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Discussion Starter #1
running hondata
software:2.6.6.0

vehicle:95 honda civic coupe, d16zc sohc non vtec. boosted vitara+rods combo

ecu: po6 with hondata s300 v3

things which may affect ecu: battery relocated to trunk, aem wideband hooked into d10 eld. running bkr7e's plugs

specific problem: car was tuned and ran nicely for about 2 hours.... then it slowly started to lean out to the point where the car was idling in the 15afr's and light cruising in the 16-17 with what felt to be a misfire. however it would run with a decent afr if holding the throttle steady, but any throttle movement would instantly bog the motor and afrs would lean off the charts. the kicker is it really only seems to do this once the car gets up to operating temperatures.

running bkr7e's gapped to .026thou, new cap and rotor, new iacv, new tps thats been calibrated, changed plug wires, fuel pump was brand new with less than 60 miles on it, injectors are also brand new, fuel line has been tucked which could cause fueling issues?, adjustable aem fpr and gauge reads 47psi at idle. swapped to oem honda fpr and problem persisted. im feeling like its a fuel or spark issues, related to something being heat-soaked, but i'm not ruling out any and all possibilities. i finally finished my build after a year, and all i want to do is drive this thing but it is currently undriveable in this condition.

i have a copy of my calibration and a few datalogs showing the problem but im not sure how to attach them to this post.
 

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Meat Popsicle
91 CRX Si
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2,936 Posts
Weird. I’m having the same kind of issue with my AFRs leaning out at idle after I’m warmed up too. I’m using turboedit though.

I have a conservative IAT ignition compensation configuration that will pull 1 degree of timing at 140F IAT but I don’t know if that would cause a lean idle.

Do you have any IAT or ECT compensation configured for fuel or ignition?

I know my walbro fuel pump kit doesn’t pick up well when the tank is below about 1/3 tank. Is your pressure fluctuating at idle?

Have you monitored/datalogged the injector pulse width at cold idle and at hot idle? That was the next troubleshooting step on my list. May be worth monitoring the ELD voltage too and checking to see if you have any ELD compensation configured since the radiator fan may be on while the issue is occurring.

What kind of injectors are you using?
 

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Discussion Starter #3
Weird. I’m having the same kind of issue with my AFRs leaning out at idle after I’m warmed up too. I’m using turboedit though.

I have a conservative IAT ignition compensation configuration that will pull 1 degree of timing at 140F IAT but I don’t know if that would cause a lean idle.

Do you have any IAT or ECT compensation configured for fuel or ignition?

I know my walbro fuel pump kit doesn’t pick up well when the tank is below about 1/3 tank. Is your pressure fluctuating at idle?

Have you monitored/datalogged the injector pulse width at cold idle and at hot idle? That was the next troubleshooting step on my list. May be worth monitoring the ELD voltage too and checking to see if you have any ELD compensation configured since the radiator fan may be on while the issue is occurring.

What kind of injectors are you using?


attached is a screenshot of my fuel and ignition compensations at their respective iat and ect's. [running in open loop(closed loop disabled)]

i thought about the possibility of the fuel pump not picking up fuel, or that i had installed the sock upside down, but regardless of how full my fuel tank is i seem to run into this issue. no fluctuating fuel pressure at idle, but definitely considering a fueling issue at this point. i can get it to idle rich if i adjust fuel pressure up past 50ish psi, but it doesnt affect those cruising afr's.

i have been pouring over datalogs from when the problem isnt occuring versus when it is, just looking for dissimilarites between the two, however i dont have any knowledge of what "normal" figures are for things; specifically injector pulse width. ive really only been focusing on my fuel maps for the time being.

running rc 750cc injectors
 

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Discussion Starter #4
i do have some iat and ect corrections, i would post images but i cant seem to figure out how, probably because i dont have enough posts to post images?

sorry for the long response time, i posted a couple days ago, but it didnt get posted for some reason.

ill try doing a comparison between cold and hot idle, thats a great idea.

im running rc750's,
 

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Meat Popsicle
91 CRX Si
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2,936 Posts
You can uplod them to Imgur and embed them with the direct link using that little picture icon above your post.

Are you pulling fuel or timing as the ECTs or IATs increase?
 

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Meat Popsicle
91 CRX Si
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2,936 Posts
Wow that’s a heck of a lot more options than turboedit has. Kind of overwhelming to be honest.

Some of those ECT fuel enrichment values look kind of high (high load, 168 degrees, 14.8%) but I can’t imagine youd actually be at that temp for very long.

Hopefully someone with Hondata can chime in. I think the before/after datalogs will be telling and will hopefully point you in the right direction. I plan on doing the same thing tonight.
 

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Discussion Starter #12
negative. i had enough and dropped the car off at my tuners shop last week and am letting them fix it. this one is outside my knowledge to diagnose.
 

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Meat Popsicle
91 CRX Si
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2,936 Posts
That’s good. Mine ended up being the result of using saturated injectors with an OBD0 ECU and not being able to tune for the latency when the voltage dropped.

I suspect yours may also have something to do with the injector latency/dwell/dead times.
 

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injector dead time has to be changed to match your new injectors. every maker has different dead times for different sizes. GL
 
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