87 R10 O2 sensor

[Inchief]

Hi, I have a '87 stepside that I am putting back in order. When I got it it ran like crap but with the help and info on these forums it is coming around. It is running a lot better but the service engine light came on and I have code 13 and 42 coming up. The code 13 I understand, there is no O2 sensor that I can see on the exhaust. A previous owner put headers on the truck and there is no place to put a sensor. I guess I could get a weld on bung and put one on but I can't seem to find the wire that it would connect to. I am thinking that the ECM needs the O2 sensor to function properly? This Fuel Injection is a whole new thing for me, but getting a crash course in it now.
The code 42 is Ignition control open/short/component failure. I am thinking that maybe this is from when I disconnected the distributor control to set the timing and did not clear the code.

 

[1987 GMC Jimmy]

Hi, I have a '87 stepside that I am putting back in order. When I got it it ran like crap but with the help and info on these forums it is coming around. It is running a lot better but the service engine light came on and I have code 13 and 42 coming up. The code 13 I understand, there is no O2 sensor that I can see on the exhaust. A previous owner put headers on the truck and there is no place to put a sensor. I guess I could get a weld on bung and put one on but I can't seem to find the wire that it would connect to. I am thinking that the ECM needs the O2 sensor to function properly? This Fuel Injection is a whole new thing for me, but getting a crash course in it now.
The code 42 is Ignition control open/short/component failure. I am thinking that maybe this is from when I disconnected the distributor control to set the timing and did not clear the code.

Yes, you always need to reset the computer after adjusting timing. That'll get rid of the 42. The O2 sensor is important. You're right on about the weld on bung, but you gotta either find the wire or rewire it from the ECM harness using a pinout diagram. It was likely cut, but it's probably dangling around down there where the manifold or Y-Pipe would have been. I believe it's purple, by the way. You'll also need to get a three wire heated sensor since there's a deficit of immediate back pressure that the factory manifolds had to help heat things up, and you need to get to closed loop as soon as possible. It's simple to do. You just need the factory sensor wire, a 12V wire from somewhere under the hood for the heater element, and a ground wire.

 

[Inchief]

Thanks for the info. I just ordered a 3 wire O2 sensor and bung so will get it in a day or two. I have not located the purple wire yet but it's gotta be in there someplace just gotta root around some more.

 

[smoothandlow84]

Hmmmm...interesting. I installed long tube headers, welded in a bung, installed the o2 sensor but ditched all of the emissions equipment ( except the egr) but still have my single wire o2 sensor...no codes...and truck runs fantastic. Why would he need a three wire heated o2 sensor when a single non heated o2 was factory installed?



...and the wire to the o2 sensor is in fact purple. The wire should be in the harness against the firewall on the drivers side close to the oil pressure sending unit.

 

[1987 GMC Jimmy]

Hmmmm...interesting. I installed long tube headers, welded in a bung, installed the o2 sensor but ditched all of the emissions equipment ( except the egr) but still have my single wire o2 sensor...no codes...and truck runs fantastic. Why would he need a three wire heated o2 sensor when a single non heated o2 was factory installed?



...and the wire to the o2 sensor is in fact purple. The wire should be in the harness against the firewall on the drivers side close to the oil pressure sending unit.

Honestly, I don't think it would trip a code for anyone who didn't. Maybe an occasional Code 45, but it'd probably be an intermittent code instead of a hard one. Those factory manifolds are restrictive as hell so there's more pressure in them. Add that to hear conduction from the engine and the convection within the manifolds due to a relative lack of escapability, and those things get hot pretty quick. In this setup, there's no lack of heat so the O2 sensor can get to 600*F fairly quickly and tell the ECM it's time to go to closed loop. With headers, even though you still have the same heat conduction from the engine, you loose the restrictive component and a bunch of that convection. It takes longer for the single wire O2 sensor, now further away from the exhaust ports mind you, to get to 600*F if it does at all. You'll still run well, but you'll run in open loop with more liberal fueling for longer or just constantly. The heated sensor mimics the heat input so you can get the sensor going and have the truck running nominally just like if you'd never switched over to headers. I wish I knew how long it'd take to get to closed loop with long tube headers and a single wire sensor, but I don't. I can, however, say with confidence that it'll take longer at the minimum.

 

[akchevrolet]

Now what's the best place to wire the positive wire for the heated