New to the forum!! Idle issue after start up?

[95g-s-x]

I just purchased a 95 gsx with a bunck of goodies. 97 style head (CAS on pass side of head), Evo 3 16g, FIC 750cc injectors, walbro 255, denjon intake, hard upper and lower pipes, full 3" exhaust, greddy BOV, and dsmlink. For $1400....i know, I stole it.

I'm having a bit of an issue. After I start the car (cold motor), It idles up to about 1500 rpm, then falls back down to 1000. This is what the idle is set in on dsmlink. LTFT is at -3.3, so the injectors seem to be dialed in pretty close. About 10 seconds after starting it, the car starts sputtering like it wands to dies. Does this for a good 2-3 minutes, then runs like a champ. In dsmlink, the cas signal is inverted, and the plug wires are swapped like they are supposed to be. Let me also state that warm starts are fine. Im thinking coolant temp sensor, but i can watch the coolant temp rise normally while datalogging.

Anyone have any suggestions for a newbie?

 

[boostinout]

I just purchased a 95 gsx with a bunck of goodies. 97 style head (CAS on pass side of head), Evo 3 16g, FIC 750cc injectors, walbro 255, denjon intake, hard upper and lower pipes, full 3" exhaust, greddy BOV, and dsmlink. For $1400....i know, I stole it.

I'm having a bit of an issue. After I start the car (cold motor), It idles up to about 1500 rpm, then falls back down to 1000. This is what the idle is set in on dsmlink. LTFT is at -3.3, so the injectors seem to be dialed in pretty close. About 10 seconds after starting it, the car starts sputtering like it wands to dies. Does this for a good 2-3 minutes, then runs like a champ. In dsmlink, the cas signal is inverted, and the plug wires are swapped like they are supposed to be. Let me also state that warm starts are fine. Im thinking coolant temp sensor, but i can watch the coolant temp rise normally while datalogging.

Anyone have any suggestions for a newbie?

you have two temp. send units. one is for the gauge and other for ecu. Check the one too ecu it will cause the car to be hard to start and idle rough untill it warms up.

 

[95g-s-x]

you have two temp. send units. one is for the gauge and other for ecu. Check the one too ecu it will cause the car to be hard to start and idle rough untill it warms up.

Yeah, I was watching the coolant temp that is logged with dsmlink.....it rises normally, nothing erratic either

 

[boostinout]

Yeah, I was watching the coolant temp that is logged with dsmlink.....it rises normally, nothing erratic either

i dont know if your using a gm maf translator but it does have a rich start up selection on it.That will cause it to idle rouhg some times untill it warms up.

 

[95g-s-x]

nope.....stock mass airflow sensor

 

[95g-s-x]

I think, or should I say hope, that I found the source of the issue. I hooked my laptop up , and started logging in dsmlink before I started the engine.

From watching the displayed values, it appears that as soon as the ecu enters closed loop, is when the sputtering starts. I then looked at the front O2 voltage, and it was just over 1 volt, and holding steady. It wasnt cycling at all. After ablout 2 minutes, it started dropping in voltage and the engine started smoothing out. Even after smoothing out, the O2 voltage was cycling very slow.....like .90 for 3-4 seconds, then .22 for 3-4 seconds.

I ordered a new sensor today. Will be in tomorrow. I will post back with the results.

 

[95g-s-x]

My issue was indeed the front O2 sensor being bad. Just thought I would post up incase someone else had this issue.