jeff5347

Ok so i have a few things i had ?s on and decided to throw them on here to get some clarification. I installed my WB AEM Uego a week ago. After driving streets, hi-ways, and such i have a good idea on where my AFR tends to go.
Driving to work on roads at 45 or slower the AFR reads between 14.4 and 15.1. This is with no WOT throttle.. maybe going to half throttle but thats it. On the hiway im in the same area of the 14.3-15.1. Once i let off the gas in any driving situation it shows way lean until i get back into it.
So the other night coming home i went down a long stretch of road and in 2nd gear went WOT. The AFR stayed again in the 14-15 range.

So basically im wondering this.. Is this too lean?
I thought going WOT put you in open loop reading off the MAF and richening up the mixture a bit for insurance on the engine? When i have gone open loop my AFR doesn't differ from granny driving.
Does the CAI make the AFR leaner and then prevent the computer from doing its job correctly.
Lastly i am trying to get a SAFC to richen it up to 12.8-13.5 as you guys state the VQ responds the best to this. Would dropping fron the mid 14s to 12-13.5 give some power gains?
I know this is a long post but im just trying to figure out why i dont richen up under WOT

Thanks

NmexMAX

iTrader: (22)

Where's your O2 bung, and is it AFTER any pre-cats? Pre cats have given me leaner than actual readings before.

What is interesting is that you are in the 'normal' range when 'cruising'.

Intakes (vs stock) make my car go a bit leaner (0.3-0.5) as I need to add fuel in order to compensate. But yes, if there are no pre-cats before your WBO2, that is fairly lean.

jeff5347

I have the WB about 3 inches before the Cat (replace that and have a test pipe long ago). Have stock exhaust manifolds which i think have the precats. I have no leaks with from the weld on the bung or the test pipe. Nmex from what i have read of your posts full throttle makes the VQ go to high 12s to 13s. Only time i get that is if i say rev the gas in park and it hits there after letting off the throttle but then returns to stoich.
Also i have noticed sometimes after starting the car, staying parked the car seems to run a little rough and the AFR reads in 16-17. Usually if i shut it off and restart it returns to 14-15. If i had bad factory o2s would i always have a code saying they are not working correctly?
Oh also i notice on warm days going up a hill putting a load on the car i hear a slight ping.. which i know is either to much timing, bad gas or not enough gas but that is when it is warm and the car is under a load from a hill.
I am just trying to figure:
1. Is everything working correctly as i have no codes
2. Will having the car run at the stated AFR be a reduction in power..
The car as it is pulls like a bat out of h$ll.. i have no cause for alarm as everything i have done gains me power but i am just wondering if i adjust to the 12-13 with the SAFC will it gain the engine more power?

In person im long winded with questions as well...most ppl hate this haha

NmexMAX

iTrader: (22)

My guess is that you're getting a false reading because of your precats.

Also about that lean start issue, how is your intake set-up? Do you have the PCV tube connected properly from your valve cover?

Our O2 sensors tend to fail in "fail safe" as in, when they fail, you will run rich, very rich. (i.e. dead O2 sensor = 10.0 AFR during normal operations when it should be 14.7 or so, etc.).


Get headers

Or, you can remove your primary O2 sensor, plug in your WBO2 and check the reading then. You may or may not have enough wire for that, but it's a fair verification, IMO. And, you will also only be seeing 1 bank.

MoncefA33

iTrader: (6)

for headers.

jeff5347

Well i had to leave a little while ago and when i started the car it did go to 11s-12s and then work up to 14-15. Never noticed it before maybe it doesn't stay there for to long. I would love to get headers but my finances (wife) dictate it will not be for a long while,...although the car will be paid off in december woot woot. So if i go to tune the car will i tune it incorrectly since as you state it might not be reading properly?
Yes, all pcv tubes are connected, from valve cover to intake and the one from valve cover to manifold with catch can in the middle.

Nmex, are you saying since i have no headers and the wb is right before the test pipe..that my reading of 14-15 is not even what it really is..

NmexMAX

iTrader: (22)

That's normal. Closed loop since the vehicle is trying to warm up the pre-cats so that emissions are reduced.

That's what my best guess is. I'm not too sure how pre-cats can affect it and if they do, but how much.

I know my AFR was off when i had my stock main cat in place (pre cats removed) because the dyno tailsniffer vs my WB before the main cat weren't correct.

Also, when I went to a test pipe, the 2 were the same (Dyno WB/Tailsniffer & mine)

jeff5347

is there a way to get rid of the precats minus putting headers on. I would assume it would get a corrected reading as well as freeing up the flow. Also just for giggles i put the 3"maf on (no driving) and at idle it reads the same..14-15. not gonna keep it on just wanted to see the AFR difference. i cant comment on driving AFR as i just sat in the driveway with it.

jowo9

iTrader: (1)

Yeah, you just-... Oh wait, no. Just headers. Just be patient and keep nagging your wife. That's what I did

P.S. You're kinda doing your mods a bit backwards don't you think? Usually people would at LEAST do headers before even considering a WB...

jeff5347

yea i know. Im gonna get the SAFC soon. So even if its another year before headers i can still adjust now. Then with headers i can adjust right then.

Nmex or anyone that knows...im gonna get it for this but oh well.... since you say my AFR is prob off due to the precats ..what about ..um... you know... umm...gutting the precats...
I have all the tools to get at them... or would that just be stupid to even attempt...

NmexMAX

iTrader: (22)

Its been done before and it will be done again. The headers provide a tubular design which contributed to their gains. But in your case you probably have a valid point. Sure, why not. Be sure and get AFR logs before and after.

jowo9

iTrader: (1)

^^ Your case is probably the ONLY one in which I'd suggest gutting precats... Just because you have all that stuff already.
The only problem is that by far the worst part of the header install for me was getting the old rusty stuff out! It probably took about 14/15ths of the total install time just to get those damned things out! If I were in your position though, I'd probably do it. Have fun!

jeff5347

ok so ill try this tomorrow. i have all day. i broke 2 loose already and they look like they were put on yesterday. hard to break but got them. if i can get at the rest i should be ok.

unfortunately i dont have a datalogger to post my AFR. Which sucks. i know everyone wants to see it but i have no means. i can post after its done what the afr shows. although it will be in words i will post what the difference is. Only thing i wonder after reading posts on gutting is the CEL. Ive read that getting anti foulers will clear the code. Will this be need in the o2s on the exhaust manifolds or in the y pipe. Why would the foulers clear the CEL?

knight_yyz

iTrader: (40)

you could take the precats out, go to an exhaust shop and ask them to make some custom pipes to replace the precats. Then you would have shorty headers.
Or you could fit 00-01 exhaust manifolds on the car and buy a y-pipe for a 00-01...

someone correct me if i am wrong

jeff5347

Ok so this morning i gutted the front precat....wasnt to much of a pain just need to break the nuts and bolts loose. Had to use a breaker bar on some. Gutted only the front as dont have time right now to do the rear. Had to loosen the y pipe connected to the rear cat and the 2 bolts holding the cat to the engine and it was pretty easy removing it. Got it back together and started it and it is a smidge loader but no to much or bad sounding. Now in idle (as i havent been able to take it for a ride) it r eads 16-17 afr. WTF If i rev the gas a bit it goesto 13-14-15 and so but at idle it is high. I was thinking maybe i need to retighten the bolts since i have let it run for a bit as it may be getting some air into the exhaust but in all honesty i can hear even a smidge of an exhaust leak. So now why woul it say a high AFR?

NmexMAX

iTrader: (22)

How's your intake set-up? Are you sure you didn't cause any airleaks up top (intake)?

jeff5347

^^^^^^ I know, its bugging me there has got to be a leak somewhere. I retightened the bolts i loosened. Ill check the intake i really didn't think of that part. The only other thing i can think of is where the heat shield bots on to the pre cat. i removed the heat shield and the bolts that hold it on go straight thru into the pre cat. I put them back on and once i noticed they did go straight thru i made sure i tightened them real good. So the only things i can think are causing a leak are like what you said, the intake or the bolts into the precat.

I noticed the AFR at idle would sometimes go to the 14-15 range for a bit and then go to the 16-17 range and move around like that. I drove it for a few miles and the AFR read 14.3 to 15.2 but it seemed to more active (not as steady) than before.

Damn, try to fix one thing and create more problems. And for any curious i dont notice really any power difference, so dont do this just for power gains.



PS: Ok so went out and checked the intake and no leaks. Retightened clamps and all things regarding were air could leak and nothing.

jeff5347

Well i was thinking about the AFR being wacky. NMex or anyone might know chime in and tell me if im correct. Since i gutted the precat the primary and secondary front bank o2s are getting the same reading. So tonight my CEL light came on which i was expecting. Would having the 2nd reading the same as the primary make the ECU just keep adjusting constantly searching to get them to read different?
Well im gonna get a anti fouler tomorrow and see if that will solve this. I assume it will as the secondary will be pulled away from the exhaust path and get a lower reading than the primary ...in theory...so we will see if this cures this. i read it will cure the CEL but will it cure the erratic AFR readings.?

ill post back tomorrow.

jeff5347

posting this a month behind but, i did add the anti foulers and have not reiceved a CEL light since. My afr hasn't changed. It swings between 13.9 and 15.5 at a steady cruise. That just stumps me. I guess on average it is around 14.4. Gonna get my SAFc tomorrow and hopefully i can richen it up and gain some power. Maybe my next mod will be the 350z injectors so i can lean it out down the road and gain back the timing i will be taking out. Only thing i have been wondering is i have a true CAI. It goes right into the fender before the front tire. Would a CAI lean the engine out? All i read is ppl doing mods and they get richer and richer and have to lean the engine and all the mods ive done seem to lean it out so i need to richen things up

dnice02

iTrader: (1)

So is necessary to tune after you gut the pre cats? Because i will be doing this tomorrow if it don't rain.

jeff5347

as far as i know no. My AFR has stayed the same since the before and after. I think... i think it is my SSIM that changed my AFR. Im not tuned right now but will have the SAFC tomorrow

CMax03

iTrader: (3)

your readings sound pretty good to me
cruise- 14.6-15.0
part throttle (initial) 13.5-14.1
part throttle levels out to 14.6-15.0
decel throttle lift- 15.0-21.0 depends on load b4 lift
WOT initial 12.2-12.4 for really hard accel
WOT 12.5-12.8 sweet spot

jeff5347

honestly that sounds smack on. Only one is the last 2 as i havent really WOT with the AFR gauge or been able to look at the AFR when it happens.
i think i was able to glance once and saw a 12.x
Ive also stumbled upon this
3)During light throttle/cruising, ie closed-loop 02 sensor feedback, the stock ECU targets 14.7:1, so 14-16:1 range is normal. Once you go WOT or make quick throttle changes to accelerate, you go open-loop and the ECU ignores 02s so you should see <14:1, however between 12.5-13.5:1 is best torque AFR supposedly.
http://forums.maxima.org/all-motor/349883-check-out-my-wb02-results.html

CMax03

iTrader: (3)

I use books as my reference about tuning and modifying EMS, not just anything I hear on this site.....you'll be surprised by the mayhem of "he said, she said" crap that floats around here! Believe half of what you read and still research that for the truth! I read alot about this cause man you can really cost yourelf alot of money guessing at this stuff especially @ 7000 rpm...