odddoylerules

OK so I'm working on an 89 trooper, 8062 or whatever 2.8 ecu like in the blazers and s10s using winaldl and my old moates gear to start clearing out the tweeker hacks that kept this thing running up til this point, and lemme tell you there's some garbage to dig through.

But this is the one that brings me here. Rich flag, runs like **** in cl that's not the issue. The ISSUE is that to test a theory I went to pull the o2 sensor and it was busted in two hanging next to the bung it should be installed in. Aldl data said it was giving a reference voltage w key in run, but once running was pegged at .7. Problem solved right?

Busted sensor somehow still operational but exposed to atmosphere = rich. (If we ignore how on earth an unheated sensor is reading anything at 65 degrees)

Happy as a clam I climb in (after an ecu reset) expecting either it runs great and I needed a sensor or it runs like crap and I need injectors but much to my suprise the data shows a half volt reference voltage for o2 and again .7v when running.

It runs great in open loop, however 45 seconds in, IT GOES INTO CLOSED LOOP WITH NO OXYGEN SENSOR.

I was expecting open loop only with the sensor removed.

Today I'm probably testing the circuit and installing a new o2 sensor and running a new lead to the ecu if need be.

Any ideas what's up though with the phantom sensor?

odddoylerules

so theres continuity between ecm pin and o2 sensor plug, but even with sensor unplugged, i get almost a volt. .05x v w key in run/not running.

spikes to.9 and will go into open loop w no sensor

stays pegged at 1.07 w sensor connected once running, same voltage at stop w key in run.

bad ecu?

voltage has got to be coming from somewhere

odddoylerules

rrr closed loop i mean

also i am sorry but i am so used to posting here i might have misposted this.

if a mod wants to move this to the electronics/ecu area thats totally cool

odddoylerules

Ummmm

And



Not normal, right?

RBob

iTrader: (1)

That is likely OK. It appears to be a repair prior to the ECM being conformal coated. I've seen the same where a single chip looks like that. It is flux from doing a chip R&R or a re-solder of the chip/pins.

Apparently the flux doesn't get cleaned off after the repair and resides under the conformal coating.

RBob.

The_Punisher454

I have not looked at the pcb schematic, but I have an idea what you MAY be seeing with the sensor disconnected.
I noticed this myself several years ago while playing with AVR microcontrollers on a breadboard. If the input pin on an ADC input line is allowed to float, and especially if it is connected to a wire it will pick up all sorts of stray electrical energy in the air.
On my workbench I had an LCD attached to the microcontroller acting as a meter for that particular ADC channel. with a about a 6 inch piece of wire attached to that input it would spike the meter just by having a human walk past the workbench. Kind of like a proximity sensor. In your car you have a lot more electromagnet emissions than a human body gives off.

Anyhow, a floating input on an analog to digital converter (ADC) can give all sorts of crazy readings. Perhaps thats what you may be seeing.

odddoylerules

That... Is super crazy. But actually that brown stuff was cola syrup, and a new ecu has things reacting more as one would expect lol

RBob

iTrader: (1)

Cola syrup? That is crazy, may be able to wash it off with some warm water and a mild detergent. We get ECMs that are really dusty inside and do just that. In the Summer dry them out in the sun, Winter on top of the boiler.

RBob.