Ongoing P0299 underboost problems

mattbucher · **Posted:** Sat Jun 17, 2017 7:33 am

I have been plagued with problems recently with my 2006 Liberty CRD. I purchased it from my dad (original owner) in Feb 2017 given he can no longer drive. It had about 108K miles when I bought it earlier this year.

It was leaking oil from the turbo (but no CEL light at the time) and also the dealer had unfortunately stripped the oil pan and tried to hide it...

I replaced the stock turbo with the Sasquatchparts.com upgraded turbo and replaced the oil pan and gasket.

Next...I replaced the intercooler hoses (which were original stock) with the mishimoto hoses from sasquatch.com.

Then I put in a new air filter (Fram filter).

Shortly after that I had the P0299 code come up. Checked intercooler hoses and they were ok.

Got it back to my mechanic who ran some diagnostics and said boost pressures looked good driving but that the PCV valve and vacuum solenoid were bad. He also took apart EGR and tried to clean it out and also clean MAP sensor. Put it back together after new PCV and vacuum solenoid and seemed ok but after cold start and low rev speed the same P0299 came back and it was sluggish. He has also gone through vacuum lines to check for a break and couldn't find one.

So then I went ahead and replaced the vacuum control modulator with filter, MAP sensor, and mass airflow sensor.

Unfortunately this didn't fix the P0299.

He recommended I take it to the jeep dealer for a leak test...(which I have been avoiding at all costs and really trust him.

I called a local jeep dealer and talked with the diesel mechanic. He said he really felt it was the EGR given they replace them a lot and they never try to clean them because they still fail.

So after careful though about it...I went ahead with the Weeks Stage 1 & Stage 2 EGR delete from Sasquatchparts.com. I also went ahead and changed the glow plugs.

It has more pickup in the low end but seems to bog a little at higher gears and it continues to throw the P0299 (in addition to the fault codes for EGR system being removed).

I did also go ahead and purchase original MOPAR air filter and try that (given the first time the code came up was after I changed the air filter) - but that didn't help.

I have double checked both of the airbox sensors (smaller one in the front and Mass Airflow) and both are connected (even though I know that Mass Airflow is not doing anything with EGR system out).

I even put in another new MAP sensor after EGR delete was done to see if that would help - -but no luck.

I finally got it to another diesel mechanic and he did a boost pressure test and there were no boost leaks.

Next he went through the entire vacuum system and checked for leaks and could not find one.

According to the mechanic...when he has it checking boost pressure the engine wants 30-35 but is only getting like 21-22 and that is what is throwing the underboost code. I have the upgraded Sasquatch turbo (changed out around February).

He checked and the vacuum pressure from the solenoid to the turbo at idle and low rpm is only at 15 in of mercury. He hooked up a mechanical vacuum to the turbo to generate 27 in of mercury and the turbo gave the 30-35 pressure reading with no underboost code.

I have replaced the vacuum control modulator and filter and the vacuum solenoid and run new vacuum lines from the solenoid to the turbo (before he did the boost pressure and vacuum leak test) This did not fix the problem.

He does not know what to do next.

In summary we have done the weeks stage 1 & 2 egr delete, new upgraded turbo from Sasquatch, new mishimoto intercooler hoses, new air filter, new mass airflow sensor, new MAP sensor, new pcv valve, new vacuum control module with filter, new vacuum control solenoid, new vacuum hose from solenoid to turbo, replaced glow plugs(7V) and checked with jeep dealer for most up to date software. I also checked mass air flow and it was good indicating rockers weren't worn.

Do you know if the 27in of mercury is the vacuum pressure it should be giving the turbo at idle? It is only showing 15in of mercury at idle and low end and then giving low boost at 21-22 and throwing code. When they hook up a manual vacuum at 27in of mercury boost pressures match what ECM want (at 30-35) and no ECM code appears?

Thank you for your time and expertise

flash7210 · **Posted:** Sat Jun 17, 2017 8:01 am

1. I know this is gonna sound stupid, but I gotta ask.
Are you clearing the code after every part replacement? It doesnt always go away in its own.

2. The ECU is looking at absolute pressure. That is, ambient air pressure + turbo boost
If ambient pressure is 14psi and turbo boost is 21psi, then that equals 35psi.

With a stock tune, a max boost of 20-22psi is normal.
So it seems the turbo is doing its job.

flash7210 · **Posted:** Sat Jun 17, 2017 11:37 am

If the actual MAP sensor readings are in doubt, install a mechanical boost pressure gauge.
You would have to drill and tap a hole somewhere in the intake path for it to work.
I drilled the hole into my Weeks elbow when I installed my boost gauge.

I dont know exactly what the vacuum to the turbo actuator should be.
But I do know that high vacuum equals high boost and low vacuum equals low boost.
The large vacuum solenoid with the filter at the bottom modulates vacuum to the actuator in order to maintain the demanded boost level.
You can bypass both vacuum solenoids and just run high vacuum to the actuator.
You wont drive far before a overboost code is set and the engine goes into limp mode.

Clear the codes and take it for a drive.
If the p0299 returns, bypass the two vacuum solenoids and try to induce a overboost fault.
If you cant get a overboost code, then I suspect there is a wiring fault to the MAP sensor.

P0299 is not a showstopper.
It will not induce any kind of limp mode.
If it really were a boost problem you would have low power and black smoke out the exhaust.
If it were a boost leak, you would hear air rushing out when under high boost.
Youve already replaced all the parts that would likely cause a underboost problem.

WWDiesel · **Posted:** Sat Jun 17, 2017 12:04 pm

Based on your post, reads like you have done all the right things! :roll:

A few thoughts come to mind!
Since you replaced the turbo, I want to assume you inspected the rubber boot hose between the airbox and the turbo inlet and it is in good shape and not collapsing on acceleration and restricting air flow into the turbo?
Have you cleaned the CAC (intercooler) and made sure it is not clogged in any way restricting air flow?
Does it still have the CAT installed; if so, it could be partily stopped up and restricting exhaust flow which would impede turbo speed and thus boost pressure?

And last but not least:
You may want to replace the IAP sensor.
IAP sensor - 05101120AB (pressure sensor on side of airbox)
air inlet air pressure comparator pressure sensor on the side of the airbox; referred as the Mercedes sensor

It figures into the grand scheme of things on what the EMC is calculating based on desired versus actual output of engine functions! :wink:

Keep us posted, am very curious as to what you find as this one is somewhat unusual considering all that you have already replaced! :shock:

mattbucher · **Posted:** Sat Jun 17, 2017 6:04 pm

Wow. Thank you all so much. I have cleared the codes in between doing everything. It seems to throw the code at low rpm and then it throws me into limp mode. It does still have the catalytic converter and I have thought about cutting it off...but seems like I have replaced a lot of parts already without solving the problem so I was reluctant to keep on with fixing things that I was not sure would help.

I think my next step may be the Mercedes sensor. Having a hard time finding it. Any good ideas as to where to find it?

I am picking it up Monday from the mechanic who did NOTHING to help this situation.

I will keep everyone posted.

I really love this jeep and my dad really didn't run it hard and took great care if it...that is why it has been so frustrating I have ran into so much trouble.

As soon as I can fix the P0299 I want the get the GDE ECO tune for it.

Thank you all again
-matt

mattbucher · **Posted:** Sat Jun 17, 2017 6:26 pm

Also...I forgot to mention that I put a new rubber inlet hose between air filter box and turbo when I replaced the turbo.

Thank you again and as soon as I can locat the IAP sensor (on side of airbox) I will give that a try...but cannot find it on sasquatch.com or idparts.com Any suggestions???

flash7210 · **Posted:** Sat Jun 17, 2017 6:28 pm

The sensor you are looking for is on the side of the air filter box lid.

Another easy test you can do...

With the engine idling, pull the vacuum line off the turbo actuator.
You should be able to feel good vacuum at that line.
Reconnect it.
Next, engine still running, look down between the engine and turbo to see the rod that connects the vacuum actuator to the turbine housing.
Pull the vacuum line off and watch the rod drop.
Connect it again and watch the rod pull up.
This will allow you to verify the function of the actuator.

While at idle, vacuum is high and the turbo is pretty much set for max boost.
However, at idle actual boost is almost zero because there is not enough exhaust flow to spin up the turbo.

GordnadoCRD · **Posted:** Sat Jun 17, 2017 8:10 pm

https://www.concord-parts.com/goods/05101120AB/Chrysler

WWDiesel · **Posted:** Sat Jun 17, 2017 8:51 pm

mattbucher wrote:

Also...I forgot to mention that I put a new rubber inlet hose between air filter box and turbo when I replaced the turbo.

Thank you again and as soon as I can locate the IAP sensor (on side of airbox) I will give that a try...but cannot find it on sasquatch.com or idparts.com Any suggestions???

Google part No: 05101120AB :google:

You will get a lot of hits including Amazon, Ebay, and many others:

One of my favorites is "Factory Chrysler Parts":> http://www.factorychryslerparts.com/pro ... 120AB.html
I have bought many Mopar parts from them and they are fair on their prices and reliable... :wink:

mattbucher · **Posted:** Sat Jun 17, 2017 9:18 pm

Thank you all so much.

I am going to get the IAP sensor and will keep everyone posted.

Hopefully this will fix the P0299 gremlin!

Ready to get the GDE ECO tune after this is fixed!

Happy Fathers Day to all you dads out there!

-matt

mattbucher · **Posted:** Sat Jun 17, 2017 9:24 pm

Just a little confused...the IAP sensor links posted (which I understand to be the "Mercedes" sensor on the side of the airbox near the mass airflow sensor) looks like the MAP sensor that I have already replaced on the intake near the drivers side under the engine cover?

Am I looking at it right?

It is different than the MAP sensor right? Because I have a spare MAP sensor???

Thank you.

GordnadoCRD · **Posted:** Sun Jun 18, 2017 12:26 am

Yes. Very different.

As WWDiesel said, there are many suppliers, so shop around, but make sure to read the description.
If it says Manifold, or MAP, it's the wrong part.

WWDiesel · **Posted:** Sun Jun 18, 2017 10:38 am

mattbucher wrote:

Just a little confused...the IAP sensor links posted (which I understand to be the "Mercedes" sensor on the side of the airbox near the mass airflow sensor) looks like the MAP sensor that I have already replaced on the intake near the drivers side under the engine cover?
Am I looking at it right?
It is different than the MAP sensor right? Because I have a spare MAP sensor???
Thank you.

It is a totally different sensor than the MAP sensor that is on top of the intake manifold!

The IAP Mercedes Logo Sensor 05101120ab is mounted on the side of air filter box housing and is attached with two small screws!

This is what it generally looks like:

papaindigo · **Posted:** Sun Jun 18, 2017 10:49 am

So many sensors; so many names; so few asking questions bother to post the physical location of the sensor they are asking about.

MAP (manifold absolute pressure - called air temperature/boost pressure sensor in parts manual) sensor (back top of engine under wiring harness) old # 5140331AA new # 68031593AA - alternative Bosch 0 281 002 437 NOTE based on comments from MrMopar64 BOSCH # is 0 281 002 845 or GM PN 55206797 is an acceptable and cheaper substitute.

MAF (mass air flow - called air flow sensor in parts manual) sensor (airbox top next to airbox to turbo hose) 53013733AB

IAP (inlet air pressure) sensor 5101120AB (pressure sensor on side of airbox)

FYI if you go to http://colorado4wheel.com/manuals/Jeep/KJ/ and scroll down and open the tech tips PDF there is a parts list; best I could do from past posts. Scroll about 2/3rds of the way down the book marks list and click on "Common KJ CRD parts list "

mattbucher · **Posted:** Sun Jun 18, 2017 11:27 am

Great. Thank you all so much.

I just ordered the Inlet Air Pressure sensor...

I have a few more questions (if you guys aren't tired of me yet)

I am done with mechanics...I worked on my jeep cherokees for years and miss the simplicity and cheap available parts for that straight 6 4.0L engine.....but really love this diesel Liberty and want to get it running great...

1) How do I check to see if there is sludge in the intercooler? I know there was a lot of oil in the system with the OE Garrett turbo but the larger reservoir on the Sasquatch upgraded turbo should help that?

2) my transmission dipstick started pushing up and rattling loose around all the time this happened. Saw some threads about bending it but didn't want to do that...so just gorilla taped it down...fluid was clean and at a good level...is that ok to do?

3) when I put it in reverse it gets loud and kinda shudders but never stalls at all. Any idea? Is this a problem or normal?

4) Any advice on the Mann provent system to get oil out of CCV and intercooler system?

5) Also have a coolant leak (I know this thing has started having a bunch of issues at once)...took skid plate off and it looks like maybe coming from thermostat...but it is weird...it doesn't seem to leak when the engine gets really warmed up and seems to leak more if I just move it cold from driveway into garage...I did go ahead and replace the coolant temp sensor (before the leak appeared) with MAP sensor and crankshaft position sensor to try and start fresh with the common sensor that will fail on these jeeps. I cannot see any coolant leaking from the temp sensor threads...and have checked coolant lines without finding a problem. Any ideas on how I can make sure it is the thermostat before I replace another expensive part that may not need replaced?

Once again...thank you all...it is hard to find anyone local who knows about these jeeps.

I'll keep everyone posted after I get the IAP sensor!

flash7210 · **Posted:** Sun Jun 18, 2017 11:59 am

1. Remove the intercooler, tip it on its side, and see what drips out.
You definitely have oil in your intercooler.
Oil mist from the CCV goes into the turbo inlet and slimes everything including the intake manifold.

2. The trans dipstick just does that. Either bend it or find a way to hold it in place.

3. Is it only when cold? Or everytime you put it in R?
Start by checking fluid level. Engine running and trans in N. Should be at or above the full hot mark at all times.
If not fluid, start looking at engine and trans mounts.

4. Provent, YES. Just do it.

5. Buy or rent a Stant cooling system pressure tester.
Pump it up to 16psi, wait a few minutes, and start looking for drips and wetness at every coolant hose and connection.

6. If it hasnt already been done, start making plans for changing the timing belt. It needs to be changed every 100k miles.

mattbucher · **Posted:** Sun Jun 18, 2017 2:27 pm

Awesome...thank you for all of the advice. I feel like I've done a lot already since I got it in Feb...but have a lot more to do!!

The shuddering in reverse happens both when the engine is hot or cold.

I'll double check transmission fluid with it in neutral and hot.

Was thinking changing transmission filters may help?

I noticed you got the Yeti ECO Tune instead of GDE ECO tune? Any pros/cons between GDE and YETI?

Thanks

mattbucher · **Posted:** Sun Jun 18, 2017 2:30 pm

One more thing...any suggestions if I get the straight pipe exhaust and get my cat converter cut off in terms of pipe diameter or a manufacturer?

papaindigo · **Posted:** Sun Jun 18, 2017 3:14 pm

UV dye is a good way to look for external coolant leaks.

My and my son's tranny dip sticks are held down by velcro worm clamped to dip stick tube and wrapped around handle.

Noise/vibration in reverse could be from engine mount but I forget which one is louder in reverse.

I suspect GDE EcoTune is more sophisticated but don't know. My son and I both liked that GDE tune.

I would not waste money on straight pipe; no real benefit IMHO. If you are crazy enough to do so keep cat on shelf in case you sell to someone who lives in an inspection state that will look for it to be on the vehicle.

WWDiesel · **Posted:** Sun Jun 18, 2017 5:11 pm

Things to consider based on your questions:
On the tranny dipstick, either bend a lazy "Z" in it or cut about 3/8" off the tip end and it will solve the problem of it popping out!

Transmission shudder, service transmission (filters & only ATF+4 fluid) and then bring level above full mark by adding an extra 1/2 to 1 qt. of fluid.
If that does not fix problem, try adding some Lucas Transmission additive to fluid.
These transmissions like having extra fluid in them and seem to work better when slightly overfilled.

Install a ProVent filter! See this thread to understand why they need one! > viewtopic.php?f=5&t=80491
It will keep the oil out of your hoses, CAC (intercooler), and intake.

Do you know when the timing belt was last replaced?

Is the EGR system been blocked off or removed? If not, it needs to be done ASAP!

Thermostat; if it is leaking, you should replace it! DO NOT use a Crown Part, they are junk.

CAT, remove it, and put a straight piece of pipe in its place. Replace muffler with a straight through type like a Flowmaster. Engine will run better without the junk CAT and restrictive factory muffler. If you need part numbers for muffler, just ask.

Tunes: Some like the FREE DIY tunes, and some like to pay for the GDE tune. It's your call.

Lots of good advice on this forum! IF you need help, just ask...

:SOMBRERO:

Ongoing P0299 underboost problems

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