Running lean

wg3497

New Member
Jan 13, 2004
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I'm new to the forum and looking for some advice for a '94 GT (170k miles). I had engine codes indicating my engine was running lean (181, 189 if I remember correctly). I replaced the fuel pump with a Walbro 155lph and had the injectors rebuilt and tested. I also replaced the head and intake gaskets, valve springs (TrickFlow), wires (Ford Racing), and cap/rotor (Accel). Now I got a 332 engine code (insufficient EGR flow detected) and the same lean codes plus a few more. The engine had an MSD ignition, BBK 65mm throttle body and speed chip (since removed) on it before I got it. Any ideas?
 
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When was the last time the Oxygen sensors were replaced? What injectors do you have? Do you have an adjustable fuel regulator? Usually a bump in fuel pressure will take car of this problem. Not sure of all your mods though.
 
I changed the O2 sensors about 1 year ago. The injectors are stock, and according to the guy that rebuilt them, they were in good shape before the rebuild. Stock fuel pressure regulator. I did forget to mention that since the minor rebuild, it idles at about 1800 rpm. Sometimes the idle will go back to normal (~900 rpm) or stall. I've check for vacuum leaks but couldn't find any.
 
get an adjustable fuel pressure regulator and bump the fuel pressure to 45lbs from 39. this usually gains a modified car a few HP and can sure slightly lean issues. worst comes to worst run an EGT to see if the cas is actually lean or if it is just a bad code.
 
When I bought it, it had a 65mm BBK throttle body, K&N filter, MSD 6 ignition and coil, Magnaflow mufflers and a superchip. (I pulled the chip out.) I was making good money at the time and planned on dumping a FRPP long block into it. Well, I got laid off after changing the suspension (FRPP springs, Edelbrock IAS shocks/struts, Energy Suspension bushing kit)about 2 years ago. I've added a Catco H-pipe and replaced the cap/rotor (Accel), wires (FRPP), plugs (Bosch Platinum2), valve springs (Trick Flow), fuel pump and filter (Walbro 155lph), and head/valve cover/intake/egr gaskets (Fel-Pro). I also had the stock 19lb injectors rebuilt.