I had a 90-something Cavalier 4-cylinder POS. It would start when cold, run fine all day, but when it was fully warmed up it was a crap shoot if it would start. Checked all sorts of things. Tried the coil pack - not that. Tried the device under the coil pack - not that. (Can't remember what device it was.) The manager at Auto Zone was super cool, too! I couldn't start the car in his lot so I was working on it in between severe downpours and light rain. While I waited for AAA to come I worked on it, too. (Got drenched!) Manager let me bring the part back in and I bought the crank sensor. It goes under the car and I couldn't reach it in his lot. Got the car towed (rain was so hard that I was on a 5-hour waiting list due to flooding all over the area) and worked on it the next morning. 15-minute job. When I had the car in the air and reached up to remove the old one it nearly fell out in my hand. It was so loose that once it was hot I guess the crankcase pressure had pushed it out too far, but when it cooled it somehow would get close enough to start (most times). The part was only $15-20 so I replaced it anyhow. Cured the problem.
Later the engine spun a bearing and I had to replace the car. It was a $200 junker to start with so it was no loss, but it was a lesson to share!
Electronics are weird to work on, especially if you're only guessing. They aren't at all like mechanical parts in that you can't see them or feel them or measure them in a physical way. You have to have or use electronic tools to assist you.
The way you describe the knocking allows us to take it in several directions. It could be predetonation, a rod bearing knocking, a crank bearing spinning, a wrist pin, a valve, a slipped tooth on the timing chain/belt, or something else. What leads me to believe it may be electronic is that it was still running and you felt you could start it again and drive it. Also, the MIL (malfunction indicator light, aka CEL, SES) came on and went off, suggesting that the PCM was sensing something amiss but that it came back within operating parameters.
I hope it's simple and cheap. Please post what you find. We'd all like to know!
Later the engine spun a bearing and I had to replace the car. It was a $200 junker to start with so it was no loss, but it was a lesson to share!
Electronics are weird to work on, especially if you're only guessing. They aren't at all like mechanical parts in that you can't see them or feel them or measure them in a physical way. You have to have or use electronic tools to assist you.
The way you describe the knocking allows us to take it in several directions. It could be predetonation, a rod bearing knocking, a crank bearing spinning, a wrist pin, a valve, a slipped tooth on the timing chain/belt, or something else. What leads me to believe it may be electronic is that it was still running and you felt you could start it again and drive it. Also, the MIL (malfunction indicator light, aka CEL, SES) came on and went off, suggesting that the PCM was sensing something amiss but that it came back within operating parameters.
I hope it's simple and cheap. Please post what you find. We'd all like to know!
