Weird Idle Issues cold start
 

I recently did a rebuild and before my idle for cold starts were fine without AWS and the fuel temp sensor. The only changes after the rebuild were bigger ports (stock to street port) removal of double throttle from the UIM and closed off the coolant lines to the TB.

Now, the car idles fine ONLY when fully warmed up. I have to hold ~10% throttle during cold starts to keep it from choking to death and then it idles at like 300-400rpm before settling at 900 when warm. I feel like the the ISC isnt doing its job by raising the idle during initial starts but it seems to be doing its job during electrical load. The problem gets better when I open the bleed valve A LOT; like 3-4 turns lol but then the car idles high after warming up fully.

With the datalog, I am getting ~7-8 afr initially when the cranking and initial engine run, it doesn't lean out when I take fuel away initially for those cells. It just leans out AFTER (my normal idle is around 13afr). So I think that the problem can be with the ISC and temp adjustments through the PFC (dumping fuel cold), which I am not familiar with and need guidance. It could def be a combination of both since it still idles super low when partially warm @ around 12afr.

Let me know what you guys think, :icon_tup:
Joe

Hook the coolant lines back up to the throttle body and the problem will go away. This is the system that holds the throttle plates open during warm up.

Otherwise you need to adjust your water temp correction factors.

Can you give me a relative idea for what correction #'s i should have? I cant run the coolant lines to the tb anymore as they are used for my tial mvr setup.

Thanks

No, you need to tune them to your specific car.

seems like the idle is better when I take away corrections for water temp/inj however it still acts the same right when the car fires. It struggles at 300rpm and once I tap the gas it gets better.

My correction numbers are pretty close to 1.00 so there isnt much more I can do as far as that goes.

Here is the way to do it.
First get the engine fully warmed up 100%.
Then tune your idle the best you can do it. That is air, fuel, and timing.
If you are using the ISC to control idle speed, it might not work on all three speeds with a single turbo setup. And using the ISC for idle speed control prevents you from changing idle timing.
Set you idle speeds higher than the norm. You might need 1000 rpm for no EL or AC.
You should be able to get the car to idle without using your foot.

But most likely the problem is that you do not fully 100% know the PFC and the 13B-REW control systems. I have been doing it 100% manually since 2004. But then I am one of the PFC experts.

Contact arghx about the best PFC/DL tuning/info groups available.

Thanks

Your right, Using the pfc/isc doesnt work but it is set at 900. Ill try to raise to 1000 and see if it helps with the initial start.

Havnt had much of a chance to drive around to really see how the idle is till today.

So the initial start is still the same...I need to use my foot to get her settled then its good. Its good until the begins to move then it starts to die out. I did it multiple times. Idles beautifully at 900rpm then once it starts rolling down my hill (in neutral) it bogs to 200 rpm. Eventually it goes away however.

What settings should I mess with now? I know its obviously related to the speed sensor however I am not familiar enough with the PFC to know exactly what to focus on.

Thanks

hey!!
 

Got same problem here!!!!! more advice???

I'm having a similar problem as well, only mine wants to stall even after a hot-start. I reinstalled the coolant line to the TB & reset the fast idle cam but that only helped with startup, nothing for idle. It behaves like the injectors are totally cutting out for a few seconds, then coming back online.

Can't tell you much without a map and datalog.