dhdenney

iTrader: (53)

In a nutshell, did a heads/cam on a buddies 1994 LT1 OBDI car and I loaded a modded file to help it run a little better, get a baseline before he did a dyno tune. I ran the scanner on the car for 30 mins while he drove it and at part throttle and a couple of short WOT runs. Only thing that looked out of the ordinary was right O2 was behaving erratically, hitting the top and bottom ends of the spectrum while the left O2 looked more normal to me. Car would not switch to closed loop. Closed loop enable parameters are stock. Car has no codes and drove very well in open loop--no misfires, not rich. Injector PW increased at the same rates for each bank, coolant temp was reading normally at water pump (sensor at the head for the gauge needs replacing but I am 99% sure it has no bearing on engine functions). TPS voltage good, IAC counts good. Only problems are erratic right O2 and no closed loop. Not sure what to do. I told him he should probably replace the right O2 but I do not think it will effect the closed loop problem.

blade2222

I think a bad o2 will keep it in open loop.

koolaid_kid

iTrader: (21)

I have been following another thread (not in this forum) that says in closed loop the O2 readings should be bouncing all around, like you describe the right sensor. The left sensor is not bouncing all around, which indicates that it is the problem sensor. Any experts care to chime in?

dhdenney

iTrader: (53)

I keep getting the same response about the O2's but as long as I've had my car, I've never seen one act that crazy. Oh well, that's not necessarily the problem anyway. I just wanna know why the thing won't go into closed loop.

dhdenney

iTrader: (53)

I'm getting mixed responses about the bad O2 affecting closed loop. Some say it will enter closed loop regardless, others are saying a bad O2 will prevent it from going into closed loop.

HD6.0l

Don't know but CL requires the O2 sensor to regulate fueling , hence CL .
So yes will prevent it from entering CL .

dhdenney

iTrader: (53)

I guess when I talk to him again I'll be sure to tell him to replace the one O2. He had a couple extra laying around I noticed.

koolaid_kid

iTrader: (21)

Let me go do a quick run in my car. It's all set up, I just got back from a run with my scanner and my LM1, getting ready for OL tuning.
I'll post my results when I get back. A little real time data so you can be certain.

koolaid_kid

iTrader: (21)

O.K., here are the results:
Sensors bounced from sub-100s all the way into the 900s. They were not synched with each other, nor did the follow either engine speed nor vehicle speed. The run consisted of a square, possibly 2-3 miles, with acceleration, decelleration, 5 stops, 1 easy run up to 5k in 1st gear (at the top of this the O2s both went to 9xx, expected results) and a cruise when the police car pulled behind me. (Really, he did, I guess he was going home, it's rush hour traffic here.)
If you want a comma delimited file of the run, PM me your email and I will send it to you.
Hope this helps.

bigtymn

i work on 94 camaro same prob. it turns out it was the ect sensor
there is two on that car one for the gauge one for the computer
one in the head one in the water pump area

dhdenney

iTrader: (53)

Right, the one on the waterpump is working fine, where it counts.

bigtymn

you told me!

dhdenney

iTrader: (53)

Huh??

bigtymn

how did you check it?

dhdenney

iTrader: (53)

The coolant sensor? Scanner told me what its readings were. It was showing 190's while driving around. If it said 67* then I'd know it wasn't working right.

bigtymn

what it set at in the tune?

dhdenney

iTrader: (53)

You mean closed loop enable? Those parameters are stock.