CO Meter

[PandA]

Happy Thursday everyone!

To properly tune supposedly we need a good CO meter. Does anyone have suggestions? I know I am further proving the point that the cheapest part in the car is the organic thing in the drivers seat; but ~2k for a gas analyzer! Yikes!

Could we fudge it with a WBO2?

Andrew

[walt]

Gunson makes a test meter for under $250.00 but I don't know how accurate it is. Check out this thread for setting your CO.

Setting mixture without a gas tester

Walt

[diy83sc]

@PandA, if your car is an SC, you can adjust mixture with a Dwell meter. Search the 911 technical forum for the word "dwell" under username "psalt". Reason for not pointing you to a single thread, there are many threads psalt commented on explaining what aspect of the mixture is being adjusted and how to do it with a dwell meter.

[theiceman]

I borrowed a buddies old LM-1 even output an csv file and did capturing . it was great , id grab one of these in a second if I could get one at a reasonable price.

[jjeffries]

Another path to the same objective is to install a wideband O2 sensor and gauge, which lets you always see how things are adjusted and functioning, and not just at idle . That's what I did in my 82 SC. The AEM gauge I used provides an output that you can connect back to car's KJET computer to control the frequency valve (replacing the signal sent by the original, narrow-band O2 sensor). I bought the AEM kit (wideband O2 sensor and gauge) plus a mount for said gauge, from Summit, maybe $250 all told. Best of luck, John.

[theiceman]

Originally Posted by jjeffries

Another path to the same objective is to install a wideband O2 sensor and gauge, which lets you always see how things are adjusted and functioning, and not just at idle . That's what I did in my 82 SC. The AEM gauge I used provides an output that you can connect back to car's KJET computer to control the frequency valve (replacing the signal sent by the original, narrow-band O2 sensor). I bought the AEM kit (wideband O2 sensor and gauge) plus a mount for said gauge, from Summit, maybe $250 all told. Best of luck, John.

How accurate is the gauge John and how much does it fluctuate around ? are you happy with the purchase ?

[Gretz]

John, I'd also like to know which sensor and gauge you bought and your experience/satisfaction. Can you give us some more info please?

[theiceman]

https://www.summitracing.com/parts/avm-30-4110?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-aem-electronics&gclid=CjwKCAjw4uXaBRAcEiwAuAUz8OhtpCZx3f4XoSBvc2I8 DYQdaFTFR74QWfT0LvXIh-p31i58_4iK7BoCPE0QAvD_BwE

[Tippy]

Innovate MTX-L, 14point7, AEM all make WBO2’s with displays

[theiceman]

i have heard innovate are unreliable and break quickly leaving people disappointed. This is why I asked if he was pleased.

[OldSpool87]

The AEM fails are is a nice unit. It has a data logging feature which does not require extra hardware. Everything is contained in the gauge.

[jjeffries]

Ice,

Here's a good thread to review:

AEM Wideband O2 gauges

My AEM gauge and wideband sensor package is AVM 30-4100-UEGO. That was three years ago, so the p/n may have changed by now. Then it cost $197 from Summit.

I got (also from Summit) a metal universal gauge pod ATM-2204, cost $20.95 (what you'd call a "HIGH gross profit margin part", but at least it wasn't plastic).

My SC's clock works, accurately and I think it's cool so I didn't want to put the gauge there. Instead, I mounted on my A-pillar. Yes, that meant drilling two little holes in the car. It works well BUT is far from perfect due to the way in which it can reflect sunlight right in your face at certain time of the day. I have a bandana tied around it....odd, but effective. Maybe I should ask my Mum to knit a little sock to go over it.

Beyond aesthetics, it's a useful source of information, although I rarely look at it. I bought my car with the motor apart so had no reference as to how the CIS/KJET was doing. Once I'd rebuilt the engine, it started right up and drove nicely but I added the gauge instead of finding someone with a CO meter/scope just for peace of mind. After asking Sal (tuning guru...SCARCELLER here on PP) what sort of values I should be looking at under WOT and cruise, I did fatten the mixture a tad. Now I suppose the gauge will show me if anything hairball happens with my CIS (or WHEN something hairball happens...).

30 years ago when I was first into Alfas with SPICA mechanical injection, I was forever taking my '74 GTV to friendly dealerships to use their (HUGE) Sun machines to sniff the exhaust so I could dial-in what I imagined to be the ultimate adjustment. A superb Italian tech (Vince at Nick Falcone's in Bala Cynwyd/Philly...still there) showed me how he set the mixture by EAR, explaining the principles as he went and demonstrating the silliness of all my endless fussing. I still have the Alfa and having listened to Vince's admonition to never screw with it (pun), it still runs perfectly. Likewise, I know a number of (older) techs who worked on KJET/CIS is the 70's and 80's (Volvo, BMW, VW, Audi et al) who can do a similar job with CIS by adjusting the dwell of the frequency valve.

Thus in reality, my AFR gauge is essentially just for fun, but I still dig it. Kind regards to all, John/CT

[Gretz]

John, looks like you essentially install the sensor in the standard exhaust location and run the cable up to the dash through the firewall. Then you plug it into the gauge, and the gauge requires power from whatever source you choose. Is that about it?

[jjeffries]

Yep. But if you want to keep your K-Jet feedback loop, you also need to run an output from the gauge back to the port where the factory O2 sensor plugs into the factory wiring harness on the left side of the engine compartment. I did that but found I prefer to run my K-jet "unplugged."

[manbridge 74]

I like the LM-1 or similar for testing on road under load. There are air/fuel ratio to CO conversion charts online...

[Gretz]

Mine is currently unplugged and based on my research I’m not in a hurry to plug it back in.

Originally Posted by jjeffries

Yep. But if you want to keep your K-Jet feedback loop, you also need to run an output from the gauge back to the port where the factory O2 sensor plugs into the factory wiring harness on the left side of the engine compartment. I did that but found I prefer to run my K-jet "unplugged."

[theiceman]

Thanks John great review..
Think I might treat myself, although the exchange right now makes It a bit expensive. In the spring/ fall my car hunts for the first few minutes to the point of stalling. Any other time it is perfect so I'm curious as to what it looks like.

[panzerfaust]

Originally Posted by jjeffries

Ice,

Here's a good thread to review:

AEM Wideband O2 gauges

My AEM gauge and wideband sensor package is AVM 30-4100-UEGO. That was three years ago, so the p/n may have changed by now. Then it cost $197 from Summit.

I got (also from Summit) a metal universal gauge pod ATM-2204, cost $20.95 (what you'd call a "HIGH gross profit margin part", but at least it wasn't plastic).

My SC's clock works, accurately and I think it's cool so I didn't want to put the gauge there. Instead, I mounted on my A-pillar. Yes, that meant drilling two little holes in the car. It works well BUT is far from perfect due to the way in which it can reflect sunlight right in your face at certain time of the day. I have a bandana tied around it....odd, but effective. Maybe I should ask my Mum to knit a little sock to go over it.

Beyond aesthetics, it's a useful source of information, although I rarely look at it. I bought my car with the motor apart so had no reference as to how the CIS/KJET was doing. Once I'd rebuilt the engine, it started right up and drove nicely but I added the gauge instead of finding someone with a CO meter/scope just for peace of mind. After asking Sal (tuning guru...SCARCELLER here on PP) what sort of values I should be looking at under WOT and cruise, I did fatten the mixture a tad. Now I suppose the gauge will show me if anything hairball happens with my CIS (or WHEN something hairball happens...).

30 years ago when I was first into Alfas with SPICA mechanical injection, I was forever taking my '74 GTV to friendly dealerships to use their (HUGE) Sun machines to sniff the exhaust so I could dial-in what I imagined to be the ultimate adjustment. A superb Italian tech (Vince at Nick Falcone's in Bala Cynwyd/Philly...still there) showed me how he set the mixture by EAR, explaining the principles as he went and demonstrating the silliness of all my endless fussing. I still have the Alfa and having listened to Vince's admonition to never screw with it (pun), it still runs perfectly. Likewise, I know a number of (older) techs who worked on KJET/CIS is the 70's and 80's (Volvo, BMW, VW, Audi et al) who can do a similar job with CIS by adjusting the dwell of the frequency valve.

Thus in reality, my AFR gauge is essentially just for fun, but I still dig it. Kind regards to all, John/CT

i have a 69 spica gtv too. dial in properly with is high pressure injectors, it NEVER needs tuning. just filter replacements once in a while.

[jjeffries]

Panzer....agreed and not to hijack this post BUT....it's funny: you'll often read in magazines or online something like "I replaced the notoriously troublesome SPICA with Webers". Then, you'll read elsewhere someone extolling the mechanical injection on a 911 or 2002tii. It's BS; the SPICA system is a beauty and SO reliable, as you said, when you simply do the right preventative maintenance by replacing the small engine-oil filter within the pump and both fuel filters. When you understand the 3D space cam, the mini crankshaft and plungers metering out the fuel and consider the individual throttles, and the ram-air effect air cleaner housing...just a great bit of engineering.

People used to complain about SU carbs too, mainly I believe because owners or ill-trained mechanics couldn't help themselves from getting out the screwdriver and "adjusting" them....like me and my Alfa, 30 years ago...."step AWAY from the engine, sir!" Get them set-up once, PROPERLY (having made sure the throttle shaft bushings aren't leaking air) and leave them the hell alone.

Back to CO/AFR meters...

[old man neri]

I had a Gunson. Stopped working within a few months. I manged to score a slightly used LM-2 to measure my AFR and then convert it to CO. I think I almost solved my running rich issue thanks to it.