HockeyFan999

OK so now the Truck runs great, i didn't clear the error codes before taking it to my friend to see if it would pass smog (doh) and it didn't.
Now the error codes are gone, No check engine light, but I have only drove it one block since I cleared them. I checked for codes again after
warming it up and driving the one block and didnt receive any codes with the KOEO. So I thought i would try testing with the engine running.
All I get is the number 8 with a cyl above it. I am assuming this means it is firing on all 8 cylinders, but I never read anything about it showing that
during the test. Am I safe to assume that everything is fine now with no codes and no CEL? And is there a chance that it could pass smog now, even
thought I haven't done anything except clear the codes that were left in there? I don't know if the engine was running in one of the other modes because
the codes were still in memory or not. Or I have to find out why there are no codes and it isn't passing smog (california).
Thanks

Steve83

What are you talking about? A flashing light can't have a cylinder above it. Are you using some scantool?No.Sure, there's a CHANCE.Codes have nothing to do with FMEM & HLOS.Codes have nothing to do with how the engine is running. It can run perfectly, and have 20 DTCs. And it can NOT run, or run like @$$, and have no DTCs. Codes are only distantly related to emissions, but only in a diagnostic way - NOT in a symptomatic or directly-relative way.

HockeyFan999

Hi Steve, Thanks for all the information you always provide.
Yes I am using a scan tool, I guess I should have looked in the book that came with it (duh)
Nothing in the book says anything about flashing the #8 with the letters cyl above it.
I know the codes don't cause problems, I meant the errors causing the codes could effect emissions.
I have 3 days to drive it and figure out if it pops more codes or not. I have a feeling when I do a 10 mile
drive, that it will. Then back to the drawing board.

Steve83

That's why I recommend NOT using a scanner on these old trucks. Read that first caption, and use the dash light to read codes.

HockeyFan999

The truck is still running fine. I changed the EGR valve and the EGR position sensor and am still getting the error related to EGR opening not detected.
Check engine light still comes on once it warms up a little. The vaccum lines look good and I replaced the ones that didn't. What should i try next?

DarrinT04

hey guys. did the changing the EGR Valve help?

Steve83

Changing parts is not diagnosis, and it's rarely repair if no diagnosis has been done. To diagnose a fault, you first need to understand how the system works, and how the suspect parts work within that system. You also need to pay attention to what any fault code definition actually says (and it has to be the definition specific to THESE trucks - not generic definitions for all brands, or even for all Fords of that year). In this case: the definition doesn't say the EGR or EVP need to be replaced; it doesn't even say there's anything wrong with either of them. It only says the EEC couldn't detect the EGR opening (not that it DIDN'T open, or that the EVP didn't indicate that opening). Is the EVP wiring good? Is the EGR vacuum line (from the EVR) good? Is there a good vacuum supply to open the EGR? All of that & more needs to be checked before the first part is even bought - let alone, changed.

HockeyFan999

No, I changed the EGR valve and the sensor. Still got the code. The truck runs fine so I think it is an error with something communicating to the truck that everything is fine.
I can not trace where the green hose goes from the EGR. I think it goes to the EVR, which I can't find. But thats another post.

Steve83

That's not how it works. The EEC assumes everything is working right, until it detects a signal that's out-of-range. After some time (depending on exactly what signal & how far out-of-range), it sets a DTC; and some DTCs include turning on the CEL. But there are other things that can turn on the CEL, as the first caption I posted above explain. Once the CEL is on, you have to repair the problem AND clear the DTCs to turn it off. It's all explained in that caption, so you have to read it a few times to absorb it all.

HockeyFan999

So if I understand it correctly, then something is not working? Because the truck runs fine so I thought maybe it was a communication error to the EEC. So if the truck runs fine, and it gets a code, there is no way it can just be the EEC not being able to access a sensor or something? Like a bad wire going to the EEC would cause that right? A communication error.