Running Rich or Lean? How to really tell?

[argniest]

Is there a device that I can buy to tell me if my 78 Z car is running rich or lean? I see people always talking about that. And I dont mind spending the money on a meter/device that I can hook up, stick in the tailpipe, etc to tell me whats going on.

Then I will have good data to post out here too as I work through the myriad of issues to get the car back to specs as closely as possible.

THANKS!!!

[5thhorsemann]

You can put a pyromerer in the header and use exhaust temp. to dial in the mixture. You will have to do some research to find your ideal goal temp. That is the cheapest way. The best way is to put the car on a dyno and have someone who knows his stuff speed tune the intake.

[madkaw]

I am installing a wideband O2 sensor and guage in my car. Google 'Innovate' for just one of the vendors selling these.

Yes there is a learning curve, and yes it is some money, but you will know exactly what your mixture is doing real time.

Just a thought.

[ChrisZ]

Read your plugs.

[Travel'n Man]

I agree with the plug reading - it it one of the tell all's that our cars will let us know - tune in those carbs and the plugs will look great - too lean or rich and the plugs don't lie............remember - the 3 front and 3 back plugs share the two carbs.

[argniest]

Yeah, I have been reading my plugs :-) They are dirty in #6,#5,#4, but #3,#2,#1 seem mostly like they are burning OK. I have electronic fuel injection of course in my 1978 Z car.

I took the plugs to my Z mechanic friends too. I am no mechanic, but learning a lot because of my Z car. Which is another reason I bought it. Its a great project to learn on.

Of course, there are 100 different reasons why a car is running rich or lean, but if I had a tool on hand. Then I can hook it up, and see in real time the data coming out of the exhaust (I am assuming that is how I can tell for sure)

I have some money to spend, and would like to get the kind of device that I can have on hand to do the readings myself. An electronic tool that gives me real time data during idling, driving, accelarate phase of the experience.

Just wondered if anyone had a specific brand model type that I should get.

Edited January 14, 2011 by argniest

[5thhorsemann]

http://www.autometer.com/media_newsarticle.aspx?yr=2007&mo=5&pg=1&aid=66

Check this out, might be the closest you will get to your search. I love the autometer stuff, tough as nails and really accurate.

[FastWoman]

If your engine is misfiring, then readings of almost any sort can be misleading. My engine was running EXTREMELY lean and misfiring because of it. As a result, my plugs appeared somewhat sooty, falsely indicating a rich running condition. I would think any misfiring could throw extra O2 into the exhaust and fake out an O2 sensor to read lean, even if the mix isn't lean. (I might be wrong about that.) I would think you need to be hitting reliably on all 6 cylinders for lean/rich metrics to mean much. Dunno.

Perhaps the easiest/best way is to experiment to see what your engine "likes." You can pop the cover of your AFM and manually move the vane farther open or closed. Figure out whether your engine wants more fuel (opening the vane). If so, then it's running lean. If the opposite is true, it's running rich.

Once you get your engine firing reliably on all 6, then the methods suggested above would probably be more meaningful.

[5thhorsemann]

The O2 sensor is also going to be affected by smog stuff adding fresh air to the system, thats why I like the pyrometer, exhaust temp is a great way to measure the combustion process, critical on forced induction motors.

The problem is, when you find a problem with fuel injection systems, you end up throwing cash at it. I love my carbs, you can basically fix any problems with a swiss army knife.

[madkaw]

Reading plugs and fiddling with adjustments to feel the difference, are all guesses ---that will work to an extent.

Check out some wideband O2 sensor systems and you take the guessing out. Many Z cars are losing HP because of inproper tune. Most people want to add on performance upgrades before they even get the car in 'perfect' tune------ask me how I know this.

Think about spending(wideband O2) 200+$ to ideally tune your car and maybe gain 15-20 hp and then price out some performance mods that will supposedly gain you HP. Build on a well tuned engine and everything you do later will be building on a well-tuned format.

[WW2Winger]

Are there models that have multiple sensors? Looks like you could put one sensor in one collector, one in the other and be sure the carbs are exactloy the same. I'm talking of course about headers. My headers just have one O2 sensor fitting so what would I do for another?

[madkaw]

There are wideband kits that allow 2 sensors running the same time to monitor dual type exhausts. I would think one sensor in your exhaust pipe would get you very close, like on the O.P. 78 which would be injected and have a single exhaust.

Mine on the other hand has 2 SU's and dual exhaust that would warrant a dual sensor set-up. I am just going to have 2 bungs--one in each header pipe-- and just swap the sensor over from one side to the other to get them equal.