Hi, Jim. Responses inline:
jmoomaw wrote:
The shop manual says the turbo compresses the inlet air and forces it throught the CAC. It utilizes exhaust gas to compress? I assume that is why the 299 and 401 codes are related?
Chances are the MAP voltage and underboost are related. Not necessarily the EGR, but that could be sticking open and causing some issues.
jmoomaw wrote:
Disabling the EGR: does that mean the egr doesn't control the airflow to the turbo?
EGR only controls gasflow from the exhaust to the intake. The the turbo impeller is always in the exhaust path the vanes on the impeller vary based on driving conditions providing a pumping action on the intake side of more or less combustion air. All the EGR will do in this case is wreck havoc on the amount of air that the computer thinks is getting into the engine and recirculate exhaust into the intake when it shouldn't.
jmoomaw wrote:
If the Turbo has a stuck valve (underflow) would the engine start?
Don't think so. It's my understanding that even a completely seized turbo wouldn't prevent it from starting, it would just run crappy and have no boost

jmoomaw wrote:
While the value is stuck would it build up back pressure?
If the EGR is stuck shut, then the pressure goes out the exhaust. The engine actually runs a lot better that way...
jmoomaw wrote:
I just had the EGR valve replaced. If I remove the splash guard, will I be able to see if any hoses are loose or damaged?
If you just had the EGR replaced, then I would definitely look to the intake hoses for the problem. They're plainly visible with all the covers on. If you take the plastic cover off, you can easily see the problematic vent line connecting the back-center of the head to the intake hose. It comes from a hockey-puck-looking "filter" that doesn't really filter anything.
jmoomaw wrote:
I will take a few hours tomorrow to look over the system. Hope to get input by them. I have a shop manual, but if anyone has photos that show what they are describing, this newbie would be better off.
Remove and inspect the intake-side and engine-side boost hoses. They probably have oily sludge and you'll want to flex them around in your hands to see if there are any cracks that might spread under boost. Pay careful attention to the bottom sides where oil might pool and deteriorate the rubber. Assuming you do find something, there's a thread on aftermarket silicone hoses that don't have this problem. Also, you'll want to do either an EHM (elephant hose mod) or a filter (provent, PVC pipe, etc) on the crankcase vent to reduce that oily sludge in the future. It's not good for your intake.
jmoomaw wrote:
PS> I installed the HHO system in the vehicle on Wednesday of this week. The Jeep immediately ran better. The HHO is added after the MAF sensor. I will find out how long it takes for the HHO to actually reach the air intake after the key is switched on. The generator is in the rear compartment. Today, I will disconnect the generator to see if it happens without it turned on.
Hmm, interesting that H injection is smoothing things out. All that system (and propane injection, etc) does is add combustible gasses to the oxygen, so essentially small amounts of fuel that don't have to go through the fuel injection process to get to the combustion chamber. You may want to check your fuel filter head to see if it needs bleeding. Air-in-filter could cause some of your symptoms as well. There's a little rubber plunger on the head and a bleeder screw on the back side (11mm I think). It bleeds similar to brake lines (pump 10-15 times, open screw to let out air, repeat till you get diesel). A small rubber tube connected to the bleeder helps see when you're getting bubble-free fuel out of it and keeps the engine from getting fuel sprayed on it.
Dan
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2005 Silver CRD Limited

245/75R16 GoodYear Duratracs
Fumoto drain | ProVent CCV Filter
Stanadyne FM100 filter | Cummins fuel pump
GDE Eco | SEGR | BoulderBars | FrankenLift | Frankenskids