# ECU Codes.....help please



## MaxQ (Jun 3, 2004)

My car is running extremely rich (10-12mpg), and stalls on the first start or two in the morning. After that, it runs rough idle until warm and evens out. The motor is a recent rebuild and the injectors, FPR, vac hoses, cap/rotor/plugs/wires are fairly new. I ran the ECU diagnosis this morning, and just want to double-check before I go changing out parts all willy-nilly.

1. Code 13 - CHTS. I will replace soon.

2. Code 23 - Throttle Valve Switch/Idle Switch. I have my idle turned almost all the way up to keep the car from stalling at startup, but that shouldn't throw the code 23. *Does Throttle Valve Switch mean the same as TPS? Can it be adjusted, or should I replace?*
3. Code 41 - Fuel Temp Sensor. *Where is this located? Is it the sensor included with the FPR?* I've already replaced the FPR (which comes with a sensor attached). Looks like the previous owner jerry-rigged the wire going to that sensor with longer wire, a crimped barrel connector for the wire and a spade connector to the sensor. 


Thanks in advance for the responses!


1986 300zx z31 NA


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## Zen31ZR (Mar 24, 2004)

The TPS might need to be replaced, without it the ECU doesn't know when the engine is idling. Adjustment may not be enough, but you can try it. 

Your fuel mileage might be caused by a bad o2 sensor. Those don't always throw a code, the ECU just thinks the engine is constantly running lean and dumps more fuel in.


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## MaxQ (Jun 3, 2004)

Zen31ZR said:


> The TPS might need to be replaced, without it the ECU doesn't know when the engine is idling. Adjustment may not be enough, but you can try it.
> 
> Your fuel mileage might be caused by a bad o2 sensor. Those don't always throw a code, the ECU just thinks the engine is constantly running lean and dumps more fuel in.


I thought about the o2 about a month ago and replaced it. Things improved, but not by much. I'll just buy a new TPS, since it's only around $50 shipped. How do you adjust it, though? I keep hearing about adjusting it, but it doesn't appear to have any way to do so.

Thanks, Zen. I'm posting some pics of my car next week, once I get the new wheels installed.


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## Zen31ZR (Mar 24, 2004)

The FSM should have details on adjusting it. HAve you downloaded that yet?

On a side note, I don't remember if these cars are advanced enough for the ECU to use a coolant temperature sensor, but that also can affect your fuel mileage, and the hard starting. 

My mpg was in the high 20s long as I didn't cruise over 70 mph, and my car was modified for boost.


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## MaxQ (Jun 3, 2004)

I do have the FSM......I'm going to look for the TPS adjustment section. I think the CHTS is the only coolant temp sensor short of the thermostat, though. Just ordered one plus harness from MSA. Thanks!


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