Cold Start Issues - Engine sputter (77 280z Auto)

[Zed Head]

24 minutes ago, MH77280Z said:

rpms were abrupt

Not clear what this means but if the tachometer needle does not seem to match engine RPM correctly that is a sign of an ignition module problem.  

If banging on the ECU clears up the rough running, that's an ECU problem.

[MH77280Z]

4 hours ago, Zed Head said:

Kind of sounds like the bad ECU problem, or bad ignition module.  Did it smell like raw fuel?

 

 

Don’t smell any fuel.

[Zed Head]

Good luck.

[MH77280Z]

3 hours ago, Zed Head said:

Not clear what this means but if the tachometer needle does not seem to match engine RPM correctly that is a sign of an ignition module problem.  

If banging on the ECU clears up the rough running, that's an ECU problem.

The RPM needle match the rpm. When I said rpm was abrupt I meant the engine runs with a lot of hesitation during the first minute and if u don’t pump the paddle engine dies/stalls. 
 

after about 1 min while engine was still doing this it suddenly clears up and starting idling very smooth.

someone suggested build up of fuel pressure and checking FPR etc. I suspect that? What u guys think?

[jonbill]

I think its unlikely to have taken 1 minute for the fuel pressure to have come up. 

1 minute of running will get some heat into the valves and inlet, so fuel vaporisation is massively better after a minute. 

it just sounds like a lack of cold start enrichment to me. 

[Zed Head]

11 hours ago, MH77280Z said:

engine runs with a lot of hesitation during the first minute and if u don’t pump the paddle engine dies/stalls. 
 

after about 1 min while engine was still doing this it suddenly clears up and starting idling very smooth.

Try opening up the idle speed screw and see how it starts.  It's the one with the big washer head and spring underneath on the throttle body.  If it starts and runs correctly right away but the idle is too high after it warms up then that would be an AAR problem.

You've talked about how far open the AAR is but you haven't said that it closes quickly like it should, from the electrical heater inside.  It might be that the AAR does not have electrical power and that you've adjusted the idle speed for a warm engine.

[MH77280Z]

Hi, So my ignition issue is fixed (new ignition module).

I tested the temp sensor today according to manual at cold. At coolant temp of about 58-59F the resistance across the temp sensor terminals was very slightly above 3K Ohms. This is in exact range mentioned in the manual.

How can you test the continuity of the wiring harness for the temp sensor?

Also, I have cleaned the bullet connectors and can someone confirm the temp sensor connects to the two GREEN wires through these bullet connectors? (I mean the other two wires are black and both connect to the thermotime switch via bullet connectors). Trying to make sure I have not done it reverse?!!!

[Dave WM]

check it (resistance) at the ECU connector, that will verify the harness connections. IIRC its pin 13 to ground, but check your fsm to be sure. 

[Zed Head]

I have a memory of posting this before, but I'll do it again anyway.

 

[Yarb]

It’s a step by step process with the FSM or EFI bible that @Zed Headhas mentioned. You will probably find one or more connections faulty. Check each one and record your findings. Jumping to conclusions will put you in a tail spin.

[MH77280Z]

Thanks guys.

[Av8ferg]

I’d go with Yarbs advice. Just step your way through this. Could very well be a wiring issue


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