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Discussion Starter · #1 · (Edited)
SO... I have regularly cleaned my MAF sensor in my 20 year old 5.3 tahoe..

I decided to take a look at my MAP sensor and after 150k miles and 20 years look damn good.. a little wet oil on it likely from the PCV as it feeds into the intake just in front of it..

now having done some research on the DMAX I see that many times this MAP causes codes and on the L5P it seems prone as well

so with 17k on the motor I took a look at it and sure enough it was pretty sooty and even had some globby clumps on it as well.. looked like dry soot, not wet/oily but .. in my opinion pretty dirty for such low miles on a sensor that is supposed to accruable measure air mass temp/pressure

is there a recommended cleaning interval on these.. I have seen everything from do it every oil change to just let it fail?

while we are at it.. the l5P is probably the most instrumented diesel out there.. what other sensors need regular cleaning.. not running an oiled air filter but I assume the MAF should be done occaisionally?

how about the EGR... ?

for that mater, how many folks clean out the entire EGR cooler?

deleting not an option so I need to keep emissions compliant setup running as efficient as possible

anyone have a good preventive maintenance routine for the L5P??

thanks

UPDATE 1

ok so I finally found a reference and I was right on my guess that the sensor on the L5P is not a MAP but a TMAP (Temperature Manifold Absolute Pressure)

so indeed it does have a thermocouple that hangs into the charge air to
1 more quickly respond to changing charge air temps based on both turbo work and EGR

2 to ensure that the EGR is actually responding by noting the increase in temp when the EGR is commanded open.. thus hampering blocking plates (emissions compliance)

THEREFORE : I stand behind my recommendation that in the L5P while placement on the TMAP results in more soot being downstream of both the turbo/EGR/PCV .. that the use of standoff blocks to take the sensor out of the flow is a bad idea as it will slow the response of the sensor thereby making the ECM fuel map less accurate resulting in poor performance and increased soot production

reference .. Banks derringer instructions

3. On the top of the L5P engine, you will find a Temp/Manifold Absolute Pressure (TMAP) sensor mounted on the intake manifold. Disconnect the TMAP sensor plug (4 Pin) by sliding the back the grey locking tab on the OEM harness connector. After sliding back the locking tab, pull the plug from the TMAP sensor. If the connector doesn’t easily pull away from the sensor, use your thumb to slightly depress the grey locking tab. Jiggling the connector gently should allow it to slide off the sensor.
 

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Do some research on the S&B map sensor spacer. This is will help with the build up.

Sent from my SM-N975U1 using Tapatalk
 
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What did you use to clean the MAP? I'm assuming MAF cleaner is acceptable to use, but I haven't done mine yet. I bought the S&B spacer kit to install in the next couple weeks.
 

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Discussion Starter · #4 ·
Do some research on the S&B map sensor spacer. This is will help with the build up.

Sent from my SM-N975U1 using Tapatalk
saw it and not a fan.. of that design or most 'spacers' that take the sensor out of the stream

first it lays it on its side.. not an issue for the temp thermocouple but there is a pressure transducer in the top and being on its side is likely not how the engineers designed the orifice ..

biggest issue with spacers is that it slows the sensors response to changes in the airflow .. in this instance not so much the pressure sensor but the temp sensor will have no flow over it.. so its readings will lag considerably ..

depending on the design of the spacers opening .. if Venturi effect were not accounted for in the way it protrudes into the airstream the pressure can be reading higher or lower than actual...

thanks for weighing in.. I appreciate it...
 

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Discussion Starter · #5 ·
What did you use to clean the MAP? I'm assuming MAF cleaner is acceptable to use, but I haven't done mine yet. I bought the S&B spacer kit to install in the next couple weeks.
that is what I used since its formulated to not harm electronics, plastics, etc.. throttle body cleaner is likely more effective on carbon deposits but its a much harsher chemical..
 

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I pulled the S&b map spacer off to check the map and it was perfectly clean. I'm going to leave it off for a while to see how dirty it gets especially since the pcv is relocated now. Can't really tell that there is any difference in driving with or without the spacer.
 

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Discussion Starter · #7 ·
I pulled the S&b map spacer off to check the map and it was perfectly clean. I'm going to leave it off for a while to see how dirty it gets especially since the pcv is relocated now. Can't really tell that there is any difference in driving with or without the spacer.
did you notice what I was talking about.. as far as this being a TMAP sensor... pressure and temperature? the bulb in the cage that hangs down is temp.. and the pressure port is the tiny hole in the top..

GM goes out of its way to install these vertically so that moisture / condensation whatever doesnt load up in the hole by facing it down... with the sensor laying on its side.. remote as it may be. might result in that pressure port becoming blocked more easily.. and removing the bulb from the airstream would make it respond to boost temperature changes more slowly
 

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Yeah i understand what your saying. It's possible but I couldn't honestly tell a difference in drivability one way or the other. I mainly want to find out I'd the spacer is needed at all with the pcv out of the picture.
 

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I believe the TMAP will still be exposed to soot from the EGR even with the PCV rerouted.
 

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Discussion Starter · #10 ·
Yeah i understand what your saying. It's possible but I couldn't honestly tell a difference in drivability one way or the other. I mainly want to find out I'd the spacer is needed at all with the pcv out of the picture.
my guess is it will still get some soot from the EGR but there are plenty of folks now hitting 100,000 on the L5P without TMAP issues..

I would think every 20k or so maybe pop it out and blow it off but unless you have some serious blow-by or a leaking turbo seal really throwing oil through there .. the TMAP would be the least of your worries..
 

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Discussion Starter · #12 ·
Yes but I'm thinking it won't be the cruded up mass that folks have been finding.
without the PCV you should have far less oil and water vapor mixing with the mostly hot dry soot.. so yes... it should dramatically help with your re-route..
 

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Discussion Starter · #13 ·
bumping this since several people have been throwing L5P ghost codes.. and at least one person fixed it with a TMAP cleaning...
 

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Just to update for those considering the S&b map sensor. I pulled mine off to to run just the map since the pcv reroute and it was spotless after a few thousand miles so it definitely works. Can't tell any difference with or without the spacer in how the truck runs. Good purchase if your not wanting to worry about cleaning the map.
 

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Removing the TMAP was difficult as the O-ring was stuck against the aluminum of the manifold.
Any recommendations on o-ring lube on this location?
 

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I just used some of my engine oil, 15w-40.
 
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