Air fuel gauge help

[rgafitanu@gmail.com]

I would greatly appreciate if somebody can help me borrow an AF gauge/meter. I am trying to set the mixture correctly at all speeds and my only check is the color of the plugs. So I have to wait a couple of days between adjustments and, of course, if I adjust the barometer, the idle goes out, etc. The only shop nearby wants 1 hour of labor every time they hook up the gauge.
I will, of course, pay for the shipping and security deposit.

Thank you,
Radu

[wwheeler]

Hi Radu,

Sorry I do not have one to lend but have a question. If you want to test the mixture at all speeds, how does the local shop test that without a dynometer as well? Is it a mobile set up? I am wanting to do this someday and am curious.

[rgafitanu@gmail.com]

It is a mobile setup with a sniffer going into the pipe and you drive the car while reading the results. I do not trust them too much because these guys are disfiguring Honda Civic's and Subaru WRX and calling them race cars.
I was trying to get a Gunson colortune but they are out of stock everywhere.

[Shvegel]

Gunson colortune won't help unless you put a camera under your hood.  Not sure if they are designed to hold up to a fully loaded engine.

[Cees Klumper]

Aren't there meters available for not that much money, where you weld in a lambda sensor in the exhaust which would allow you to monitor air-fuel ratio? On Amazon, complete sets for less than $200.

[rgafitanu@gmail.com]

I too, fear that the color tune may not hold under load. I was hoping not to make a permanent setup although it may not be such a bad idea considering how capricious are these injection systems.

[AllenF]

This is what I installed, seems to work well. 

https://www.amazon.com/gp/product/B00N3VGPYS/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

The only hassle was welding the bung into such a tight spot, and of course, if the front 3 cylinders are differing than the rear 3....

[rgafitanu@gmail.com]

Where do you weld the bung? I would drill and weld downstream of the down tubes so I can have room for drilling and welding around.

[mbzse]

Where do you weld the bung?.../...

I welded mine on (one on each downpipe) with exhaust pipes off the car.
Second picture shows broadband Lambda sensor installed. Display device is inside the car, to be read continously during driving.
Sensor instructions say to install at least 30cm behind exhaust manifold

[wwheeler]

I will have to remove the exhaust on my car at some point soon and am considering such a device. Since this is dual exhaust (sort of), I understand you having to use two sensors at the head pipes. Does the meter allow two inputs?

Could you possibly put as far back as behind the first muffler and just use one? I am pretty sure inside the muffler, the two pipes mix and are not completely separate.

Thanks.

[mbzse]

.../...you having to use two sensors at the head pipes. Does the meter allow two inputs?

One does not have to put a bung on both downpipes... I chose to do so, in order to be able to monitor all six cylinders. However, the device I have reads one Lambda sensor, so, I must switch the sensor over to the other bung to cover all six cyl.

Could you possibly put as far back as behind the first muffler and just use one?

I guess so...   However, that is a lot of distance inside the exhaust pipe, exhaust temperature drops etc. I am unsure how this affects readings; better ask manufacturer to obtain more info about the matter.

[Cees Klumper]

Hans - is the switch-over from one sensor to the other accomplished with an actual (electric) switch, so that it's really easy to do? Or is it more involved? I'd be inclined to go the route you took.

[450sl]

These sensors like to get electric power for heating otherwise they go down quickly.

[mbzse]

The switch-over (in my case) involves lifting the car, remove lambda sensor from the one exhaust pipe and put plug in, remove other plug and mount sensor there on the other downpipe.
However, I usually use only one pipe; the second is for verification purpose only.

Once one has done adjustments to FI pump, ignition  etc and one is satisfied with the running of the engine (and the measurement values shown on the display) both bungs are plugged, and instrument is taken out of car. Say, after a weeks time or so (daily driving).

[rgafitanu@gmail.com]

Is there a cross over chart between air/fuel ratio, lambda, CO% or CO2%?

[450sl]

hereyouare

[rgafitanu@gmail.com]

Is this still rich?

[jeffc280sl]

Using an air fuel ratio sensor is relatively simple as is adjustment of the afr at idle.  Once you move into measuring afr on the road things get very complicated.  The BBB offers owners an on road dynomomter specification at two rpm ranges.  The rpm spec is accompanied by a manifold air pressure specification.  Once you achieve the rpm and map specs you can read afr.  This again is prettry straight forward.  Unlike the idle afr setting the the FIP to the dyno specs is very, very complicated and involves adjusting the white and black screws on the fip.  Unless you have many hours of testing and tuning available and a high frustration tolerance I suggest you send your pump to be calibrated.

Before sending the pump off IO would check everything else.  Ignition and the barometric compensator come to mind.  Look at my lengthy posts from 5 years ago for more info.  I think I put some details in the tech manual