1998 24v, is there a sensor for a turbo???? code?
 

I got in my truck today, started it,..and it had a CEL. So I read the codes. turbo circuit and tps (or apps) circuit inputs low.

I took my air cleaneer out a week ago and gave it a good cleaning (K&N),. also changed the alternator and lift pump last week. Did I knock a plug loose from a sensor??? I cannot see any kind of sensor plugged into the turbo,..and everything runs fine. So I am just not figuring out what I may have unplugged.
I tried to erase the codes while it was running but it failed. My first guess is that it was a few days since I ran it...and when I started it it may have had such a low voltage that it threw a few sensors off or something. But I don't really know...that's just a guess. It's never done anyhting like this before. It has about 250k miles on it. Other than having gone through 4 or 5 lift pumps and alternators..and one TPPS right after I bought it. I can't find anything that it may be.

I reset the codes by doing the negative battery disconnect thing..and letting it sit for an hour with everything on.

With a reset computer..I went for a drive and the codes did not come back. This is so odd. I would really like to know what it was that set them off.

0122, 1693 and 0237 were the names my scanner gave me for the codes...At least if my memory stayed intact when I ran into my garage to write them on the wall this morning.

The map sensor is not on the turbo it is on the drivers side of the engine back by the fuel filter there are two sensors there one is the IAT (intake air temp) and the other the map (manifold absolute pressure). I cant remember which one is first but they are approximately inline with each other several inches apart.

the map sensor is the second from the rear[coffee]

Do you think the map sensor or iat sensor is shot??? or at least weird.

Once again, this morning, I started it and the CEL came on within 1 minute or two. And, come to think of it..seems like the turbo isn't boosting like it should..I mean,..at low rpm..it is noticable..but not much. I don't drive that fast anyway. Haven't been on the freeway today.
I did find one of the sensors. Kind of not far from the fuel filter. So I'm guessing the other one is right around there somewhere. I hope I can find a loose plug or something, but if not...I have no idea how to diagnose it. I am not even sure if my live scanner knows how to read my diesel..It does work fine on my gassers...and is pretty good at real time info when I can figure out how to get at the info...but I got the feeling it didn't understand the dodge diesel very well.
ok,

Unless you threw some new codes the IAT shouldn't be an issue as the codes you mentioned previously don't point to it. I have had my map sensor go bad on my truck. When the cel came back was it for the same 3 codes or just the 237?

To be honest this is beyond my diagnostic skill level. You can test the map sensor if you can find the values which are out there somewhere. I might suggest just getting a new sensor but if I recall that one is an $80 sensor from Genos Garage and suspect even more from cummins tough to throw $80 parts at a problem that you are unsure of it is the issue. Have you checked all of your grounds? Since more than one sensor seems to be affected it could be something like that. Unsure if those two sensors (apps and map) share any wiring in the harness.

As long as your turbo hasn't grenaded it is spinning regardless of what the map sensor says and should be providing boost (unless you have a boost leak but you would probably hear or certainly notice power wise a big leak). Now if the sensor is bad and it isnt seeing the boost pressure it could be hampering the fuel delivery via the ecm (computer).

Crap, it might turn out being a vacuum leak???? I was worried my turbo might be going to hell.
I just came home for lunch and turned the a/c on...and it defaulted to the defrost vents...I think that has happenned to me 3 times last 15 years,..always due to a vacuum line coming off while changing the fuel filter.. however,..this time,..I think it is a different one, because the little elbow vacuum line dealie by the vp44 still looks connected. And at my age,..my eyes are nothing to brag about. Might take a bit to find it.

I would assume a large enough vacuum leak might be the cause of at least some of those codes?
All 3 codes were present when I read them. At the moment, the cel went back off..but I haven't tried to read which codes it set this morning. I didn't even think there was a vacuum line big enough to set a code...I mean, for a diesel,..that thing uses huge amounts of air doesn't it???
Thank you a bunch for your input. At my age I need it.

The vacuum will not set an engine code or trigger a CEL..

Take a look at the vacuum lines that go along the firewall. Just follow the line from the vac pump up to the firewall and go from there.

The boost codes can come from the sensor being defective or also from leaks, especially the wastegate hose having a leak, causing the wastegate not to open.

HTH

I had no idea my diesel had a vacuum pump???
Does my 93 cummins also have a vacuum pump?
Holy crap. I was wondering how a diesel could generate any vacuum....Now I realize it can't unless there is a pump. Ok,. when I get home I will try to follow vacuum lines and find the culprit,..but if none of those will set a code...does that mean my turbo might be starting to die? How does a turbo die anyway? Do they just seize..or what? I guess I could pull of the duct in front of the turbo and see how easy it spins. If I recall..it seems like those things are supposed to spin really easy.

I also do not know what a waste gate is..but it sounds kind of important. Is there an official diagram of the 98.5 motor and turbo...and all that stuff that goes with?

See if it spins easy, should be a little up and down play (journal bearings) but no in and out play. Excessive play will result in the wheel contacting the housing. Low boost problems are almost never because of the turbo.

Wastegate is just a valve in the exhaust housing that lets exhaust gas bypass the turbine wheel to control boost. It is controlled by an actuator on the side of the exhaust housing, driven off manifold pressure.

You can test it with shop air in the reference line (no more than 30psi) and it should start to move the lever around 15-17 psi and fully open around 22-25. Should also return quickly once air is relieved.

Your waste gate hose is the small one just under the inlet boot to the turbo, you may have Munger it up when you were checking the turbo...

I checked my turbo and it spins freely. It is kind of black,..I mean, my fingers looked like they had black magic marker or grease on them from handling and spinning it. I think that is normal? I just redid my k&n on there..so maybe I overdid it with the oil. It has been a couple weeks....just enough time to cause trouble I guess.

Also,..what is the function of a waste gate..and how does it work?? I see that little hose underneath the turbo,...does that thing lead to the waste gate?

CEL came on again this morning for a few minutes then went off. I used my old autoxray (rather than my bluetooth app) on it this time and it had a code 1693, which mentions a fault in a companion module, whatever that is. NO other code or pending code.
p1693, fault in companion module. I just had it set for chrysler vehicle 1998. No way for me to select dodge diesel 1998.

According to the service manual, there are some faults that can set a CEL but clear when the fault goes away. In that case the DTC will also be cleared from the PCM memory.

The complication with our diesel Rams lie in the fact that we have two computers, the Dodge PCM, and the Cummins ECM. That is where the P1693 code comes in. That code can be generated by either computer, and serves as an acknowledgement code that one computer had a fault condition that the other computer can see too. Unfortunately, the 1693 code can linger and keep the CEL lit.

Here's how the CEL/MIL (Malfunction Indicator Light) works. Faults fall into two categories, active and inactive. An active fault will keep the CEL lit all the time until the fault is fixed and set a Diagnostic Trouble Code (DTC). If the fault was temporary, it will go inactive. A recent inactive fault will keep the CEL lit for 3 good trips. Once 3 good trips have occurred without the fault going active again, the CEL will turn off. Then the DTC will be stored for 40 good trips and then be erased from memory. Keep in mind this doesn't apply to the small number of faults that can be cleared immediately by the PCM, there are not many that do this. Most DTC get stored.

A great example of a intermittent but quickly turns into an inactive fault is the wheel speed sensor fault (P0500 I believe) which can be set if the truck is driven on snow, ice, or other low traction surface (especially if 2 wheel drive). If the rear tires are spinning but not at the same rate as the front wheels, then a DTC will get set for wheel speed mismatch by the ABS module.

The CEL can be reset and the DTC's erased from the memory manually with an appropriate scan tool, or by disconnecting the batteries. Disconnecting the batteries may not get them all though.

So that is the computers in a nutshell. In your case I would check the connectors to your APPS sensor, as well as the IAT and MAP sensors. It also would not hurt to pull the IAT and MAP sensors for cleaning. Especially the IAT since it is in direct airflow in the intake (between cylinders 4 and 5). If they are original to the truck, then they have been in service for about 18 years now. Plus, if you over-oiled the K&N, some of that oil probably got pulled free and gave your IAT a light coating of filter oil. Sure sounds like your compressor blades in your turbo got some too.

Since you are stock, then you have an HX35 turbo, which has an external wastegate. There should be a stainless steel braided hose on top going to the turbo center section. That is the oil feed line for lubrication. There is a oil drain pipe on the bottom leading to the engine crankcase. You should have a short hose on the compressor outlet leading to an actuator. The actuator has a linkage to a butterfly valve in the exhaust side of the turbo. What that does is if the boost pressure goes too high (risking turbine overspeed), the actuator will open up that valve in the exhaust side and dump engine exhaust directly into the exhaust pipe, bypassing the exhaust turbine and reducing boost pressure. It's set for around 22 PSI if I recall correctly.

Also, the ECM will act as a wastegate of sorts. If it senses the boost pressure going too high (using the MAP sensor), it will pull back on the amount of fuel getting injected to bring the power down and limit the boost pressure. When the ECM does this, it is called defueling.

Hope this helps.

Yeah, the K&N filters got a bad rap early on due to people over oiling them and/or not a high rated filtration. I'd junk it and run a stock paper element. It'll catch just as much debris as the k&n...