start up issue...and then some :(

[x3rikaa]

okayy so i heard that when the engine is cold and you start it up, it should warm itself up right? as in the RPM's should be at 1200 or so?? but when i start mine up, it goes straight to 700? i have no idea where to start to figure out what is the problem but could that be from a vacuum leak? i say vacuum leak because when i hold the RPM's at 2000, it SLOWLY goes down. and at every stop light my idle changes. 1st stop light-1200 2nd stop light-750 3rd stop light-1500 and so on... does that sound like a vacuum leak? oh AND when i drive, my temp gauge goes from normal->VERY HOT->normal->VERY HOT in maybe 5 minitue intervals? can someone help me out, i was just starting to like my 240sx

[Fibre guy]

Could be lots of things....Check engine light?KA24DE or KA24E? s13 or s14?A place to start for idle:IACV could be freaking out.I have heard of faulty ecu temp sensors doing similar things to idle.MAF could be dirty.A place to start for temp:When you pull the cap is it full? Clean? water or antifreeze?Is it boiling over when you turn it off?Gauge temp sensor might be misreading too.KA's are normally riddled with problems, welcome to the club.

[x3rikaa]

oh sorryyy!its a '91 ka24de in an s13theres no check engine light and the coolant is brand new and doesnt boil in the resevoir. except i have a big leak in my coolant system now. possibly a cracked radiator? :'( i think that might be the cause of the over heating?

where are the ecu temp sensors located? is it easy to replace?

anybody else have any ideas?? :/

[AZ89two4Tsx]

A cracked radiator might have something to do with your overheating problem.

[xX RB Xx]

A cracked radiator might have something to do with your overheating problem.

yeah it would be the root of all your problems.

also...

you could have air in the system.. when the air goes by the coolant temp sensor it will go hot and will go back down when coolant goes by.

[x3rikaa]

ohh okay thats how it works thanks...my friend is coming over now to test out the pressure system or something. idk he said he has a kit...and i hope the RPM's thing is from that AIVC thing because the hoses look alright

[x3rikaa]

okay UPDATE:

there was a small leak from my upper radiator hose not being connected good so i gotta tighten that up (dont have tools) so hopefully my tempreature problem will be fixed

and for my idle, he said it could be a number of things, and one thing he noticed was the fuel pressure regulator wasnt even connected! he said there wasnt a hose there. i gotta go pick one up tomorrow but can anyone confirm that that could be the culprit of my weird idle? hmmm im starting to like my 240 again...