edwardb
04-01-2015, 09:36 AM
Posted this over on the other forum, but will post here also. Did a lot of searching and reading, but still would like to pose this question. I'm very seriously considering picking up an air/fuel ratio meter to tune my just completed carb'd Mk4. But also to have in my tool collection for future projects. The Mk4 is running well with the Quick Fuel SS-750 out of the box, but I'm positive it could probably be better, and at the very least be more efficient. Finding a local tuner is hit and miss at best, and for a session or two could own my own tester and learn to do it myself. I'm looking at the Innovate LM-2 with an RPM pickup. I'm pretty tech savvy (retired IT guy) so confident I can figure this thing out and get the desired results. Plus I enjoy this kind of stuff.
Based on multiple suggestions, I'm not considering a tail pipe exhaust clamp for the sensor, but will do it right with a welded on bung. My question is placement for the O2 sensor. I've read the instructions, and for this tester seems only two requirements: (1) Upstream from the catalytic converter, which doesn't apply in my case, and (2) Between 10:00 and 2:00 position, and not below the 3:00 or 9:00 position because condensation can form in the exhaust pipe and permanently damage the sensor.
Please provide your thoughts and hopefully real world experience recommending one of these three options. Keep in mind I would only have the sensor in place for testing, and then remove and plug the rest of the time.
Option 1: In either #1 or #2 exhaust header. Advantages: Underhood, pretty easy to do, easily meet the 10:00 to 2:00 position requirement. Disadvantage: Only reading AFR of one cylinder. Not sure how much this matters for a carb situation, because I would expect them all to be similar. Plus this is for test readings, and not actually providing real time feedback to the engine and making adjustments like a full-up EFI install. But still a consideration.
Option 2: Right behind the 4-into-4 collector on the side pipe, on the outside. Advantages: Sampling 4 cylinders, can meet the 10:00 to 2:00 position requirement. Disadvantages: Not real excited (in fact not excited at all) to have the welded bung on the outside of my shiny GAS-N pipes. The sensor and wire would be sticking out to the outside, but this is minor since I would only have it there for testing. Also some questions about how effective the sensor is this far from the engine.
Option 3: Right behind the 4-into-4 collector on the side pipe, on the inside. Advantages: Sampling 4 cylinders, out of site, minimize changing appearance of my side pipes. Disadvantages: Because of the closeness to the body, the best angle I could get would be in the 7:00 to 8:00 range. I understand this would unacceptable for a permanent installation. But for testing only and 99% of the time the bung would have the plug in it, so I'm wondering if the condensation concern is really an issue. It would NOT be in the 6:00 position, which the instructions say is the absolute worst position. Also the question about distance, like option 2.
Probably right now I'm leaning towards option #1, with option #3 a serious consideration. Probably not option #2 unless I could be convinced the others just wouldn't be acceptable.
Thanks in advance for your feedback and experience.
Based on multiple suggestions, I'm not considering a tail pipe exhaust clamp for the sensor, but will do it right with a welded on bung. My question is placement for the O2 sensor. I've read the instructions, and for this tester seems only two requirements: (1) Upstream from the catalytic converter, which doesn't apply in my case, and (2) Between 10:00 and 2:00 position, and not below the 3:00 or 9:00 position because condensation can form in the exhaust pipe and permanently damage the sensor.
Please provide your thoughts and hopefully real world experience recommending one of these three options. Keep in mind I would only have the sensor in place for testing, and then remove and plug the rest of the time.
Option 1: In either #1 or #2 exhaust header. Advantages: Underhood, pretty easy to do, easily meet the 10:00 to 2:00 position requirement. Disadvantage: Only reading AFR of one cylinder. Not sure how much this matters for a carb situation, because I would expect them all to be similar. Plus this is for test readings, and not actually providing real time feedback to the engine and making adjustments like a full-up EFI install. But still a consideration.
Option 2: Right behind the 4-into-4 collector on the side pipe, on the outside. Advantages: Sampling 4 cylinders, can meet the 10:00 to 2:00 position requirement. Disadvantages: Not real excited (in fact not excited at all) to have the welded bung on the outside of my shiny GAS-N pipes. The sensor and wire would be sticking out to the outside, but this is minor since I would only have it there for testing. Also some questions about how effective the sensor is this far from the engine.
Option 3: Right behind the 4-into-4 collector on the side pipe, on the inside. Advantages: Sampling 4 cylinders, out of site, minimize changing appearance of my side pipes. Disadvantages: Because of the closeness to the body, the best angle I could get would be in the 7:00 to 8:00 range. I understand this would unacceptable for a permanent installation. But for testing only and 99% of the time the bung would have the plug in it, so I'm wondering if the condensation concern is really an issue. It would NOT be in the 6:00 position, which the instructions say is the absolute worst position. Also the question about distance, like option 2.
Probably right now I'm leaning towards option #1, with option #3 a serious consideration. Probably not option #2 unless I could be convinced the others just wouldn't be acceptable.
Thanks in advance for your feedback and experience.