how much fluctuation in afr is reasonable/acceptable in regards to part throttle (14.7) attached i have one of my latest logs and you can see that my afr is close, but jumps around at time. it seems pretty sparatic so i cant say ive pinpointed an issue. what do you all think?
If the car is in closed loop, the AFR will drift around a bit. I would be more concerned about getting the WOT AFR to match the commanded AFR. I guess you are in open loop.
Russ Kemp
yeah. I am in OL. Is that normal? If I go back to CL, should i enable both stft and ltfts or just one?
Nino, enable both if you are going closed loop. Leave LTFT off if you want to tune with STFT's.
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Thanks EC. I thought that if i enabled those two, it would throw off my afr?
If you're really happy in OLSD and things are running well, you don't really need to change. Closed loop just takes up a little slack where there might be some. Keeps things humming along at 14.7 once the o2's are in the game. Except when you nail it! hehehe
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the tune is off and im not happy. Id like to run the maf because the car does run stronger with it plugged in. I notice my throttle response is much better with it than in SD. The only problem is that the car wants to die pretty often. mainly when coming to a stop or when after each startup.
Try adding a little starting airflow (1 g/sec to start) and use the decay value (start with 80 cam counts) to decay it out later. That helped a lot of cammed car's I've worked on.
BTW: What is the fuel ratio like just after starting? Lean/Rich Hot start/Cold Start
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afr with the maf or without? with it, im not sure because i dont have a log of it yet. Once I get my ve inline, then i planned on getting the maf taken care of. as far as the starting airflow, what tables are those? startup airflow inital and startup airflow decay? what value do i put in the decay? .80?
AFR: Either one.
Startup Airflow initial +1 g/sec
Decay = .1 (slows the decay rate so it doesn't drop off rapidly)
Delay = 80
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each time i check the afr its different, but im usually 14.2-7 or at least i have been in the past two days after messing with the tuning a bit.
thanks again. these damn decays, delays, and follower/cracker stuff are still very confusing to me. Im trying to understand them more and more. I think i may have fixed my idle dipping issue using the cracker table. the dip didnt show up today, but the idle is still a bit bouncy. just a few 100 rpms. I did also do some RAF tuning.
Sounds like startup AFR is OK just need a bit more air to keep it running.
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ill get the maf plugged in soon so that i can post a log and try those tables out. thanks again!
If you are having problems in SD, sort them out there first. Then attack the MAF. The MAF won't necessarily bandaid problems with the SD mode.
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i know. thats the reason i havent moved on. I think im getting them sorted out though. Its just those slight fluctuations in afr while crusing. Ive been focusing more on the areas that i drive on a daily bases and idle. My mpgs are garbage and ive been trying to square that away first and foremost. Its my DD and gas in hawaii is expensive
By "slight fluctuations" how much are we talking? .1, .5, 1, 2 AFR's?
BTW: How much are they jabbing you for gas in HI?
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check out the log i posted in this thread. some points it will go up to 16.x, but not too often. other than that its about 13.5-15.3. gas is about 2.89 for 92, but when the car gets 11mpgs city, it adds up
The decel areas seem a bit rich on the average. I would imagine that varies a lot with the "environment". Eg. hot start after getting a cup of coffee, cold start in the morning, etc.
Yeah, I think it's time to enable CL without the LTFT's.
Here's a config I made up for "generic Gen III" applications without LTFT's.
You'll have to put in your AFR meter in place of mine.
Something else I like to do is turn the Long Term Idle Trims off until you have everthing stabil as well.
Attachment 625 Shows you how to turn off LTIT
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how do i go CL without my trims? i thought if enabled closed loop, i would have to have either short or long trims enabled wouldnt i?
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