I just got a 93 acura vigor. It runs well most of the time, but sometimes the check engine light will come on and the automatic transmission won't shift into the next gear. The light will come on sometimes when I am stopped at a light, and then I have to shift into neutral and restart it. I checked the dtc codes and it flashed a 4, 8 and a 9. I'm guessing that is three different one digit codes. The codes are:

4 Crankshaft Position Sensor
8 TDC Sensor (Top Dead Center)
9 CYL Sensor (No. 1 cylinder position)

as the codes.

So what would that mean? Are three of the sensors broken, or is it something else? Please help. I love this car, but I don't want to put a lot of money into it, so if it is something I can fix myself I want to try that before I take it in.

 

try changing the auto trans fluid, that will most likely fix it

 

This may sound strange, but here's the likely answer.

Your alternator is bad and needs replacement.

The faulty alternator gives out voltage spikes which makes the computer think one of the sensors is bad (ie. crankshaft position sensor- Code 4) and puts the engine in "limp mode" which in turn limits the engine's rpm to about 3000 rpm and causes tranny shifting problem.

To test the alternator, drive the car with no accessories on. The check engine light should not go on. Now turn on all your electrical stuff (lights, blower, defroster) and the check engine light should come on. If it does, replace alternator.

 

Hi,
I have just been through this.
When I first start my car, it runs fine. After a few minutes, the engine light goes on and it starts hesitating at 3000 rpm so I back off the gas pedal a bit, let it change gears, ease on the gas pedal again, then do the same for the rest of the gears. When I stop at a light it runs rough and sometimes stalls.
Sometimes, I can turn the car off, restart it and be able to drive normally again for a few minutes.
I have had it to 3 garages including the dealer and have spent $1,000.

This a list of the components that have been changed:
1) distributor
2) crank sensor
3) fuel filter
4) computer

NONE of these worked even though the Acura dealer swore it was a computer problem.

Another mechanic researched bullitin boards and found this problem to be common and that it is the fault of the alternator. Even though the alternator light doesn't come on (it is still charging the battery). The alternator rebuilder showed me a schematic which shows the choke running from the alternator!!!(either way, the alternator seems to control or affect many functions that are not obvious).
Anyway, he changed the alternator and now it runs great.