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FORD PLUGGED EXHAUST

posted Jun 13, 2016 00:56:07 by Richard Horn
I HAVE A 2000 F150 4.6 FORD PICKUP. I HAVE A MODIS ULTRA SNAP-ON SCANNER. IS THERE A WAY TO USE THIS SCANNER AND CHECK FOR BACK PRESSURE, LIKE MAYBE FROM A PLUGGED CAT. THIS VEHICLE HAS FOUR CATS, ONE MUFFLER AND ONE EXHAUST PIPE OUTLET. ALSO DOES THIS VEHICLE HAVE A SHUT DOWN BECAUSE OF OVERHEATING AND IF SO, WITH THE SCANNER, IS THERE A WAY TO CHECK FOR THAT.
THANKS RICHARD
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Tyler said Jun 13, 2016 01:54:42
I HAVE A 2000 F150 4.6 FORD PICKUP. I HAVE A MODIS ULTRA SNAP-ON SCANNER. IS THERE A WAY TO USE THIS SCANNER AND CHECK FOR BACK PRESSURE, LIKE MAYBE FROM A PLUGGED CAT. THIS VEHICLE HAS FOUR CATS, ONE MUFFLER AND ONE EXHAUST PIPE OUTLET.


Hey Richard! Diagnosing a plugged cat may be challenging with just a scan tool, but there are some tests you can do to point you in the right direction.

First one that comes to mind is comparing the scan data BARO HZ reading with what you should be seeing at your particular altitude. Use this chart to compare the value from your F-150 to what it should be. A significantly lower reading would point towards a breathing problem.

Second would be the O2's during a wide open throttle run, as well as fuel trims under load. If you had one cat that was plugged, then this would result in one bank of the engine breathing better than the other. You'll be looking for one upstream O2 going lean at WOT, with the other one reading rich. You'll also be looking for imbalanced fuel trims from bank to bank, i.e. one bank way rich, the other way lean.

If you don't mind getting your hands dirty, you can also use the DPFE sensor hoses to get a quick and easy backpressure reading, using a vacuum or backpressure gauge. ScannerDanner did a great video covering this exact test. Keep in mind, the DPFE only samples one bank of exhaust, so a passing reading here doesn't mean you're in the clear.

ALSO DOES THIS VEHICLE HAVE A SHUT DOWN BECAUSE OF OVERHEATING AND IF SO, WITH THE SCANNER, IS THERE A WAY TO CHECK FOR THAT.


There's some trouble codes that Ford will use associated with overheating conditions, typically P0217 and P1299. These don't guarantee that the engine was actually overheating, just that the temp sensor (coolant temp or cylinder head temp) indicated a problem.
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Noah said Jun 13, 2016 02:19:06
Second would be the O2's during a wide open throttle run, as well as fuel trims under load.

Here is a video on the free channel showing the test Tyler is describing. It starts with how to check for a back pressure issue by monitoring upstream O2 activity on your scan tool during a wide open throttle run.
[Last edited Jun 13, 2016 02:22:21]
Massachusetts, USA
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