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ThaCaddieMan

04 Deville struggling to accelerate

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Long story short, a mechanic that I no longer use decided to power wash my engine after changing the oil pan/valve cover gaskets, and now my caddy struggles terribly. When it idles, the car jumps around, when accelerating from a stop, the car struggles to get up to 30-40mph. I am receiving a code P0354, which is misfire #4, but the coil and plug appears to be fine. I had a huge rip in the manifold coupling, so I changed that as well. 

Can anyone assist me in finding out what's wrong with my vehicle?

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Not to be confused with p0304.....p0354 is a different code...

 

The ignition system uses individual ignition coil/module assemblies for each cylinder. The powertrain control module (PCM) controls the individual coils by transmitting timing pulses on the ignition control (IC) circuit of each ignition coil/module to enable a spark event. The PCM monitors each IC circuit for improper voltage levels. Each ignition coil/module has the following circuits:

    •  An ignition voltage circuit

    •  A ground

    •  An IC circuit

    •  A low reference circuit

If the PCM detects a failure on the IC circuit of the ignition coil/module, it will set 1 of the corresponding DTCs:

    •  DTC P0351 for ignition coil/module 1

    •  DTC P0352 for ignition coil/module 2

    •  DTC P0353 for ignition coil/module 3

    •  DTC P0354 for ignition coil/module 4

    •  DTC P0355 for ignition coil/module 5

    •  DTC P0356 for ignition coil/module 6

    •  DTC P0357 for ignition coil/module 7

    •  DTC P0358 for ignition coil/module 8

 

#4 is front of engine....2nd one in from passenger side. The 2004 uses individual ignition coils for each cylinder.

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Once you repair the problem on #4, if the engine still struggles, check for a clogged cat.  A single misfiring or dead cylinder shouldnt cause the engine to struggle as you describe.


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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On 1/7/2017 at 0:06 PM, BodybyFisher said:

Once you repair the problem on #4, if the engine still struggles, check for a clogged cat.  A single misfiring or dead cylinder shouldnt cause the engine to struggle as you describe.

Does it maybe sound like the MAF sensor?

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It NEVER "sounds" like anything.  You have an on-board diagnostic system that runs tests and when something is wrong, it sets a trouble code.  If there is NO trouble code, there is no trouble....

However, there a few problems that won't set a code in all cases such as the fuel pressure regulator clogged cats, fuel pressure (it may set a lean code). 

Please post ALL your codes.  That will help us know what is going on.

Refer to my signiture here for how to check for codes, post all P and B codes.


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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With the high pressure spray.....sounds like he may have gotten water down into the spark plug wells.....you would have to pull each coil and check.

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I missed that the engine was powerwashed or steam cleaned, sorry.  


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Well I know I have a high voltage code to the pcm have not figured it out yet but I know it ran great before I had to take the tranny out I think its in the main wire harness that runs in between eng and tranny major miss fire is the problem

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