Saturday night i was driving to a friends house at 75mph on the highway and suddenly i see a little orange light on my dash... the "check engine" light blinked at me really quick. so i hit the brake to turn off the cruise and slowed to 65 and drove at that for awhile, nothing. Well then i hit resume to 75mph and was driving there for a few minutes, and the damn light did it again, only it took slightly longer to blink. After that i got off the highway and stopped in at a Meijer gas station and went over all my hoses and belts with a fine tooth comb, and a flashlight...nothing wrong that i could tell. So i got back on the highway, did 75 the whole way, and even drove around for an hour after that, stop and go traffic, and there was nothing. nothing at all.
Here´s my theory: the pipe coming off the header and before the resonator is sort of rusted out and there´s a hole. could that be causing my O2 sensor to read too much O2 in my downpipe, causing the ECU to richen the mixture? I´m hoping thats it.
Could I be right, or am I an idiot?
well i don´t know if my Scort had the same problem you´re having, but it did do the same thing kinda with the engine light: last winter after some really cold days, it wouldn´t start right away and the light would come on, but there weren´t any noticable leaks or anything, and it still ran strong after it started. eventually, cuz the light kept coming on, and because it didn´t warm up very quickly, i took it in to get it good and checked. found out that the radiator had the slightest leak, like a drop every couple days, and after replacing and fixing that, i´ve been perfectly fine ever since
Run a self-test at the diagnostic connector. Use a jumper wire to connect the TEN connector and the GND connnector, then turn the ignition key to ON. The check engine light should flash error codes, if any are indicated.
One thing you could try, especially if the car shudders or shakes at higher speeds as well is to replace the TPS. My car´s check engine light used to come on all the time, as well as shuddered at around 80 MPH, and it also idled a little rough on occation. Since I´ve replaced the TPS, I´ve had no problems, not with that anyway.