Monte Posted December 15, 2003 Share Posted December 15, 2003 There are 2 questions here. My story first. I got my Innovate Motorsports wide band 02 sensor installed. This thing is the bomb. I did more in 4 hours than in the last 3 months of tuning. First off I had a plug reading problem. The plugs kept telling me the mixture was too rich. So, I kept going smaller in jets until the car just didn't seem to be pulling as hard as it should. (I never got lean surge) I knew it felt, sounded, and the heat from the engine said it was too lean, but the plugs still said too rich. ( the black sooty look ) I started checking things out and it turns out that it was a valve seal problem. Now, I know your wondering how I could mistake oil for gas but, the plugs were never wet and always had that dark gray/black flaky look just like when its too fat. So last weekend I fixed the seal problem. Making no changes to the tune up I hooked up the meter today. At idle (1400 rpm for me) it said 11.5 to 12.0, light tip in 12.5 to 13.5, same for easy cruising at 20mph. When I got the car under some load, 14.5, 15.0, 15.5, 16.0 mostly. (a few times 18.0 and 22.0 when getting off throttle) My cylinder temps were 1450 to 1550. I think the high cylinder temps may have been causing the oil to bake away any wetness??? Has anyone had that happen??? I had been ignoring the high temps because I have been told so many times that egt's are not always that accurate and that any unburned fuel in the exhaust can make the temps go high. With the dark plugs I thought it was still fat and basically ignored the temps as being inaccurate. Anyway after doing some driving around it became clear that under load I was way to lean but ok around idle. I have 2 600hp double pumpers. They come from holley with the factory set up of 70 jets front and rear, and a front and rear 5.5 power valve. I was down to 65 jets front and rear and I kept the 4 power valves. So I started driving around today with the meter. I watched my my idle and light load cruise readings being sorta ok but, any real load being too lean. So I blocked off the power valves and went up to 74 jets front and rear both carbs. That was a very positive change. It netted an average afr of about 12.0. It varied from 11.5 to 13.5 under cruise, light load, load and WOT. WOT was usually 12.0 or less. Exhaust temps went down to around 1200 to 1300. So I went down to 72 jets in front and rear of both carbs. The car ran even better. This time driving around afr netted an average of about 13.0. It varied from 12.0 to the 14.0 range with 1350 exhaust temps. I decided to take the car for a 1/4 mile burst. For the first time since I lived in Phoenix I got the rear tires to spin. In a 15 sec run @ full WOT the average AFR was about 12.5 in second gear. I had to got out of it right after shifting into 3rd. One interesting thing was I started recording as I was loaded on the converter. You can see at about 3 sec into the run the afr drops to 10.0. I believe that was from the 4 accelerator pumps on the carbs. You can see on the graph where it clears out and hovers at around 12.0 to 12.5 in first gear, but then is fairly steady at 12.5 to 13.0 in second. I still have a lot more to do but I think this one of best tools I have bought yet. I ran out of time today so that is as far as I got. I do have one other question. Example, driving in 3rd gear at 2,800 rpm and let off. The afr immediately spikes way up to 14.0, 15.0, 16.0 or so. I would have thought that at close of throttle it would first go way rich then spike lean. My thinking is that since fuel is coming out of the booster before closing the throttle, it would momentarily go rich and then lean because of lack of fuel. I understand the closing of the throttle blades stops the fuel from being draw out of the booster, but I would still think it would go rich for a second and then go lean. Can anyone expand on this? Thanks for listening. Monte Link to comment Share on other sites More sharing options...
wallaby Posted December 16, 2003 Share Posted December 16, 2003 I have to admit, it's an interesting process. I have the standard autometer AF gauge in mine. I tried to use it to setup my new carb. Down at the dyno, the guy had different results with his tailpipe sniffer and informed me that I was running way lean. Now my gauge is mostly just pretty light show under the dash, and I don't pay much attention to it. My carb still isn't right even after trying to make changes. I wish the gauge were more accurate. Oh, and what was your first question? As to the A/F ratios when you close the throttle, I'm not sure...my gauge has no numbers, just lean and rich with LEDs inbetween. Maybe it helps to remember that the throttle blades control AIR flow. Link to comment Share on other sites More sharing options...
kc8oye Posted December 18, 2003 Share Posted December 18, 2003 What'd that o2 sensor cost? I'd liek to get one of those for setting up my qjet a bit better. Link to comment Share on other sites More sharing options...
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