low boost pressure on a 03 isl

[waltmack]

Good evening everybody. just trying to bounce this off of everyone. has anybody have any issues with a low boost pressure on a 2003 isl. My Mountain Aire seem to lag along and has a terrible time in passing on the interstate. I was fortunate to have a friend that had access to Jpro Fleet Diagnostics and I learned at full throttle my boost pressure is at 2.4 to 2.8 psi. My thinking is my wastegate is stuck open. Is there a sensor that controls this? I am thinking that the rig has sat for a while and this is why its stuck. Is this a common problem. Do I need to pull the turbo unit and service the wastgate? Was told the wastegate is not a componet and I have to replace everything. Any help would be great as the costs to replace the turbo is high. Thanks Walt

[Harry B]

The controller for the turbo is directly opposite the turbo on the other side of the valve cover. They so go bad. I had mine replaced due to a vacuum leak. Cummins had 164 in stock, which tells me that it is not an uncommon part to go bad

Follow the vacuum line from the turbo to help locate the controller

[skipwil]

From post Low boost pressure '01 I S B Cummins
"Well after a months work-much sweat and in general no one having a concrete answer-the problem is repaired. I found a broken hose on the passenger side of the e ngine. This was on the intake manifold near the turbo boost sensor is located. It goes into the front of the engine. When I can get to the Cummins dealer I'll find the correct name for the hose and post that info.
With the suggestion post from gknott I bought a turbo boost sensor. When I attempted to install it that's when I found the broken hose.
Thanks for all the suggestions- What a great forum..."

The hose above is the air compressor feed hose -About $65.00
This is only my experience.
Safe travels

[spike45]

Quote:

Originally Posted by waltmack Good evening everybody. just trying to bounce this off of everyone. has anybody have any issues with a low boost pressure on a 2003 isl. My Mountain Aire seem to lag along and has a terrible time in passing on the interstate. I was fortunate to have a friend that had access to Jpro Fleet Diagnostics and I learned at full throttle my boost pressure is at 2.4 to 2.8 psi. My thinking is my wastegate is stuck open. Is there a sensor that controls this? I am thinking that the rig has sat for a while and this is why its stuck. Is this a common problem. Do I need to pull the turbo unit and service the wastgate? Was told the wastegate is not a componet and I have to replace everything. Any help would be great as the costs to replace the turbo is high. Thanks Walt

If you are testing boost at high engine idle speed in Neutral, otherwise in a not loaded running state, the boost will be almost nothing. Turbo boost pressures are not attained until the engine is under load. If you measured that boost while driving and accelerating then you do have a problem. Places to look for loss of turbocharger boost pressure are:
* loose hose connection on the turbo air outlet pipe to the charge air cooler, an orange colored hose with metal rings on the outside
* cracked charge air cooler tanks. You may be able to hear the air escaping during rapid engine acceleration while in Park or Neutral. You may also hear it as a whistle if somebody is in the back of the MH while traveling and the engine is under some load.
* charge air hose from the cooler to the engine intake manifold may be loose or leaking.
* the VGT contoller is unable to adjust the nozzle ring to increase exhaust turbine speed under load
* air cleaner is restricted. Check the air filter restriction gauge.
*air cleaner may be a Farr Ecolite disposable housing filter. remove the outlet to inspect the paper pleats. Are they broken or burst out of the pack? Replace the air filter.
* get a Cummins Insite ECM scan for fault codes

[Gary RVRoamer]

Check the simple things first. What does your air cleaner gauge look like? When did you last change the air filter. The turbo can't boost if it can't get air through the intake.

[Mr_D]

Quote:

Originally Posted by Harry B I had mine replaced due to a vacuum leak. Cummins had 164 in stock, which tells me that it is not an uncommon part to go bad Follow the vacuum line from the turbo to help locate the controller

Where do you get vacuum from the intake side of a turbo'd diesel unless you're reading the air cleaner gauge?

[waltmack]

Good morning everyone!!! Just to bring everyone up to speed, I spoke with a old time mechanic with an extensive cummins background. Told me that he didn't believe that the torbo was out so he gave me a crash course on how the whole system works. Pulling the hatch inside so I can look at things from the top, I started to check all the hoses, clamps and boots. Looking down through the fan assembly I noticed a one inch wide line that ran from the left tank to the right tank on the charge air cooler. It looked as if something was backed over and made a gouge that looked as if you ran the pointed end of a tire iron down it. I made a soap solution in a small hand pump and sprayed the crack as good as I could, spraying around the fan. Running back up front, I started the coach and gave a quick static rev and walla, Lawrence Welk was in the yard, go figure. I am loosing all my boost through the damaged charge cooler. Guess thats what you get when you buy used. New charge cooler 500, experiance priceless??

Anyways, Thanks for all the replies, I let you all know how it goes from here as I have one ordered and am going to replace it myself. Walt

[spike45]

Charge air cooler crack was on my list of things to look for. Glad you found it. CACs are one of the most often replaced heat exchangers on large trucks, more so than radiators.