The truck is a 2000 7.3 auto 100,000 miles. It started running very rough, like it's not firing on all the cylinders. I drove it on home ( about 50 miles) and no check engine light ( or any warning lights) ever came on. So I hook up my code reader to the port under the dash and it shows nothing ether.

What is the most common thing that goes wrong with these trucks while NOT setting any codes or tripping any lights?

Thanks in advance.

 

That's difficult to say as there are numerous things that can cause such an event. Are you using a Scanner that is capable retrieving all codes? Most DIY Scanners can not. It needs to be a "Phase 2 Vehicle Media Communications Unit" or better.

Do you have a Scanner which can display sensor information in real time? If so, monitoring the following information can provide a window of what's happening.

V-PWR 10.5 VDC Minimum.

RPM 100 RPM Minimum (0 - CMP Suspect)

ICP 500 PSI or 3.4 MPAM Minimum

ICPv (KOEO) Spec 0.20v - 0.30v

ICP Duty Cycle% Spec: 10%-12% at idle, engine at 140F or >

FUEL PW: 1 MS - 6 MS (<1 / >6 IDM Suspect)

*V-PWR - If indicating a low voltage condition, check battery voltage, charging system or power and ground circuits to the PCM.

*DC% - Cranking NTE 20% / 65% is closed. (IPR Suspect)

2. ICP - A minimum of 500 PSI (3.4 mPa) is required before the injectors are enabled. No or low oil in the reservoir, system leakage, injector O-Rings, or faulty IPR could cause pressure loss.

Note: If no RPM signal is received, IPR duty cycle will default to 14%

3. FUEL PW - Even though a 1 to 6 mS FUEL PW is shown, it’s possible the IDM did not receive the signal due to a CI or FDCS circuit fault or internal IDM failure.

Knowing these basic parameters in real time will give you a way forward in your diagnosis.

Hope this helps,

Tom

 

No, I am trying to retrieve DTC's with a hypertech power programmer. Could it be cam sensor or the under valve cover wire harness? Or would they throw a DTC?

Thanks for the help, sounds like I need to invest in a real scan tool.