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Marajin · 02-18-2017, **(Subject: 2973 help )**

Check to see if it has an after-market CAC unit on it like a duralite etc. Those things cause a lot intake flow problems. Nothing but restrictive crap junk. Stick to OEM CAC units only.

FC2973 - Intake man pressure data erratic, intermittent, or incorrect. <= this can be a tricky one ...

> Another bad sensor.

> Wiring issue with imap, crank case pres, exhust pres, sensor etc.

> after-market CAC restricting air flow

> Maybe large CAC leak

> Restriction from device installed inside the intake piping between the CAC and the intake manifold. Seen this more than a few times.

> Some model enigne will also compare the imap pressure readings against the exh. bp sensor and/or the ambient (or crank case filter sensor). etc. Make sure all those sensors are up to date and have been replaced too. not just the imap.

==

It could be fuel related but what you describe with the turbo dropping back sounds just like classic symptoms of engine silent derate more than anything else.

If it has a bad delete program in it then there is no telling what corrupt damage programming the ECM is having to deal with. Delta-P sensor or some other egr sensor may have gone bad and is getting it into a derate if the del programming is crappy. Bad del shops are everywhere like a bad plague. I have seen delta-p sensor on both factory stock trucks and bad delete cause engine to completely loose throttle response randomly or have large hesitation at take-off or less power at higher rpm. even make derates and force boost to drop back just like you describe.

You say it is 2008. 871 - this would mean it has or had a doc-dpf can too. Most guys who do deleet will not hollow cans properly. They do stupid sh$it like only make a bunch of small holes in them and later you get a lot of reflected heat that damages injectors and causes other engine problems. They ere too dumb to know that it is heat you are trying to let out not so much air. Anything heat can bounce off of or get absorbed by in exhaust is bad for them.

You never did say what kind of truck, etc. -- or who did the mods/dleete to the engine. A history alway helps. Maybe also list all the other codes is having including inactive.