Charging System Problem
I just got a '90 LX Hatchback a couple of weeks ago (new to the forum) and its pretty mint except for this one problem which has just begun. Last week sometime, when I started the car up in the morning the check engine light came on briefly. I ignored it and then the following day when I was driving to work, it flashed on again briefly. Again I didn't pay it much attention and made a mental note to flash the codes out of the MIL later. Then a couple days later when I was on my way back from a store in the evening I noticed that the Voltmeter was reading pretty low. Not in the red, about two notches above the 8. Usually it's right in the middle of the gauge and I didn't have the HVAC blower on, or the rear window defroster, or any other major electrical load. When I got home I did the KOEO and KOER tests and produced a code 31 in the continuous memory. This is what the Chilton manual describes under code 31-PFE, EVP or EVR Circuit below minimum voltage. Since then the check engine light has come on and off in the same manner, Usually for only 2 or 3 seconds and then goes off. One night it stayed on for probably 15 minutes while I way driving home on the highway, but shut itself off before I got home. Before I had gotten on the Highway the light was already on and the system voltage was pretty low at idle and low speeds, but came back up to normal once I was going. The low voltage and the MIL light being on sometimes accompany one another and sometimes not. The problem seems to be affected by heavy acceleration. A couple times when I have had my foot to the floor and am rowing through the gears the MIL light will come on while I am still accelerating and will come off as soon as slow down. The base battery voltage of the car is about 12.05V, the system voltage with the car running is about 14.5V. If I run the car and turn on the blower, rear defrost, and high beams and then shut them off and let it charge for a couple seconds and then shut if off, I get a battery reading of about 12.7V. So, the car seems to be charging properly most of the time. This doesn't seem like a huge problem right now, but it's kind of irritating and I want to catch it before it develops into something worse leaving my stranded somewhere. Has anyone ever had similar problems with their 5.0L? Or is this the first you have ever heard of such a problem? I don't want to just start replacing parts. Thanks for reading this far, and any input would be greatly appreciated.
1990 LX 5 Speed - Ford Racing LCA's . 16" Pony Rims, Maximum motorsports stock brake upgrade (stainless caliper sleeves, hawk performance brake pads, braided stainless flex hoses). Flowmaster American Thunder Catback w/polished stainless tips. FMS GT40X turbo swirl heads, BBK equal lenth cerarmic coated shorties, bbk catted x-pipe, and FMS E303 cam.