This has been an ongoing issue for weeks now. I recently got the car dynoed my AFR was in spec within 12.0-12.5:1. The SAFC settings are fine, they are not on the negative side. The O2 sensors are new, maybe 4,000 miles old. I keep on getting this 0115 code. It NEVER comes on when I go WOT. It only comes on when I'm IDLING, or close to idling.

It seems to be coming on quite frequently, atleast once a week. I'm concerned that I really may be running lean. The car runs GREAT, no issues at all, fuel pump is a Walbro.

I do have an exhaust leak between the y pipe and cat, nothing major though. I showed it to Tilley and it boggled his mind too so I'm counting on you guys for all help. I am very **** about my car and sh8 like this eats me alive. So I'm counting on you guys to help me get this resolved. Sh8 I'll even paypal you $15 !!!

 

Anyone know?????????????

 

How is the MAF? Is the manifold seated right? No intake leaks? Leaky injector? Any misfires?

 

MAF seems to be alright, no symptoms that I know of, what should I check for as far as the MAF goes?

Intake Manifold should be seated right as it hasn't been moved and it just recently started popping up.

Not sure about intake leaks, but don't have any since I don't have any idle issues, or starting issues, hold's idle just fine.

But I will have Tilley double check the IM and for vacuum leaks, and other suggestions? Thanks Kevlo!

And misfires hmm? At idle sometimes when I'm stopped the car does start vibrating a little like the RPMS drop 20-30 RPMS and it just start vibrating a little then just stops. Would you consider that a misfire?

 

Naa I doubt that is a misfire. As for the MAF, the best way to test is to swap with someone and see if the car drives any different. You are using the 00vi and I know the ports do not match up IIRC. It maybe be leaking.

 

Any idea what it might be if it's not a misfire?

I will see if I can get a spare MAF to test out, but the car does pull nicely, and drive fine. I'll have Tilley double check the IM to make sure there aren't any leaks.

I'm just starting to worry that I really may be running lean, although my AFR on the dyno was within spec for all motor, and I haven't made any changes to the car or the SAFC-II.

 

Where was the wideband on the runs? Try to barrow someones wideband and put it in each bank and see if the results are the same.

The idle thing is normal, most autos drop a few RPMs at a stop and vibrate. A misfire is more like a hiccup.

 

Is the AFC a new install? Try checking the wiring and make sure that the wiring is good and snug. Also...are you running the same gas that you tuned on?

I have had to stress to my wife that putting in the 'cheap stuff' is no longer an option with the car...and to put in a minimu of midgrade.

If you want to eliminate the tune...why not hookup the second AFC MAP as a baseline (no modifications)...and see if the issue goes away.

 

AFC was on before the dyno runs, afc has been on for quite some time.

The sniffer was in the tail pipe. Not positive if they used a wideband, I don't think so though, as they had a sniffer in my tail pipe.

 

Can you barrow a wideband? Make sure it is the kind that you connect to the ECU so it does not throw a code. Connect it to the front bank and then the rear and check out the AF. That will tell you 100% if a bank is running lean or rich.

 

....Here's a code breakdown from the '98 Nissan Max. Fac. Serv. Manual p.EC-219:

P0171/0115 (Right bank)

Malfunction is detected when:
<>Fuel injection system does not operate properly
<>The amount of mixture radio compensation is too large. (The mixture ratio is too lean.)

Check Items (Possible Cause):

<>Intake air leaks
<>Front heated oxygen sensor
<>Injectors
<>Exhaust gas leaks
<>Incorrect fuel pressure
<>Lack of fuel
<>Mass air flow sensor

Time for me to take a break from codes....

 

At idle sometimes when I'm stopped the car does start vibrating a little like the RPMS drop 20-30 RPMS and it just start vibrating a little then just stops. Would you consider that a misfire?
-somehow, can't explain why, I get the feeling that one of the coils might be starting to fail. Reduced spark intensity could change the output gases of one cylinder.
Test: Put the car on a diagnostic computer and examine the HT trace on the scope.

 

I will check to see if Tilley has a wideband with which he can check the banks.

My dilemma is, I was just dyno tuned maybe 1.5 months ago, my AFR was completely in spec 12.5 or so : 1. I haven't done any other changes to car so I don't see how the AFR would just change like that, but regardless I'll try to get it tested it out with a wideband O2.

Also, say I was running lean what would my AFR be ideally?