Now a long time ago I learned that my wife is always right and that her descriptions of things that go wrong with her baby are normally pretty accurate. Not only that, but her sense of what might be wrong and her "quick fixes" usually amaze and sometimes amuse me. This time was no exception. It was July of 1993 and she had come back from a mall trip. The traffic was pretty bad somewhere along the way and the 86 Buick was forced to sit there in the sweltering heat at an idle. That normally wouldn't have caused any sweat since the cooling system was up to snuff and had been able to handle those conditions in the past. But, this trip was different. Arleen described what happened next. "I started moving slowly along in traffic when I realized that no matter how far I pressed the accelerator it would barely begin to move. When it did move it stumbled and faltered and would barely make it to 15 M.P.H.." Well, if you know Arleen you might imagine that 15 M.P.H. just won't do. Old lead foot wants 60 or nothing. She further told me that after she went along the shoulder of the road for a half mile or so it started to get better. She figured it had something to do with the heat (woman's intuition) and she tried a trick she had heard about long ago. She popped the hood release to the first notch. Now you might all be a tad worried that she had done a stupid thing in that the hood might just likely fly up over the windshield and cause a major tragedy. BUTTT, this was an 86 Buick and those of you who know the vehicle know that the hood opens backwards! It does pop open about three inches in the front but then tips forward from the cowl. Sooo, the problem is a non issue.
What did happen when she popped the hood was to let cool air circulate in the engine compartment and cool off some, as of yet unknown, offending component in the engine compartment. Soon, to her delight she was cruising along at 60 once again.
Well, as usual I didn't have time to check it out right away but I soon wished I had. The next weekend we took a trip to New Jersey and stopped along the way in Easton PA to do some sight seeing. It was hot - temps in the mid 90's. And as luck would have it the Buick started doing it again. This time I was driving and this time I was on a two lane with traffic backed up behind me. I could barely do 20 with it floored. With horns honking and lights flashing behind me Arleen calmly said, "Just pop the hood - it works!!" I did and once again it began to clear up and run smoothly once again.
After returning home a few days later I decided that enough was enough - I had better start debugging the problem. It was a hot Saturday afternoon and I told Arleen I was going to work on the problem. "Not hot enough", she commented. "It has to be 90 or better for the problem to occur." I went inside and turned on the weather channel. Forecast for cooler and less humid - high only about 80. Well - I guess that's that! Can't fix a problem unless its there, right?? Arleen changed my mind quickly. She started showing me ads for new Buicks in the Saturday paper. "Maybe we should take a look at the new ones! I saw a really pretty red one with air and a sun roof and . . . . . . " My mind blurred. All I could see was a book of new car payment coupons in front of me. Three hundred an eighty bucks a month for the next three years . . . .uh-uh.
I quickly changed my mind. "Well, maybe I could hook up the computer and see what's going on" I mumbled.
"I knew you would see it my way". she smiled.
Now this car is equipped, as are all late model GM products, with a connector under the dash that is used to access the computer that is the brains of the beast. I have a really good friend who has this swift little gadget that plugs into the connector and connects to a laptop computer. I guess you could use a non laptop but it might get ugly if you decided to take it for a road test with the computer plugged in. Anyway, I went over to his house and borrowed his laptop and the gizmo and plugged it in. All was well; no faults set, engine temperature up to normal. I took it for a spin around the block. Everything checked out just fine. This thing is really neat. You can see everything the computer sees - right there on the screen! It is a bit dangerous cuz you are tempted to watch as the shift solenoids switch on and off and the oxygen sensor goes from lean to rich. But who's watching the road!!!!?? Vouchsafe to say and what have you, there was nothing wrong and it ran like a top.
That summer remained cool and the problem never re-occurred for the remainder of the year. I couldn't figure out what was going wrong, but I knew one thing - fall was coming and I had better things to worry about.
Time passed and before I knew it summer of 94 arrived. Along with it came the familiar cry, "It's doing it againnnnn!!"
This time I was lucky. The forecast for the weekend predicted temperatures in the 90's. I borrowed the computer stuff again and set out determined to find out what was causing this erratic problem. I hooked it up and went to work. This time I decided to really give it a stress test. I could monitor the coolant temperature by watching the computer readout so I felt safe in disconnecting the electric fans. Then I closed the hood and let her sit there and idle for ten or fifteen minutes. It started doing it! Right there in the driveway! I quickly jumped in the driver's seat and put it in gear. The wheels were chocked and the parking brake set. I dropped it into drive and slowly pressed the accelerator pedal. Uggggglllly! It stumbled, backfired and generally did what Arleen had described, and what I had experienced the previous year in Easton PA. I ran a "save data" program on the computer and let it store information for a minute or so. Then I shut her down and reviewed screen after screen of data - NOTHING WAS WRONG!! At least that's what the computer had told me. I knew better and set out to start thinking out of the box to see what I could find out on my own. Remember, the computer doesn't tell you everything - nothing about fuel pressure, nothing about ignition voltage, nothing about engine timing. Air mixture values are there as are oxygen sensor readouts, but all that was normal and within range I needed to do some brainstorming.
The first thing I checked out was the ignition coil set. This engine has three ignition coils, one each for every two cylinders. I got out a heat gun to accelerate the problem. You see, every time the problem occurred it would stop about a minute after I opened the hood! Arleen's trick was working - but just when I didn't want it to! I started the engine and heated each of the coils until they were well above normal operating temperature. No problem. Next I heated the injectors and the fuel rail thinking it might be a vapor lock problem, knowing that the fuel rail is under 45 PSI pressure and that was unlikely. Wrongo. What else?
I started to change my thinking about the problem. I knew I could cause it by running with the hood closed and the fans off - why not try cooling components one at a time instead of heating them. So far I was getting nowhere using that approach.
Here's where thinking "out of the box" pays off. I knew I could cause the problem and it would persist as long as I kept the hood closed, but as soon as I opened the hood the symptoms left within a minute. What I needed to do was to selectively cool components with the hood closed. Now you may think this way out but it worked. I took a length of windshield washer tubing and hooked it up to the windshield washer pump. Then I wired the business end of the hose to line up with one component as a time. I had been told somewhere along the way that the likely candidate was the ignition module upon which rests the three ignition coils. That was my first attempt. I filled the windshield washer with ice and water and closed the hood. Soon it started bucking and coughing and I just sat in the driver's seat, in the nice cool air conditioning and turned on the windshield washer. There was no improvement - it continued to cough and sputter - one component eliminated. By a process of elimination I wired the tubing so as to cool one item at a time. Next the fuel rail, then each injector, then the MAP sensor, the throttle position sensor - nada - no improvement. But as least I was eliminating possible candidates without the expense of having a mechanic replace them one at a time, with the ultimate comment that "it probably needed replacement anyways".
I was just about at the end of my rope when I remembered two sensors that I hadn't cooled. They are the crankshaft position sensor and the camshaft position sensor. But they should have caused a computer fault, right? And they would have been indicated on the computer screen, right? After a bit of reading in the service manual I discovered that the computer won't set an intermittent fault - the fault has to persist for at least seven seconds (or some rather large number). Perhaps the fault was so intermittent that it wasn't picked up by the computer.
Both of the sensors are hidden behind the serpentine belt, the water pump and lots of other hoses and junk. But I was able to snake the thin windshield washer hose down to the area and pointed it first at the crankshaft sensor. Five minutes later and another cup of ice water squirted at the sensor yielded negative results. There was only one component left, the camshaft sensor. Now most of you probably have had the experience of looking for something in a dozen places and have found it on the twelfth try, right? Well this was no different. It only took about two seconds of squirting and the engine cleared up and ran as smooth as a baby's er, elbow! Voila! That was it! After two summers of wondering I had finally isolated the problem.
I removed the sensor and looked at the schematic of it in the service manual. I put it in a vice and measured the resistance of the coil contained inside. Just perfect. Fire up the Bernzo torch and apply some heat - INFINITY . . . OPEN . . .NO CONDUCTIVITY! The problem was confirmed. Down to the local parts store, whip out the Visa card and 27 bucks later I was on my way back to the garage with the solution. Ten minutes later she was running like brand new once again and to this day the good old Buick doesn't falter a bit even in the heaviest of traffic in the middle of a sweltering August day.
One thing this points out is the importance of diagnostics. Most shops would have found the problem eventually, maybe sooner, maybe later, but with no diagnosis but the old replacement therapy. That costs big bucks! I admit that my ice water diagnosis was a bit unorthodox but it worked. That's the kind of thinking I would like to see in any good service organization. Cause the problem to occur by listening to the customer (my wife) and doing whatever it takes to do the simulation. Then methodically eliminate possible candidates by whatever means necessary (except replacement therapy!) until the villain is found!!
Tools required: A 3/8 drive socket set. A set of box wrenches. An ohm meter. Two trays of ice cubes and a gallon on cold water. A good bit of ingenuity. Patience.
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