Ok, so FSM didn't work for me the first time so I tried again. I drove across town and was sitting in my grammas driveway and decided to try it again. As I sat there in park and idled with the engine temp at about 165* I watched the SES light. The light seemed to flash once per second but quite evenly... not on more than off or vice versa. As I watched the light, about every 10 seconds it would stay on more than it was off but would only do it twice and then go back to the even flashing again. I revved the engine a little bit and no change... it would flash evenly and occassionally stay on more than off. What does this mean?? I don't understand it. The O2 sensor is new. I'm running headers but the O2 bung I had welded in was put towards the end of the header where all the exhaust combines together before going through the Y-pipe and the rest of the exhaust.

------------------
1986 Trans AM
355 TPI
4 Wheel Disc Brakes
9 bolt Borg Warner Rear (2.77's....oh joy) :P
6" rods, approx. 9.7:1 Compression, Stock TPI (soon to be ported), 24#/hr LTI injectors (cleaned and flowmatched by Cruizin Performance), Hedman Shorty Headers, 3" exhaust with 80 series flowmaster, SBC 993 heads completely redone and modified for 1.6 RR, 1.52 RR (for now), Comp Cams XE262-14 TPI Cam, Holley AFPR, TPIS airfoil, MSD wires, MSD 6-AL Ignition, Hypertech 53,000 volt coil.

Track times to come.

 

the slow flashing(bout once per second) means u are in closed loop which is a good thing

------------------
*89 Trans Am GTA
*Moderator at www.transamgta.com

To hell with the GM vs Ford war. We must unite, as brothers to fight the plague that is overtaking the world...RICE

Tony

 

Yeah, that's good to know especially since I'm not using a heated O2 sensor. I just don't understand why it flashes evenly and about every 10 secs stays on more than it's off a couple times then goes back to the even flashing again. In theory, I should be running rich judging by 1. the smell of my exhaust and 2. the fact that I'm running 24# LT1 injectors with a 305 computer chip.... of course I am running just under 40psi of fuel pressure. Maybe the rich smelling exhuast is because of the bluish white smoke coming out the exhaust since my engine doesn't have enough miles on it for the rings to be fully seated yet.


------------------
1986 Trans AM
355 TPI
4 Wheel Disc Brakes
9 bolt Borg Warner Rear (2.77's....oh joy) :P
6" rods, approx. 9.7:1 Compression, Stock TPI (soon to be ported), 24#/hr LTI injectors (cleaned and flowmatched by Cruizin Performance), Hedman Shorty Headers, 3" exhaust with 80 series flowmaster, SBC 993 heads completely redone and modified for 1.6 RR, 1.52 RR (for now), Comp Cams XE262-14 TPI Cam, Holley AFPR, TPIS airfoil, MSD wires, MSD 6-AL Ignition, Hypertech 53,000 volt coil.

Track times to come.

 

When it flashes fast and even that means you are in open loop. Since you have headers you're O2 sensor is farther away from the engine and has a hard time reaching operating temp at an idle. Go drive it down the road and watch the light. It should go into closed loop when you're driving. When it goes into closed loop, on means rich and off means lean. It's OK if it fluctuates slow, just as long as it doesn't stay rich or lean for more than 30 seconds or so.

------------------
91 Z28
Come see The Vicious...

 

i have a similar problem figuring out the resoults of the field service mode.
its on and off about the same amount of time(flasing slowly), but when i drive it around and give it bit more then half throtle the light stays off untill i lay of the gas to shift. ?

 

Well I must be pretty damn good at getting things right the first time then. When in open loop the light is supposed to flash about 2 1/2 times per second.... mine was flashing once per second but evenly which indicates to me that it was in closed loop... even at idle. I took it down the road today for a trip and watched the light as I drove. Same thing as what I got when I was idling.... it flashed about once per second evenly and would occasionally stay on more that it was off but it would only do that a couple times and then go back to the normal even flashing. So it wasn't staying rich for more than about 5 seconds. I'll know more once I have a "proper" way to check it but for now this is gonna hafta do until I get a job.

------------------
1986 Trans AM
355 TPI
4 Wheel Disc Brakes
9 bolt Borg Warner Rear (2.77's....oh joy) :P
6" rods, approx. 9.7:1 Compression, Stock TPI (soon to be ported), 24#/hr LTI injectors (cleaned and flowmatched by Cruizin Performance), Hedman Shorty Headers, 3" exhaust with 80 series flowmaster, SBC 993 heads completely redone and modified for 1.6 RR, 1.52 RR (for now), Comp Cams XE262-14 TPI Cam, Holley AFPR, TPIS airfoil, MSD wires, MSD 6-AL Ignition, Hypertech 53,000 volt coil.

Track times to come.