02 Gt Bad Idle

BlackStang00

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A little backstory, I bought my 02 gt from a small time dealer on the east coast. He didn’t know much about it but it was clean and ran well so I picked it up. I will say the previous owner cobbled together a cai so I’m thinking it was supercharged and the po threw together an intake after removing the supercharger. Anyway, It runs pretty well but has issues where it’ll surge and run like crap until you give it some throttle. It’s throwing a bunch of codes, a lot of them have to do with the front o2 sensors and lean on both banks. I’ve had some time to tinker with it so I’ve been doing some datalogging. Nothing looks out of place but the fuel trims are pegged full rich. When I drive around, the short term fuel trims will go back to normal but as soon as I let off the gas it shoots back up to full rich. The only thing that stuck out is my maf lb/min bounced around from .3-.5 at idle. I’m not a tuner but that seems low compared to other 2v’s I’ve seen. Anyone have a similar experience? Everything physically checks out. I’m thinking maybe maf and tune? Any input would be appreciated. I have a copy of the log taken on Forscan that I could send out if someone wants to take a look

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Dusten

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The car is running lean. The ecm is trying to correct by going max fuel. It sounds like there is a massive ****ing vacuum leak.
 

BlackStang00

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I figured as much but can’t find a vacuum leak. Maybe there’s a leak in the evap system? It’s never stalled on me either but I’ll do a smoke test just in case.
 

ar_snl

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May 16, 2023
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Dusten is correct on what is goin on regarding your explanation.
You have heater circuit codes which point to 02 sensors but...
I would first see where the extra air is getting in from first. It is after the Maf and before the 02 sensors. Check the intake manifold, intake, and exhaust manifold.
The GT is known for cracking at the plastic intake manifold.
Check Egr hard hose too but youll hear it if its exhaust leak but itll be before the 02 sensors. I would change the 02 sensors after making sure there are no air leaks.
P1150 and P1151 basically point to faulty 02s.
 

hotcobra03

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Some engine bay photos may help..

I had work done at dealer on our 03 and got it back with evap codes 455/457

Ford had put the vacuum hose after throttle body when it was supposed to be on air inlet tube .


I also had those 02 codes and drivabilty things .heater and lack of switching.
Caused by po171/174 .

Mine was the main pcv hose connection,leaking
 

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