Wideband AFR readings?

[Mysterio]

I'm wondering if my car is running proper AFR by reading my wideband and I'm not really entirely sure where the readings should be.

It seems usually at idle I'm between 10.2-10.8. Full boost it seems to be at 12.5

But sometimes when I'm idling it will be at 10.0-10.2. Just regular cruising as I accelerate and press on the gas when the boost gauge is at around 10'' vac I'm at like 11.5 afr ratio. As I get to 0 I get to about 13-14. Then it goes back down to around 12.5 and settles there until full boost. It seems to randomly read richer or leaner and is never 100% consistent. BUT when it goes richer or leaner it will stay that way usually for a little while. So it's not just randomly going lean, rich, lean, rich.


I'm not entirely sure where it should be at during idle, light cruising, light acceleration & at full boost. Are these readings about right? It seems to be running great now that I got the O2 sensor hooked up right and it's not running COMPLETELY pig rich. But isn't 12.5-13.0 too lean for 15 lbs of boost?

My car is an 87 shelby charger. Mods:

+40's
3bar map
stage5 cal from FWD P
walbro 255 fp
accufab afpr
spearco fmic
4 wire o2 sensor
12* timing (if that matters)
stock fuel pressure

Also. Due to not having the port for my charge temp sensor it's not plugged into the intake manifold right now. I have it sitting ontop of the fuel rail area. Will this cause fuel ratio problems? What exactly does it do? Is it possible for me to temporarily tap the charge temp sensor into my charge piping right before the throttle body? Will that still work or does it actually need to be right in the intake manifold? I'm not sure of how it adjusts fuel ratios or not but I would imagine the air inside the intake manifold would be warmer than normal beacuse of the heat from turbo/exhaust manifolds.


Anyways. This is a pretty long post but I'd like to make sure I'm not lean too rich before I blow something up because I lean out. I thought I remembered reading 11.7-12.0 was where I wanted to be under full boost but I can't remember. Thanks in advance to anyone that can help

[BadAssPerformance]

I would definitely get that air temp sensor in the air stream somewhere, even if it is in an easier to install than the intake manifold location such as the IC pipe ahead of the TB. That sensor needs to be used to be 100% correct.

With that said, the ambient temp out (you're in OH?) should currently be a little cooler than the charge air temp in your engine so having the sensor outside would make it run richer. This may be why it runs richer at idle? But on the contrary if you put the sensor in at WOT you will run leaner which is not good!

The 12.5:1 A/F is absolutely as lean as I would go in one of these cars if you want it to last a while. And I would say that is VERY lean at 15psi. You want it to be ~11.5:1 at WOT in a turbo car.

You did not mention cam timing or plugs... I would make sure the cam timing is dead on and make sure you have colder plugs in like teh RN9YC's

So the checklist...
1 - check cam timing
2 - install colder plugs
3 - charge temp sensor
4 - drive car carefully watching A/F closely and lifting if it crests 12.5:1 at WOT to confirm if any of this fixed the leaness of the cal
5 - get a new cal with more fuel in boost at WOT

[Mysterio]

I would definitely get that air temp sensor in the air stream somewhere, even if it is in an easier to install than the intake manifold location such as the IC pipe ahead of the TB. That sensor needs to be used to be 100% correct.

With that said, the ambient temp out (you're in OH?) should currently be a little cooler than the charge air temp in your engine so having the sensor outside would make it run richer. This may be why it runs richer at idle? But on the contrary if you put the sensor in at WOT you will run leaner which is not good!

The 12.5:1 A/F is absolutely as lean as I would go in one of these cars if you want it to last a while. And I would say that is VERY lean at 15psi. You want it to be ~11.5:1 at WOT in a turbo car.

You did not mention cam timing or plugs... I would make sure the cam timing is dead on and make sure you have colder plugs in like teh RN9YC's

So the checklist...
1 - check cam timing
2 - install colder plugs
3 - charge temp sensor
4 - drive car carefully watching A/F closely and lifting if it crests 12.5:1 at WOT to confirm if any of this fixed the leaness of the cal
5 - get a new cal with more fuel in boost at WOT

Ok that's a lot of good info that I will work on. I wasn't sure If I could just put the temp sensor into a charge pipe in front of the TB or not but if I can i'll definitely do that for a temporary fix until I can get my new intake manifold on. I checked the cam timing a few months back and it seemed to be right on (As far as I could tell, never had to check cam timing like you do on these cars before). I haven't noticed a difference since then so I'd think it's still the same.

Also if I remember correctly I bought RN9YC champion spark plugs. I'm pretty sure that is what the part number for the spark plug was.

And yes. The weather out here right now is fairly cold.

[Reaper1]

Where is the WB sensor located in your exhaust?

It seems to me you are running WAY rich idling and kinda lean while in boost. That's strange to me. I wonder if your O2 sensor is working?

Check your codes to see, but from what the WB is doing I don't think it is. Something just seems out of whack to me.

Also, what brand WB are you running? you may be able to use an anologe output to the stock computer and get rid of the NB O2 all together. That *may* help.

[mario03SRT]

If you have an Innovate WB be sure to do a free air calibration of the sensor.

The car must idle at or around 14.7. At a 10.5 idle afr you outta be gagging on fuel fumes.

Check your map sensor connection too.

FYI,
Marion

[cordes]

Getting the charge temp sensor installed properly will make a huge difference in the fueling. Follow JT's list and report back.

[GLHNSLHT2]

10.5 is flooding the car at idle

[Mysterio]

Ok. I'll check through everything you guys said. I'm going to tap a hole in the intercooler piping right before the throttle body and install the intake temp sensor there. I'm fairly confident the o2 sensor is working. I just hooked it up *properly* a few days ago and noticed a difference in afr readings afterwards.

The smell of raw fuel is immense while driving and idling :P BELIEVE that lol...

It is an autometer cobalt wideband gauge. The installation instructions didn't mention anything about a free air calibration.

I'll double check the codes and see what codes I'm throwing and work from there too. Thanks. I'll keep everyone updated.

[cordes]

If it is running that rich consistently at idle, I would not drive the car unless absolutely necessary. You will wash down the cylinder walls in a hurry.

[Mysterio]

If it is running that rich consistently at idle, I would not drive the car unless absolutely necessary. You will wash down the cylinder walls in a hurry.

I've been driving it this way for like a year lol.....

[cordes]

I've been driving it this way for like a year lol.....

Well, I guess there isn't any real hurry at this point then.

[BadAssPerformance]

10.5 is flooding the car at idle

True... I don't know why a cal would be that rich at idle I would not get crazy but at idle with no boost it can be 14:1 or higher w/o issue

[GLHNSLHT2]

my car idles at 15.2 with the stock O2 and 16.0-16.3 with the wideband controlling things.

[Reaper1]

hmm..well, I was wondering how high I could make the switch point on my LC-1 for the second anologue output. I suppose I'll aim for about 15.3-15.6. Mine is always around 14.5-14.8 at idle on the WB. I have yet to hook up the WB to the computer to control the car...I have to hook it up the my laptop and tune in the other output first.

BTW, I'm running a similar set-up:
FWD S5 cal
+40's
Accufab FPR
255 pump
3" exhaust
stock engine

My fuel pressure is at 45# static and my WOT WB reading was 10.1(but that's with the meth-injection on). There is definatly something not correct if it's idling THAT rich...

[CSXT802]

bad coolant temp sensor.?

[Mysterio]

bad coolant temp sensor.?

I was attempting to set timing once and when I would unplug the coolant temp sensor the car wouldn't keep itself running w/o giving it some kind of throttle after i unplugged the sensor. Does that mean anything?

[CSXT802]

I was attempting to set timing once and when I would unplug the coolant temp sensor the car wouldn't keep itself running w/o giving it some kind of throttle after i unplugged the sensor. Does that mean anything?

If the coolant temp sensor is out of range it can cause a rich condition. The sensor could be telling the ECU the motor is cold when it's not. I'm just about sure it will keep you from going into closed loop.

[cordes]

I was attempting to set timing once and when I would unplug the coolant temp sensor the car wouldn't keep itself running w/o giving it some kind of throttle after i unplugged the sensor. Does that mean anything?

That is normal. When you unplug the coolant temp sensor it pulls all timing, and kicks on the fan etc. All the tables will revert to the limp mode for a bad coolant temp sensor. You can test yous by first pulling the codes, and then you can use a multimeter to measure the resistance between the two posts on the sensor. I forget what it is supposed to be for a given temp though.

[Mysterio]

I had no idea my car was running as badly as it is lol. I had no idea I was supposed to be running 14.7 at idle.

On cold startups the car leans out at like 15.1 but runs really rough for the first few minutes until it warms up some then richens up and runs better lol.

And for whoever asked before. The o2 sensor bung for the wideband is about 1-2 feet back from the turbo on the downpipe.

[MiniMopar]

Mine bounces around 14.5-15.1 while in closed loop, idle or otherwise. The ECU is looking at the narrow band sensor and trying to bounce around 14.7. Cold start or WOT it tends to run rich. At WOT you want 11-12 as JT said.

You are running the 255 pump at stock pressure. Have you verified that when in vacuum (at idle), the FPR is able to drop the pressure correctly? It should read around 45psi at idle with the vacuum line connected. Often the FPR/return line can't flow enough to keep the pressure correct when using that pump. YMMV...some people can get away with it, some can't Personally I think it is a matter of how bad the wiring is to the pump (big voltage drop = lower fuel flow), but who knows.