Hard start when hot - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

jdm_dean · 06-12-2010, 07:32 AM

Cold the car starts fine, just gotta rev it a little for it to stay running, after about a minute it stays running by itself.
After driving more than 20 minutes when i go to start it again, i have to start it and rev it fast or it will die and wont start for another 10 minutes.

It'll crank and try to start and you can hear an explosion like it starts then dies.
If I gas it while trying to start, it makes it start worse and it wont even have a full combustion cycle.

I'm stomped, tried cleaning the coolant temp sensor, same problem though..

blueshark123 · 06-12-2010, 08:00 AM

replace it dont just clean it and make sure u removed the right 1

jdm_dean · 06-12-2010, 08:04 AM

Quote:

Originally Posted by blueshark123

replace it dont just clean it and make sure u removed the right 1

i removed the one on the bottom radiator hose but realized thats just the switch for the fan. i removed the one ontop of the intake mani and cleaned it.

what exactly does a bad ct sensor cause the car to do..

Duosx · 06-12-2010, 11:20 AM

whats your fuel setup?

jdm_dean · 06-12-2010, 01:18 PM

Stock fuel system...and stock ka24e

Neejay · 06-12-2010, 12:46 PM

I'm having the EXACT same problem on my RB25. I even replaced the ECU coolant temp sensor. I think it's in the wiring somewhere, but I think the wire is shielded.

What motor do you have?

Triperformance · 06-13-2010, 05:44 PM

Sounds like a rich warm start senario, got any codes/ check engine light? Theres quite a few things that can do this as well.

jdm_dean · 06-14-2010, 07:38 AM

Quote:

Originally Posted by Triperformance

Sounds like a rich warm start senario, got any codes/ check engine light? Theres quite a few things that can do this as well.

it is, if i pinch the fuel line the car runs better so its definately too much fuel. no codes though, thats the weird part :\

Triperformance · 06-14-2010, 11:23 AM

Check your fuel pressure regulator and make sure it's functionng properly with and without vaccum. Do you have any codes/ check engine light on?

jdm_dean · 06-15-2010, 09:30 AM

Quote:

Originally Posted by Triperformance

Check your fuel pressure regulator and make sure it's functionng properly with and without vaccum. Do you have any codes/ check engine light on?

No check engine light. How would I check? Disconnect the vacuum line and see if the idle changes?

Triperformance · 06-16-2010, 11:38 AM

Hmm, yes you can pull the vaccum line and see if idle changes. It could be possible you have a fuel injector issue (staying open). When was your fuel filter changed last as well?

jdm_dean · 06-17-2010, 09:26 PM

Quote:

Originally Posted by Triperformance

Hmm, yes you can pull the vaccum line and see if idle changes. It could be possible you have a fuel injector issue (staying open). When was your fuel filter changed last as well?

It was changed about a month ago.

Only thing thats not leading me to believe its a fuel issue is that its just rich initially. Like once its running it runs fine other than a bog around 2500 rpm and when you floor it in a high gear, which i think is due to improperly gapped plugs, forgot to gap them once i put them in.

Its just once it first starts cold it wants to die unless you gas it and hot starts it wants to die unless you gas it but 2 mins later it will stay on by it self and drive fine.

jdm_dean · 06-18-2010, 03:52 PM

Okay so I got it fixed. Checked my tps it was out of calibration, was at .39 and should of been between .45-.55. Got that set and got a new temp sensor from the junkyard, car cuts on every time now with no gas given.

Figured it out because when i disconnected the NEW ECT, it would idle lower and when revved it would backfire out the ass which is a sure sign of too much fuel. Reconnected it and idle raised, no backfire.

So if anybody has the same problem, definately check your tps and coolant temp sensor.

06-12-2010, 07:32 AM	#1
jdm_dean Join Date: Oct 2009 Location: Raleigh Age: 38 Posts: 40 Trader Rating: (0) Feedback Score: 0 reviews	Hard start when hot Cold the car starts fine, just gotta rev it a little for it to stay running, after about a minute it stays running by itself. After driving more than 20 minutes when i go to start it again, i have to start it and rev it fast or it will die and wont start for another 10 minutes. It'll crank and try to start and you can hear an explosion like it starts then dies. If I gas it while trying to start, it makes it start worse and it wont even have a full combustion cycle. I'm stomped, tried cleaning the coolant temp sensor, same problem though..

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06-12-2010, 08:00 AM	#2
blueshark123 Post Whore! Join Date: Apr 2006 Location: North Jersey Posts: 5,481 Trader Rating: (55) Feedback Score: 55 reviews	replace it dont just clean it and make sure u removed the right 1

06-12-2010, 11:20 AM	#4
Duosx Leaky Injector Join Date: Jun 2006 Location: Kansas Posts: 149 Trader Rating: (1) Feedback Score: 1 reviews	whats your fuel setup?

06-12-2010, 01:18 PM	#5
jdm_dean Join Date: Oct 2009 Location: Raleigh Age: 38 Posts: 40 Trader Rating: (0) Feedback Score: 0 reviews	Stock fuel system...and stock ka24e

06-12-2010, 12:46 PM	#6
Neejay Post Whore! Join Date: Jan 2004 Location: lol Age: 39 Posts: 2,586 Trader Rating: (2) Rides Gallery: Neejay Feedback Score: 2 reviews	I'm having the EXACT same problem on my RB25. I even replaced the ECU coolant temp sensor. I think it's in the wiring somewhere, but I think the wire is shielded. What motor do you have?

06-13-2010, 05:44 PM	#7
Triperformance Leaky Injector Join Date: Jan 2008 Location: Maryland Posts: 62 Trader Rating: (0) Feedback Score: 0 reviews	Sounds like a rich warm start senario, got any codes/ check engine light? Theres quite a few things that can do this as well.

06-14-2010, 11:23 AM	#9
Triperformance Leaky Injector Join Date: Jan 2008 Location: Maryland Posts: 62 Trader Rating: (0) Feedback Score: 0 reviews	Check your fuel pressure regulator and make sure it's functionng properly with and without vaccum. Do you have any codes/ check engine light on?

06-16-2010, 11:38 AM	#11
Triperformance Leaky Injector Join Date: Jan 2008 Location: Maryland Posts: 62 Trader Rating: (0) Feedback Score: 0 reviews	Hmm, yes you can pull the vaccum line and see if idle changes. It could be possible you have a fuel injector issue (staying open). When was your fuel filter changed last as well?

06-18-2010, 03:52 PM	#13
jdm_dean Join Date: Oct 2009 Location: Raleigh Age: 38 Posts: 40 Trader Rating: (0) Feedback Score: 0 reviews	Okay so I got it fixed. Checked my tps it was out of calibration, was at .39 and should of been between .45-.55. Got that set and got a new temp sensor from the junkyard, car cuts on every time now with no gas given. Figured it out because when i disconnected the NEW ECT, it would idle lower and when revved it would backfire out the ass which is a sure sign of too much fuel. Reconnected it and idle raised, no backfire. So if anybody has the same problem, definately check your tps and coolant temp sensor.