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Discussion Starter · #1 ·
2018 Cruze diesel, RS hatchback. 6spd manual.


As the title states, my MAP sensor was plugged solid. For a while I’ve been experiencing

1.) Deteriorating fuel economy (nothing drastic but enough to notice).

2.) Feels sluggish. Doesn’t have that pep that it had when new.

3.) Upon cold start the car hiccups VERY badly for 2 mins before clearing up. The “hiccup” never, ever, occurs with the RPM’s above exactly 2000 rpm


I took the engine cover off and this helped make room to reveal the MAP sensor. I forget the size of the screw in there but it was a torx.

I removed the sensor and sprayed it down with WD40 and picked out the tar and carbon, which was much harder in texture than I imagined. I don’t have a photo of the “after”.


I reinstalled the sensor, started the car, and the car ran terribly for 30 seconds. It cleared right up after that. I took the car out for a long drive and I can say with absolute certainty that this made a noticeable difference in acceleration and pedal response. Big difference. We’ll see how MPG plays out. I’ve got 50,000 miles.


I can’t comment on the cold start hiccup just yet because I need to let the car sit overnight but I figured I would pass this info along and urge others to carefully inspect their MAP sensor. It’s easy to get to and cleaning it was not difficult.



 

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Oh yes, that will be a big help with mileage for sure, now the ecm can accurately see the charge air pressure and temp and adjust fuel accordingly. One thing, last time I cleaned mine at around 100k the o-ring got carbon packed around it and stuck in the bore and it broke off the plastic cage around the temp sensor. I was about to get it out with a right angle pick and replace the sensor but when I went back in with it I lubed the o-ring with a bit of antisieze. I'm getting close to needing to clean it again and I'm hoping it comes right out.
 

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A known common issue and fix also for the Gen 1 diesel engine. Not surprising to see it is common in both engines. Thanks for posting.
 
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Discussion Starter · #4 ·
Oh yes, that will be a big help with mileage for sure, now the ecm can accurately see the charge air pressure and temp and adjust fuel accordingly. One thing, last time I cleaned mine at around 100k the o-ring got carbon packed around it and stuck in the bore and it broke off the plastic cage around the temp sensor. I was about to get it out with a right angle pick and replace the sensor but when I went back in with it I lubed the o-ring with a bit of antisieze. I'm getting close to needing to clean it again and I'm hoping it comes right out.
Good point, my o-ring was still pliable and wasn’t hard or packed with carbon but this is something I’ll keep an eye on when I go to take a look at this again (inevitably) in the future. Seems this is something I’ll have to routinely do, since the EGR is spewing this crap into the intake.

20k miles ago I made the dealership address a plugged EGR system. They refused to look at or touch my EGR cooler but as a compromise they replaced the EGR valve in my intake. Flash forward to now, 20k miles later, it’s **** near close to being plugged up again. I learned my lesson and do very little idling if I can avoid it.

Most of my driving is highway driving and I’m pretty spirited when I drive. I really really hate to see what the inside of my intake manifold looks like and I don’t even know where to begin in terms of figuring out how to do it myself as a DIY (no idea where I’d find detailed instructions to remove and reinstall). I doubt I would have even the faintest shred of luck asking the dealership to address the carbon buildup inside there
 

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Discussion Starter · #5 ·
A known common issue and fix also for the Gen 1 diesel engine. Not surprising to see it is common in both engines. Thanks for posting.
You’re welcome! It was very easy to get to and wd40 really helped. This is something I’ll be looking at yearly. I don’t mind having a DPF and I can deal with an SCR and adding the exhaust fluid, but the EGR clogging up my intake and stuff is absolutely maddening and I wish I could make it stop
 

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2014 Cruze Diesel, 2007 Cobalt, 1981 Camaro Z28, 2017 Volt
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A known common issue and fix also for the Gen 1 diesel engine. Not surprising to see it is common in both engines. Thanks for posting.
Yeah...something I've been meaning to tackle on our '14...done the EGR/Throttle Valve twice, but never the MAP.
 

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Yeah...something I've been meaning to tackle on our '14...done the EGR/Throttle Valve twice, but never the MAP.
Oh man. So if it won't budge you can try twisting it a bit back and forth like a stubborn bolt, not too much or it will definitely break. If you're lucky once it seems to move free it should come out, in maybe one piece too! Lol honestly maybe just have a sensor on standby because that plastic does not like all that heat over time.
 

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2014 Cruze Diesel, 2007 Cobalt, 1981 Camaro Z28, 2017 Volt
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Oh man. So if it won't budge you can try twisting it a bit back and forth like a stubborn bolt, not too much or it will definitely break. If you're lucky once it seems to move free it should come out, in maybe one piece too! Lol honestly maybe just have a sensor on standby because that plastic does not like all that heat over time.
Oh boy...sounds like it's going to be a blast. I presume it's at least easy to access? I haven't actually looked for where its at in the car. WD40 doesn't seem like the right thing to clean it off, maybe brake clean will be a better option, though I'm always leery when it comes to a sensor.
 

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Discussion Starter · #10 ·
Any idea how hard it is to remove the intake manifold? It’s a tight fit. Seeing how my EGR got plugged up, my MAP sensor got plugged up, and now my new EGR is looking close to plugged up again after 20k miles, I really hate to see what the intake looks like inside.

Anyone ever take the intake manifold off?
 

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I have an alldatadiy account and it has instructions for intake manifold replacement. The book time for replacement is 4.8 hours. Just scanning over the instructions - it looks like alot of stuff to get out of the way to get at it...

Jeff
 

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Does anyone have the instructions on how to do it? I think I could figure it out myself, but it is a lot easier when you follow someone's work on YouTube :)
 

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Discussion Starter · #14 ·
Does anyone have the instructions on how to do it? I think I could figure it out myself, but it is a lot easier when you follow someone's work on YouTube :)
Your MAP sensor is where the green circle is in this photo (ignore the red, I took this photo off the internet where someone else was point something unrelated out).

Remove the sensor, very carefully clean using WD40 or kerosine or electrical cleaner and a tooth pick, maybe a cotton swab as well. Inspect your O ring on the sensor to ensure it’s not broken or brittle or missing

Hand tighten back into place.

 
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