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I think I will need to put something in to help me see what’s up A/F wise when I get this project together. Personally I don’t like the flashy look of the stuff available but I don’t have the energy to design something more fitting to the car — 74 GTV. Here’s a few questions I need help with

1. Where exactly is best placement? Let’s assume I’m going for a single sensor (not two whic I realize would add extra discrimination). How deep into gas flow do I need to get the sensor tip but not impede flow too much? Stock exhaust on 74 GTV

2. For the sake of tuning, has anyone done a temp install, get the mixture set up, then remove it vs having it there all the time? I’d prefer to have a temp setup I think??

3 prices are pretty reasonable these days. Any kits recommendations/ for a permanent install how/where are you installing the gauge?

Thanks! The motor is waiting for some RJR cams.... vroom vroom
 

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When I got my car tested, Tom Sahines used an Innovate LM-2 with the adapter for exhaust mounting. So non-permanent mounting, you just stuck the sensor in the exhaust. Seemed to work okay but I don't own one.
 

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I have an LM2 and have used it on many cars. A bung welded 3-4 feet down the exhaust is preferred over the tail pipe adapter because the tail pipe adapter can be slightly off at very low rpm (ala idle). I liked it so much I put a bung on all my classic cars. I use a suction cup mount to install it temporarily (and tape the cable to the side of the car). Once I have my carbs dialed in, I remove the system from that car. I've lent it to friends for the same purpose, but with the tail pipe adapter. It's still working nicely after many years.

I would never leave it permanently mounted in a classic street car. On a race car , maybe I would consider a permanent install because of the cost of a new race motor ($15k and upwards).

John
 

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Three of us in the area sprung for a Zeitronix ZT-2 a few years ago. It has been a very good tool. The O2 sensor can be purchased at NAPA for about $55 to save a few dollars. Similarly, cabling costs can be reduced by shopping around or making your own. I bought the cable from the O2 sensor to the ZT-2 from Zeitronix however. With this arrangement, we only do temporary installs of course. Regardless of the particular brand you decide to buy, data logging capability is a requirement IMO.
 

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I have had a Zeitronix ZT2 in my Spider for about 5 years and I have posted many AFR charts from it in various threads. It has several extra inputs for rpm, EGT and some for linear voltage sensors. I always log rpm and AFR and for a while I logged EGT. My wideband sender is just after the final merge from the headers. I have replaced one sensor during my time of ownership.
I installed a Zeitronix ZT3 in my GTV6 with Megasquirt that I recently sold. When I first installed it I still had Bosch L-Jet engine management with the wideband sensor in the bung for the original narrowband. The ZT3 sent an emulated narrowband signal to the L-Jet computer. The ZT3 does not have the extra inputs for rpm etc.
IMO, rpm logging is essential for engine tuning and I would not consider a Wideband without it unless it was used with Megasquirt or similar which has its own data logger.
If you plan to dyno your motor then you can save a lot of time and money at the dyno by sorting out the carbs or fuel injection with the wideband ahead of time. In my experience there should be no need to tune AFR on the dyno and you can concentrate on tuning ignition timing, cam timing, etc.
I have the Zeitronix in the car at all times and it is very useful if anything feels a little different in the performance or driveability or fuel consumption.
 

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Ed
The only place I’d disagree is on the need for logging rpm. This is because I generally don’t mind glancing over at the AFR while
Driving and I almost always know my approximate rpm (tack is fairly accurate). If I had logging (I don’t), I’d put a throttle position sensor on my carbs (DCOE).

Carbs transition from one circuit to another over ranges of rpm so I don’t find a benefit to knowing the AFR per RPM more accurately than perhaps 300 rpm. Now, if I were doing EFI and Ifnition tuning then I agree that logging is really helpful and you want RPM, ignition advance, throttle position and MAP.
 

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Ed
The only place I’d disagree is on the need for logging rpm. This is because I generally don’t mind glancing over at the AFR while
Driving...
For comparison, analysis, and troubleshooting purposes, I completely disagree. Sure, if the only objective is to gain a general understanding of the AFR at approximate engine speeds, then the gauge is fine (although things can get pretty busy during wot runs). Perhaps the difference of opinion is due to different objectives or needs.
 

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John F,
You are a better man than me. I cannot remember exactly where the AFM is changing wrt rpm when the car is on the dyno and I don't have to look where I am going. I can only get a general impression which is nowhere near good enough for Weber tuning unless I wanted to spend an entire day at it.
 

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ZT2 data log

Here is a typical data log of a 3rd gear WOT run for my Spider. You can easily see where it is a little rich and where it is a little lean and you can then make an informed decision on what changes to make to the jets. In this case it might be going one step smaller on the air correctors. Then a repeat WOT run after the changes and you can carefully compare the AFR curves and decide what further changes to make. And you can go back and look at all of the other runs for different Weber setups and gain a good understanding of the effects of changes.
 

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For comparison, analysis, and troubleshooting purposes, I completely disagree. Sure, if the only objective is to gain a general understanding of the AFR at approximate engine speeds, then the gauge is fine (although things can get pretty busy during wot runs). Perhaps the difference of opinion is due to different objectives or needs.
Yup,
That is it.
you guys are doing tuning at a much finer resolution (higher performance).
I only use mine to get rid of obvious driving flaws. The data plots are really nice. Were i to do it again I'd get that ZT2 rather than the Innovate.
 

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Very happy to find this thread and the ZT2 recommendation. I have a mostly stock (motronic, 10548, 123 diz) SPICA car I'm setting up from scratch. I don't know what I don't know about AFRs and have gotten it running as well as I can using sounds/smells/plug-reading. I'd like to know more about the car. I do not have plans to race or otherwise modify the car heavily.

I would like something without a gauge and with phone, not laptop, connectivity and came across below PLX option, however it does not data log without additional software.

Very curious to hear you all weigh in on +/- of plain old realtime gauge, iphone gauge, laptop datalog for the kind of dial-in tuning I'm after. I presume Zeitronix means you MUST use a laptop?

 

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I have used both ZT-2 and ZT-3 units. If you want to tune your car at WOT then you must data log it. There is no way that you can watch the AFR, the tach and the road at the same time. If all you want to do is say verify that the AFR does not go above a certain number then you should be able to manage that with just the gauge readout on a road with no other traffic. In my experience 3rd gear is best for this and with a 4.1 axle 7000 rpm is around 80 mph.

I used the ZT-3 which is pure AFR in combination with Megasquirt engine management which logged rpm and everything else and it was easy to see the response to throttle and the AFR throughout the rev range.

I have a ZT-2 on my Spider which also inputs rpm and can input other signals. I monitored EGT for a while. I use it with a small notebook computer sat on the passenger seat to data log, and the free software allows you to see rpm and AFR on the same plot. This has been invaluable for tuning the Webers and evaluating exhaust system modifications. A splitter enables you to connect the gauge and the laptop at the same time. My ZT-2 is attached to the underside of the parcel shelf with Velcro. I also used Velcro on the gauge when I was transferring it frequently between my Spider and my GTV6.

Richard Jemison plans to use the Zeitronix logger with his ZT-2 in his Duetto race car. It will record the data to a memory card which can then be downloaded into a computer and evaluated using the same Zeitonix software. It costs about $100.
 

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So fair to say the ZT-3 does all of the above: dash gauge for incidental checking / monitoring over time, data logging for WOT tuning. How did you add RPM input, was that on an EFI car or have you added RPM on a MFI/Carb car?
 

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How much practical adjustment is possible with a Spica system?
Mixture is infinitely and very easily adjustable overall by screwing the fuel cutoff solonoid in or out.. There is zero adjustment by idle/progression etc available. However adjusting mixture is somewhat related to other things and SPICA's Thermostatic Actuator is known to die over time effecting mixture so keeping an eye on AFR is a way to keep an eye on SPICA internals.
 

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You cannot log rpm with a ZT-3 unless it is used in combination with an engine management system.
 

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The O2 sensor plugs into the Zeitronix box. This is the only input on a ZT-3. Sure you can log it but you will have a hard time interpreting it if you don't know the corresponding rpm.
The ZT-2 accommodates 6 additional inputs, one of which is rpm. You can then log any or all of them with whichever device you have connected to the serial output port.
 

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Thanks that helps a lot, i hadn't considred the value of AFR data without anything to match it to. Nice that the RPM can be logged off the coil with no add'l sensors:

RPM Input (tachometer, primary side ignition coil, crank, cam sensor).
The RPM input works in any car and any ignition system. No additional adapters needed!
 
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