help with fuel compensation

Nistune topics related specifically to the 6303 cpu

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inifinity
 

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Joined: Fri Oct 05, 2012 10:51 am

help with fuel compensation

Post by inifinity »

RB25det s1 with z32 ecu type 2 nistune board with z32 maf. Changed maf in the options setting and clicked on adjust tp scalers. After I adjusted the K constant to deliver an adequate supply of fuel while on boost (checking AFR's with my aem wideband), I noticed that the engine starts to "hunt" for an idle. With the K constant where I would like it for boost, the idle revs from around 400-1400rpm which to me implies too much fuel in that area. The engine seems to run well with the multiplier where I have it set at aside from the idle hunting issue. Do I need to just "0" out the raw values on the low rpm part of the fuel map to fix this issue?

Also another issue I'm having trouble with is I have my BOV vented to atmosphere and I can't figure out how to compensate the maps for the extra fuel being dumped into the engine. I believe its under the TP min part, but unsure. Probably simple things that I'm just unaware of at the time, but if anyone can please help, would really help me out. Thanks.
Matt
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Re: help with fuel compensation

Post by Matt »

You need to plumb back the BOV. There is no adjustment available for the missing air which was measured but no longer there (because it has escaped)

With regards to idle hunting, this is normally the case when the RPMs fall below the target idle RPM table, so then the ECU increases timing to pull the idle back to normal

Have you tried adjusting latency to get AFRs back on track at idle? Does the 'TPS idle' indicator work as expected (turning off when touching the throttle). What are your AFRs at idle?
inifinity
 

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Joined: Fri Oct 05, 2012 10:51 am

Re: help with fuel compensation

Post by inifinity »

I'll make sure to plumb back my bov. As far as idle hunting is concerned haven't adjusted latency. All I have adjusted was changing the maf and letting it automatically adjust the scalers. I was under the impression after reading the Nistune manual that all I needed to adjust was maf setting and not the injector latency for a fairly stock setup. TPS idle works just fine as I've noticed. AFR's at idle are, according to my AEM wideband, under 10.

Update - I backed off injector latency and tweaked my K constant to get my desired AFR's. Idles at around 12 fully warmed up as opposed to the overly rich mixture before. At WOT I run around little over 11 AFR, do you recommend anything richer than that? Timing map is the stock map provided with Nistune.
Also, one more quick question, I seem to be reading knock as I see the knock fuel and gear maps highlighted at idle, but I'm quite sure that there's no knocking going on. I've installed the resistor in the ecu as per the instructions and done the mods to the circuit as recommended but still seems to highlight those maps. Knock timing comes on under throttle as well. What triggers the knock signal so I can narrow this down? What I've done to bypass this is replace the knock maps with the primary maps thus eliminating the knock maps. I know it's just covering something up and I'd like to find my problem. Thanks for the help.
Matt
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Re: help with fuel compensation

Post by Matt »

Around 11s should be fine to start with

Make sure you are using 0.12 version since 0.11.x versions had the knock indication backwards (bug)
User_Name
 

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Re: help with fuel compensation

Post by User_Name »

Matt wrote:You need to plumb back the BOV. There is no adjustment available for the missing air which was measured but no longer there (because it has escaped)

With regards to idle hunting, this is normally the case when the RPMs fall below the target idle RPM table, so then the ECU increases timing to pull the idle back to normal

Have you tried adjusting latency to get AFRs back on track at idle? Does the 'TPS idle' indicator work as expected (turning off when touching the throttle). What are your AFRs at idle?
Doesn't the z32 ECU have a fuel cut closed throttle option? Wouldn't that compensate for it not being so rich after it has vented? Could have sworn this was the "fix" to that uber rich problem when venting.
Matt
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Re: help with fuel compensation

Post by Matt »

You would have to try it out. Fuel cut/recover will cut fuel on deceleration within the specified RPM range when TPS is idle. You could try it if the rich condition only occurs within those ranges but usually it is best to fix the main problem rather than work around it
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