Mdibah
New Member
- Joined
- January 31, 2011
- Messages
- 3
- Reaction score
- 0
- Year, Model & Trim Level
- '97 XLT, 5.0L
1997 Explorer XLT, 5.0L V8, 155k Miles
I've been having an intermittent check engine light with code P0401: Insufficient EGR Flow. Pulled into the garage and spent a bit of time poking around back by the firewall. Saw that the tube from the DPFE to Exhaust Manifold was cracked. Got some replacement tubing, but needed to take the DPFE off in order to get enough of a visual to actually put it on. Also had the throttle body off at one point trying to get eyes / hands on all of the tubing.
Then comes the exciting bit. Everything reconnected, went to start up the engine...crank no start. Several hours of troubleshooting later, I'm still stymied.
I started with the "Engine No Start Procedure" sticky thread that @2000StreetRod posted in the forum, and that led to the "PCM Power Procedure" thread.
Current Conclusions and Observations:
1. No CEL with Key On Engine Off. The CEL was working when I started this repair.
2. I have an OBD diagnostic scanner: doesn't detect the vehicle when plugged in (both Key On Engine Off, and Key Off). There is power to the port, the scanner starts searching as soon as I plug it in. The scanner was previously working in this vehicle, and still works in other vehicles.
3. Inertia fuel pump switch not tripped.
4. Pulled a spark plug wire and tried to get a spark to ground while cranking. Nothing.
5. Checked fuel pressure test port on the rail. No pressure.
6. Went through all the fuses. All test okay with test lamp.
7. On to relays. Placing a finger on the PCM relay, there is a definite click when the ignition is turned to the on position. The fuel pump relay does not click however. Swapped relays around, same result (i.e. putting the relay that was in fuel pump slot into the PCM slot makes that one click). Verified using test lamp.
8. Bypassed the fuel pump relay with a jumper wire. Was able to heard fuel pump turn on, and got gasoline at the fuel pressure test port.
9. Broke out wiring guide for the PCM harness connecter. Tested that all the ground pins were still connected with a voltimeter, as with battery power (memory) and power from PCM relay. All good.
As best as we can figure, *something* got bumped / dislodged while getting a ratchet and/or hands back by the EGR system or throttle body. It doesn't make sense that multiple systems in the car would have simultaneously failed while sitting in the garage for a couple hours. Currently thinking that the PCM is at fault, but am at a loss of further things to try.
Other than getting a replacement PCM, what else should I check?
I've been having an intermittent check engine light with code P0401: Insufficient EGR Flow. Pulled into the garage and spent a bit of time poking around back by the firewall. Saw that the tube from the DPFE to Exhaust Manifold was cracked. Got some replacement tubing, but needed to take the DPFE off in order to get enough of a visual to actually put it on. Also had the throttle body off at one point trying to get eyes / hands on all of the tubing.
Then comes the exciting bit. Everything reconnected, went to start up the engine...crank no start. Several hours of troubleshooting later, I'm still stymied.
I started with the "Engine No Start Procedure" sticky thread that @2000StreetRod posted in the forum, and that led to the "PCM Power Procedure" thread.
Current Conclusions and Observations:
1. No CEL with Key On Engine Off. The CEL was working when I started this repair.
2. I have an OBD diagnostic scanner: doesn't detect the vehicle when plugged in (both Key On Engine Off, and Key Off). There is power to the port, the scanner starts searching as soon as I plug it in. The scanner was previously working in this vehicle, and still works in other vehicles.
3. Inertia fuel pump switch not tripped.
4. Pulled a spark plug wire and tried to get a spark to ground while cranking. Nothing.
5. Checked fuel pressure test port on the rail. No pressure.
6. Went through all the fuses. All test okay with test lamp.
7. On to relays. Placing a finger on the PCM relay, there is a definite click when the ignition is turned to the on position. The fuel pump relay does not click however. Swapped relays around, same result (i.e. putting the relay that was in fuel pump slot into the PCM slot makes that one click). Verified using test lamp.
8. Bypassed the fuel pump relay with a jumper wire. Was able to heard fuel pump turn on, and got gasoline at the fuel pressure test port.
9. Broke out wiring guide for the PCM harness connecter. Tested that all the ground pins were still connected with a voltimeter, as with battery power (memory) and power from PCM relay. All good.
As best as we can figure, *something* got bumped / dislodged while getting a ratchet and/or hands back by the EGR system or throttle body. It doesn't make sense that multiple systems in the car would have simultaneously failed while sitting in the garage for a couple hours. Currently thinking that the PCM is at fault, but am at a loss of further things to try.
Other than getting a replacement PCM, what else should I check?
