84 2.8 Error Codes and Running Issues

[wadehilts]

Hi All,
I rebuilt my 2.8 v6 cologne a few years ago. Initially had a rough time because I had set the valves too loose. Ended up bending a pushrod. Exasperated, I went to a mechanic and he replaced the pushrod. Machinist warned me that if the loud valves started to creep back after a few hundred miles then I probably ruined the cam. The valves got noisier so I thought I f*cked up big time and ruined the cam. I bought the most street friendly mellow cam for the 2.8 that Comp Cams sells and installed it (not a small job, basically had to pull the engine again). Turned out that mechanic had just put in the wrong valve adjustment screw on the valve that had bent a pushrod and it had just worked itself loose, I found out after doing the replacement... bummer. But since then, the car hasn't ran right. Here are my symptoms:
1. Car runs better cold in general, but still has a power dip under high load.
2. When the engine is hot, and under higher load (usually past 50-60% throttle on flat ground), the engine will suddenly loose power - feels like its going lean or something. No backfiring or anything, but the engine will suddenly dip in power. Sometimes the engine will stumble and struggle to run very much. Up until that point the engine pulls really nicely.

I got an analog meter and went to read the codes from the EEC-IV computer. Here is what I got:
Key ON, Engine OFF: code 31 [EGR valve position or Pressure Feedback EGR Transducer (PFE) sensor out of range.]
Continuous Memory Codes: 31, 41, and 63. Where 31 is the same as the Key ON Engine OFF code 31, 41 is a system running lean warning and 63 is a Throttle Position Sensor signal too low (grounded or open circuit).

So it feels like my intuition of the engine going lean at some point is correct. The engine has the Motorcraft 2150 feedback carburetor and I can't seem to locate where a throttle position sensor would be. There is a throttle positioner solenoid that appears to be fine. I haven't done a running test and I've traced and double checked all the connections to the EGR valve and they seem good. Can't get the Key ON engine OFF code 31 to clear after doing that either.

Anybody have any experience / theories on what would have happened? I suppose I should double check the timing. The Comp Cams guys said that their camshaft shouldn't require a rejetting of the carb or anything.

I can provide pics or anything else if that's helpful!

Wade

 

[wadehilts]

So I have an update. I ended up fixing the problem but I'm not exactly sure which thing I did fixed it.
Since error code 31 was a persistent problem I replaced the EGR position sensor that mounts on the EGR. The code did not go away, so I don't think it did anything.
The other area of suspect was the TPS, which I found underneath the electric choke heater mechanism. I sprayed some contact cleaner on the TPS.
I did a full dynamic and static timing check and found the timing to be spot on.

Additionally I ran the Key ON, Engine Running Test and got the following codes:
13: (R) Idle Speed Control motor or Air Bypass not controlling idle properly (generally idle too high)
23: Throttle sensor out of range or throttle set too high
31: EVP - (O, R, M) EVP signal is/was out of range
EVR - (O, R, M) EVP signal is/was low
PFE - (O, R, M) PFE signal is/was low
33 ALL - (O, M) EGR did not open/ respond during test or if memory code, did not open intermittently
44 AIR (thermactor) system inoperative

My theory is that cleaning the TPS potentiometer fixed the issue.
It also looks like I have a persistent problem with my EGR system, I did replace the EVP (EGR position sensor) but I can't seem to locate the PFE (which appears to be the same or very similar part on rockauto) and I don't know what the EVR is..
Seems like my idle is set too high as well but whatever. As long as I can get thru DEQ!

Wade