Im having a intermittant SES light and all around rough running on my 91 sse. car has 73,000 miles, family owned, very clean car, thats why im surprised its running this way.

when the SES light comes on It seems like a miss and then I lose my speedo, coolant light flashes, battery light flashes, has trouble keeping an idle without me holding the gas, sometiems the speedo goes crazy back and forth, and sometimes the speedo will work but still have a SES light. when the SES is on, it idles super high about 1800, and is extremely sluggish when I hit the gas, EATS GAS LIKE CRAZY. I can smell raw gas and maybe my cat burning, it stinks!!!!! but when the light goes away all these symptoms are gone runs OK, still not great.

even when it is not acting up, sometimes has trouble holding an idle, will surge occasionally and all around rough idle, hunting, etc.. but sometimes it runs great.

When the light is not on and car is running OK, I can get into diagnostic mode and it flashes 12'* all day, but if the SES is on and I try to pull the code, it will not even flash just stays lit. so I have no idea what is going on.

in search of this problem the following have been done,
1. new plugs, and wires(oem)
2. cleaned TB, IAC, MAF
3. new battery

the TB cleaning and IAC cleaning have made the car run better when my SES light is not on, but it still goes on sometimes and runs just as crappy as before. another thing is when the SES is on, I disconected my MAF, and did not see and change in idle or anything, plugged it back in and did not see any change. I tried it 20 min later when the code went away and my car raised idle when disconnected, and died when I reconnected the MAF. has my MAF gone bad???


sorry for the huge explanation but Im having some crazy things happening here im stumped anyone ever had this happen??? ANy help is appreciated, thanks,

kyle

Kyle, long explanations are good if they help get the details out and ultimately help you fix your problem(*).

Answer some more questions for me.

Prior to this happening, was there any work done on the car? Or did it just start out of the blue, so to speak?

How old is the battery and have you checked for corrosion on the battery terminals?

Does this happen when the motor is cold, hot or both? Have you tried testing your coils?

I too am interested in the answer to Lash'* questions. It sounds like you have an electrical fault going on somewhere and the fact that you cannot read the ECU tells me it could be the computer itself. Are you jumping the A B terminals to get the codes as explained in Techinfo?
The ECU'* were weak in the 87-91 era. Is it original?
Usually you would get multiple codes that don't make sense and the car will start dumping fuel and smoke out of the tailpipe. Just had it happen on my 90.

I had been driving the car with a bad cam sensor for a few weeks when these symptoms started on top of what I was already experiencing with the cam sensor. I figured that maybe it was going bad and then completely went bad. so I coughed up the loot, did the teardown, replaced the cam sensor(which was no longer present in the cam gear), timing chain, guides, etc, etc. I am positive that I aligned the timing marks correctly. I installed and reinstalled about 5 times just to be sure. Well the cam sensor code went away but I am still left with this problem.

the battery is brand new as of threee days ago, and terminals are shiny clean. I just ran out to have a look at the wires and my positive cable coming from the batt is corroded where the wire goes into the terminal connector, imnot sure how I missed that..... Could this be my problem? I would think if it were bad I would have some charging issues?

now this is totally random, sometimes I start the car up, no code, runs great then throws the code down the road. Sometimes it has the code when started and then goes away down the road. and sometimes it will not throw a code, or not clear a code for days. It is absolutely random, not when cold or hot. It does seem to act up more on humid days, and run better when it is cool and dry, this is pointing me towards a wireing problem or possibly a ground?

I have not tried testing coils, but Im on my way to pick up my multimeter from a friend to do just that.

The computer is factory, up until I bought the car and threw the cam sensor code there have been NO problems, it was my uncles car for 8000 miles, then my grandma drove it up until 70,000 or so when I bought it.

I am positive I am jumping the correct terminals, because when the code goes away it will go into diagnostic mode and flash 12'* all day, I even have the proper key to plug in from autozone(a friend who works there hooked me up).

I appreciate the help guys, this is my daily driver and 10 mpg is getting pretty old, not to mention expensive. what else you got for me???

thanks,

kyle

I have seen other cars act exactly as you are describing with battery terminal or cable corrosion. It seems weird but it happens.

i had looked them over when I changed plugs and wires and they looked ok, never tested them. I decided to cut open the positive cable near the connector and it is just coated with blue crap.

im not even going to check the ignition yet im going to hit the parts store first for some new positive and negative cables, if it still persists then I will check the ignition coils.

thanks

thats definetly a electrical problem.. clean all grounds and power wires on the car..(with electrical cleaner) and also clean the cable from the battery'* positive to the engine. clean both sides of each wire..

i picked up a new positive batt cable tonight, gonna put it in tommorow, the one on there right now looks real bad. I am also going to go over all grounds.

thanks

Do you mean the inside and the outside :?: When the wire inside the insulation has turned blue, it is time to replace the cable, as he has already figured out. I'm sure when he gets that taken care of, he will get back to you.

The corroded cable may not be the only problem, but replacing it is definitely part of the solution.

by both sides i mean both connection corners of the wire.. the side on the battery and the side on the engine...