lean spikes with ss afc.

J

jamesk

Member
:
mazda protege 2002
ok, i pretty much finalized my fuel map with my pacific set up with the ss afc, but i was wondering something.


some times the car will experience some spikes with leaning. for example, i will be driving normally everything seems fine. when i get into wot, sometimes the car does not want to go into open loop. sometimes the car will immediatly go into open loop and sometimes i have to let off because the air fuel ratios are not changing.

i also notice my air fuel ratios not being consistant. most of the times they are around 11.5 to 12.0, but sometimes id see a number of 12.5. only sometimes. all these problems happend when my car was NA as well, so it can not be my maps or the protege ecu's. the car did the same thing with the mp3 ecu and the msp ecu.

could it be my primary 02 sensor? since closed and open loop makes the switch over with the ss afc, do you think that could be the problem.

i do not use my IAT sensor. i didnt use it for my na set up or my current set up, i just zip tied to my maf sensor. so not using my IAT sensor, could that be the problem?

this stuff only happens occasionally so its kind of annoying. any input would help. im going to call ken if i can not figure it out.
 
So this happens when you punch it while cruising? Does it usually happen when you punch the throttle and your below 4K rpm?

If so, I was told this is normal/typical...cause the msp ecu stays on closed loop until 4K rpm...usually happens when the car is fully warm.

Let me guess.....from a cold start up, everything seems to react well A/F wise right? It could last 20 minutes or even hours...but say you stop somewhere shut off the car and 10 minutes later you get going again...the A/F are off...lean until 4K rpm right?
 
yea it happens when im driving then punching it. a dyno would not solve anything cause the car switches to open loop fine, but it only happens sometimes when i all of a sudden i punch it.

it happens before 4 k for sure. after 4 k, im deff. in closed loop

yea the air fuel ratios change similar to what your saying about shuting off the car and stuff.

when i first made the changes to the map, the car was running perfect, if anything too rich, but the more i drive it, the car seems to go leaner and leaner.
 
I always get open loop and closed loop mixed up....the msp ecu stays on one of the 2 until 4k rpm.

This happens with the Unichip but I've never heard people with a SS mention it before.

So when you punch it, it stays at 13-14 a/f until 4k rpm...then drops to 12's?
 
yea i guess but not all the time. its in consistant. i guess my question is how to make my air fuel ratios more consistant? is it the fact that im not using the IAT or having a bad primary o2 sensor or soemthing else?
 
Bump for you!

I'd really like to know if people running the ss afc with a wideband have consistent afr's?
 
the guy from split second said there could be something wrong with the box, but he does not think so because it does not do that all the time.

i told him about the IAT sensor and i have it dangling in the engine bay. he said that can play a big factor. so ill drill a hole for it in my intake piping and ill let you guys know what happens. thanks
 
Don't bother doing all that...just run it to the driver side frender. There's a harness goinf in the hole...you'll need to extend the wire but I've had mine zipped tide there for years. It reads colder air...compared to engine bay.

You risk a vacuum leak if you drill it and plug it to the intake. Vacuum leaks after the maf hurt performance.
 
I've been running a V1 since 04'. I can honestly say that I experience the same exact issues you do. Rpm seems to play a role in how quickly the afc takes over. If you whack it open at 2800 rpm, watching my wideband, it hovers around stoich for a while, drops into the 12s and then hits my target mid 11s. This process is even more delayed when the temp is colder. My afc is way more consistant in the summer than the winter. I've checked to make sure that my O2 clamp is working properly as that is what helps it go into open loop quicker, and it is. I really think its just the nature of the beast. The annoying beast! I've countered my leaness going into boost w/ meth injection and it loves it.
 
so staying in stioch for a few extra seconds is not a big deal or is it? i feel it is but i want your opinion
 
We have the same issues with the Unichip... actually, we're having more of the issues since we don't use the clamp.

One thing a friend brought up in our conversation is the nature of the O2 sensor. I don't know if ours are, but for those of you who do: (yes, that sentence was a mess...) are our O2 sensors heated or unheated?

Basically, a heated one is the three-wire one, that doesn't react to the cold, the heated one is. He suggests changing to a heated one, which would keep O2 readings consistent from hot weather to cold weather. Apparently, the air blasting on the sensor from the radiator plays some part in the erratic open-closed issue, but we've yet to look at the sensor. This could help explain why things are different in cold driving and in hot driving conditions. A sudden blast of exhaust at WOT brings the O2 back up to heat, but not right away, causing the delay in closed-open switching.

Whaddaya think?

----

Oh, and PS... I prefer having the IAT sensor in the intake... just stick it in before the MAF... the cooler intake air pushing past it makes it run better than if you have it tied off somewhere in a cooler part of the engine bay. Moving air cools better than still air. ;)
 
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yea that can deff. be a issue with the hot vs. cold. thing.

the way the ss afc makes the switch between open and closed loop is based off the primary o2 sensor. i think your on to something niky.
 
The heat from the engine will after some time give you a cell. Which means the afc will pump more fuel at idle. I placed my iat after the filter. There is a lag in the wide band reading the AFR. My wb probe is on the DP almost to the bottom.
 
Okay... checked. Four-wire. Back to square one. :(

We're working on the second O2 sensor right now... still thinking about disconnecting the primary.
 
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