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Discussion Starter #1
I’ve kinda gone crazy trying to figure it out. I’ve replaced the upstream o2 sensor, replaced the wideband sensor and bought a new aem digital gauge. I checked the exhaust around the downpipe near the sensor and see no exhaust leaks. I ohm'd out the coil packs and injectors, I replaced one coil pack. Replaced the spark plugs. I had the injectors cleaned and flow tested. I’ve used electrical cleaner on the MAF, MAP and IAT sensors. I installed a fuel pressure gauge (fuel pressure is consistent). I’ve swapped around the fuel injector and fuel pump relays, I even tried a friends MFI relay. I just resoldered the injector pigtails, I figured it wasn’t this but did it again anyway. I did a boost leak test, it’s the first time I’ve done it but I couldn’t find any leaks.

The car ran great and had been through multiple tanks of gas and then one day cruising on the highway I saw the AFRs spike lean and kinda stayed there. I drove it home as it felt mostly okay but misfiring a little. That’s when I changed the plugs and coil pack it Seemed slightly better but AFRs were still bouncing everywhere. Once day cruising around town it would stall at the stop lights and had to keep my foot on the gas a little, wouldn’t idle. I got home and that’s when I replaced the o2 sensor, wideband and did the injectors. I also found one of the bolts loose on the manifold to turbo. Since then It runs but the AFRs are still bouncing everywhere and when turning on the AC it wants to stall.
The thing that kinda confuses me is that the fuel trims while logging say they are happy and are within +-3% but I can watch the gauge and see it jumping everywhere. I know the tune is fine because I haven’t changed anything and have been through several tanks and like I said this started just cruising on the highway. Kinda at a dead end here with ideas. The last thing I can think to do is a smoke test and maybe a leak down test. Any help would be much appreciated
 

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Have you SWAPPED MAF sensors? Log again and watch the airflow counts. I've seen this once before with a bad MAF with very similar symptoms.
 

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Discussion Starter #3
I swapped out MAFs with a buddy and it idled like crap and stalled with the AC on, so I don’t think it’s the MAF
 

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Do a compression test next. Hopefully you didn't burn a valve.
Look at your plugs. One could be bad. Also torque your intake manifold bolts as the stock gasket is painfully thin and doesnt take much to leak. I replaced mine with a thicker one that also is thermal resistent. Or you could have a vacuum leak
 

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Look at your plugs. One could be bad. Also torque your intake manifold bolts as the stock gasket is painfully thin and doesnt take much to leak. I replaced mine with a thicker one that also is thermal resistent. Or you could have a vacuum leak
And if you run through all that and its still doing it it’s probably the tune,as i went through this same problem and ran all the tests you have replaced about everything then got a new tune and it was gone
 

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And if you run through all that and its still doing it it’s probably the tune,as i went through this same problem and ran all the tests you have replaced about everything then got a new tune and it was gone
or it could be your main computer going out....Any check engine lights, if so get a scanner it will give you more definite answer.
 
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