I'm having a real hard time working on my 1994 ls400. I took it to my school to replace the timing belt and water pump and I got all the way to the water pump almost (I didn't take the belt off). So I put it all back together and when driving it home it died on me and wouldn't start off a jump or anything. I got it home from a tow and I took it all apart and saw the serpentine belt chewed through the right CPS and it jumped timing. I replaced the connector and sensor, timing belt (in time), and water pump. I started it up and it would idle around 500 and then jump to 750 and then back down. Sounds like a misfire and when I go to check codes I get a code 13. Since then I did a compression test and compression was good, new spark plugs with a spark test (all spark is good), new crankshaft position sensor, new driver side ignition coil, remanufactered ecu from Toyota. I'm very confused on what it could be causing a code 13 and why it idles so low and why it surges a bit. I've also checked vaccum leaks by spraying b12 on all vaccums and still nothing. I feel like im turned vision so im looking for advice on what.

 

Code 13 is RPM Signal #2. I would be tearing it back down and start with checking out the camshaft sensors and ignition rotors.

 

I'd simply check the signal from the crank position sensor first.

 

I fixed the issue but now when I have the serpentine belt on it runs bad and stalls immediately but with no belt it runs perfect. Any ideas?

 

serp belt runs the alternator...check that it's charging well or not seizing on you. it's typical for an alternator to go bad from the power steering reservoir leaking onto it for years! a simple oring at the bottom of the reservoir to the pump can remedy the leak - and ultimately prevent premature alternator failure.

 

I pulled codes on it and it has a code 13, code 24, and code 31. Could a code 13 be caused by the code 24 and 31? Also im still very confused why with the serpentine belt on it doesnt start and if it does it surges or stalls right away. But with it off it starts first try and idles. I did forget to check voltage of the alternator tho but I am doing that tomorrow. And with the maf sensor unplugged it just cranks. I did forget to add that my maf connector is cracked and very broken so I am replacing that tomorrow too.

 

Judging from the code 24, I worry that the harness to the ECT sensor is open or damaged. The code 31 may be caused by the broken MAF connector. I worry that the engine harnesses were damaged while the big job was done.

 

why would a code 24 be caused by the engine coolant temperature? I thought a code 24 is air intake temperature and that it is built into the maf sensor

 

Sorry, It's my mistake. A code 24 is air intake temperature.
Those 2 codes are not directly related to the code 13. Anyway there should not be 3 codes at the same time. I worry that the engine harnesses were damaged while the job was done.