1999 LS400 with a single code, P0100. I've seen other threads about this code, but they always seem to come alongside P0110 and/or other codes.

The symptoms: the car runs pig rich, I can smell the fuel from the exhaust and I drove about 50 miles today, and used over a quarter tank. Check engine light is on, vsc light is not illuminated when the car first starts, but comes on after a minute or so. 3k rpm limit, engine is slower to accelerate, occasionally sputters but not too badly, idles okay for the most part (5-600 rpm) but when it is first turned on, dips to about 100.

The car runs no differently with the maf unplugged, so it seems as though the ecu is not cooperating with the maf. I will attempt to get my hands on a new maf sensor and replace it to see if there is any difference. All related fuses are intact, including the efi no. 2 that Yamae suggested.

The heater control valve recently cracked due to being extremely brittle, and a quart or so of coolant poured down the back of my block/transmission. Does the maf line run behind the engine here, and could possibly have been shorted by the liquid? That is currently the only thing I can think of. Any help would be appreciated. Thank you!

 

Something is strange, in most of the case, a 98-00 engine does not run when the MAF connector is removed. The ECU goes into an inhibiting mode.

 

Is engine coolant full?
What brand? Coolant/water mix%?
Is thermostat original?
Is ECT sensor original?

 

I had thought so too, but I was able to start the car with the maf disconnected, and also disconnect the maf while the car was idling and saw no difference either way. I'll read up on that thread about the inhibiting mode.

 

Coolant level is full, I had drained and refilled/bled woth Toyota OEM prediluted red coolant when I did the starter job a few months ago and had to remove the rear coolant bridge. I had some left over and added the amount that poured out when the heater valve cracked. The thermostat is original, I replaced the ECT sensor with a Duralast one when I did the starter job, I accidentally knocked it with a tool and it snapped clean off.

 

This started after starter replacement?

You reattached the connector for the Intake manifold ACIS butterfly valve gang vacuum solenoid?

Are you planning an engine diagnostic?

 

This just started yesterday, I did the starter job almost 6 months ago and had similar issues; it ended up being the efi no2 fuse being blown that was causing all of my problems.

Also, an update. I bought a new maf sensor and replaced it, reset the ecu by deleting the codes with a obd2 scanner and disconnecting the battery for 10 minutes, but there was no difference and the CEL came on immediately. The cold start idle, I have noticed, surges from 900-1000, to 900, to 1000, etc. I slowly brought the rpm's up to 3k and jt cut out as usualy, but it seemed a little less sputtery. However, the smell of gas from the exhaust is even stronger now. I went back and checked all of the intake tubes for leaks since I had removed them to plug my idle up valve on the ps pump with a teflon wrapped drain plug, but found no considerable leaks. I reseated all of the tubes, reset the computer, and started the car again but of course, no difference. Oh and also, the car runs no differently with the new maf disconnected as well.

 

Update pt 2...
I pulled out my voltmeter to test voltage on the maf plug, and got some interesting readings. None of the pins read more than ~0.02 V DC with both the key in the on position and the car idling, except for the first pin, which reads 5 volts consistently. I am using the known body ground by the intake on the passenger side. I was under the impression that if I shorted out a wire in the back of the block from the coolant spill, there would be no power at all from the battery, not even 5 volts. Definitely confused.