Hello Folks !

Quick question here, pretty sure this is not right!
As I am doing some prep...I noticed that the O2 sensor has four wires coming out of it.
Two of the wires seemed to be completely disconnected, either cut or torn out of the O2 sensor body.
Now...on the vehicle side of the wiring harness, the connector that mates with the O2 sensor only has three wires on it! But there are actually four wires in the plastic wrap/harness that goes to the vehicle side of the O2 sensor.

So it seems I have this setup?

O2 sensor...has four wires...only two are actually connected though to the sensor itself
Vehicle wiring harness...has four wires....however...only three actually make it to the O2 connector.

This doesn't seem spec

This is all part of my quest to try to get my SRF above 110mph which seems to be its speed limit right now. I'm going over the entire fuel system, wiring harness, ignition, and exhaust. A few weeks ago at Watkins....I found over 6 volts of drop between the front dash and the computer! Grungy connectors near the fuse panel and the computer. Fixed that and it was running much better.

At any rate...can someone confirm or deny that my O2 sensor setup is screwed up?
I'm going to call Motion Dynamics here soon, but...figured I would post this in case it happens to someone else in the future.

If the O2 sensor is not connected right, which I do not see how it could be.... I am thinking either the heater wires for the O2 sensor are not hooked up, or the signal return is not working, or a combination of both. Wouldn't that put the computer into some 'limp' mode as well and might not make the right engine power? I seem to be chasing some top-end power loss perhaps above 4200 rpm?

Or maybe its just lousy driving?? but I don't think so

I think most cars have the heater wires cut.

Have you had the car on a dyno?

and I believe that at wide open throttle the O2 sensor is out of the loop.

hi, probably not a big deal if the heater coil in the O2 is disconnected.
and steve...you are probably right at wide open! I know my other car that has a Holley programmable EFI, there is a setting for which TPS range to operate in closed loop.

maybe this is not a big issue then with the O2, I'll make a call today though

"Limp mode" is really really limp. You're not that slow. And, as noted above, as long as you're not in limp mode, the O2 sensor stops providing input at less than 4000rpm. I forget exactly, 3500? 3800? Something like that. It isn't exactly irrelevant to how the ECU decides what the spark advance and fuel squirt duration should be, but it is nearly so.

Michael Hausknecht (NE#60)

When you hit 110, what were others hitting? We just had a car that was hitting 100 when I was hitting 112. The culprit was a previous weekend spin into the dirt where he got the wheels spinning backwards which caused the timing belt to jump a tooth.
I had heard of this mythical creature but had never seen it in the wild until Gateway a couple of weeks ago.
Apparently no other symptoms other than dead motor feel and lowered speeds.
Easy enough to check though if you can get the cam cover off .
Denny

Racer X wrote:When you hit 110, what were others hitting? We just had a car that was hitting 100 when I was hitting 112. The culprit was a previous weekend spin into the dirt where he got the wheels spinning backwards which caused the timing belt to jump a tooth.
I had heard of this mythical creature but had never seen it in the wild until Gateway a couple of weeks ago.
Apparently no other symptoms other than dead motor feel and lowered speeds.
Easy enough to check though if you can get the cam cover off .
Denny

Great suggestion, Denny.

You can just drill a peep hole in cam BELT cover to check cam timing...

Dave

Hi!

Thanks for the idea on the cam belt timing. I have easy access to it right now as I have the fuel lines away, alternator off/etc. Should be able to get the cam cover off to check that. I was reading the mummbrothers items on the cam belt tension and being +/- 1 hp.

I have data from another car, using the same type of data system, showing that we were both at ~75mph at turn 1 apex at Watkins glen. We both then brake at nearly the same point way down before the bus-stop. He gets to 120 and I get to 110. I started too at only 65mph turn 1 apex, still only got to 110. Got more daring and began raising my entry speed and exit speed at T1 to about 73mph....still only got to 110. However, my car and his, show we pull exactly the same coming out of the toe of the boot (pretty steep uphill). So I am thinking that there may be some loss issue above 4000 rpm? SCCA enterprises confirmed the O2 sensor doesn't apply above 4200.

I've also found some wheel drag issues. I've installed new fuel injectors, 2% matched, new fuel filter, adjustable regulator, am going to insulate the air intake tube (suggested by scca!) and wrap the exhaust which I managed to get completely off (what a pain!!). I'm hoping to get it to a local dynojet in about a week. I'm also going to do this flow-test on the fuel pump that enterprises told me about.

Even still....every time I go out, I am getting ~1-2 seconds off my lap times. I'm down into the 2:19 at WGI, last time I was in 2:22 range. If I can get it up near 120, I have mathematical proof that I can shave another 2-3 seconds off my lap times

Since you are coming to the Fun One, chase a few of us in qualifying that are sub 2:19's and see how you are doing Steve (barring a rain day). Of course i have tried to stay with a few faster than me and that helps but with my tired motor, i may be waiting for the new 1.6 sooner than later
PS i sent you an email about a nose and tail so hope you receive it and email back. Thanks!

Mark! I am hoping to have some fun chasing and passing a couple people I hope!
I'll check my email on the nose/tail.....but still needing them both for sure! Part of my winter rebuilds