Engine Performance problem
2001 Chevy Impala V8 Front Wheel Drive Automatic 151000 miles
My car stalled out on me while I was driving on the freeway. When my speed reached the 60- 65 mph mark, the rpm's dropped and the car shut down. After letting the car sit 2-3 mins. I can start it up again and drive off but the same thing repeats itself. I just got a new fuel pump put on this summer so I don't know what it could be. So, I took it to the repair shop and the guy told me that he couldn't find anything wrong with it. He said he drove it around the corner off and on for about 3 hrs. And he checked the censors and even the fuel pump I just put on there and couldn't find anything wrong. I went and picked it up, drove it on the freeway again and got around 65mph and the samething happened again. I'm just lost right now and I need some help on finding out what it could be.
All " crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.
Every engine requires spark, fuel and compression to run. That's what we have to look for.
These are the basics that need to be tested and will give us the info required to isolate a cause.
1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.
2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.
3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.
4) If all of these things check good, then you would need to do a complete compression test.
Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
September, 12, 2010 AT 11:30 PM
This is the kind of problem that has given the Impala a bad reputation. When you take the car to a mechanic and he can't find anything wrong, it can be very frustrating. It's almost impossible to do the tests for the diagnosis when in only 5 to 20 minutes the car can be started.
I had a similar problem with my 2000 Impala. It was shutting down while I was driving on the freeway.
I found a mechanic who would stick with the job until he found the problem. It took almost a week and a declaration by the mechanic that the car was possessed, but he finally found the cause of the problem. It was the Crankshaft Position Sensor.
There must be a heatsoak problem that affects the ability of the sensor to relay data to the computer.
Anyway, I believe if you change the Crankshaft Position Sensor the problem will go away.
September, 13, 2010 AT 4:19 AM
Just because the Crank sensor was the cause of a problem in one care DOES NOT mean it will be in your car and simply throwing parts at it will get very expensive and it the car is not tested during the failure, that's exactly what you are doing.