rough idle when cold???

I just fitted 6 new injectors in my NA 300zx auto my car now start allways but when it is cold it idles low about 800rpm only sometimes does it idle at 1300rpm when cold ?Do they have a automatic choke?Someone said my water temperature sensor could be the problem?Car still burns too much fuel ?Could someone please advise me?

 

I had a similar issue, I simply cleaned the water temp sensor connector. Problem went away.

 

+1 ecu water temp sensor and/or its connector. Before my Z it would idle a little funny from time to time a little above 1000 sometimes 800ish depending on its mood even after warm up. Then one day it didnt want to start. Found my connector was heavily corroded. Mine was still a little funny still after cleaning up the connector. Perhaps dirty sensor inside rad pipe.

Its cheap enough just to replace the sensor and connector, so you have one less potential thing that can go wrong. I changed my connector to the Bosch easy release type.. Very nice and much easier to release than factory one.

http://carcraze.com.au/nissan-300zx-z32-coolant-water-temperature-sensor-part-no-22630-51e02/

http://carcraze.com.au/bosch-electrical-connector-2-pin-quick-release/

 

Just curious how can that little sensor play with the idle so much?Would it cause higher fuel consumption?Thanks

 

In simple talk - if the sensor is out, the ECU will increase the flow of fuel to the engine as it suspects the engine is colder than what it is.

What I would suggest you do is buy some electrical cleaner (spray) and a tooth brush and one by one go through every connector in your engine bay and clean all the gunk that has accumulated both from the male and female side. It may even give you a power gain, better fuel economy and may assist in fixing your idle issue.

 

Thanks mate I am currently overseas till end of sept do u mind having a look at my 300zx when I get back to melb?

 

Sure, just PM me when you are back and I'd be happy to check your condition and fix anything easily fixable plus check codes on your ECU.

 

If you do get around to cleaning up the eletrical connections, make sure you apply some dielectric grease (silicon grease) to protect the connections from moisture etc so you dont have to do them again for a very long time.

 

Thanks a lot I appreciate it do you know anything about transmissions? Mine is flaring from 3 to overdrive mostly all other gears change properly?Tranny oil is fine???

 

Thanks mate the car I is over 20 years old now I doubt its ever been done before I hope I see some results

 

It could also be the 02 sensor if its not the water temp sensor

 

Hi mate I will be back in melb on the 14th oct do you have a contact number ?If you can check out my zed I think it might be a temperature sensor?funny idle burning a lot of fuel cheers

 

PM sent.

 

hi james I am in melb can you contact me 0416348654 thanks