Ok, right off the bat I'll apologize for the post. I did look through a bunch of posts on this issue (basically the engine isn't coming up to temp) and decided that I needed to post.

Here's what I've done:
replaced t-stat (twice) - 192 degree
flush/replaced coolant and purge air
replaced engine coolant temp sensor
replaced blower motor resistor - was gone, only had high speed...
...thought this was my problem got great heat and AC now...

The catch is that the gauge barely touches the 'N' (Normal), but I
do see it go down lower and then climb back up as if the t-stat is
working. But, that doesn't make sense since it's a 192 degree t-stat
so I'd expect a higher reading on the gauge and not get the ECT code.

I didn't believe the facory gauge, so I added an aftermarket gauge
(mechanical bulb type) with a brass 'T' where the sensor is and it
didn't move (130 degree min), BUT it did move up when I shut the
truck off...maybe hit 170 max. As soon as I start the truck up, it
comes right down at idle (seems to be due to the coolant circulating)
and stays at the min setting. As it drops down, on cue, the check
engine light comes on.

I did another test where I took the heater hose and made a bypass
of the heater core and didn't see any difference. Then, I crimped that
bypass hose so no coolant would flow and sure enough, I saw the temp
come up a little higher and it was just enough to NOT get the check
engine.

Pardon my french, but what the 'F'?

 

Turned out not to be a ECT code...I guess there's a big difference
between 2 and 3 digit codes... oops.

This is looking more like a combo of EGR and O2. There is also a code
about the CPP (clutch pedal position). I still don't believe that the engine
is at the proper temp, but until I get the correct code for that, then I'm
going with what I have.

 

For the clutch, I believe the pedal needs to be held to the floor during the test on the six cylinder trucks.

 

Using a T fitting to add an oil pressure gauge works fine. Using one for water temp doesn't work. The sensor needs to be in the flow of coolant, and that doesn't happen when you use a T.
I don't know how your 95 is set up, but my 90 has two temp sensors. The one right by the thermostat has two wires and is used by the ECM to adjust fuel mix. The other sensor has one wire, and is used by the dash temp gauge. This sensor is located under the manifold, on the passenger side, and close to number 4 cylinder.
You can always use a candy thermometer in the radiator with the cap off to get an idea of what the water temp actually is. I would expect 10- 20 degrees lower than the thermostat temp.

Hope this helps.
Good Luck Frank

 

For what it's worth, my 95 4.9 temp gauge stays between the second line and the "N" 99% of the time.

 

Hey, thanks for the responses. I've suspected that "T" was not right and that surge in temp after the truck was turned off seemed to prove that. I heard of a 2nd temp sensor for the gauge, but I couldn't find it. Thanks for the tip on that.

I did see the part on the clutch pedal being down for the KOEO test (that's the one, right), so I wrote off the CPP codes as TBD. I just ordered the EGR valve ($78 ouch!), and will get that in and recheck codes.

Just for sanity sake, these are my codes:

KOER - 172, 332, 528
KOEO - 522, 332

The only strange thing was the '172' (O2, lean). Again, I'm writing that off to getting
the EGR replaced first.

Thanks again!

 

One more thing, would a EGR valve not opening explain real crappy gas mileage? That's my actual problem. I'd be happy to block off the EGR valve, but doing that is just as much work as replacing it so I decided to do the right thing. I don't have emmission testing in my state for a vehicle this old.

 

Code 332 could be a problem with the EVP(position sensor on top of the EGR valve, but could also be a broken vacuum line between the valve and EVR(vacuum regulator) which is usually located over by the coil. The valve itself could also be clogged or jambed with carbon.

 

I just got done chasing the 332 code on my '95 Bronco. First the EVR had a wire pulled out of its connector by a monkey at a shop. Then I found several pinholes in the coffee can reservoir. The tech info on the EVR and EVP over at fordfuelinjection.com helped out A LOT! I was able to verify all the pieces using my multimeter, a wire with an aligator clip and a section of clear tubing.

Good luck and don't take the old EGR off until you've ruled out everything else in that system! You can verify it by using a piece of tubing to suck the air out of it while the truck is idling. If it stumbles and almost dies then the EGR itself is probably good.

 

I got it. Try to draw a vacuum from a tube and see if the valve opens. If it does, then it's probably a sensor (bad or elec conn) or vacuum line (cracked).

What's with the coffee can? I see the one up front near the battery. but I thought that had something to do with the excess fuel return. Are you saying that is a vacuum resevoir or there's another coffee can somewhere else?

The truck's got a ton of miles (over 180,000) and it doesn't look like anyone has touched that motor or much in the engine bay. Thanks.

 

Ok, I went throught the entire system and it came down to a combination of a break in the vacuum fitting near the "coffee can" (vacuum resevoir?) and what looks like a leaky coffee can. I say that since even after I fixed the break I still had no vacuum at the base of the EVR (EGR control solenoid). Once I made a "loop" and bypassed the can I finally heard a "hiss" from the EVR and plugged everything back and now the check engine light is off. So, it looks like I need a new can but was wondering what the harm was, if any, to have a loop in the system for a while? Thanks.