hey just looking at your pictures its easy to see wires beneath your braiding that look chaffed and possibly shorting. cut open the braiding from the firewall to the front of the engine and start looking at what you got. the backpressure sensor (the ebp) it a frequent problem. btw what year is your vehicle again. what dennis said about mbenz wiring is giving them the benefit. i give them a D.
Turbo Intake Reassembly - Help
- Thread starter actionmack
- Start date
actionmack
Member
Given the codes I have is there any guidance on other sensors it could be other than the EBP? Trying to narrow down the culprits. The EBP seems to have good continuity although I have not been able to rule out a short. Other than visual inspection how should I do that?
I have checked the MAF, MAP, and EBP... although only for continuity and without referencing an actual harness diagram.
Since this electrical issue (if it is truly electrical) was caused during the glow plug/turbo charge pipe assembly I would assume that the issue has to be somewhere around that.
actionmack
Member
If the EBP is a frequent problem. how can I verify it is wiring and not the sensor itself?
if you dont have xentry substitution is about the only way short of checking your continuity. if the continuity is ok you still may have a bad sensor
actionmack
Member
Ok so I'm going through the circuits again to see if I find continuity on multiple circuits. Still have more to go through but wanted to update here to check if you were able to find the wiring diagram?
I believe I've found one short. It is for the connector at the air intake right at the turbo. Shown here....
I'm not sure what it is called but I found continuity on 2:20 and 2:90. Unless these are both ground or something this seems like a good lead. For reference (1:12 and 2:20/90) for that sensor.
Thanks again for all the help
VIN: 75209309
believe thats a heater element for pcv valve. that in itself will not cause runablity problems
actionmack
Member
OK interesting... upon further inspection I'm not able to show continuity between that plug and 20 or 90 MCU anymore. I am however able to verify continuity between 20 and 90 (short?).
The new continuity for plug to MCU (which only lasts 1-2 seconds before resetting is between 2 and 48. Very weird.
lindenengineering
Well-known member
OK let's return to the issue at hand, because like so many who tackle such harness pin out tasks,they get thrown off on tangents.
The EBP. Part number 0091535028
We have never had a sensor go bad per se !
It either gets short circuited by water ingress into the plug socket, or is more often plugged hard with carbon on the sensor side .
Being a piezo membrane sensor nothing flows through it which possibly explains the plugging tendency.
What we do find is the wrong sensor installed. (there are 5 variations available) .
Harness pinouts are as follows from sensor socket to ECM socket .
Pin3 Signal pin to ECM pin #81
Pin2 Ground signal to ECM pin #9
Pin1 Voltage reference supply pin from ECM pin #18
Check these out first and physical condition of the sensor.
Dennis
The EBP. Part number 0091535028
We have never had a sensor go bad per se !
It either gets short circuited by water ingress into the plug socket, or is more often plugged hard with carbon on the sensor side .
Being a piezo membrane sensor nothing flows through it which possibly explains the plugging tendency.
What we do find is the wrong sensor installed. (there are 5 variations available) .
Harness pinouts are as follows from sensor socket to ECM socket .
Pin3 Signal pin to ECM pin #81
Pin2 Ground signal to ECM pin #9
Pin1 Voltage reference supply pin from ECM pin #18
Check these out first and physical condition of the sensor.
Dennis
actionmack
Member
Apologies everyone.... soo it looks like the electrical fault was a Red Herring. I don't think they did their due diligence, or even listened to what I asked them to do; which was check and reinstall the intake assembly.
After checking for continuity and more or less verifying all wiring was in good order I viewed the Merc codes using a newly acquired scanner. I then cleared the codes and drove around to see if they would come back, they have not, and I had the shop verify. On their initial diagnosis they said the codes came back immediately after clearing (possible that they never cleared them?).
In all likelyhood those codes are related to OBDII codes that pop up when the MAF or MAP are disconnected which often happens during troubleshooting. I then clear the OBDII codes but didn't have means to view/clear the merc codes.
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Van still runs poorly. And to clarify I can still drive it at maybe 80% capacity. The turbo does fire at low speeds but getting above 60 uphill on highway the RPMs hit 3-4K and turbo still doesn't fire. When it does fire at low speeds I need to press much harder on the gas pedal than previously. I can also hear it spooling at a much higher pitch, which sounds like air is escaping.
I mention this because shop said that they are surprised no "low boost" codes show up. They did a smoke test the first visit but never tested under load. I would bet money, given my symptoms, that the air only noticeably escapes under load. That makes sense right?
Anyways I'm curious if these symptoms align with the assumed mechanical assembly issue?
After checking for continuity and more or less verifying all wiring was in good order I viewed the Merc codes using a newly acquired scanner. I then cleared the codes and drove around to see if they would come back, they have not, and I had the shop verify. On their initial diagnosis they said the codes came back immediately after clearing (possible that they never cleared them?).
In all likelyhood those codes are related to OBDII codes that pop up when the MAF or MAP are disconnected which often happens during troubleshooting. I then clear the OBDII codes but didn't have means to view/clear the merc codes.
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Van still runs poorly. And to clarify I can still drive it at maybe 80% capacity. The turbo does fire at low speeds but getting above 60 uphill on highway the RPMs hit 3-4K and turbo still doesn't fire. When it does fire at low speeds I need to press much harder on the gas pedal than previously. I can also hear it spooling at a much higher pitch, which sounds like air is escaping.
I mention this because shop said that they are surprised no "low boost" codes show up. They did a smoke test the first visit but never tested under load. I would bet money, given my symptoms, that the air only noticeably escapes under load. That makes sense right?
Anyways I'm curious if these symptoms align with the assumed mechanical assembly issue?
- Symptoms came up immediately after glow plugs and never had issues previously
- Symptoms did end on a few occasions when I reinstalled the pipes with "no gaps"
- likely stopped when boost pressure moved pipes and created a gap
- No "low boost codes" because boost is being built but just not as efficiently
Last edited:
actionmack
Member
ONE MORE THING.
This is technically the turbo outlet!!! Not intake as I have mistakenly been calling it.
This is the side that feeds the compressed air to the engine's intake manifold.
Semantics but wanted to clear it up for anyone reading this and getting super confused
This is technically the turbo outlet!!! Not intake as I have mistakenly been calling it.
This is the side that feeds the compressed air to the engine's intake manifold.
Semantics but wanted to clear it up for anyone reading this and getting super confused