Rich in the Spring?

[T4RunnerSteve]

So... this is probably a stupid question but I’m hoping the answer confirms my suspicions: my 4Runner with the TRD supercharger was tuned on 380cc injectors in the Winter and ran well. Now that it’s warmer outside it idles really rough when cold and then is fine shortly thereafter (when the truck warms up slightly). Eventually it throws a P0172 code (too rich). Do I need to create a warm-weather tune to get a smooth idle again? I’m running the AEM FIC-6.

Thanks!
-Steve

 

[gamefreakgc]

Do you have the ability to read your fuel trims, such as via a Scanguage or a bluetooth code reader and the Torque app? That will help more than anything else. If it says, say, -20 at startup, you need to pull 20% fuel at vacuum.

 

[T4RunnerSteve]

Thanks Jerod. Yeah, the ST trim is showing -22%... -23% at certain moments shortly after startup which is surely what is triggering the code. What’s tough is that when it warms up it smooths out and I’ve seen it at 0% ST when sitting at lights idling. I probably need to pull some fuel on idle... somewhere in my map. Also regretting the 380ccs... wish I could have a redo on those.

 

[19963.4lsr5]

You need to look at the long term fuel trim. The ST is the right side of the decimal point.

Every time the ST maxes out (-30 or +30) it adds a 1 or subtracts a 1 to the LTFT and then the ST resets to zero.




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[gamefreakgc]

You need to look at the long term fuel trim. The ST is the right side of the decimal point.

Every time the ST maxes out (-30 or +30) it adds a 1 or subtracts a 1 to the LTFT and then the ST resets to zero.




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IF it maxes out it throws a code. I've seen my LTFT adjust with only +3% STFT, it works pretty hard to hit 0.

Remove an additional -10% in the RPM ranges when cold, so from 500 RPM to roughly 1250 RPM when at vacuum, 1000 if you are worried it'll affect driving. The vehicle never drives at that RPM range so will only affect idling. You may run into some situations where it's adding fuel into the +'s but should take away the code, which is the bigger issue.

Be sure to clear the code first though. I agree, 380cc's is a little big but it is definitely tuneable so it doesn't throw codes.

 

[19963.4lsr5]

Watch the LTFT for bank 1 sensor 1 and see how negative it is. I forget if the code sets at -15 or -20.

It’s suppose to be in percent so you can look at it and see what it is under certain conditions and look up that fuel table and adjust it.


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[T4RunnerSteve]

Thanks guys! Super helpful — I definitely need to pull fuel out of the map and this is good feedback on where to do it. I know some guys run multiple tunes on the AEM FIC6 - switchable via a toggle switch. Wasn’t sure if seasonality was one reason to toggle here. I definitely pulled timing (post tuning) to reduce knock to basically never (safety vs highest performance is my goal)

 

[T4RunnerSteve]

Totally different vehicle and setup but the exact same symptom:

Rough Idle in Warm Weather - Automotive | DSLReports Forums

And an explanation from another site:

Cold weather means denser air and leaner AFR's.

I've also noticed richer A/F ratios in hot weather. I originally tuned my A/F ratios in summer weather. I then found that in New England winter conditions I was running too lean under WOT. I retuned the A/F for cold weather but now I run too rich in the summer.

 

[gamefreakgc]

Totally different vehicle and setup but the exact same symptom:

Rough Idle in Warm Weather - Automotive | DSLReports Forums

And an explanation from another site:

Cold weather means denser air and leaner AFR's.

I've also noticed richer A/F ratios in hot weather. I originally tuned my A/F ratios in summer weather. I then found that in New England winter conditions I was running too lean under WOT. I retuned the A/F for cold weather but now I run too rich in the summer.

I was told to tune cars in the Spring, although my temperature differences aren't that extreme here, only a 50 degree swing from winter to summer. If you tune in that "middle" temperature, so for me 75 degrees, it'll be happy in summer or winter.

Most toggle maps I've heard of are to make a vehicle safe and "streetable". So one tune for stoich AFR's and conservative timing, and a second map for a richer ratio and aggressive timing.