Single channel O2

[Adger Smith]

Micahel,
In this hot humid weather when you see a little area of the curve being rich. don't try to lean that area out. leave it rich and hit that part of the map with a little timing. See if the engine combo likes that. Some do some don't. It might make a little steam out of the humid air. :~) Oh! Watch the egt's in that rpm range. They should go down a few degrees when you hit it with timing. That is because the heat stays in the chamber, not in the ex pipe.

[Michael Beard]

Been running 38deg, except for down low, had it at 32deg (3000-5400rpm)to get it to hook previously. With the CalTracs (plus being down on power), had absolutely zero hook issues this weekend, and bumped the timing up to 38deg across the board.... only worth .01-.02. Even started putting clicks in the shocks, and the car shrugged its shoulders.

But even in much better air, similar deal... try to lean it out at all, and it noses over by 12.5:1 at best.

[Adger Smith]

The fuel and timing go hand in hand. Watch the EGT's when working the fuel and timing. Usually, as you lean the engine it will want less timing to make power. When you have it fat it usually takes more timing to light the mixture because there is less air (O2) around the fuel. Same goes for more vapor pressure. It displaces the o2. As an example I'll try to post a PM I got from a racer I was helping tune in bad air. oops, Sorry already deleted the exchange.

[Altronics]

O2Alert features single or dual widbands plus RPM and Battery voltage standard. Has Auxially inputs for EGT, Drive shaft RPM, and Pressure/Temperature/ voltage.

Data can be read back on screen or comes with software to download to a computer and graph/overlay.


THis system also features automatic recording capability, so that there is NO user interaction required to start recording. You can sit in the lanes for hours and then make your run and do not need to remember to push a button!

Also features AFR average which is very useful in determining what tune up change has effected performance. In carbed applications fuel slosh can cause fluctuations in AFR. I like to be able to look and the entire run and see not only what the AFR is a specific points but more important what the average AFR is.

Also, This is a CONTINGENCY item!

See our website for more info www.altronicsinc.com/pages/o2alert.html

[Michael Beard]

First thing we did today was physically check the timing at the balancer, and lo and behold, it was reading around 30 degrees, not 38! It's more than a little disconcerting to me that it could've moved that much in the first place, but it sure does explain the car running like a pig lately. It's a FAST Dual-Sync distributor. We went through the setup procedure again, checked it against the timing light, and tweaked to match. We marked it before going through setup again, and you can see the distributor is definitely in a different position than it was.

Just goes to show you can't overlook the basics, even if it "shouldn't" have happened. Hindsight, Sherlock Holmes, Occum's Razor, etc, etc.... I'm sure I'll have to punch the fuel map around a bit again now, but feels good to have actually found and corrected something that is a definite problem.

[Adger Smith]

Now you know the lean/rich for 30 deg of timing! ;~)

[Signman]

Same thing just happened to me. The car was slowing down for no reason.

First it slowed up .05 for no reason. Ran the valves, looked over springs, drained oil and cut open filter. Nothing.

Next race slowed .10 1st round for no reason. Put it in the box to look it over at home. Plugs were rich but O2 didn't show it, then O2 would go to 15.98 just running it at idle and off idle up to 2k. Shut down ignition and restart would be fine for a while.

Next race go day early to test. First and second runs O2 wacky. Install new O2 sensor and start to get good info, pick the car up .2 but it's still .1 slow. First qualifier picks up .02, second slows .05, third another .05 I'm lost. My buddy comes over and tells me to go back to basics and check timing. Do it just to please him. It was 16* advanced. Match up what timing should be as shown on the laptop to actual.

What do I dial first round? What map do I run? How long has the O2 and timing been messed up?

Go back to test session where the car ran deadly consistent and load fastest map. Use that run vs. weather, and fastest run of the weekend vs. weather to come up with a dial. It's a .14 window. Throw a dial on the window in the middle. Kill a few and run over but flat out would have been dead on the dial. Lucky guess. The car should be a little faster but it's a little fat for what it likes.

Next time out will verify timing and tune it up, should run normal numbers.

This year has been a learning experience. Earlier in the season the car would speed up or slow down .05. Found that to be a rear suspension issue. Fixed that then the O2 and timing gremlins show up.

They say they come in 3s, so things should begin to get back to normal. Maybe!

[Michael Beard]

That's what I like about Adg.... always thinkin' positive! LOL

Heard a funky one at Bristol a few weeks ago. Guy running FAST XFI on alcohol said he went up to the lanes for 2nd rnd, and the car was running horrible. Dials up a second, not knowing what to do... Turns out he had the ignition on while charging the battery, and somehow it reset to a default (gas!) program. Better yet, when he went WOT, it reverted to his alky setup, and it's flying.... he pedals it, and as soon as he gets out of it, it goes back to the gas default and dies. Crazy!

So the big question is, why have we experienced a massive change in timing?!