I'm new here, although I've been lurking around for a while. My wife has a C5 and we'er having problems.

First, a few weeks ago the A/C turns off randomly. Then it will come back on after a minute or two. Also, when you start the car, the A/C takes about two minutes to come on. I suspect an electrical problem.

The battery reads over 12 volts before starting and over 13 after. Those readings are with a multi-meter. The volt meter on the dash reads slightly lower. Not sure why the differnce. Ocasionlly, the dash reading will go down to 11 volts for just a few seconds and then back up. But the A/C doesnt go off when this happens. I'm going to try a differnt battery.

Second problem, Yesterday we started on a two hour trip and after 15 minutes the check engine light came on and car started running rough. Didnt seem to be related to the A/C. We cancelled the trip and I took it to auto-zone and they plugged in the computer. It said one O2 senser and random misfire. (Duh) I ordered a fuel filter because it felt like it is running out of gas. (Both codes said that fuel pressure could be culprit)

If anyone has a coment on either issue, please speak up. I did some searching, but my computer is so slow it takes 5 minutes to open a page and find out it is of no value.

Thanks

 

My first reccomendation is that you upgrade your PC/ISP. Waiting 5 minutes for a page to open is a serious problem when there is so much good info to be found here and elsewhere.

 

My computer is brand new top of the line. Aparently, it is my satelite that is slow.

I got the codes from auto-zone.

The first was cyilinder misfire detected-random cylinder.

The second was cercuit condition (heated o2 sensor bank 1)

 

You still need to help us help you. Pull your own codes, write each one down than post them here. It's real easy to do and a good thing to use with any problems that WILL occur.

 

The C5 was the only car model in the world that would let you read and reset all of the possible codes on the car from the instrument panel. No need to make trips to Autozone and you get better data.

Bill

 

OK, I went to that page and tried to take codes. It says turn ignition on (no start) and press reset to get rid of warnings. Then push and hold options and press fuel four times.

On mine when you get to three times the screen imediately shows QC 114441. it will do nothing else for about two minutes and then return to brake before start.

Question-where is the fuel filter? I have a new filter from advance auto, but I cant find it anywhere on the car. I've got a manual I bought from GM for about two hundred bucks and it doesnt show one. (that doesnt surprize me, it has never helped me on anything I've done to the car) I guess I should have bought a Chilton.

 

That page does not tell you how to clear codes.

 

To exit the diagnostic mode at any time, press "E/M". If you want to erase or "clear" codes, press "reset." Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory

I believe our fuel filter is located in fuel tank, not sure which one though.

 

The car is a stock 97' with an automatic. (150,000 miles)

I did print the page, but it did not print far down enough to show clearing codes. Of course, it printed to the end of a paragraph, So I didnt realize I didnt get it all. LOL.

in any case, like I said it wont show anything but QC 114441. I tried it about four times. I'll try again tomarrow.

I found another thred on the fuel filter and just got it changed. (runs the same) Fuel psi at rail is at least 50.

I also pulled the battery to change it and the screw terminals were full of white powder. I cleaned them good and put the same battery back. (My extra battery was too big.) This may have cured the A/C problem.

I will attack it again tomarrow. I'm sorry if I sound frustrated. I use to have a C3 and it was a whole lot eazier to work on. I could pull the transfer case on my Bronco in the time it took to change the fuel filter on this thing.

Thanks to all that tried to help.

 

I've never heard of that display reading before "QC 114441" and no clue what its meaning. Whenever we hear of a random misfire, the first thing to check is the ground connection on the rear of the driver's side head. A bolt there holds a couple of wires to the engine head that ground all of the coil packs.

 

OK, I'm getting somewhere. I unplugged the main plug that hooks to the coils and injectors on the drivers side. The car runs the same. Just to be sure, I unplug the other side and the the car wont start. I plug just the drivers side and the car wont start. I plug just the pax side and start the car. Runs rough. While it's running, I plug the drivers side in and no change.

It would appear that the car is running on four cylinders. (It is amazing how good it runs considering) I guess it's because the car is over powered.

In any case, I'm guessing that plug leads to the ground that Dgrant mentioned. But I cant see where it is. Is this something you can get to with out taking the intake off? Its so tight back there, is there access from the bottom, interior?

 

I thought I would give an update on this. I took it to the dealer and he replaced a fuse. There are two fuses named injector 1 and 2. They each power four cylinders. When he replaced the fuse, it blew right away. He figured it was a short somewhere. He never found one, but he did find a wire that ran real close to the exhaust. He put some insulation around it and it seems to work. I have to say, i dont like his "fix". But at least it drives.

 

Very interesting. Are you having full power now?

 

Yea, it has full power.