check engine light problems on 91 s10

[dodgedude99]

my sons s10
130k miles, 4cyl 5 speed.
after the truck has had time to warm up and such, the "check engine" comes on for a few minutes and then goes off, a few minutes later it comes on, and goes off.
on and off, on and off, etc, etc,.

i replaced the O2 sensor with a Bosch piece figuring that i had 1 that i didnt put in my K5 yet, and that it could probaly use it, seemed to make sense.

but that didnt solve the problem.
i did the onboard test grounding the test port, but it just kept on flashing 13 (which according to the chiltons is everything is normal).

it has new plugs, wires, cap & rotor.

gas mileage is kinda crappy, when its revved up when its cold, it spit all kinds of black crap on the house.

the shady thing is the exhaust, looks like it could use a new one.
the guy i bought it from is the service manager at the local chevy dealer, and is the cousin of my buddy, he claims that a bad Cat will trip the light, thoughts on that?

any insight would be appreciated.
thanks

 

[K5MONSTERCHEV]

When you jump the terminals the light should flash:1 2 1 2 1 2 etc. a few times, then stop, then flash the code.

Did you clear the code after you replaced the sensor?

Code 13 is O2 sensor. Maybe the wiring or wrong sensor?

 

[dyeager535]

On other setups, code 12 is what tells you the ECM test is working IIRC. I'd be surprised if a '91 used code 13 for the same thing. /forums/images/graemlins/confused.gif

 

[dodgedude99]

like i said i was going by what the Chiltons said and we know how much we love those.
it might of been 12, what ever it was it was what the book was saying is ok.

i checked the part numbers on partsamerica.com and it was the same # for my 88 k5 as the 91 s10.

the sensors are cheap so i might just try another one then.

 

[Thunder]

If you are getting a CEL and the only code is # 12
The problem is usually a distributor module going bad.
Could also be a bad magnetic pick up coil.
Code 12 does not necessarily mean everything is ok.
Code 12 means there is no distrubutor reference siginal.
A code 12 will always come up with engine off and key on because there is no signal generated in the dist module.
An intermittent loss of dist module siginal while the engine is running will show up an a #12


Code 12 shows the ECM is functioning and is in diagnostic mode.

 

[dodgedude99]

is that part just plug and play?

is it the same thing as a ignition module/ control unit?
as seen here.
http://www.partsamerica.com/PartDetails.asp?SourceArea=&SourcePage=SEARCHRESULTS&MfrCode=GPS&MfrPartNumber=EL123&PartType=194&PTSet=C

 

[Thunder]

Yup. That's the one

 

[dodgedude99]

sweet thanks.
it will make the boy happy then to actually get better gas mileage also.
right now my ram on 37's is probaly getting better gas mileage.
he just started working so must of his paycheck has been going for gas!