Poor running when hot

[ChemDog]

Need some help pls. I have an S13 with the KA24DE motor. When the engine is hot it stutters and stalls and blows smoke. Wont accelerate either. When the engine is cold it will start and idle and run great. I cant figure it out. Need some serious help here pls.

[IHeartTurbo]

coolant temp sensor

[OutToWinPAHC]

Could be a few things.... I dont think its a CTS because it idles good.

What color is the smoke, blue, black, white, does it smell sweet, how are the fluids is the oil clean or is it milky or does it smell sweet, is the coolant full without oil in it?

Any check engine lights?

How do the plugs look?

[ChemDog]

smoke is black. running way rich. plugs are dark but not wet. if i unplug the coolant temp sensor it will not start at all. cts makes some sense though because if i let it sit for a while it will start and run great. then run like s*** again when it gets hot.

[OutToWinPAHC]

Could be in the A/F loop. MAF, 02 sensor, TPS. Timing or an injector issue, but I cant imagine all four.

Try replacing the T-Stat, bleed the system, Cap, rotor, plugs and wires, time the motor, clean the IACV and check codes if there are any. If that does not help, tray swapping MAF's and an o2 sensor, check compression.

[IHeartTurbo]

Could be a few things.... I dont think its a CTS because it idles good.

He said it idles good when it's cold, not when it's hot. It sounds exactly like the coolant temp sensor is bad...

[OutToWinPAHC]

Usually when a CTS is bad it idles very very high because it defaults open which makes the ECU think its -200. Same thing for our LS motors. This will cause the motor to try to idle very very high like 2500rpm

[OutToWinPAHC]

But a CTS is only like 10 bucks, so if you do that, also do a Tstat and bleed the system... since you have to anyhow

[IHeartTurbo]

Usually when a CTS is bad it idles very very high because it defaults open which makes the ECU think its -200. Same thing for our LS motors. This will cause the motor to try to idle very very high like 2500rpm

Hmm, I've never had a bad cts cause a motor to idle extremely high. They've just been running fine when cold then barely running when it gets hot.

[ChemDog]

will the cts cause it to sputter and spit though?? plugs, wires, cap, rotor are all new. i cant see it being the timing because of how it runs when it is cold. it runs great and is fast as s!#t. but once it warms up it runs like s!@t. and how do i get it to go into diag mode to get the codes??