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1984-86 Toyota Camry 2S EPosted 8/6/1997By Brad Davis
1993-95 Chrysler Concord, New Yorker, LHS, Dodge Intrepid and Eagle Vision.
Problem: Car stalls intermittently when fully warm and usually under load. Restarts almost immediately. Repair solution: After having the technician determine there were no stored codes, I asked him to test drive the car with a fuel pressure gauge hooked up and strapped to the windshield (so he could see if it lost fuel pressure) and a timing light strung into the car (so he could see if spark was lost when the problem occurred). I also suggested that he hook up a voltmeter to the B+ terminal at the computer to see if the computer was losing power intermittently. Taking a passenger along assured me he would make it back to the shop safely to call me with the results! After quite a bit of time on the road, the car finally stalled, but it did not lose spark, fuel or power to the computer. The next test was to check the injector pulse. Down the road it stalled again - with injector pulse. On this particular test, the technician said the engine seemed to turn over fast when he first cranked it, but wouldn't start. After letting it sit for a minute, it cranked normal and started.
The fast cranking speed was the tip off. The only logical reason the engine would crank fast is from a loss of compression, most likely caused by the valves hanging open. Further inspection showed heavy carbon build-up on the valves. They were sticking slightly at high engine speeds and temperatures. The hydraulic valve lash adjusters would compensate for the clearance, in return opening the valves even further. They would stick again and the lash adjusters would compensate. This process continued until the vehicle lost power and stalled. Then, the oil pressure would go to zero and the valves would close, regain compression, start and run fine.
"Check Engine" Light On, But No Trouble CodesPosted 8/6/1997By Jamie MacFarland
When a vehicle comes into the shop with its 'Check Engine' light on, one of the first things that comes to mind is 'something is wrong' and usually this is the case. However, if a 1988 Ford Ranger equipped with a 2.0 liter carbureted engine comes in with the amber 'Check Engine' light on, getting out the scan tool to pull codes will only lead to a headache. In 1988, Ford equipped the 2.0 liter Ranger with an electronic idle speed control system (ISC-E). This MCU-looking module sits under the hood on the inner fender. It has both the single wire and six-cavity self-test connectors just like any EEC-4 system would. This ISC-E system is only on the vehicle to control idle speed, via the idle control motor. It is a relatively simple system that incorporates a temperature switch, an RPM input and a tracking switch input from the tip of the ISC motor. This ISC-E system does incorporate a KOER (key on engine running) self-test that is performed with the aid of a scan tool. The KOER self-test will result in either a pass code "11" or a trouble code if a system fault is detected. The kicker here is that the "Check Engine" light is not connected to this ISC-E system in any way! It is a timed EMR (emission maintenance reminder) light. Like other Ford EMR lights, it is timed to come on after approximately 60,000 miles of driving. The "Check Engine" light in this case is controlled by an EMR module behind the glove box. This EMR module incorporates a small micro switch that is used to reset and turn off the "Check Engine" light. It should also be noted that there is a list of required emission system maintenance procedures that need to be performed before turning off the EMR light! Refer to the vehicle's recommended maintenance schedule for a list of these required services.
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Copyright (c) 1996-2008. Automotive Service Association. All rights reserved.
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