O2 signal not working... big race soming up must fix ASAP!!!!!!!!!!!!!!!!!!

[shelbyplaya]

Ok, the car is an 87 Daytona Shelby Z with a full 89 T2 smec converion. It's been running fine for the last few months.

I started to have an O2 sensor issue last week. I change O2 sensors with an known good old and the issue was still there. Ok, so the connection is a little melted and the wierins looks corroded so i buy a new plug and sauder everything up and IS connected proper. Only to have the same issue!!!!! Bought a NEW o2 sensor today only to have the issue still.

I check the wiering between the SMEC and the o2 sensor and it all checks out fine. Changed SMEC's as well. I was told I should swap injectors/fuel reg and also check my fuel pressure.

Anything else I should check? I have an event coming up this weekend that I would like to attend so I would like to get this figured out so I can tune the car.


Thanks in advance.

[cordes]

S60 cal and race gas for the weekend?

[shelbyplaya]

S60 cal and race gas for the weekend?

Nope. Havent ran anything but 94 on a stock cal.....

[shelbyplaya]

I installed new grounds and cleaned old ones, fuel pressure is steady at 55psi w/ vac (60psi dissconnected). Even dissconnected the a/f gauge and hooked up a differint one and still no change..... Guess i'll install new injectors and see what happends....

[86Shelby]

What's the problem with it?

[cordes]

I was suggesting that since you were having O2 issues you could run the S60 since it isn't an O2 feedback cal.

[shelbyplaya]

What's the problem with it?

My O2 sensor is not cycling.

[shelbyplaya]

things i've tryed but no change.
New o2
New grounds/cleaned old grounds
3 SMEC's
3 set of injectors/fuel regs
dropped fuel pressure to 30psi
checked cam/crank timing and dist timing
advanced/retarded timing
dissconnected a/f gauge
Tryed differnt a/f gauge
reset the computer after every change
plugs look good

I'm gonna go return the o2 sensor cuz it might be faulty???

any other ideas would help


Thanks

[shelbyplaya]

I was suggesting that since you were having O2 issues you could run the S60 since it isn't an O2 feedback cal.

It is. I had an o2 sensor fail when i was running the s60 cal and all hell broke loose! it just dosent use feed back at WOT like the other MP cals. they are also set up for ported g-heads so it's got an aggress timing curve.

[shelbyplaya]

installed nother new out of the box o2 sensor and still nothing

[86Shelby]

Does it stay at 0V?
Check for continuity between the sensor plug and the ECU and repair as neccesary.

Stays near 1 volt- check for short to power.

[shelbyplaya]

Does it stay at 0V?
Check for continuity between the sensor plug and the ECU and repair as neccesary.

Stays near 1 volt- check for short to power.

Stays at rich. I've checked the wiering and it checked out just fine

[86Shelby]

What are you using to check the O2 signal? An O2 guage like autometer or a scantool?

Have you checked the voltage at the pin in the ECU while the engine is running, not just using a scanner or O2 guage for the data?

Have you ran the engine with the O2 disconnected to get that data? - if it still reads 1V with the sensor disconnected it's not the sensor. I would be looking at the wiring or the guage. If the scantool still says 1v, there's voltage being fed into the circuit somehow. As for a guage; I'm not a big fan of those, try disconnecting just the signal from the guage and see what it reads.

[shelbyplaya]

I was getting the same voltage at the plug and smec end. .63ish.

[86Shelby]

Is the .63v with the sensor plugged in or not?

[shelbyplaya]

Is the .63v with the sensor plugged in or not?

unplugged with the car running

[shelbyplaya]

Put a new wiering harness in the car this monring and i STILL have this same o2 issue!!!!! ALL of my old wiering is out of the car including the sub harnesses!!!!! WTF is going on this is effing stupid now. It would be nice to spent more time driving the car and spend money on race fees insted of spending time with failed attempts and spending money to fix it!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[shelbyplaya]

o2 feed back pluged in is .93 and with it dissconneced is .45 and continuity is fine. I dont know what to check or do next :'(

[bakes]

try a spare smec

[shelbyplaya]

yep. 3 of them