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2G Rough idle and bogging when cold

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smills1840

smills1840

10+ Year Contributor
365
22
Nov 8, 2011
Blacksburg, Virginia
I recently installed fic 950s on my 2g GSX. I'm using ecuflash with ceddymods to tune with. My injector scaling ended up around 860ish, and I added .315 to my latency table, but have tried everything from .200 to .450. Nothing helps the stumbling idle, but it does change the afr. My afr at idle is between 14.4 and 14.9 at idle, so I think my latency is in the ball park of where it's supposed to be.

The car misses every few seconds at idle, and it boggs down under light load until it's at full operating temperate. Once the car warms up it drives fine, but still stumbles at idle.

Mods:
14b
Fic 950s
Ngr bov (vented)
Stock maf
3in exhaust
Ebay intake

I got new ngk plug wires in March, and my bpr6es plugs don't look fouled.

I know I need to be recirculating my bov, but the car ran fine before installing the injectors.

Anyone have any ideas or suggestions?
 
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Mine was doing the same thing when it was completely stock, I replaced the IAC and it went away. Might be worth looking into
 
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You need to check your fuel trims not afrs. If your ltft is over -8% then you need to lean it out. In closed loop your ecu is going to change fuel trims to try to correct your afrs. Just because your afrs are around 14.9 at idle doesn't mean your latency is correct. Your ltft could still be way negative.
 
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What are your fuel trims. I have ecmlink so I'm not familiar with creddy. Could be as simple as a iac or maybe a pulled vac line when you changed the injectors.
 
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So I should tune my latencies based on my trims, even if it throws my idle afr way off?
 
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I started from the stock latencies, and added .1 ms to all the values instead of the suggested .315-.330 ms. The car doesn't idle any better, but my idle fuel trim logs at .58%. Can that be correct?

Where else should I start looking for the cause of my rough idle?
 
Upvote0
I'd say vac line if it sputters like crazy and if you pulled your plugs make sure your spark plug wires are in order. I'm not sure if your running individual coil backs on each cylinder but it's worth a look.
 
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