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Discussion Starter · #1 ·
Hey everyone, I have an issue that I'm trying to sort out before I ultimately head to the local dealer. Car is a 2018 Forte5 SX, DCT auto with around 20K on it. Mods are: Sxth intake, catch-can, breather delete, cold pipe upgrade, intercooler res delete, gutted 2nd cat, MAC wastegate solenoid upgrade, vac block for boost gauge hookup. I've had these mods done for most of the life of the car, and the car has always ran fine and does run fine in normal everyday commuting. Not sure if any of these are playing a part..

So here's the scoop, car threw a CEL and went into limp mode in the midst of a full-throttle pull. I pulled over, turned the car off, restarted it and it came out of limp mode and drivability was back to normal (CEL still on obviously). Pulled the codes and got P0102 - Mass or Volume Air Flow Circuit Low Input, which also ultimately caused a P0299 - Turbocharger/Supercharger Underboost Condition, understandable. Went ahead and cleared all codes, check various hoses, intercooler piping, intake piping, MAP sensor itself, electrical connection - everything checked out fine. Then it happened again maybe a week later, also during full-throttle. Same procedure - cleared the codes, checked things out, all seemed normal.

I did some research and came across the MAP sensor 'update' to the newer part # 39300-84400. I had the old sensor and thought maybe could be the issue and was cheap enough so I went ahead and bought one of the new part# sensor. Installed it, no real change, and still was able to get the car to throw the same CEL and ultimately back go into limp mode. Again, only during hard full-throttle.

So, I'm sort of at a loss now. Not sure if anyone has came across this themselves, any input is appreciated.
 

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Waste gate malfunctioning and pumping too much/too little air from turbo?

Mass air flow does not really make much sense, as the engine is MAP, not MAF controlled.
From your mods actually the first one suspect I would have is waste gate solenoid... but I might be very wrong.

A thing to check, though, will be your spark plugs and fuel. Sure, it does not really make sense, but I found that sometimes when I was getting CEL (in 2015 MT) it did not make sense at all only to be cured by higher octane (only partially) and new spark plugs (completely).
Sorry, it has been a while, but symptoms similar - hot day, partial to full throttle - power gone. No boost, max I was getting was 5 psi. Restart after a few minutes - all good until next time. And it would almost die at idle.
 
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Discussion Starter · #3 ·
Good thinking - I did check the routing of the wastegate solenoid to make sure I didn't cross any vac lines, which all was good. I could try putting the stock one back on and see if anything changes.

But yes, pretty much the same symptoms I am getting as you had. I also did think the same thing about the code. After doing some research the code was referring to MAF vehicles. Odd..

Thanks for the input, I typically run 89 but ill be sure to check the plugs.
 

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I'm in the same solenoid camp. It sounds like its not working right. Could also be the w/g solenoid.

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Discussion Starter · #5 ·
Not sure how, but if the spring inside is 'stronger' do you think the solenoid is just too much for a stock wastegate?
 

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Discussion Starter · #6 ·
Well, got it fixed. Replaced the vac lines on the wastegate solenoid and it’s back to normal. Must of had a leak somewhere. Thanks for all the input.
 
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