Stock B20VTEC has very rich idle

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JDM_Ego
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Joined: Sun Jul 09, 2023 4:19 pm

Stock B20VTEC has very rich idle

Post by JDM_Ego »

I have a fully rebuilt B20VTEC, stock block, B16 head, stock injectors, Edelbrok performer x manifold, 70mm throttle body and a high flow fuel rail. Relatively light build. I tried a stock b16 base map, stock Integra type r base map and I believe even a GSR base map all of which gave me a 10 AFR reading. With throttle it goes more around 12-13 as I would more expect it to. I also noticed when I let off the throttle there seems to be a slight delay before showing the lean reading but that could be nothing as I’ve only got to drive the car for a few mins. I know it’s a base map and it’s not gonna be perfect and needs to be modified but what should I be looking at to fix the idle AFR and how should I got about adjusting fuel properly? It stays at the same idle AFR from cold start to operating temp. I messed with over all fuel and took away up to 29% over all and it made idle more around 12.2 but when I tried 30% it would go full lean and not even try to run. I don’t think that’s the actual way to fix the issue I was just trying to get a feel for how much it was over fueling but the drastic jump seemed off to me. Any guidance on how to get a manageable fuel map is appreciated. I know it needs a legit tune but for a stock set up I feel it should be a bit more straight forward to get a decent running tune in the mean time
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Spunkster
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Re: Stock B20VTEC has very rich idle

Post by Spunkster »

Do you have a wideband?
JDM_Ego
Posts: 13
Joined: Sun Jul 09, 2023 4:19 pm

Re: Stock B20VTEC has very rich idle

Post by JDM_Ego »

My bad man I never saw this response. But yes I have an aem wideband with the white wire going into D10 ELD with the resistors cut and my parameter is set to look for it at D10. I’ve tried a bunch of tunes and basemaps all of which do the same thing. It idles at straight 10 and if I slowly push the throttle down it stays at 10 but when I’m moving I’m around 12.5 - 13ish. I didn’t really touch ignition timing much but I did have to retard my distributor a lot just to get timing at the right spot
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Spunkster
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Re: Stock B20VTEC has very rich idle

Post by Spunkster »

It sounds like the injectors are flowing differently than what would be normal. You will have to try making fuel trim adjustments then fine tuning it in the fuel tables.
JDM_Ego
Posts: 13
Joined: Sun Jul 09, 2023 4:19 pm

Re: Stock B20VTEC has very rich idle

Post by JDM_Ego »

I’ve tried base maps as well as maps from the vault people had luck with with stock injectors and I’ve always had this rich idle. I was thinking about trying another set of oem injectors I think I have some lying around. When I adjust trim I take away about 25-30% overall fuel and it goes to like maybe 12.5 at idle and then 1% more taken away and it goes full lean and wants to die or actually just dies on me. And in the tables in order to get close to 14.7 idle I have to drop it drastically and raise it drastically for when I start putting a load on it
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