OM642 bogging, weak power no limp, or codes

[87tdwagen]

Hi All,

After spending a considerable amount of time replacing the oil cooler seals and cleaning the mess from that plus a turbo support gasket oil leak and buttoning up the whole shebang I got her started within 4-5 crank cycles. It idles nice, and so far, no coolant or oil leaks, odd noises nor trouble codes.

But when test driving, I was low on power. Stopped, did a driveline adaption and it was definitely peppier, but soon there after was weak again, bogging at WOT.

I had replaced the short right angle fuel filter return hose but with a straight piece made to bend to fit the filter. I think that the bend is too much, probably 100 degrees and is constricting the fuel flow. This is the larger of the two hoses, so presumably from the tank. I assume that a constriction here is what's causing my problem, fuel starvation. Is this reasonable or am I missing some other possible cause to the lower power?

I'm trying to locate a correct bent hose in the mean time, any advise or other suggestions of what to check would be greatly appreciated.

TIA

[Murkybenz]

Pop a code reader on it and just go through all the modules looking for codes .. I have a 06 Gc 3.0crd and only major stuff ever seems to put the lightning bolt icon on or an engine warning light on.
It’s that short stubby hose ? .. just get a longer hose about 4 feet long and join one end up then lay it over engine in a loop to the other and that should give it no kinks and let you try it out.
The pressure from tank is 58-62 psi and even with the kinked hose it will still achieve this and also the ecu will not pop a code up for fuel starvation as such it only monitors the line pressures on the high side.
Code reader will show tank pump supply pressure with ignition on but once you fire engine up the rail pressure readings are then from the cp3 pump.
My experience with fuel starvation on this engine in a Jeep (tank pump gauze covered in years of dead flies and junk) is that the engine runs ok but at higher constant speeds it feels like the front wheels need to be balanced , there is a slight shake

[87tdwagen]

Thanks Murkybenz.
I replaced the fuel line with the correct elbow, the short stubby one. While a tad bit better, still sluggish on hard acceleration.

I was thinking over what else I messed with on this job that could lead to this situation. I did recall that I had erroneously soaked the Exhaust Back pressure Sensor while cleaning the left intake manifold. Although I caught it, it had been immersed for a while before realizing my error. I did remove that, and sprayed it down with electrical cleaner and let it dry out for several days in the sun before reassembly. I thought, if I messed it up, surely I would get an error code.

Thus far, no codes come up on my scanner. Going by what you mentioned, as well as others comments on the EBP sensor, codes are not always present with a bad sensor. The symptoms, of sluggish acceleration, low power seem to match what I am experiencing, so I'm currently leaning on that being a possible cause. Any insights?

Any other possible areas to check? All of this happened directly after replacing the oil cooler seals, prior to that, if ran like a scalded cat.

Thanks

[87tdwagen]

Does anyone have a test procedu6for the Exhaust Back Pressure sensor?

Im having a hard time researching details. So far all I have is it's a 3 wire sensor, 1 wire sends constant 5v, the second wire is the return signal to the ECU based on pressure, should decrease from 5v at idle to 1.5v at WOT. The third wire is a ground signal from the ECU, and apparently is also grounded to the sensor body base.

So far, I cannot get continuity between the ground pin, nor the other 2, to the sensor body. This may indicate that the sensor is bad. Can anyone confirm?

TIA

[Murkybenz]

https://youtu.be/hLW1FYretVE

[dieselbenz1]

Not certain which scanner you are using but maybe easier to look at real time values with the engine running?

[87tdwagen]

Thanks folks. That video is pretty informative and I had based my diagnosis on the info therein. Unfortunately the test on the sensor ground pin to sensor body does not work for all of these sensors. Even the new sensor did not show continuity on the ground pin, so not definitive. A voltage test is a better method. In my case the sensor was getting both 5v on the feed and a solid ground from the ECU, but the feedback loop to the ECU was off. I could only get that signal to produce 3,8v at max load. In essence the sensor was telling the ECU light load fueling, although my pedal was calling for max fuel, thus the sluggishness.

A new sensor corrected the signal issue, and now all is good. Had no idea of how much the EBP sensor plays in turbo boost management, but apparently, a lot.

Something for future readers to note if you experience similar sluggishness and have no codes.

I have 2 code readers, both can read live data, but neither could display boost nor exhaust pressures making it challenging to diagnose on the live data alone.

Thanks again