1986 buick lasabre stalling

I have a friend that is having trouble with her car stalling. it would start up fine run fine for about 1 to 10 mins and then stalling running rough. this can happen when Idling or going done the road at 65 and it last 5 to 30 sec and then comes out of it and runs fine for the rest of the trip it seems to be at the intermediate stage of the motor warming up. replaced oxygen sensor, fuel filter . I am thinking the egr valve or cam sensor.

Thanks
Lane

What is the condition of the vacumn line for the EGR? It should look like this:

<-to-throttle-body-----vac-line-----[EGRsolinoid]------vac-line------[EGRvalve]

Sometimes people will by-pass the solinoid for some reason or other.

I'm not entirely sure as to what the problem is, but from the description I gathered that at the point where the ECM switches to closed loop operation is when the problem occurs. This means that the things it could be are sensors, ignition, or timing.

If you have a laptop that has a serial port, you can make a cable that will read computer input/output (sensor data, computer outputs), and tell you where the problem(s) may lie. There is a program called Winaldl that will enterpret the data, and put it out in an easily readable user friendly interface. The site is:
http://winaldl.joby.se/
I suggest reading what it says, and hooking it up to your car to find the problem. I use this program for my 86, so I am fimiliar with it and how to make the cable. The web site also tells you this. Radio Shack (or similar store) will have all the parts you need (~$10). This eliminates a lot of guesswork. If the program sounds like it is something you want to try (see web site for supported GM vehicles by motor description), I can help you with getting it up and going.

I changed out the egr valve and wanted to see if that made a difference before I posted here. It sounds like it is still not working right. I can get access to lap top I think. It doesnt look to bad. The one question I have it looks like there is a GM connector is that something you can get at the electronics store? where does it plug into on the car. I would like help on the cable if you wouldnt mind. did you build it like the web site? I noticed there were several different versions.


Thanks
Lane

I have not been able to find a GM connector for the ALDL. I just put the wires directly into the ALDL.

Yes, I built it as the web site has it shown.

You will need
-2 10k resistors
-1 NPN transistor (of the listed types, 2n2222 is the one I used)(Do not use PNP transistors)
- Serial db9 connector (for back of laptop)
-for the 12v+, try the diagram that has it going to pin 4 on the serial connector. If that doesn't work, then use the cig lighter.

These diagrams are very straightforward. R1 and R2 are the 10k resistors, and Q1 is the transistor. On the back of the packages these come in, it will tell you which is the base, emmiter, and collector. Resistors don't have polarity (they can be put in backwards or forwards and still work). The collector and the 10k can be soldered together, and then soldered directly to pin two on the db9 connector. He included a picture to illustrate that.
you only need two wires, as shown, for the cord. They can be wrapped together, as long as they have individual insulation (shown in picture) The wires just get inserted into the correct terminals of the ALDL connector, also shown.
If you run into any other difficulties, let us know.

Well I tried the computer diognostic and could not get it to work. I am not sure what is wrong. did you have any initial problems?

Thanks
Lane

Most problems will be with the cable.
How did you make the cable? Did you use the cig lighter for the 12v signal, or pin 4 on the serial connector?
also note that R4, a 1.5k resistor, will cause the cable to not work on your car (fuel injected).

When you enter the program, make sure you select the correct computer type. It is listed in the readme file. If it is getting a signal from the computer, the small box on the top of the screen with nothing in it will flash green, or have the #25 in it, or both.

Most problems will be with the cable.
How did you make the cable? Did you use the cig lighter for the 12v signal, or pin 4 on the serial connector?
also note that R4, a 1.5k resistor, will cause the cable to not work on your car (fuel injected).

When you enter the program, make sure you select the correct computer type. It is listed in the readme file. If it is getting a signal from the computer, the small box on the top of the screen with nothing in it will flash green, or have the #25 in it, or both.


I used the cig lighter for the 12V. did not use the 1.5K resister. I will have to look at the computer type in the readme file tonight.

Thanks
Lane

Right immediately after it starts to do it, if you shut it off and restart it, does it clear it up temporarily? I had an 87 Oldsmobile that did that. It would run good at first and then after about 10 minutes it would go into a shudder and spudder mode. If I shut it off and restarted it, it would clear it up temporarily. Eventually, it progressively got worse. I blinked out the codes out on the dash and it said bad ignition module or bad computer-per the book. This wasn't much help, because those were the 2 most expensive things involved with the electrical. I replaced the ignition module and that didn't fix it. Put in a remanufactured computer and that solved it. I think it went into a limp home mode when it ran rough.

It would sometimes quit and start right up and would run rough and then smooth right out after usually giving lots of gas and would work for the rest of the trip fine whether it is 5 min or couple of hours. it would run rough for 30sec to 1 min. is there a way to do the code by the lights on the dash?

Thanks
Lane

I don't know if your car will be the same or not, but the Oldsmobile had a little plug in for the diagnostics directly below the steering wheel (kind of up and under). From what I recall, it was easily accessible. It wasn't that large of a connecter; it didn't have room for many pins. All you had to do though was to jump two of the pins together with the key in the on position. A paper clip would work or a short piece of wire. It would then blink the codes out via the check engine light (watch the instrument cluster) in sets of 3. There would be a pause between each set of 3. You just had to count the blinks and write down the numbers. The Haynes manual has the meaning of the codes. The codes were 2 digit numbers.

I have the book here now -never throw anything away. It says this can be done for 93 and earilier models:

Hook a jumper wire between the ground terminal and the diagnostic test terminal. The two terminals are right next to each other on the top row, when facing the connector. They are top two pins on the far right, top row. Connect them with a short wire. It says though, if the connector has a 12 pin connector, it won't work. For those you need a diagnostic tool.--That may be the case for yours, not sure, but you might as well see if it will work.

This book doesn't say to put the key in the on position, but I thought that you had to. Might try it without the key on first. Book calls i the ALDL (Assembly Line Data Link). I think I have another book around here that is more specific on how to do this. The book has a list of about 40 or more codes and what they mean.

That only works if the Service Engine Soon light has come on for some reason or another. Any code it does display if it hasn't come on since the problem started could be from a previous problem.

You jump terminal a to b with the paperclip, put the key in the "On" position, and watch the light. It will flash the value of the tens digit, then the one digit, in that order, for each code. When you first start, it will flash "-..--", or code 12. Every code will be displayed three times. So, for code 12 the light will flash like this (- means light flashes on, . means light off)
....-..--....-..--....-..--....

The check engine did flicker when the car would stall. I dont know if is still as my friend is the one driving it. I have not looked at the program. been too busy. I might try the shorting of the code just to see if I can get anything out of it.

thanks
Lane

I had one here in my shop this past week and had very bad miss stalling and did a diagnotic and said it was the egr valve i replaced it and is running great.