CoffeeCommando

I found my problem; brake booster is a giant vacuum leak when off, and when the brake pedal is pressed.

I started checking all my hoses for vac leaks with a hand pump and a gauge Saturday and found that only the heater **** controls had a small steady leak. The brake booster didn't hold a fraction of an inch however. The CEL usually started blinking when I would press the pedal, or while holding it steady at idle.

I was certain when I hooked everything back up and ran a long hose for the vacuum gauge to the **** pit so I could see what the vacuum was doing when I pressed the pedal. I would drop 7-10 inches of vacuum every time I pressed the pedal! I think the momentary dip in vacuum on throttle was helping something reseat, and so far it still does occasionally get stuck in lean 17+AFR mode. Pulling over and shutting it off clears it up so far. Seems like relieving the vacuum helps it reseal internally somehow. Given small throttle blips also works, even in mid drive. If I have to brake too hard too fast though that usually means I will be making a pullover to power cycle it to clear up the leak though.

And in case anyone is wondering, you can't drive this machine without the vacuum to the booster. I workout and with all my might it's hard to get it to slow down at slow speeds. It's probably a good idea to get a booster replaced ASAP in case it completely fails mid drive. I don't have an E-Brake at the moment to fall back on.

Anyways, after much searching it wasn't until just now, two days after I identified the problem, that I found an article that even made the association between brake booster vacuum leaks and misfires. Axle Addict will be a site I use more in the future.