WRX hesitation

Question

Hi Scotty

I am sending this email in regards to get some help from you on my 2019 WRX. I got my engine rebuild as it cylinder 4 crankshaft bearing spun out. Anyhow after the engine was put back together and everything seemed to be running fine. But after few days of driving, i noticed that when i tried to accelerate faster (doesn't matter what gear i am in), the engine hesitates and sometimes stutters. The boost pressure builds up but it feels like not enough fuel is supplied. The boost reaches 15-20 psi but there is no power. It only happens when i accelerate where the turbo has to kick in.

The weird part is until now it has been couple of weeks of driving and the hesitation is randomly fixing itself and then comes back again. But whenever i disconnect the battery, to reset the ecu, it drives fine for a while. I couldn't figure out any pattern.

My mechanic suspected the O2 sensor but after replacing it, no difference. He is also struggling to get to the root cause. We checked for leaks, did smoke test but didn't find anything. We installed new oem spark plugs with 0.024 preset gap. Also installed a new pcv valve. No help. We also put 4 gauge ground cables from the engine and chassis directly to the negative terminal.

Please help and guide me as the car feels even worse than driving a Elantra. FYI, the engine is stock with no mods.

Mantek Bhogal

scottykilmer · Answer

Well sad but true I'd say find yourself another mechanic. If you were near Clarksville, Tennessee when I'm here or Portsmouth Rhode Island when I'm there, I'd gladly check it out for free. And try to figure out what's wrong with it. A good mechanic has a very good scan tool which can record and analyze data. I would hook my machine up and drive it around until it acted up. When it acted up. I would analyze that data. There are thousands of lines of data. A mechanic has to know how to analyze them. Of course the good mechanics have good machines like I do which are color coded. So we can see problem areas because the data will not be in black. It will be in red or yellow. Then we have to analyze that data. Obviously your mechanic does not know how to do this so you're going to have to find somebody who does. Otherwise you just guessing