Engine Performance problem
2000 Oldsmobile Alero 4 cyl Automatic
I have done everything I can think of, so hopefully someone can help point me in the right direction!
Four days ago, I added some fuel injector cleaner to my gas tank. I drove it for about 15 minutes until it began to idle rough and eventually stall while I was stopped at a stop sign. I shut it off and had a hard tme starting it back up - I tried several times until it finally started. Since then, it has idled really rough and the tachometer jumps around just under 1000RPMs and has hesitated whlie I take off from a stop or idle. It runs fine at highway speeds though. I took it to Autozone where they said that it didn't pull any codes other than the engine having " multiple misfires". I changed the spark plugs and " wires" (more like boots), replaced the IAC valve, replaced the MAP sensor, replaced the throttle position senor, replaced the fuel filter, replaced the air filter, checked a vacuum hose and didn't see anything suspicious, and I checked the coils which all appear to be sparking fine. My next thought is that the problem cound be the fuel injectors. Does anyone have any feedback/ideas that may help? I have no idea how to change/replace fuel injectors and I'm at a loss for ideas about what could be wrong. Any information would be helpful!
My daughters Alero (4cyl 2.4, 178,000 miles) also had the same problem. Would stall coming to a stop or when coasting. Rough idle and stumble or stall, sometimes both if you put the slightest pressure on the accelerator when stopped in gear. No check engine light.I eliminated the obvious. Had fairly new spark plugs. Replaced the spark plug boots/connectors and fuel filter (original filter!). But still had same problem. Then I saw it! When the engine was at idle the vacuum was sucking the hose to the map sensor closed! Replaced with $2.00 peice of vacuum hose. Problem gone. Still has inherent shaky idle but runs good. Im happy. And solved the problem myself. Sometimes the vacuum hose looks fine at the sensor but is split where it connects to the vacuum port on the other side.