Logoleaf Posted June 13, 2016 Share Posted June 13, 2016 My 83 na start to have an issue since last year. It has very low idling when cold start (500rpm). When driving at cold start, it splutter at 1,500 rpm. It will goes off Once come to the stop sign. So, i have to crank each time i stop until the engine is getting warm. When engine is warmed, it runs fine. I've bought another cold start valve to replace the old one out. That doesnt seems to change. Fuel pressure is good. No leaks. Im thinking of bad wiring some where between the CSV and the ECU. Does any one been having the same problem like mine? Please give me some help what to look for. Thanks guys! Kevin, Quote Link to comment Share on other sites More sharing options...
NewZed Posted June 13, 2016 Share Posted June 13, 2016 The cold start valve only operates during Start. It squirts fuel only while you're trying to start the engine. Once the engine starts it's done. Running problems after the engine starts aren't likely caused by the CSV. For about a minute after starting, the air regulator (aka AAR) should be open to keep the idle speed up. Usually though, the engine is still cold when it shuts completely. You can test the AAR to see if it's opening and closing correctly. You might have a vacuum leak. They can cause a lean condition that is more significant at idle when cold than after warm up. Quote Link to comment Share on other sites More sharing options...
Logoleaf Posted June 14, 2016 Author Share Posted June 14, 2016 How do i know if the air regulator is bad? If the vaccum is leak, how come the problem exist only when engine is in cold condition (low idling and splutter when acceleration). When engine is warmed up, problem is gone. I know this is a boring questions but i would like to learn more about the Z. I owned it for 10 yrs and never seen something like this. I know something is not right but cannot find the problems. Thanks newzedd. Quote Link to comment Share on other sites More sharing options...
NewZed Posted June 14, 2016 Share Posted June 14, 2016 Test the air regulator. A cold engine needs a richer mixture than a warm engine. A vacuum leak makes the mixture lean. Quote Link to comment Share on other sites More sharing options...
NewZed Posted June 14, 2016 Share Posted June 14, 2016 Sorry I can't be of more help, but if you haven't been in to how the EFI system works, you're starting from scratch. There are several things that can affect idle behavior. Testing is fairly simple but you need to understand how the parts work individually, and how the system works as a whole. It can take some study. Quote Link to comment Share on other sites More sharing options...
Logoleaf Posted June 15, 2016 Author Share Posted June 15, 2016 Thanks newzed. Will do! Quote Link to comment Share on other sites More sharing options...
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