A while back I added a PLX devices A/F gauge to monitor. I have gotten consistent readings from it. When all out on the throttle the reading go to 11 or 10.8 HOWEVER I took the car out this weekend and it goes past 11 (lower) and then the device flashes "rich".

I'm wondering what I should be checking. I've changed nothing on the car since adding the gauge nor has it been to the dealer and reflashed.

Could it be the plugs ?

 

It's that tune you have... <--- Sarcasm Everyone chuckle a little..........that's enough

When was the last time the plugs were changed and what are you using?

Might also want to look at the wires.

Tossing any misfire codes?

Is this only at WOT? What happens if you lift off throttle fast, get a rich reading then too?

What ever you do check one thing at a time and test. If you toss a bunch of fixes at it at once you won't know which one stuck.

 

im pretty nieve about this but isnt it nearly impossible to achieve stoic at all times?

 

using Denso IK22 - 20,000 miles
wires stock
I'll test the throttle lift.
no codes but will check

 

20K on the plugs is a lot IMHO

I'd start there.

Not trying to start any wars here....

I like the NGK BKR8EIX for our hotter climates on Modded cars.

 

this is the part number - correct?

ZFR6FIX-11

 

just as an fyi i was having problems with my denso's at about the 17k mark. I didn't have a wideband at the time to check... but after pulling the plugs the electrode's looked worn.

 

Don't think so...

I get these NGK-BKR8EIX from Sparkplug.com 8 bucks a pop. Usually order 8-12 at a time and change them like every 5k miles or after 4 track weekends, what ever comes first.

 

Temp changes can do this. The air temp map in the ECU normally removes fuel as the temps go up (less dense air), but there is normally a temp where it starts to add fuel back in to control detonation. So if it is hotter out, this could by why. Your AFR meter, what is the richest it reads?

Also if you have a vacuum leak in your system, the engine runs lean until the ECU corrects for it. This can make the long term fuel trims go way up, and these trims can carry across under full load, which also can cause a sudden rich reading.

On a number of occasions i have seen knock add fuel. Meaning the ECU hears knock and not only does it pull timing, but it adds fuel. Just a thought.

 

appreciate all of the input but I'm back in the Bahamas (car is in Miami) so the weekend coming I will study this further.

1) yes, temps have jumped up (Florida)
2) I'm going to order plugs as a first step.

will keep you informed

 

Show us your plugs if you take some pics Bart.

Good luck!

Jeremy

 

Plugs rarely effect AFR, unless they are really bad causing misfires, which you will feel and most likely the ECU will pick and throw a CEL. But i hope that if you are getting plugs, you might try some of the Brisk Silver plugs? I will make you a deal you can't refuse! they are just about the nicest looking plugs out there, and they do work!

 

Lets not forget to check the cleanliness of the air filter.

 

Stoic would likely blow this motor at WOT, wayyy too lean for an FI motor. The issue is that the car appears to be displaying "Rich" (AF's so rich it's reading past the intended design of the Wideband).

Have you ruled out issues with the wideband? If you really were going that rich the car would feel like it was hesitating when it happened.

FWIW I never liked Denso's. Just seemed cheap, I replaced mine with NGK's when I got my head at about 17k miles.

 

Appreciate the offer but I ordered the NGks so I would have them this weekend.

 

At this point I haven't been able to rule anything out . Clearly, its time I replace the plugs so that will be step one.

 

BKR7EIX-11 6988 NGK Iridium

 

As long as we're on the subject of AF (don't mind me Bart)...I've been getting #3 misfire code even after completely replacing coil/wire/and plugs...could it be injectors? I'm using 400cc. Occasionally, the CEL will also throw "bank too rich"...but the plugs looks perfect...

If I stop and reset the codes, the rest of the trip will be normal until I shut down the motor...then the restart would trip the codes which is a PITA to have to stop again and reset...

 

Sid, look for a vacuum leak.

 

I wish that was easy...vacuum leak = boost leak...

 

Ive been getting p172 codes with my 400m7's. I thought it was with my overboost code, but I have been getting just the rich codes while driving normally. Kind of weird, but they have been poping up while I have my AC on, and not with it off.

 

I get 172 bank one too rich along with 303 misfire #3...

 

I was getting that combo, before my head port and polish and new cam. so far the only code I have been throwin, is the 172. Pretty weird.

Before the head work, I was getting the same thing, 172 (rich bank one), 108 (overboost), and 303 (miss in #3). I then blew out a ngk plug, and needed to do some head work. I think that 303 is a BAD sign! but I cant confirm or deny. i'm up to NC for a rmw tune. Hopefully it will clear it up.

does it pop up under load or while cruising? Mine seems to come on while just cruising, with my AC on..........(makes no sense to me)

 

I would check a couple of things. There probably are misfires going on. This could be because of the 400cc injectors you have either running too rich, or being the wrong impedance.

First off the ECU is programmed for the OEM injectors, and anytime you increase the injectors beyond stock the car will run rich. The cars already run rich to start with so this just compounds the problem with getting rich misfires. Now, the ECU will remove fuel until it runs 14.7 AFR at idle and cruise, so your mileage may not change. But under full throttle and higher loads, it can run excessively rich causing misfires. If your ECU tuned for those 400cc injectors (which is great!) then you could be getting misfires from the injectors being the wrong impedance. If the 400CC injector resistance is different than stock, it will cause the injectors to need more or less "On-time" and this can cause issues with misfires. I have never measured the M7 400cc injectors so i do not know.

My experience is customers tend to just throw in bigger injectors when they are running pulleys and other parts, not understanding that they didn't need to in all cases. Not saying that this is the issue here, but truly it comes down to what the ECU is programmed for as to what injectors you should run.

We have a plug we built that allows us to put compressed air into the engine starting at the intake. This works great to find leaks, and something i would recommend most anyone to build. But you will quickly find that the inlet hose blows off the SC at about 10psi or so. But don't worry they all do!

 

im running a GIAC 19% pulley and 380cc flash. i didnt think the 400's would make that much difference, so you might be right about the resistance.