P0171 P0420 P0430 - Little enging power - 03 Expedition

Asked by Feb 05, 2010 at 04:11 AM about the 2003 Ford Expedition

Question type: Maintenance & Repair

The 2003 Ford Expedition 4.6L 2WD idles fine when cold at about 1000 RPM, but upon warming the idle drops to 700 RPM.  When the throttle is past 1/3 the power flattens out.  The Freeze frame data from the past 5 times the Check Engine Light came on shows the following items (results side-by-side):

OBD2 P0 Codes 171&430 P0171 420&430 171&430 P0430 P0171
Fuel Sys1     CL CL CL CL CL CL
Fuel Sys2    NA NA NA NA NA NA
Calc Loan%     92.94 79.61 50.98 90.20 71.76 88.63
ECT (f)     89 89 90 92 90 94
STFT B1%     3.13 7.03 -6.25 5.47 -2.34 9.59
LTFT B1%     24.22 29.69 14.06 24.22 8.59 24.20
STFT B2%     0.00 1.56 -0.78 3.13 -4.69 -2.34
LTFT B2%     -12.50 -14.64 -9.38 -10.16 -9.38 -12.50
Eng RPM     2608 2970 1278 2723 1434 2621
Km/h     94 37 59 100 54 61
Spark Adv (0)   20 18 38 23 31 21
IAT (C)     6 18 7 17 21 15
MAF (g/s)     78.01 81.22 18.77 70.98 25.00 63.62
TPS (%)     61.96 45.88 22.35 56.08 27.45 49.40
O2S B1 S1(v)    0.75 0.10 0.87 0.14 0.80 0.09
STFT B1 S1(%)   3.13 7.03 -6.25 5.47 -2.34 8.59
O2S B1 S2(v)    0.79 0.12 0.82 0.21 0.72 0.25
STFT B1 S2(%)   99.22 99.22 99.22 99.22 99.22 99.22
O2s B2 S1(v)    0.76 0.90 0.76 0.11 0.26 0.78
STFT B2 S1(%)   0.00 1.56 -0.78 3.13 -4.69 -2.34
O2S B2 S2(v)    0.82 0.83 0.19 0.37 0.55 0.75
STFT B2 S2(%)   99.22 99.22 99.22 99.22 99.22 99.22

P0171  =  System too lean (bank 1)
P0420  =  Catalyst System Efficiency Below Threshold (Bank 1)
P0430  =  Catalyst System Efficiency Below Threshold (Bank 2)

I had just replaced a bad fuel pump and filter.  The two hoses going from the exhaust to the EGR EVP keep blowing out when under a full load, perhaps the catalytic converter is shot and is blocking the exhaust?

I put the new PCV valve on the wrong valve cover so it ran with two PCV valves and an extreme amount of vacuum for a while, not sure if that messed something up.

Any ideas on what is causing the problems would be appreciated.

Thanks!

John

1 Answer

10

sounds like the cats are plugged or there is a heavy restriction in the exhaust. unbolt the y-pipe and go for a drive and see if your power is restored. or you can use a back pressure guage to confirm the diagnosis. unfortunantly there are 4 cats on your vehicle. If it was my vehicle I would get the cats removed and install two O2 simulators.

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