Hello everyone. I'm new here to the forum and a new 240SX convertible owner. I'm hoping someone here can help. My apologies if I've broken some rule or ettiquette.
So this is the deal: I bought a 93 convertible off a private owner. It ran and drove fine on the test drive so I bought it. When driving it home, I got 3-4 miles down the road and it stopped responding to the throttle. It slowed from about 45 to 40 mph and stepping harder on it didn't help. At some point, though, the transmission (automatic) downshifted and it started building RPM as if there were molasses in the engine.
Soon after that, it picked up RPM like it was supposed to and the car rocketed to about 90 mph! Well, since it was low on fuel (less than a quarter tank), I stopped at a gas station. I waited for traffic to pass and then I made the left hand turn. Fortunately traffic wasn't all that heavy because stepping on the gas did nothing. It only moved because it has an automatic transmission and my foot was off the brake. I put fuel in it and drove it home with no changes.
So I get it home and over the next week or so, I change the spark plugs (not all that bad), distributor cap and rotor (the rotor showed some signs of wear but wasn't terrible), oil and filter (the oil was dirty), and the fuel and air filter. No change in the performance. A friend of mine told me it likely needed a throttle position sensor since this car is almost 30 years old, has 200,000 miles (for the most part) and probably has mechanical parts to it. I bought one (Beck Arnley) and installed it.
After I installed it, it wouldn't start. I did all the things I thought I was supposed to do but they didn't work. I pulled the spark plugs out, dried them off with a towel and some carb cleaner and left it open overnight to dry. The next morning, I put them back in and the car still wouldn't start. I thought maybe it was getting too much fuel, so I pulled the fuse for the fuel pump. It started for a few seconds and then stopped (no fuel). With the help of a friend, I sprayed some starting fluid in it and it started and ran. I put the fuel pump fuse back in it and it wouldn't start again.
The only thing I had really changed was the TPS and was really careful to line it up correctly and it was a lot of work to install. So, just for shiggles, I unplugged it from the car and plugged the old TPS in. It started and ran with starting fluid. When I stopped the starting fluid and put the fuse back in for the fuel pump, it started and ran. Thinking something might be wrong with the new TPS, I unplugged the old one and plugged the new one back in and it started and ran.
Talk about bizarre!!
It didn't change the throttle sometimes not responding, though. Does anyone have any ideas of what to replace or check next? What could the problem possibly be?