[skinautique]

All,

I have searched the forums for a solutions to this one... no joy. So here goes.

'96 7.3 check engine light comes on when decelerating.

I have changed the cam shaft position sensor (motorcraft gray) with no success. Vacuum line from the intake to the sensor on the passenger side of the fire wall is good. Fuel filter changed and fuel source change.

So far no codes . . .

The problem seems to be temperature sensitive (i.e. occurs more when hotter).

Pulling my grey hairs out (always being careful to leave the brown ones) on this one.

Thanks in advance.

Chris

 

[batkerson]

Mine has begun doing that the last week or 2 as well. I think I have 2 problems though...

Mine, the torque converter is locking up in every gear as soon as it starts rolling.

And, the check engine and OD lights look like blinking Christmas trees. But, it does tend to flash the check engine light on deceleration. This, I believe, is the TPS sensor on the pedal going bad again.

 

[mayaguezcctv]

My 1995 F350 is doing the same but when acelerating. i have read in lots of forums and everyone say the same. The TPS sensor. i even have the part number from Auto Zone 779-3537. I will try this solution and post back my results.

 

[ryhed]

or uvc harness and connectors to them. mine did that when the uvc's melted.

 

[skinautique]

Update

Pulled off all connectors on top of engine for the valve cover gasket pass through electrical to glow plugs and injectors. No burnt pins or melted connectors.

Replace the throttle position sensor (TPS) with no change.

Replaced Camshaft Poisiton Sensor (CPS) twice with no change.

Checked for air leaks on intake, none

Check vaccum line to map sensor... no leaks not plugged.

Still go the problem....highly air temperature dependent

 

[skinautique]

Update No. 3

Scan Tool Ran Injector Buzz Test. Injector No. 8 Low. Replaced valve cover gasket and internal wiring to cylinders 2 4 6 and 8. Could see burned wire to injector upon removal and wiggle back and forth. Replaced external to cylinders 6 and 8. Injector Buzz Test Pass. Solenoids 2 4 and 8 all checked at 3 ohms with meter.

KOER tests pass (Key on and Key off)

Cylinder Contribution Test pass

Still getting the problem, but only when the engine is hot. Rerun Injector Buzz and KEOR (key on and key off) all pass.

Still getting the Check Engine light on deceleration. Check engine does not seem to correspond to any of the sensor changes that the Auto Enginuity scanner sees. Listening to the engine in skips upon deceleration some time. Almost like it know something is wrong but can save it and thus not throw the check engine and kill halt the cylinders.

Am I down to replacement of the Injection Pressure Sensor (IPS) or Injection Pressure Regulator (IPR)? In the seconds before check engine light (CEL) the injector control pressure DC was cycling between 10 and 13 % then there was a small increase to 17% and back to between 10 and 13%. Two seconds after the 17 spike the check engine light came in. Injector control pressure (ICP) psi was between 530 and 610 psi (corresponding to the 10 and 13% DC) and rose to 773 psi for the 17% spike then returned to 536 psi. After the check engine light clears, the ICP DC is more steady between at 12.89, rising to a steady 13.67 and ICP is more steady between 560, and rising to 575 to 585 psi.

Another part of me says try another camshaft position sensor as when she hickups on deceleration the camshaft position "error" may be what is throwing it into limp mode (i.e. shutting down cylinders).

Fuel pressures as measured by mechanical gauge are 50 psi, fuel filter is new.

engine oil level is full and engine oil is rotela 15w40 diesel so I don't see a engine oil problem as the source.

She runs and accelerates great. And fuel mileage last measured tank is 19 mpg (yes I drive 55 mph on the highway).

Any thoughts? Any logging of parameters to narrow this down or just bite the bullet and to the IPS and IPR.

 

[skinautique]

Update No. 4

Unplugged the injection pressure sensor (IPS) as some have suggested. The engine will still go into limp mode upon deceleration.