changed the EGR valve - is the EGR solenoid the next logical step and/or the O2 sensor?

The day was blown apart so the exhaust leak has not been found. I did find a separated tailpipe that is more or less below the back seat of the cab. Will get it taken care of and go from there - don't think that is what I'm hearing since it seems to come from up front just forward of the passenger side firewall.

 

Any exhaust leak after the oxygen sensor isn't going to cause enough problems to throw a code. You aren't getting any EGR codes anymore so it seems that is fixed. You can check for vacuum at the solenoid and check for power, but without a code it should be working fine now. I have seen some other posts about the MLP and according to those with that problem, changing that sensor made a big difference. One way I check for exhaust leaks is with the engine cold, I start it up and feel around close to flanges and connections for air escaping. The engine will heat up quickly, so be careful.