Question about 1991 Volvo 940
SOURCE: no pulse at injectors
The normal way that injectors are controlled is via the permanent application (ignition on obviously) to one side of the coil that operates the enclosed piston, and the precisely timed application of ground (negative) to the other side of the coil.
The transistors that control this switching under the command of the engine computer are typically contained within the computer itself.
Measuring the voltage at the injectors is not productive since the common multimeter is incapable of detecting the very short pulses that activate the coil. Some kind of visual means would be needed to observe this pulse such as an oscilloscope or an engine analyzer equipped with a 'scope.
It's unlikely that all of the switching transistors (or the injectors) have failed simultaneously so either the computer has a problem or there is no fuel being delivered to the fuel rail that feeds the injectors. You should find a pressure regulator that sits between the fuel line coming from the tank that controls the fuel pressure for the injectors. This device seem to be a sore point in many vehicles and can make it appear that the injectors are not working. Many fuel rails have a fitting similar to a tire valve to allow the testing of the pressure being delivered. I would recommend you check this before assuming that the injectors are at fault.
Posted on Nov 14, 2008
95-97 Maximas had a problem where condensation from the A/C would accumulate in the a/c evaporator case from the drain becoming restricted or blocked, When this would occur, condensation would drip onto the ECM and a problem would develop with misfire and/or starting. I would look at the ECM where the harness connects to it for corrosion problems. If you find it, there is a chemical spray which can be used to clean the terminals and/or you can clean them, although it is time consuming and difficult to due because of how small the terminals are. After things are cleaned up, lightly coat the connections with a dielectric grease. This will prevent electrolysis.I believe you can buy these at Radio shack and possibly at an automotive parts supplier.
Also a drop in voltage during the cranking phase will cause a weak spark. Your ignition is what pulses the injectors. It takes a minimum of 9.6 volts, but ideally you want at least 10.5 or more during the cranking phase if you want to get a spark worth anything. Check the voltage on the primary side of the coil while cranking the engine.
I'll watch to see if things work out for you, let me know. ....mybunkey
Posted on Apr 18, 2009
Very important that if you are not savvy of working on your Vette ...you would be better off - taking your car to a dealership for repairs on your trouble codes. However if you feel that you want to, First locate your car's alcl this component is located just below the instrument panel and to the left of the center console. Remove the plastic cover the first two slots to your right are the A & B slots.
The A slot is the diagnostic slot and the B slot is the ground slot. Insert the computer key into these slots if you do not have a computer key, a paper clip or wire jumper clip will do, (with the engine off) this is very important...now only put the ignition key to on ( not start !!!) the check engine light will display a code 12 which is one flash followed by two flashes. This code will be flashed three times ..followed by the trouble code stored in your car's computer.
What ever the code is it will be flashed three times. Have a paper and pencil ready and write down the code.
Code #12: Normal No Codes.
Code #13: Open Oxygen Sensor Circuit.
Code #14: Coolant Sensor Circuit Low.
Code #15: Coolant Sensor Circuit High.
Code #21: Throttle Position Sensor High.
Code #22: Throttle Position Sensor Low.
Code #23: Manifold Air Temperature Circuit High.
Code #24: Vehicle Speed Sensor.
Code #25: Manifold Air Temperature Circuit Low.
Code #32: EGR System Failure.
Code #33: Mass Air Flow Sensor High.
Code #34: Mass Air Flow Sensor Low.
Code #36: Mas Air Flow Sensor Burn-Off Function Fault.
Code #41: Cylinder Select Error.
Code #42: Electronic Spark Timing.
Code #43: Electronic Spark Control.
Code #44: Lean Exhaust indication.
Code #45: Rich Exhaust Indication.
Code #46: Vehicle Anti Theft Fault.
Code #51: Faulty Mem-Cal.
Code #52: Fuel Calpak Missing.
Code #52(1990-91 Corvette Only): Engine Oil Temperature Sensor Low.
Code #53: System Over Voltage.
Code #54: Fuel Pump Circuit Low Voltage.
Code #55: Defective ECM.
Code #62: Engine Oil Temperature Sensor Circuit High.
Please remember that if you have the computer key installed in the alcl and you start the engine (you will ruin the engine's computer) only put the ignition to on (not to start).
If you should get a check engine soon display.. you can use the above procedure and codes to buy the right part or at the very least to keep from getting taken for a ride and be made to pay hight prices for some inexpensive module that you could have installed yourself.
If your engine displays a trouble code ... your engine will go into limp mode ..it will still run but very poorly. You might be able to reset the computer if it will not start (just to get home) by disconnecting both battery cables and re-installing them ...this is not recommended ..but if you are stranded it might help unitl you get your car home or to a repair shop..good luck.
Good luck and hope this helps.
Posted on May 08, 2009
This sounds like a main relay problem here is a diagram its located under the dash under steering column its the brownish -orange box in the picture. http://www.tegger.com/hondafaq/mainrelaylocation/7-main_relay_closeup.jpg Good luck and thanks for using FIX YA
Posted on May 15, 2009
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