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Discussion Starter · #1 ·
Had a guy replace my radiator. When I got the car back, there was an engine needs service indicator (not the regular maintenance message). Resetting the ECU didn't help. Car ran a little rougher than normal, but it worked otherwise.

Then I was showing the car to a buyer, and while we were looking at the engine, i noticed the MAF sensor plug wasn't plugged in. Elated, I pugged it in, reset the ECU, and the warning light went away. Off we went.

But there was 0 boost. So we pulled over, reset the ECU again, buyer starts the car, and it shuts off. Repeated this process several times, it would run for a few seconds, and it would shut off. We were stranded on side of the road.

So I unplugged the MAF sensor, and reset the ECU, car started and continues to run, but rough. And still with zero boost. Obviously no sale.

Aside from being disappointed with my mechanic for leaving this plug off, what damage could be caused by doing so? Just plugging it back in should have returned car to normal operation, which was smooth and aggressive. MAF has never been replaced, but then never had any issues before now. Would ECU decide to shut off engine if it didn't like the readings coming from MAF sensor?
 

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Obviously no sale.
Sorry but this made me lol

Do you know if the MAF was plugged in before sending it to the mechanic? If you never unplugged it that would mean he had to right?

Only reason I can imagine a mechanic doing that is if they were a dishonest mechanic and somehow damaged it while they were working. A mechanic would know that unplugging it would allow the car to run, just inefficiently. The owner might not notice for a long time and then never put two and two together that the mechanic did something. But replacing a radiator, they shouldn't have even been in the area I don't think.

Car shutting off with MAF plugged in most likely means bogus readings from the MAF. Do you have a scangauge, VIDA/DICE, or the torque app for you phone? Being able to read MAF readings will tell you right away if it's the MAF sensor.

Other than that, you can buy a can of MAF cleaner for $7 and give that a try but to be honest, if your car can't even run, it's probably faulty not dirty. Usually if it was dirty you would throw CELs for running rich or lean and you might have some stumbling at idle but I haven't heard it causing instant death.
 

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Was the lower hose changed too, because I'm baffled why your guy would have touched the MAF to change a radiator?

If he had to pull and replace the lower hose I could see why he might have had reason to pull the airbox and MAF though.

My only other theory is that he stole your working MAF and gave you someone elses bad one if it was plugged in and working when your car went into the shop.
 

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Discussion Starter · #5 ·
Do you know if the MAF was plugged in before sending it to the mechanic? If you never unplugged it that would mean he had to right?
It was plugged in prior. We had together just replaced the AC condensor and compressor two weeks previous. It was boosting solid 19 psi up until the day I let him replace the radiator without me being there.

Do you have a scangauge, VIDA/DICE, or the torque app for you phone? Being able to read MAF readings will tell you right away if it's the MAF sensor.
Yes have DICE, but just wiped my laptop so need to reinstall VIDA.

Was the lower hose changed too, because I'm baffled why your guy would have touched the MAF to change a radiator?
If he had to pull and replace the lower hose I could see why he might have had reason to pull the airbox and MAF though.
Hoses not changed, but removing the airbox definitely makes it easier to remove radiator. He's just an unemployed mechanic, not a shop. I'm not blaming him, even if it's something he did. Just looking for ways to solve the problem.

I'll get VIDA up and running and see what it reports.
 

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I haven't done it myself but I would assume VIDA can monitor MAF readings? That is what I meant by using VIDA but it may also show you diagnostic codes that you aren't aware of.

I don't know how much you know this guy but I just question whether or not he noticed the car wouldn't run with the MAF plugged in and decided to unplug it and hope you wouldn't notice.

Since you are having zero boost, I would say there is a good chance an intercooler hose is off completely. This would also make sense why it won't even start with MAF plugged in and runs with 0 boost with the MAF unplugged. If it was only a MAF issue, the car should be able to achieve positive boost levels when unplugged. Sounds like you have a major boost leak. I would assume the lower intercooler to throttle body hose must be removed for a radiator swap so I would check there first.
 

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He probably just forgot to plug it back in as to remove the fan you'll want to remove the air box. Maybe it doesn't help that the ecu keeps getting reset. Maybe you need to just continue trying to get it to run until it eventually has the ecu relearn and have the car drive right .
 

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Is the maf facing the right direction. (Trust me... It happens)
 

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Discussion Starter · #9 ·
Check pressure side piping for leaks
Solved. Helps to tighten the clamps on the high pressure piping couplers.
Good call @contrast

 

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Solved. Helps to tighten the clamps on the high pressure piping couplers.
Good call @contrast

Looks like he's Unemployed for a reason.
 

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lol
 
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