2003 Ford F-150



March, 31, 2007 AT 9:07 PM

Thanks to all in advance. You were right on the money the last time I posted here. : )

Started looking at my step sons 2003 ford taurus with the 3.0L duratec v6. The car has 68Kmi and stumbles under load or climbing a hill.

several mechanics have looked at the taurus and with $600 worth of repairs the same issues occur. The mechanic also says the next step was to replace the catilytic converter. So, I have taken it upon myself to try to fix the car.

by the looks of the documentation, they appeared to see p0300 code and replaced the following:

1) plugs and wires with motorcraft
2) coil pack
3) body assembly aaf 3f1z-9e926-aa
4) air filter
5) body gasket

The car was used when he purchased it. Looking at the regulator, it and the rubber tubing appears to be brand new. The rubber tubing between the line side and the regular appears to be older which is why I make this observation. This may be why the got rid of the car in the first place.

The MIL is on and when I initially pulled the obd II codes via a laptop, I found only a p1506 code
P1506 Idle Air Control Over Speed Error.

I cleared the code and we took a test drive. P1506 did not return. I noticed the fuel pressure per obd II was 38psi, acc on, idling, and driving. We then replaced the fuel filter. It was horribly dirty gas that poured out of the line side. The drop side appeared to yield clean gas. Replacement of the filter yielded a 2psi improvement and now show 40psi. Per the repair manual this is still low and it says 50-56 psi running and 45-56 key on engine off. I can't seem to locate the fuel pressure access point on the injector rail or anywhere close by to verify obd II sensor readings.

we performed another test drive and event that he said normally occured happened. The stumbling occured, the MIL came on, and remained on. I pulled the codes and found a p0300
p0300 random misfire

Sitting in the yard I brought the rpm to 3000 and the car began missing. At 4000 the missing was horrible and the car will not go above 4000 rpms. I also noted the fuel pressure dropped to about 28psi when the stumbling began. It almost immediately recovered the fuel pressure to appx 40psi, but the stumbling continued.

if the car has been sitting a while, grey smoke is observed on start up but quits after 5-10 seconds or so. Not sure if this has anything to do with it, but thought I would mention it anyway.


6 Answers



March, 31, 2007 AT 9:40 PM

Try a compression test with misfires its either spark gas or mechanical. Does your laptop software let you graph injectors? Log info on a drive? Try that. If you have autotap save the log and pm me. I'll give you my email and I'll take a look!



April, 1, 2007 AT 7:58 AM

Thanks for the post. I was logging the 1st time and during the 3000 4000 rpm test. The software I was using was " diagnose.&Quot; I can provide you with the link for the software and hardware. The version was 4.1. It has trim readings, but nothing about the injectors. I have upped the log files to you. The 1st one was while driving the car. The 3000-4000 rpm test was sitting in my yard. I can reproduce the stumbling at these rpm rates.

I also cracked open the filter to see if the intake side of the air filter may be clogged with somthing. But, it made no difference @ 3-4K rpms

I pulled the plugs on the front side 4, 5, 6. The plugs appeared to be new, but significant fouling was present.

I had another gander at the fuel system and I cannot locate a port by which to verify the obd II reported fuel pressure.



April, 2, 2007 AT 8:48 AM

Unfortunately the log file will only work for me if you have Autotap tool. When an engine missfires at these RPM it's usually a timming advance probem.
Try the crankshaft position sensor and the camshaft position sensor. Crank is easier to replace so start there. If you have a P0401 Take off the EGR valve and clean the port out with a coathanger. Go right thru to the Butterfy. If you got a lot of carbon out, reset the PCM, And test bedore you replace parts. If the P0401 sets again, replace the EGR Position sensor.



April, 2, 2007 AT 12:33 PM

The logs have the timing advance in them.

Just curious, does the fuel pressure not raise questions or what I have presented is considered normal? With the fuel pressure dropping off when the stumbling occurs?

Would the timing advance explain the new plugs appearing fouled?

I will check the cylinders for proper and equal compression.

I still am unable to locate a fuel pressure access port. Does a way exist to check this?

I will also start checking the timing sensors



April, 2, 2007 AT 2:40 PM

Well I have a 99 Sable and the test valve is at the end of the fuel rail. Looks like a bicycle tire valve stem...called a schreader valve. If you have a noid lite you can test each injector for power...




April, 5, 2007 AT 9:57 PM

K. Here is what I have. Disregard the 4000 rpm stumbling while in the drive way. Seems the computer has a limiter and this is normal. I have a 2001 that is mine that behaves in the same manner and stumbles at 4000. In fact the timing jumps to 40 degrees to cut out the engine on both the 2001 and the 2003. Back to the drawing board.

Next Steps: I have an inline fuel pressure and compression tester on order. My 2001 has the test port on the injector rail. The 2003 has a sensor with wires and a vacuum line where the 2001's test port is. According to research, I will have to break into the fuel line to take this reading on the 2003. I will compare the 2001's and the 2003's fuel pressure to bench mark since the 2001 runs perfectly. This should verify the computer's sensor readings on the 2003. I will also check the compression on the cylinders.

Also, can anyone tell me what type of noid light to buy for this car?

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