1998 Ford Expedition Mode 6 Help

[OxfordFordMan]

My 1998 Expedition 5.4 Triton has experienced very rough idling, rough running and hard starts.
Changed out all spark plugs, COPs, O2 Sensors, EGR valve, MAF sensor, DPFE sensor.
Checked all vacuum hoses.
Cleaned throttle body.
The rough idle, rough running and hard starts persist.
The computer is not throwing any codes.

My Mode 6 flags two issues.
1. Unknown Test TID 21 CID 0 Value 32768 Limit >=60160.00
2. Unknown Test TID 41 CID 12 Value 65440.00 Limit <=860.00

I'd really appreciate any help is resolving this trucks issues.

 

[jr1under]

Those Mode 6 tests are emissions-related and probably don't have much to do with the issues you're experiencing. TID 21 is the EVAP monitor and TID 41 the EGR monitor. On my 1999 5.4, one or both can be out of range one day and normal the next. From the OBD SysOp manual, "...a monitor or sensor is considered OK if there are no DTCs stored for that component or system at the time the monitor is running."

As poorly as your Exp is running, you'd think it would have stored a DTC by now. How long has it been since the battery was last disconnected? Some tests require a certain amount of time or driving cycles since the last reset before they complete. That's all I've got but there's plenty of posters here who can offer more insight.

 

[jr1under]

You might get useful Mode 6 data from TID 53: CID 01-08, the cylinder-specific misfire rate. On mine, the values are almost always zero. You've changed the coils and plugs but maybe there's something else.

 

[OxfordFordMan]

It's been just a couple of weeks since the battery has been disconnected.
I've driven the truck for several miles and still no codes.
The rough running of the engine persists.

 

[OxfordFordMan]

Mode 6 data shows no misfires.
Engine still starts hard and runs rough.
Fuel pressure is 40 psi and steady.

 

[jr1under]

Trying to eliminate the obvious...what about the fuel filter or possibility of contaminated fuel?

 

[jr1under]

In my 1999, TIDs 21-00 and 41-12 were already out of range when I got my first scanner but there haven't been any problems so I've never pursued them. Recently, out of curiosity, I ran the Mode 6 output through Grok and got these unexpected results. Haven't dived deeper yet but those tests might be relevant to your 1998's issues.

 

[Billme]

Personally I’m beginning to be more trusting of grok, but what choice do I have? Lol

 

[jr1under]

My Mode 6 flags two issues.
1. Unknown Test TID 21 CID 0 Value 32768 Limit >=60160.00

Don't know if grok would pick this up but I'm leery of 32768 just because that's the borderline of 16-bit integers. In binary, it's a 1 followed by 15 zeroes, an unlikely reading and more likely an indication that the data isn't valid.