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Discussion Starter #1
I have a D15 mini me which was tuned on a dyno with wideband lambda sensor. Now I run without the oem lambda sensor. Mine is dead and the tuner said I don't need to change it.

Now it's winter and the car still runs fine but the last couple of days outside temperature fell to ~5 degrees fahrenheit and starting the car was a problem. I managed to start the car only by pressing the gas pedal then I had to keep the revs up for a minute or two and after that it was fine. The strange thing is that day I got a CEL too. It was error 10 - intake air temperature sensor. When temperatures outside raise to ~32 degrees fahrenheit I had no problem starting the car and the CEL disappeared.

So to fix the starting up in very cold days do I have to change the IAT or do I have to hook up a working lambda sensor ?
 

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EG8
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IAT should have nothing to do with it.

Do you have a chip? Or a neptune/hondata.

Based on the little info, I'd check ignition timing/base idle air. Did the tuner set ignition timing when he tuned it?

Could be cranking fuel trim/cold start adjust.

I'm also assuming the battery is fine, car turns over fine. All the relays are clicking and etc because you haven't brought it up.

I also pause for the main relay to shut off before I start the car.
 

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Discussion Starter #3
I have a P28 with a chip. Ignition timing is fine, set by the tuner with ignition timing light. Battery is fine too and all the relays.

As I understand it the ECU should enrich the mixture if the IAT reports low temperature. I think I'll change it just in case. But the problem might be elsewhere.
 

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EG8
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Damn too bad. You can adjust cranking fuel trim if you did.

Hondata IAT values:


That would put you right in between column 2 and 3.


But you may be right maybe? (I'd say that O2 might not even be working at that point, It would still be warming up) We never get below 40 here really, so no IAT adjustment (=unplugged) is perfect.

According to this post: 7th Gen Honda Forum - The #1 Community for 2001-2005 Honda Civic Enthusiasts - View Single Post - Kpro Cold Cranking - Post 33 - Interesting discovery.

But according to above, you should experience this on a wider range of temps... hmm.
 

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Discussion Starter #5
So I should rule out the lambda sensor, that's good to hear. I'll try with a new IAT sensor and if it doesn't help seems like the only one who can fix this is the tuner.
Thank you for your greatly detailed posts.
 

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Most tuners will do the bare minimum to impress the customer.

Usually including WOT and warm idle and thats about all they can be bothered with.

Their time is oh so expensive, you should be thankful they even market their service.



In reality I find the cold regions to be overly rich and under advanced.

This is why I REALLY hate Neptune "New Injector Size Scaling" because it royally fucks up all the trims.

It multiples by the ratio difference all trims. This means all trims are *.60 or what not, meaning I need almost double the change to see any result. This effect is compounded and can result to a very dirty tune.

He also does not properly factor in cranking trims and how this effects post start trim,.

James is an arrogant man that will not explain outside of what he sees as necessary. He does not provide adequate documentation to fully utilize his functions or describe how fuel values are calculated.

The Accessibility to many of the functions are so improperly sorted that tuning becomes a hassle rather than a process.

As such I will never recommend his product again, unless I see him pull his head out of his ass.

He's shooting himself in the foot with something that could (ve?) be great.
 
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