7.3 can't make power - 1247 low boost
 

This is my first 7.3 so I am not sure what to expect from it. I am having a LOT of trouble pulling my 9000 lb travel trailer which I would expect it to pull with ease. I’ve done a lot of repair work on the truck since I bought it two months ago, mostly cleanup / maintenance. Since the power felt low I added a SuperChips Tuner to it, I ran it in “safe tow” mode this weekend for our first towing outing. I also added ISSPRO boost and pyro gauges with the tuner just to be safe.

Once up to highway speed it runs at about 5 lbs of boost, 2100 RPM and 1050 degrees (it was painful to get to 65 mph) . This is on flat ground. As soon as I hit a SMALL incline I either have to slow down or watch the EGT shoot into the red (1250+). At WOT in 4<SUP>th</SUP> gear at 2500 RPM the most boost I ever see is 8-9 lbs. When I got home I checked codes and found 1247 Turbo Boost Pressure Low and 1211 ICP Not Controllable Pressure Above Desired. For what it's worth I went back out for a ride in stock tune mode, the performance was worse as expected but the temps were just as bad.

Here are a few engine related things that have been done / checked before this trip:
<O:p</O:p
- Removed the IC pipes / boots cleaned and re-installed (minus foil)<O:p</O:p
- Added ISSPRO boost and pyro gauges<O:p</O:p
- Changed MAP sensor hose, it was cracking when I installed the boost gauge “tee”<O:p</O:p
- Fresh synthetic oil 5w-40, new filter<O:p</O:p
- New fuel filter<O:p</O:p
- 6637 Intake mod (thanks to all the advice on this site)<O:p</O:p
- Checked glow plugs due to starting issue, found 1 bad and replaced<O:p</O:p
- New Batteries

What can I do / test next? We are going to the Pocono 500 in two weeks and I’ll have to take my Dodge (CTD) if I don’t get this resolved!! :-banghead<O:p</O:p
<O:p</O:p

Thanks,<O:p</O:p
John<O:p</O:p

8-9 PSI of boost is way low ! Sounds like you have a turbo issue to me ! I get about 18 PSI with my chip that I have now and that should go up when I get my DP tuner installed very soon ! Look for other turbo leaks ! Up pipes may be leaking..look for soot there as well !

sorry bout your issue, i jus looked in my 7.3 book and its a MAP Sensor Code, it could be this or the turbo., the other code is the IPR valve is failing, stuck, or shorted

Any ideas on how to troubleshoot it? I know the boost is way too low, but how do I find the cause?

I'd buy a new turbo now if I was sure it would solve the problem, but I'd have to explain it to my wife if the truck was still "broke" after spending the $$$...

You definitely have major exhaust leaks somewhere to rob you of all that boost. A leak = loss of power also, and would cause your EGT's to jump up like yours did. The Superchip is definitely capable of boost levels up to 26psi. I just made the change recently from Superchip to DP. After you find your leak, which is probably up-pipe and another leak also.......think about selling that Superchip and getting a DP. I know that is said in every other post on here, and probably gets old reading.......but I know first hand! The maximum setting on my Superchip is slower then my 60hp tow setting on the DP. Good luck with those leaks!

I agree with all of the above, have you looked at your turbo wheel to check condition?

As Wes mentioned.. Check that MAP sensor. Good idea Wes.... I had a no power issue when I first got my truck and it was the fitting on the bottom of the MAP sensor was broken off.. The MAP is around 100 bucks if I remember correctly,.. maybe less ! Thats kind of where i would start if thats the code that came up.. and as I and others have mentioned before.. check those up-pipes !

RussB,

Since the computer reported the problem (low boost) and I have a gauge that verified it, wouldn't that mean the MAP sensor is working? Does the MAP sensor control the boost or just monitor it?

Thanks,
John

Edit: What filter did you have before the 6637? Was it just the stock set up? As Jim mentioned, take a look at the turbo wheel.

Here's some reading for you.

John,

I pull a 15K 5er, and I would say it's a little slow getting up to 60, but once there it will hold that speed below 1300 EGT up some pretty steep grades without much trouble. Pulling only 9K I'm guessing it would feel like a stallion. I use an Edge Evo II and the on-board pressure sensor has never shown over 15 lbs, usually 14 max WOT and pulling a grade. 5 lbs is bad. Got to be something wrong with the turbo or sensors. The 7.3 is a real strong motor.

I agree with you here, the map reads and your gauge confirms. I would first check the turbo out make sure it appears in working order. Check the compressor wheel. Then look for all the leaks possible; you can make a jig and pressure the system with 25lbs. If it is leaking on the intake side you will find it for sure. Do you know if the waste gate is stuck open? You might try disconnecting the red line to the actuator to see if it helps any.

Someone that knows more about it might chime in but I think the MAP sensor controls the amount of boost more than just monitors it ! Not 100% on that...

When my tube was broken off the bottom I got no SES light on or anything.. Just no power / no boost ! I think you have a major leak ! Process of elimination at this point !

Thanks for all of the info and responses. I know the hose and connection to the MAP sensor is OK since I replaced the hose when I installed my gauges. But it looks like I have a lot of connections to check out and some sensor testing as well.

I know my turbo wheel is in rough shape, here's a picture. I'm not sure how bad this is, it was the reason I changed out the factory air filter for the 6637 mod.

http://lappie.org/photos/posts/Turbo.jpg

John

Man that is not good, however, I have seen worse wheels that that. If you are going to run a tuner I definately suggest getting a Wicked Wheel seens as it would be a good idea to get a new one before long. I don't think that is the cause of the low boost though.

Ouch! :eek: