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View Full Version : Idle thread number 1.405.394. Cold start idling

Shirohige
05-07-2018, 12:26 PM
Cold start, want to drive, car almost stalls unless i put my foot on the clutch and slighty press the throttle. Works perfectly fine when its warmed up around 65+ celsius. No hesitation nothing

It is not a vacuum/boost leak as I had the car tuned last week around 315whp. It would also hesitate before the tune.

- Redtop SR20
- Power FC D-Jetro
- S15 BB turbo
- 555cc Injectors
- new tps

Checked the gap today on spark plugs they are all fine. Cleaned the whole IACV last weekend, including the springs and shit. Checked for kinked hoses towards the IACV but everything was fine. Water temp sensor is also fine.
Timing is at 15.
TPS at .46v
Coolant is fine

I can't reset my PFC as I don't have the datalogit thingy and my tuner lives pretty far away.

There are so many topics with this problem, but no one has found a solution other then: "i just warm it up and drive"

Last thing I can think of would be a faulty IACV, but I don't feel like spending money on another unit and still having the same problem. Im losing braincells here
edit: According to other forums, a bad IACV would cause bad idle? My idle is good, its just starts to hesitate when I start to drive with a cold engine\
edit2: gonna set my tps voltage higher tomorrow and ill update it then; nothing happened. still the same
edit3: adjusted my water temp correction. Almost felt like it was working but it didnt
anthony_240
05-07-2018, 02:06 PM
What’s your wideband reading at at cold start?


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Shirohige
05-07-2018, 03:01 PM
What’s your wideband reading at at cold start?


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I think it was around 13 or something. Ill check it out tomorrow in the morning!
pacotaco345
05-07-2018, 04:12 PM
Sounds like enough time wasn't spent on the cold start tune. It took a day to get my car dialed on the dyno for operating temp, normal driving and WOT pulls, then another couple weeks or so of talking back and forth with my tuner to dial in cold start every morning since you can only really do that a couple times a day. This is also PFC D-Jetro
Shirohige
05-07-2018, 11:35 PM
Sounds like enough time wasn't spent on the cold start tune. It took a day to get my car dialed on the dyno for operating temp, normal driving and WOT pulls, then another couple weeks or so of talking back and forth with my tuner to dial in cold start every morning since you can only really do that a couple times a day. This is also PFC D-Jetro

Thats possible, he did tune it with a warm engine. Then again, this problem way before it got tuned. And there is like no tuner here in my country who tunes a car like that

Ratio’s are:
First few seconds 14.9
After those few seconds- 13-14
And then goed back to 14.7-15.4
this is all during the cold start
jedi03
05-08-2018, 07:44 AM
mine would of it sometimes too...I was told to set idle higher via iacv...fuel pressure ok?
Shirohige
05-08-2018, 09:26 AM
mine would of it sometimes too...I was told to set idle higher via iacv...fuel pressure ok?

Setting the idle via the iacv doesn't really do much. I can hear it idle lower/higher if I turn the screw but it will still hesitate when cold.

Can it really be the fuel pressure? Haven't checked it but the car drives amazing when its warm
Shirohige
05-09-2018, 02:58 PM
Alright since yesterday, the car had some misfires. Engine was popping, weird to explain. They are gapped at .028, running 1.1bar boost. Tried a .025 gap but also misfired. I don't think its related to my cold idle since the popping also happens when the engine is warm

Jesus christ i lost like 2.4 million braincells the last couple of days. Ordered a brand new IACV, water temp sensor, gaskets and shit.

If anyone has some suggestions, let me know!
Shirohige
05-10-2018, 04:40 AM
I guess I found the problem, if anyone can confirm this.

So I read something about setting the idle with disconnecting the TPS. I went ahead and did that, started the car and checking the timing on my PFC. And with the tps disconnected it was set at 21 degrees. With the tps CONNECTED it is at 15. Im no car expert, so can anyone confirm if my timing should be 15 with the tps DISCONNECTED?
staying_chuki
05-10-2018, 08:53 AM
I could be wrong so feel free to ignore this, but i believe 15 is what it should be at with tps unplugged.


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Shirohige
05-10-2018, 09:33 AM
I could be wrong so feel free to ignore this, but i believe 15 is what it should be at with tps unplugged.


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hmm have been researching for a while now. The timing with the tps unplugged appearently doesnt matter for a PFC since it doesnt go into timing mode or something like that
jdm213
05-27-2018, 03:41 AM
This same thing happened to me I cleaned my iacv blah blah blah ... so the problem is that the idle is rough especially when you start it on the lower kick panel where the fuses go and see if you have a blown fuse for the idle. replace it your car should now idle normally. trust I believe it 10amp and it’s called
St. signal