Hello and welcome to just answer Dodge. The most common problem for this complaint is a failed map/boost sensor. If the boost sensor fails then the computer does not see the correct amount of boost and then limits the fuel. The map/boost sensor is mounted at the left rear cylinder head intake area. It threads into the intake.
The waste gate is purely mechanical and is operated by boost pressure. Here is a picture for you.
Hope this answers your question and if so would you please click on the accept button? If you still need more help please let me know.
I sent you the wrong picture and now realize that your engine is not computer controlled so there is no boost sensor. However there is still a waste gate that will be mounted on the turbo. Sometimes the hose cracks and leaks so look for the hose from the turbo to the waste gate diaphragm. I am at home right now, but will get back to work tomorrow. I have more resources there and see if I can get more information to you. Meanwhile check this also: remove the air intake hose at the turbo and verify that the turbo blade spins freely. Also check for excessive up and down free play. A little freeplay is ok.
I will get back to you asap.
Hello again. I tried to find a picture for you today but cannot locate one for a 1991. However I talked to my other diesel techs today and they said that the 2 main problems that they remember about these engines was: 1 the waste gate diaphragm itself would leak and cause low boost, and 2 the diaphragm on the injection pump would leak and cause the same problem. Try this: disconnect the hose that goes to the waste gate actuator at the turbo end. Apply a little compressed air using an air nozzle to the hose you disconnected (try to regulate the pressure to no more than 15 psi). The waste gate actuator rod should move, and there should be no air leaks from the waste gate actuator diaphragm. If you see any puffs of air/dust from the actuator then it is leaking and needs to be replaced. Also check the hose that tees over to the injection pump diaphragm for leaks. Check these and let me know what you find.
Hi again Chris--
Sorry to be a bother, but I just got out from under the hood, and it does not have any visable waste gate on this turbocharger. It is a Holset. The only lines are the oil inlet on top between the forward part of the turbo and aft part which is connected to exhaust manifold, and oil return line on the bottom which goes into the oil pan. Nothing else on this unit. I took off the hose like you said and the intake side of the blades turn freely with no side play of wobble of any sort. Any other ideas? Also, does this particular unit have the map/boost sensor and is it called an "air charge temp sensor"? I called a parts dealer and that's what they told me. Thanks for the help.
Ok, you must have an early build '91. Is yours intercooled?
I am thinking at this point that your injection pump is the problem. If the turbo is good, and there are no air leaks between the turbo and intake system, and fuel delivery to the injection pump is good, then I would suspect the injection pump is failing.
Ok. No map boost sensor, sorry to mislead you on that earlier.