CEL on and engine runs rough

[pneps]

So I finally got the water pump changed out and have been able to drive the car (1992 SHO 5 speed) enough to try and see what else is going on with it. It has an intermittant CEL light. While this light is on, the engine runs rough, has no oomph and the tach is either sporadic or reads about 1000 rpm lower than actual. Every now and then the CEL just goes off, the tach reads correctly, and the car runs like it should.

I have run the codes, first the engine off and stored codes:

111- system checks OK
176- O2 sensor not switching
217- primary circuit failure, ignition coil 3
542- fuel pump open, bad ground, or always on
557- low speed pump relay primary circuit fault

Now the engine running codes:

172- O2 sensor not switching

So at least I need to change the O2 sensors. But I cannot see what or if the O2 sesors have anything to do with the intermittent running/CEL problem.

Any ideas?? Thanks.

 

[msteiny]

It is your O2 Sensors, time to change them. And it sounds like your cam sensor is on its way out as well. Cam sensor runs the tach and works with the crank sensor on the firing order.

 

[pneps]

I had replaced the crank sensor when I changed the water pump. so sounds like I should do the cam sensor now too.

 

[rubydist]

many times a sick cam sensor will be worse than a dead one - the sick one can screw up timing and make it run real bad. a sick cam sensor does not always set a code. I would replace the cam sensor as well as the 02 sensors, reset codes and see what happens next.

 

[pneps]

OK, good to know that the cam sensor may not always throw a code. Also, stupid question, how many O2 sensors are on a 92 and where are they? The chilton's I have is very vague on that subject.

 

[rubydist]

one on each bank, just below the manifold.

 

[pneps]

OK guys........

Replaced the cam position sensor and both O2 sensors. Disconnected the battery for 10 minutes to clear out the old codes.

CEL light STILL on on and tach Still not reading correctly.

KOEO 114= IAT sensor out of range (this is new)
217= Primary circuit failure, ignition coil 3 (same one as before)

KOER: 172= O2 sensor not switching, system is or was lean, rear sensor (same as before)
136= O2 sensor not switching, system lean front (new code, but still O2 sensor related)
536= Brake on Off open or shorted to ground. (This one I know.)

Still shows O2 sensors not working????????

HELP? Ideas? Car still runs rough, and the tach still acting up

Thanks.

 

[rubydist]

one of my many SHOs would take much longer than 10 minutes disconnected from battery to reset the codes.

so, the real way to reset codes is to disconnect your paperclip while the codes are in the process of being displayed. you turn the key on, and while the cel is still flashing out the codes, pull the paperclip out.

then run the car a while and re-check the codes.

 

[pneps]

one of my many SHOs would take much longer than 10 minutes disconnected from battery to reset the codes.

so, the real way to reset codes is to disconnect your paperclip while the codes are in the process of being displayed. you turn the key on, and while the cel is still flashing out the codes, pull the paperclip out.

then run the car a while and re-check the codes.

OK, this is done, Here are the new code

KOEO

114- IAT sensor out of range
212- Ignition TACH signal erratic
217- Primary circuit failure ignition coil 3

KOER

172- O2 sensor not switching
136- O2 sensor not switching
536- Brake light open or short

Car still runs rough. CEL goes off occasionally for short periods of time, and the car runs great.

Running out of ideas....

 

[rubydist]

I have never ever seen a SHO run right if it had a 114 code - you need to figure that one out for sure. Start by tracing wiring or just grab a jy sensor and replace it.

212 is the spout circuit grounded. when that is the case, timing will be fixed at 10* and power will be way down. you will want to figure that out too. it may be related to wiring for the iat, or it may be completely separate.

217 can be set by either a bad coil or a bad dis - my experience is about 50-50 on which. of course, the car will run like crap when running on 2/3 of the cylinders.

the check engine light is not set for any of those - it is set from the o2 sensors not switching, which we would expect if the engine is only firing on 4/6 cylinders.

I would flip a coin to see if I buy a coil or a dis first.

 

[Ishodu]

The 114 code will appear is you do the test below 50F. Sounds like a coil or dis issue. Did you do the cylinder balance test? It may confirm the coil.

 

[pneps]

I have never ever seen a SHO run right if it had a 114 code - you need to figure that one out for sure. Start by tracing wiring or just grab a jy sensor and replace it.

212 is the spout circuit grounded. when that is the case, timing will be fixed at 10* and power will be way down. you will want to figure that out too. it may be related to wiring for the iat, or it may be completely separate.

217 can be set by either a bad coil or a bad dis - my experience is about 50-50 on which. of course, the car will run like crap when running on 2/3 of the cylinders.

the check engine light is not set for any of those - it is set from the o2 sensors not switching, which we would expect if the engine is only firing on 4/6 cylinders.

I would flip a coin to see if I buy a coil or a dis first.

What is interesting is the way that new codes come and go each time I check it, except fot the O2 sensor codes.

The 114 code will appear is you do the test below 50F. Sounds like a coil or dis issue. Did you do the cylinder balance test? It may confirm the coil.

Well, being winter and all, the latest testing has been under 50 degrees F. I guess I'll try the cylinder balance test next and see how that goes. Of course it's gonna rain up here for the next two weeks or so....

"If it ain't raining, it ain't training" as my old Drill Sargent used to say....

 

[luigisho]

if you have ignition misfires it may be enough to set off the O2 sensors. Look at the sensors and ignition system.

 

[rubydist]

in my experience, the 114 code will not appear correctly unless the ambient temp is below -20F the sensor is supposed to read from -40F to +120F

 

[Ishodu]

112 - ACT sensor circuit grounded or reads 254°F
113 - ACT sensor circuit open or reads -40°F
114 - ACT outside test limits during KOEO or KOER tests

 

[pneps]

Got a used known good DIS module and switched out this morning. So far so good, no CEL and tach signal correct, engine runs smmooooooooooth.

 

[pneps]

Oh, yes. The heat sink paste used on the old DIS was the same thing that NAPA tried to sell me.......Dilectric grease.:shakehead

 

[bertha66]

Had the same problem going on with my 1993 SHO MTX. Changed out the DIS module and she is running great again.

Thanks