Bails098

As the title says it is running rich leaving a black spot on the ground under the exhaust it has a rough idle seems to be not bad until the car warms up then gets pretty bad.
I changed coolant temp sensor seemed to with starting and idle a bit.
fuel pressure looks good its a stock regulator.

I have scanned i recetly fixed code 15 low coolant temp. i bled the system and it seemed to take care of that code.
It is showing code 68 a/c relay short circuit.

I am at a loss for ideas and dont have the money to spend on all new stuff that might not be the problem.
I do have a datamaster file saved if anyone has time to have a look.

Lt1son

I ran into this with my car.. it was very intermittent never scanned car so not sure what code I had.. but when I wiggled o2 sensor it would start missing n running rich. The wiring in the o2 was.. just an idea good luck

Bails098

I changed o2 sensors still runs like crap i noticed its decent until it goes into closed loop then runs like garbage. it doesnt put any black down on the ground during warm up only once it has gone to closed loop.

Injuneer

If you had DTC 15 for low coolant temp, it has nothing to do with bleeding the system. The code indicates a problem with the coolant temp sensor. For a 94, the code sets when the ECT sensor is indicating -56*F. That is most likely a problem with an open circuit = infinite resistance = indicated low temperature. If you have replaced the coolant temp sensor in the water pump housing with the correct 2-wire sensor, and DTC 15 set after that, I would check the wire and the harness connector for an intermittent break.

Additionally, it isn't going to go into closed loop if you have DTC 15, because entering closed loop requires that the coolant temp reach about 120*F.

DTC 68 will prevent your A/C from operating, but it's not going to cause the engine to run rich.

Bails098

I had a lot of air in the system i got it all out and havent seen the code since... Im guessibg that is why the code was thrown but i am pretty new with the computer stuff.

The only code now is the ac one.

Could vaccuum have anything to do with it ima little suspicious about the lines going from disyributor to intake. At work right now so i cant check.

Injuneer

Why would air in the system make the CLT sensor read -59*F? Totally defies logic. Unless you were spraying the radiator with CO or N20 there is no way the coolant can be -59*F.

Are you asking if the vacuum lines from the distributor to the intake manifold can cause an electrical problem with the A/C relay? Simple answer - no..... but you probably won't believe me on that one any more than you believed what I told you about the CTS.

Bails098

Im sorry if i came across the wrong way i did beleive you about the coolant temp i had recently had a -40 reading on it changed the sensor didnt help. changed the connector and it fixed the reading, it read around the same as my gauge does. i had thought with air in the system it was messing the sensor up... As i said i am new to the elctronic stuff and dont know very much about it.

As for the vaccuum lines going to the distributor i wasnt wondering about the a/c sensor i was curious about it causing a rich running condition.

My o2 mv is steady at about 1097 and 1101

Injuneer

The worst thing that could happen with the vacuum line from the Opti to the intake manifold would be a leak after the flow limiter and check valve in the vacuum line. That would impact the engine like any other vacuum leak. The engine would run lean because air would be bypassing the MAF sensor, the O2 sensors would tell the PCM it's running lean, and the PCM would add extra fuel to match the amount of air leaking into the intake manifold. The engine should continue to run at the correct A/F ratio.

bw_hunter

Hmm, I thought the O2 sensors had a range of zero to one volt. That makes a reading over 1000mV impossible. Steady readings on O2 sensors usually indicates a problem with the sensors and I can't guess what a value completely out of range means. I certainly would check all the sensor associated wiring looking for breaks or burns...

Injuneer

They can develop voltage in excess of 1000mV. I've seen it many times in data logs. But not the levels you are quoting. I'd say you have the heater 12V circuit leaking voltage into the sensor wires.

bw_hunter

Thanks for clearing that up....

Bails098

By "heater 12v circuit" is that one or more of the other wires in the o2 wiring that are leaking into the sensor wire???

Injuneer

The O2 sensor has 4 wires. Two supply 12V and ground to the heater in the sensor, and two provide signal and ground for the thimble that measures the O2 content.

http://shbox.com/1/1995_pcm2.jpg

It would be odd that both sides have a short in the wiring or in the sensor.

Bails098

I'll have a look and see i guess ive had stranger things happen with this car... I dont really know what else to look for anymore.

Bails098

So i unhooked the o2 sensors and the bad idle is gone. Im gonna run new wires for the 02 sensors and hope that fixes my problem. hopefully it wasnt just because it wouldnt go into closed loop.