I am trying to help a friend of mine to fix his 97 Grand AM with a 3.1L V6 engine automatic. The car ran fine till today with the exception of that it would sometimes need longer to crank the engine to start it (either cold or hot). Today it suddenly died at a traffic light, and a couple of times on his way home after that. We checked it parked, it idles smoothly at about 600 RPM but sometimes will start shaking and losing RPM and then die. It seems to do this completely at random times either in park or in gear. What could the problem be? Thanks in advance for any info.
Need more info... An engine needs air, spark, and fuel in the correct amounts, and correct timing of each. When you figure out which is not correct, post back here with that info.
Thanks to you all guys for the info. Just an update. Today we unplugged the MAF sensor and drove for a while, no problem (of course the light was on). We then plugged it back and again no problem. Will have to wait until it stalls again to check if really this is the sensor. Will pull the codes off the computer. Is this a simple procedure like on Ford's OBD-IV, or it needs a special scanner?
Touchy aren't we? I'd recommend re-reading the followup Mike. My query was regarding the California Bar decision to not "allow" Autozone to pull codes from vehicles. [FLONK right back at ya] ;-)
I knew working 80 hours a week would cloud my vision......Guess I should FLONK myself.
The BAR in California has determined that Automotive Parts stores (ie. AutoZone) can't perform free services to help their customers diagnose their car problems.
In California, AutoZone was told to cease it's free check engine light program because the engine codes only referenced a circuit that the trouble code referenced - not the actual part; For example, a code on an 02 sensor could be a failed sensor - or the wiring. They did not want auto parts companies misleading their customers into purchasing parts that may not be the problem. As you know, the check engine light codes can be sometimes confusing, and several different codes may be caused by a failure in one system. Of course, the real problem is that not every parts-person is qualified to do this and there could have been a percentage of mis-diagnosis. Also the repair facilities were up in arms because they were charging anywhere from $40-$80 to perform this service that AutoZone was offering for free. A large percentage of codes I see out there (OBD2) relate to engine misfire, or a faulty fuel cap. Can you imagine getting charged to find out you forgot to put on your fuel cap and it tripped a check engine light? AutoZone was only trying to help it's customers save some cash by offering this free service. In addition the BAR was trying to also regulate charging system tests and battery tests. They were not sucessful in doing that.
It really comes down to cash. The BAR in California wanted to charge AutoZone an unspecified amount per employee for the privilege to help its customers by pulling diagnostic codes. For the fee the BAR could regulate the program as it does with it's repair facilities. This way the BAR could send a vehicle into a store and see if it was properly diagnosed. If it was not, they could leverage a fine.
As the complexity of vehicles has changed somewhat, and the quality of the parts counterperson is going downhill, I can somewhat side with the BAR on what it was trying to do, however I think that Auto Parts Stores should have the right to tell the customer what codes they have as a free service, and let the customer decide how to troubleshoot and repair their system. OB2 cars are very simple to retrive codes from. Plug in the scanner and read. It is more complex on OBD1, however GM, Ford and Chrysler made it pretty simple... All three rely on a flashing check engine light to self diagnose their computers - all very simple to read.
Homer Simps> Mike Graves bellowed in an authoritative tone:
Apparently a service facility is allowed to 'charge' a customer to pull his codes and then sell 'em a bunch of parts. However, Autozone isn't allowed to pull the customers codes for 'free' and then sell 'em a bunch of parts. [This isn't as much of an exaggeration as one might think.]
A large amount of parts returned to EMS suppliers are NTF (no trouble found). There are a multitude of reasons for this.... but part-swapping- roulette is NOT the least likely. I can speak to this from personal experience.
I s'pose Autozone could have chosen to "lend" scanners to customers and provided a 'code chart' to allow them to make there own determination. However, who wants the hassle of a bunch of blood sucking lawyers breathing down your neck. ;-)
This makes the situation a bit more sensible I s'pose...particularly since I see (via google) that the BAR also regulates emission compliance. I s'pose they basically want the consumer to respond to an MIL with the appropriate diagnostic.... and fix/avoid excessive emissions.
Not that I'm agreeing..... just makes more sense. ;-)
Just one more update a couple days later. The car ran with no problem whatsoever. I am now guessing maybe there was a bad contact to MAF sensor. When we disconnected and reconnected it, this made the contact better. Or, there are some spliced wires in the same region. Maybe there is a bad contact there. Again we moved them a bit and this made the contact better for a while. BTW, tapping on the sensor did not make the engine stall. Interestingly, the same testing method -- tapping is given in the Hanes manual for this car. Are there some fragile parts inside? The sensor itself looks very solid.
I'll try to make this short. I had a "TPS TEC" chip on at one time on a '95 GA. When installing it, all appeared normal, but when I started the car, the fan was on, and the SES light was on. Simply unplugging and replugging changed SOMETHING, I don't know what, but it was VERY sensitive to how well the connection was.
Now, I don't really see how it would have just came loose or anything, but, I hope that you really have solved the problem. That would be nice.
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