Bought a Basket Case 2007 for $800...

So, I have a pretty long commute that I am taking on, and my main daily is an Acura MDX. I found a 2007 Prius locally that I decided to pick up.

What I was told is that the engine runs for a second and shuts off. Engine was recently replaced and so was hybrid battery. Dealership says the hybrid ECU is “too old” and doesn’t know what to do with the battery… or something. I was skeptical.

So I get there and the hybrid battery had enough umph to start the engine. P3190 - poor engine performance. So I tried a trick that helped me get home a few times with my old GM vehicles. I unplugged the MAF - PO said he had replaced that. Oddly enough, that got the engine going. After a minute or two, it had enough juice to move the car.

In perusing the engine bay while waiting, I noted that the engine appears to have been reinstalled rather poorly. Everything seems plugged in correctly but not routed properly, there is a negative wire just hanging off of the intake going nowhere, fasteners not installed, etc. It also sounds like a lawn mower - the exhaust is either loose or has a giant hole near the collector.

So the engine got the car going so it would move. Drove it some and it was slow going but I was about 30 miles from home. Figured out it would drive for a minute or two (slowly and never over 40mph) and then go into limp mode, engine revving like I had it in first gear and it’d start shaking really bad until I’d pull over and restart it. Rinse and repeat until about 15 miles later when I pulled over on a rural backroad and sat for a few. Dinked around under the hood looking for unplugged harnesses and such.

One thing I noticed is that the traction battery didn’t seem to charge at all. And the PO nor the dealership paperwork seemed to mention the 12v battery.

So I opened the hatch and took a look and found the positive cable basically hanging on by a thread and the negative cable slightly loose but not tight. Slapped my forehead, removed the positive entirely to clear codes and then twisted both cables on so they were fairly tightly wedged in place.

Voila, sort of. Engine fired up (MAF still had to be unplugged) and it seemed to cruise at 40-60MPH fairly happily without chugging. Plus, the traction battery was now taking a charge. Once it got to 2/3 charge, the engine seemed to cycle off, sort of. The MAF being unplugged made it fairly unhappy but semi-cooperative.

But it is definitely not where it needs to be. Still have to have the MAF unplugged to even run the engine at all. Anyone have any insight as to what might be happening? Airbox seems tight, hoses seem good, it’s not throwing any diabolical codes other than the coolant pump (P1121) and MAF codes and engine power code. MAF looks good after taking it off, engine seems to be overheating (220-240*F) when driving, but I expect that's partially low coolant, partially because the engine is running high a lot of the time.

I guess I need to find out what the engine ignores when the MAF is unplugged to find out what is unhappy.

My other question is whether spark plugs and coils might be bad without *any* misfire codes. While the engine seems to run like nice person, I never get any misfire codes anywhere.

Any other Gen2 owners deal with anything like this?