Who's good at diagnosing using PIDs?

[jon_s_brady]

Well, I'm back...it took me a while with family illnesses, work and other things that get in the way of fixing my car...

Well I finally succumbed and pulled the engine out again to see what the deal was. Lo and behold did I screw up...I had somehow not seated the torque converter all the way onto the two splines - I guess I only got it on the first. That extra 4-5 mm made a huge difference. The engine cranks over at 250-300 RPM now.

So I still haven't got the car running nicely but I did get it started and it ran for may 15 seconds. And not the first time it cranked over. I pumped the accelerator quite a bit and then it would almost catch.

I think I may have a fuel supply issue though. I luckily had the FORScan running when it caught and ran. I had the engine up at around 2500 RPM for a while and the engine was running so I let the RPM drop and it died on me. I noticed that the Fuel Rail Pressure value is around 40psi with KOEO and stays roughly +/- 6psi whether it's cranking or running at 2400 RPM. That looks to me like a fuel pump/regulator issue. Any opinions?

I'll start a separate thread on FORScan and the ELM327 that may help others with diagnosis.

 

[imp]

I looked thru my Haynes Manual and couldn't determine if the connecting rods are offset on the SOHC V6. Does anyone know? If they are offset and installed incorrectly the pistons will bind against the cylinders. Did you purchase new oversize pistons and install them on the stock connecting rods? I'll try to find more info on rebuilding the engine.

Edit: I found the following in my 2000 Shop Manual:

1. NOTE: Apply a light coat of Super Premium SAE 5W-30 Motor Oil XO-5W30-QSP or equivalent
meeting Ford specification WSS-M2C153-G to all parts. Install the piston in the connecting rod with
the cylinder number side of the rod and the indentation notch in the piston on the same side.
Install the large chamfered side of the connecting rod bearing bore facing toward the engine front on
the RH bank connecting rod and facing toward the rear of the engine on LH bank connecting rod.
2. NOTE: The oil hole in connecting rod must face the RH side of the cylinder block and the arrow on
the piston must face the front of the engine block."

Do you mean, by offset, the piston pin holes are bored off-center through the side of the pistons? If so, ALL pin holes are off-center in all engines having conventional connecting rods. This is done to minimize harmonic effects resulting from the "swing" of the rods from side to side. When the crank has moved from 0` (top center) to 90` (1/4 of the rotation), the piston has moved LESS than halfway down the cylinder. From 90` to 180` (bottom center) the piston completes it's stroke, making up for the amount of movement lacking at 90`.

Pin offset is not much, hard to see by "eyeballing". I cannot see how installing pistons backwards could possibly cause them to bind in the cylinder. The engine would run with vibration. imp

 

[2000StreetRod]

Rod offset, not pins

Do you mean, by offset, the piston pin holes are bored off-center through the side of the pistons? If so, ALL pin holes are off-center in all engines having conventional connecting rods. This is done to minimize harmonic effects resulting from the "swing" of the rods from side to side. When the crank has moved from 0` (top center) to 90` (1/4 of the rotation), the piston has moved LESS than halfway down the cylinder. From 90` to 180` (bottom center) the piston completes it's stroke, making up for the amount of movement lacking at 90`.

Pin offset is not much, hard to see by "eyeballing". I cannot see how installing pistons backwards could possibly cause them to bind in the cylinder. The engine would run with vibration. imp

My concern was rod offset relative to the crankshaft journals not pin offset. If the rods have an offset and are installed on the crankshaft with the offset in the wrong direction the rod bearings will bind against the crankshaft connecting rod journals. If the pistons are installed on the rods with the piston front on the rear side of the rod and the piston front is used as the reference for installing the piston rod assembly then the rods would be facing in the wrong direction.

 

[2000StreetRod]

fuel pressure

. . . So I still haven't got the car running nicely but I did get it started and it ran for may 15 seconds. And not the first time it cranked over. I pumped the accelerator quite a bit and then it would almost catch.

I think I may have a fuel supply issue though. I luckily had the FORScan running when it caught and ran. I had the engine up at around 2500 RPM for a while and the engine was running so I let the RPM drop and it died on me. I noticed that the Fuel Rail Pressure value is around 40psi with KOEO and stays roughly +/- 6psi whether it's cranking or running at 2400 RPM. That looks to me like a fuel pump/regulator issue. Any opinions?

I'll start a separate thread on FORScan and the ELM327 that may help others with diagnosis.

Your 3rd generation Explorer has a fuel pressure/temperature sensor on the fuel rail.

The PCM uses the output of the sensor to control the fuel pump motor speed (pressure) via a Fuel Pump Driver Module (FPDM).

I don't know what the specified fuel pressure is for your 3rd generation but I suspect that 40 psi would be adequate up to 2400 rpm. I suggest that you determine the specified number. Unfortunately, I think there is no longer a Schrader valve on the fuel rail to read the actual pressure. And the pressure sensor seems to be a little unreliable from what I've read on the forum. The PCM "thinks" the pressure is 40 psi. If that is significantly lower than specified I suspect the PCM would set a DTC. However, if the sensor is bad the pressure could be significantly less than 40 psi and the PCM might think the pressure was within tolerance.

EDIT: According to JustAnswer the fuel pressure limits are 55 to 65 psi for a 2005 Explorer with the 4.6L V8. I don't know how reliable the answer is.

 

[jon_s_brady]

Fuel pressure sensor

Dale,
Thanks for pointing me in that direction. It seems like the 40psi as reported in the PID is correct. I stumbled on an excellent explanation of the fuel pressure sensor and the pressure measurement. Here's the link... http://www.underhoodservice.com/Art...x2019s_electronic_returnless_fuel_system.aspx

At this point I'm getting closer. The engine starts regularly but after some long cranking. The engine will run forever at 1600 RPM and I can nurse it to stay on when it gets down around 1100 RPM but it starts running really roughly and when left to it's own devices it will stall.

I'm looking for vacuum leaks at the moment. It seems this engine is really touchy about vacuum. I found one connection that wasn't seated nicely and when I fixed that the situation improved markedly although not completely.

 

[2000StreetRod]

egr valve?

That was an excellent explanation of the electronic returnless fuel system. I plan to install a fuel pressure sensor when I install my M90 supercharger and use the output to control the fuel pump speed using a pulse width modulation motor controller.

On my 2000 the PCM disables (closes) the EGR valve at idle, WOT and heavy engine load. If the EGR valve sticks open the engine will die at idle. Here's a link about my 2nd generation EGR system: EGR System O&T

Your engine has electronic throttle control which I'm not familiar with. I think other forum members have had idle problems due to a defective throttle control. I think the PCM usually sets a DTC when it detects a defective throttle control. You might monitor the associated PIDs.