Is anyone familiar with ECU problems? I have a 2002F150XL 4x2 with a 4.2/5sp w/23,500 on it. The truck is running real lean. Despite running lean the idle is hyper. I checked to make sure the rear diff was OK, made sure the caliper pistons and emergency brake were not binding. Made sure the wheel bearings weren't seized. I did this because at first it felt like I was dragging something. Apparently it is the processor or the engine. I have no check engine lights, truck starts right up, no stalling, clunking or chattering. Just lean as hell. I did recently install a Fordchip but removed it after I did not really feel a difference other than the engine leaning out. It did not run differently after I pulled it(Keyoff/engineoff when I pulled it). I did remove the PCU when I installed the chip, battery was completely disconnected prior to removal, during install and after the install of the PCUw/chip. I did add octane boost once chip was installed and battery was re-connected.

I was thinking when I re-installed the PCU maybe it did not plug into the harness it attaches to properly. Any advice would be appreciated

Thanks

 

How do you know it's running lean?
You may have a clogged fuel filter.

 

"idle is hyper" please explain.

If you can detect lean without some sort of feedback (like a O2 sensor reading) you are better than me.
Give us specific details on the symptoms please.

 

You guys are right I have not tested anything yet. The engine was breathing and running strong now it feels weak, it takes alot more pedal to get it up to speed when before it was flowing great I could easily get rubber out of the first three gears, now I can't even spin the tires in first. The idle is higher than normal instead of an idle I assume was around 800rpm (I don't have a tach), it feels like it's up a few hundred rpm like it is trying harder. The exhaust note is flat. I have a mac high flow muffler it used to kind of rumble and flow real nice now it is basically quiet. I did check the MAC cold air intake. I checked the air filter and rubber connectors for leaks to make sure no unmetered air was slipping buy, I tightend up the clamps a little as well.

This performance situation happened pretty abruptly about two weeks ago, prior to me working on it. The situation started prior to the chip install.