Alright so I bought this car last April. It's a 2001 cavalier z24. When I first bought it, it was in BAD shape. I couldn't even tell you everything I did during the first month but after that, it ran perfectly. Last November out of nowhere, the car went nuts. The long story short is that the speed sensors on the wheels were dirty, triggering traction control to come on, it shut down 2 of my fuel injectors and my PCM then over compensated, flooding my exhaust with unburned fuel and killing my catalytic converter. List of parts replaced: Fuel Injectors, throttle position sensor, spark plugs, changed oil, fuel filter,air filter, and oil sending unit. I even replaced the crankshaft and camshaft position sensors, ignition coils, ignition control module, and ignition coil boot, but after no luck I returned these things. However after cleaning the speed sensors and cutting off my catalytic converter (it was burned up completely), the car ran perfectly. Since I was then BROKE the car has run since then with a piece of straight pipe in place of the catalytic converter. Yeah, it throws the o2 sensor codes, and sounds like a pissed off weed whacker, but it actually has run a lot better than ever before and even runs better than my previous 01 z24 did. I figure I'll replace the catalytic converter someday.
But I did put in an aftermarket head unit in the stereo, hooked up an amp (with a toggle switch to turn off and on) and I have noticed some weird stuff. (The battery is mildly old, the alternator was replaced in February 2012 - I stole it off my previous z24 and put it on this one in April) Whenever I have my heat on, the car runs a little rougher but no noticeable MPG change or anything, and the previous car did too so I ignore that, however, if I have my heat on, stereo on, and headlights, I've noticed if I brake my headlights will momentarily dim and sometimes the stereo head unit will blink off then turn back on. This occurs more frequently if I also have the amp turned on, but also happens with the amp off. I have no idea what is causing this. I suppose it's significant to note that the same amp, head unit, alternator, and battery worked fine in the old z24.
Then today I started my car and noticed first that it idled a bit high until it reached full operational temperature, but also I smelled a faint smell of gas. Once the car hit operational temperature, it smoothed out in the way it ran but I still smelled the whiff of gas, and when I turned on my heat it was like I was at a gas station, much stronger. If I turned the heat off, the smell went back to being a faint whiff. I checked the CEL codes and it's only throwing the same o2 sensor code it's thrown since November. I was on my way to work when this happened so I haven't actually popped the hood and poked around yet. My MPG has not changed at all since this started, but obviously smelling gas concerns me. I guess it's significant to note, somewhere around May last year is was found the Fuel Pressure Regulator was defective and so I stole the working one off my old z24. That FPR was the original for that car and had about 220k miles on it, so I will be checking the FPR as soon as I pop the hood. Any other ideas on what I should check out? Any ideas on my stereo issue?
It would seem that you've had your share of Cav Z24 issues for 2014!
the fuel smell gets my vote as the most important issue. Check the hoses under the hood and look for leaks along the frame; the fuel tank area should also be inspected. All that said, I'm guessing you are correct that the FPR is probably leaking again.
Electrically it seems that the voltage regulator (internal to the alternator) is not keeping up with the demand. If you can, put a voltmeter across the output terminal while you have someone cycling things on/off. I just put an alternator on my Cav because the volt reg was slow to respond.
dennis
