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View Full Version : sr20det hard to start when cold


STEVES14
05-06-2008, 04:25 PM
setup
95 240sx with sr20det swap
GT30R, JWT ECU 3 bar program 740cc nismo injectors, Z32 mafs, intercooler, exhuast clutch, and so on
(no cams, stock)

Parts replaced before i start asking for help
CAS, coolant temp sensor, ingnitior, coil packs, O2 sensor, PCV valve, spark plugs, recheck grounds, to the coil packs and ecu grounds
oooooh.... and ecu code 21


ok heres the problem, it's been heappeing the last 2 months for some reason when the car is cold its a bitch to start i have to keep it at WOT for like 5 sec just for to catch alittle and then i feather the gas stumbles a bit for like .5 sec and idles like a champion at 1500-1700 rpm warms up a bit and drops down to 900rpm and holds strong the car drives fine all the power is there, so after i drive the car for a bit park it for like 2 hours go back to it it fires right up like it was a new car strange :-/ but after i drive the car again and park it over night it starts all over again

so to sum it up
when the motor is cold hard to start
when the motor is warm or hot FIRES right up with no issue
no matter what temp it's outside 30F or 100F if the motor is cold it's a bitch
to start

please help :loco:

STEVES14
05-08-2008, 12:29 PM
never mind figured it out it was the start signal for the ecu pinout 34 it's suppoesed to get 12 volts when you put the key in start mode so the computer knows it's being started :2f2f:

SoguRacing
05-08-2008, 12:53 PM
good job!!!!

Yellow4g63
05-08-2008, 04:42 PM
never mind figured it out it was the start signal for the ecu pinout 34 it's suppoesed to get 12 volts when you put the key in start mode so the computer knows it's being started :2f2f:

Too bad I saw this late I was just going to tell you that too.

Sideways_blksr20
10-20-2008, 05:58 PM
And how do u fix this?im having the same problem

Yellow4g63
10-21-2008, 09:22 PM
Here is what I found when I did my RB swap into my S13 (RIP). There is a wire thats suppose to go to ecu for the cold start signal. I'm sure it's the same on the SR20 too. Without the cold start signal the takes a little longer to turn over vs just turning right over right away.

Sideways_blksr20
10-21-2008, 10:10 PM
how do I find this wire

Sideways_blksr20
10-28-2008, 08:42 PM
anyone it only gives me a hard time when it's cold

Yellow4g63
10-28-2008, 10:08 PM
S13 or S14?

Sideways_blksr20
10-28-2008, 11:14 PM
S13 with s14 black top

Yellow4g63
10-28-2008, 11:30 PM
I remember the cold start wire been in the dash plug for the S13's. It's been so long I think it was a 4 wire plug? it has the tach signal in it too.

Sideways_blksr20
10-28-2008, 11:41 PM
so it goes from tach to ecu

Yellow4g63
10-29-2008, 12:09 AM
more like the dash plug to the ecu. SR20DET Swap Engine Harness Wiring Diagram Guide SR SR20 (http://www.frsport.com/SR20DET-Swap-Engine-Harness-Wiring-Diagram-Guide-SR-SR20_t_26.html) it's that 1st plug it says to cut the orange wire is the one that needs the voltage going to it so the ecu knows the car is trying to start. But since u have a S14 harness in your car I'm not 100% sure which wire your going to use. The KA dash plug will still be the same orange wire tho.

Sideways_blksr20
10-29-2008, 07:15 AM
thanks bro

s14zouki
12-28-2008, 04:16 PM
my sr is doing the same thing, and always has. it doesnt matter if it's cold out. just like steve said though. i have an s14 with a s13 sr...can anyone help?

ZooMxxl
01-25-2009, 07:58 PM
3 years of dealing with the rough cold start and going through a couple batteries (les schwab warranty), my car finally starts up on the first go like it should. so glad i found this.

Sideways_blksr20
02-09-2009, 08:24 PM
more like the dash plug to the ecu. SR20DET Swap Engine Harness Wiring Diagram Guide SR SR20 (http://www.frsport.com/SR20DET-Swap-Engine-Harness-Wiring-Diagram-Guide-SR-SR20_t_26.html) it's that 1st plug it says to cut the orange wire is the one that needs the voltage going to it so the ecu knows the car is trying to start. But since u have a S14 harness in your car I'm not 100% sure which wire your going to use. The KA dash plug will still be the same orange wire tho.
its an s13 so what do i need to do to fix this?

Sideways_blksr20
02-09-2009, 08:27 PM
so what i understood its that i need to find this oraange wire from the tach and then rewire it to a 12v?

Sideways_blksr20
02-09-2009, 10:26 PM
???????????????

Alpha Residence
02-09-2009, 10:48 PM
so what i understood its that i need to find this oraange wire from the tach and then rewire it to a 12v?

From the tach? No it comes out of the main harness from the ECU

http://www.frsport.com/writeups/SR_Wiring1.jpg

that white plug has a orange wire thats the "ignition start" wire. Directly above the stock ECU location there is a dash plug. That wire needs to be ran up and spliced into the orange wire up on the dash side. If you're still doing your swap, cut that white plug off of your KA harness then match up all the colors and just plug that harness in.

Sideways_blksr20
02-10-2009, 09:37 PM
the car its already running i bought it with the swap
so what i need to do its look for the orange wire from my ecu ,after i find this wire on the ecu i have to cut it and run it to the one from the dash side rigth?

Sideways_blksr20
02-10-2009, 09:44 PM
????????????????????????????????

Alpha Residence
02-12-2009, 10:54 PM
the car its already running i bought it with the swap
so what i need to do its look for the orange wire from my ecu ,after i find this wire on the ecu i have to cut it and run it to the one from the dash side rigth?

yup, that about does it

speedy13
02-14-2009, 11:08 PM
hey guys! I just joined in since I have the exact same cold start problem. I have tested everything possible, but no luck. But this thread sounds sensible. ok, I have an sr20de, p10 primera. it started having the same problem mentioned at the very top straight after I had my starter motor rebuilt. it starts up perfect when the engine is warm/hot. But needs throttle to start when cold.
H E L P!

Sideways_blksr20
02-15-2009, 05:44 PM
car its at the paint shop ill try to do the wire thing and i let u know

speedy13
02-17-2009, 02:21 AM
Thanks bro! I just couldnt follow up as to what is to be done with that start signal wire.:bash:
That pinout 34 seems to be color purple in my sr20de.

GSXRJJordan
02-17-2009, 02:35 AM
Thanks bro! I just couldnt follow up as to what is to be done with that start signal wire.:bash:
That pinout 34 seems to be color purple in my sr20de.

More likely that the pinout is different - look for a orange wire with a silver stripe that goes to the dash plug, like in the pic.

But since the SR20DE came in USDM cars, why not just check the FSM for a ignition start wire?

obsolete
02-17-2009, 10:21 AM
does battery have anything to do with this?

speedy13
02-18-2009, 01:13 AM
The battery is new. I replaced Fuel filter, distributor, fuel pressure, coil, fuel rail, MAF, Ignition Barrel, & spark plugs.

tacoboy
03-26-2009, 12:45 AM
I'm having the exact same issue as the OP. However, all of the wiring is legit and the orange wire is getting 12.5 volts when starting. Any other ideas? Could it be coolant temp sensor? Only happens when cold, the throttle needs to be cracked a bit, and I get a bit of black smoke (unburnt fuel).

Cheers!

GSXRJJordan
03-26-2009, 01:06 PM
I'm having the exact same issue as the OP. However, all of the wiring is legit and the orange wire is getting 12.5 volts when starting. Any other ideas? Could it be coolant temp sensor? Only happens when cold, the throttle needs to be cracked a bit, and I get a bit of black smoke (unburnt fuel).

Cheers!

Could definitely be the 3-pin CTS. It's only a few bucks from FRsport, good idea to replace it if your wiring's all 100%.

beatd
03-30-2009, 01:07 PM
would this work on my KA-T. because i'm having the same exact problems right now and i'm tried everything you can possibly think of

93 Sr Hatch
04-09-2009, 11:21 PM
setup
95 240sx with sr20det swap
GT30R, JWT ECU 3 bar program 740cc nismo injectors, Z32 mafs, intercooler, exhuast clutch, and so on
(no cams, stock)

Parts replaced before i start asking for help
CAS, coolant temp sensor, ingnitior, coil packs, O2 sensor, PCV valve, spark plugs, recheck grounds, to the coil packs and ecu grounds
oooooh.... and ecu code 21


ok heres the problem, it's been heappeing the last 2 months for some reason when the car is cold its a bitch to start i have to keep it at WOT for like 5 sec just for to catch alittle and then i feather the gas stumbles a bit for like .5 sec and idles like a champion at 1500-1700 rpm warms up a bit and drops down to 900rpm and holds strong the car drives fine all the power is there, so after i drive the car for a bit park it for like 2 hours go back to it it fires right up like it was a new car strange :-/ but after i drive the car again and park it over night it starts all over again

so to sum it up
when the motor is cold hard to start
when the motor is warm or hot FIRES right up with no issue
no matter what temp it's outside 30F or 100F if the motor is cold it's a bitch
to start

please help :loco:
i am kinda having the similar problem but im on e85... but it just recnetly started being a bitch to start

STEVES14
05-31-2010, 04:08 PM
i am kinda having the similar problem but im on e85... but it just recnetly started being a bitch to start

Did u check to see if your ecu is getting 12 volts to pin number 34???? that was my problem the whole time!!!! and i blow my money on coolant temp sensors tps sensors mising with the tune, u name it!!!!! and the whole time it was the wiring!!

obsolete
11-19-2010, 08:35 AM
Does anyone know what I should look for for a s14 sr20 in a '97 240? I am having this exact problem as OP

edit: looks like this start signal is Orange on 97 240 so if that connects to pin 43 for s14 sr ecu, then it should work the same? How does the car start without the ecu getting this signal in the first place?

obsolete
11-25-2010, 09:21 AM
Best thread ever!

spools420a
10-13-2016, 04:28 PM
Sorry for bumping such a old thread but could you just cut the orange wire at the ecu then run a wire from ignition "start" wire directly to the orange wire or even just splice a wire into the orange wire without cutting it or would this interfere with the tach?I had cut and redid my starter wiring and now have this cold start issue.

S14kouki805
10-13-2016, 05:20 PM
Subscribing for later viewing...

spools420a
10-15-2016, 02:53 PM
Subscribing for later viewing...
In that case all that needs to be done for s13 sr20det is wire a wire directly to starter ignition switch the wire that's on the starter that connects from ignition switch that's only live when turning the switch to start "cranking" from the new wire you wired to this goes directly to ecu pin 34
Its a orange wire with silver stripe but don't confuse it with boost solenoid wire directly opposite from it as its orange as well.look up pinout to be sure.anyways the reason we wire this to ingition wire is this tells the computer
you are starting the engine and therefore compensates by spraying all 4 injectors while it cranks which fires up engine faster.BTW I did accidentally wire up to orange boost solenoid by accident and no damage happened just to let you know,but when I wired to the correct orange wire she fires up instantly.I did not cut orange wire I just spliced into the wire and alls good.