P0299 & Lack of Power

tigafila · **Posted:** Sat Aug 25, 2007 9:03 pm

Does anyone have any ideas on a cause of a P0299 low boost code, lack of power, and hard start? I've given it a good visual inspection, even pulled both CAC hoses to look at them because it just made sense based on Sir Sam's experience, but they were fine. It's got me stumped. Tia, Tigafila

Cowpie1 · **Posted:** Sat Aug 25, 2007 9:57 pm

Lost boost and got a P0299 a while back. my problem was a vacuum line. Replaced it and works fine. Without that turbo, the CRD is a real weak engine. Even floored, I lost about 10 mph on every little hill.

Sir Sam · **Posted:** Sat Aug 25, 2007 10:18 pm

tigafila wrote:

Does anyone have any ideas on a cause of a P0299 low boost code, lack of power, and hard start? I've given it a good visual inspection, even pulled both CAC hoses to look at them because it just made sense based on Sir Sam's experience, but they were fine. It's got me stumped. Tia, Tigafila

Visual inspection didnt reveal the leak, it was under that braided protector over the hose, it would be good to do a boost leak test, that will reveal if its at a vacumn line or a hose somewhere.

tigafila · **Posted:** Sun Aug 26, 2007 12:28 pm

I removed the braided covers from both hoses, no bad spots. How do you do a boost leak test? Cowpie, where was your broken vacuum line? I traced them as best I could and even pumped the waste gate actuator with a hand held vacuum pump and its fine. Tigafila

Johnboy · **Posted:** Sun Aug 26, 2007 12:42 pm

I got that code when the 1st EGR went out. Low turbo boost code and faulty EGR code. Never came back after EGR replacement. Proly not much help but...

Joe Romas · **Posted:** Sun Aug 26, 2007 12:59 pm

Johnboy wrote:

I got that code when the 1st EGR went out. Low turbo boost code and faulty EGR code. Never came back after EGR replacement. Proly not much help but...

You can check it for being stuck closed by taking the charged air hose off the Flow Control Valve on the driver's side and checking for the butterfly plate being opened or closed. It should be open. There are two valves relating to EGR. One is the EGR valve and the Flow Control Valve is the second and ether one can cause a EGR failure. The FCV seems to fail most on the 05's because they had plastic gears :cry:

Sir Sam · **Posted:** Sun Aug 26, 2007 2:45 pm

tigafila wrote:

I removed the braided covers from both hoses, no bad spots. How do you do a boost leak test? Cowpie, where was your broken vacuum line? I traced them as best I could and even pumped the waste gate actuator with a hand held vacuum pump and its fine. Tigafila

here is a simple one:

here is a nicer one:

basically the idea is that your just pushing some compressed air into the intake, that way any vacumn or boost leaks show up. just use whatever to push some air into the intak, we used a nitrile glove and quick connect air chuck, whatever gets the job done.

Endurance · **Posted:** Sun Aug 26, 2007 4:33 pm

Bad turbocharger or leak I would guess. Check all your vac hoses, if they are fine its more than likely the turbo. Is your Jeep not under warranty anymore?

tigafila · **Posted:** Sun Aug 26, 2007 9:04 pm

It is under warranty, I just hate the thoughts of removing all of the improvements to take it to the dealer if it's something simple. The wierd thing is sometimes it's completely normal and sometimes it won't get out of its own way. Sir Sam those are cool looking adaptors, I may have to make a couple. I'll keep you all posted, if anyone has any other ideas fire away. Thanks for the help, Tigafila

tigafila · **Posted:** Mon Aug 27, 2007 7:00 pm

I bought a scan tool today that I needed for one of my other vehicles and pulled codes. Now I have a P0234 high boost. If I clear them and baby it it stays off but if I drive it normal to agressive it throws the P0234 and goes into limp mode. When this first happened and I had the P0299 I found a mouse nest in the airbox, I understood why I had the low boost code, but I don't understand why with it removed I get a high boost code? Maybe I should put half of the mouse nest back in :lol:

Please advise, Tigafila

e010584 · **Posted:** Wed Jun 09, 2010 12:41 pm

I know this is an old thread, but I'm having similar issues. I even recently replaced the driver side CAC hose. Anybody get this one resolved?

onthehunt · **Posted:** Wed Jun 09, 2010 2:09 pm

EGR and /or FCV.

TJ2 · **Posted:** Thu Jun 10, 2010 11:18 pm

onthehunt wrote:

EGR and /or FCV.

Yep, GDE tune eliminated my P0299.

geordi · **Posted:** Fri Jun 11, 2010 12:28 am

This sounds like what I'm STILL dealing with... No resolution yet. Changed the sensors (Map, maf, Mercedes) and the airbox wires... No changes. Gonna send the CPUs into GDE next week finally for the updates, probably do a full leak-check on the intercooler at that point. If it leaks, at least I'll know what the problem is. If not, and the computer change doesn't fix this... I don't know what I'm going to look at next.

e010584 · **Posted:** Wed Jun 16, 2010 11:40 pm

I had the EGR and FCV out sometime back and no issues there beyond the usual filth. I've been running the ORV mod to keep it clean until I go the GDE route. I'm presuming it is a vacum line issue. Anybody have specific experience on which vacum line and where for this kind of problem?

e010584 · **Posted:** Thu Jun 17, 2010 11:08 am

Success!!!! I no longer have to presume a vacuum line issue as it has now been confirmed. The main vacuum line from to the vacuum modulator melted through under it's heat shield causing the problems. Apparently the metalized coated plastic heat shield is insufficient protection from the exaust manifold it was routed near so I re-routed it away from the heat. Now I've got to tackle an overheat situation on the wife's CRD. Several posts on the topic but i'm presuming a fan clutch either way.

OhmegaMike · **Posted:** Thu Mar 01, 2012 1:02 pm

Here's what fixed my P0299... I did all of the above, pressure tested, visually checked hoses, vac lines, FCV. All were OK.

I removed both of the solenoids controlling the turbo vane actuator. I sprayed them out with some (safe for plastics) spray cleaner. I used an electronics flux remover spray, MAS cleaner would probably be OK. I would NOT recommend carb or brake cleaner in there! I also cleaned the little foam breather/filter on the smaller solenoid. I just filled them with cleaner, shook them around, and drained the liquid out, blew through them, several times.

Road tested at WOT, and the Jeep has more power and virtually no black smoke at WOT. When the code was happening, power was less, and quite a bit of black smoke at WOT. Hope this info helps! -Mike

jayleonfb99 · **Joined:** Thu Apr 04, 2013 12:24 am **Posts:** 9

I replaced my Vacuum Control Solenoid and all my problems went away. I just went over 70,000 miles. I broke the old one in pieces just to see how it worked and it appeared to have some rust in it. Not sure what was going on there or how the rust got in but no CEL and great boost. I love the CRD.

P0299 & Lack of Power

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