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95 volvo 940 turbo has had intermittent starting issue. Replaced crank position sensor and cleaned idle air control valve and problem mostly solved, but has now (6 weeks later) same problem but worse. Won't start at all, but if I hold gas pedal part way down it tries to start but acts flooded and won't quite start. Replaced IAC with junkyard part which tested ok, but no change. Plugs, cap & rotor & wires seem ok. Using small amount of stater fluid does not seem to help. Tried to test fuel pressure but test port is located such that I can't hook up my tester. Ideas?
So sorry I had not deleted this post. Problem is fixed. Turned out the spark plugs were getting soaked with lots of xtra fuel under hot start conditions due to a faulty coolant temp sensor. Replacing faulty part and new plugs has fixed this. Thanks for all your help.
So sorry I had not deleted this post. Problem is fixed. Turned out the spark plugs were getting soaked with lots of xtra fuel under hot start conditions due to a faulty coolant temp sensor. Replacing faulty part and new plugs has fixed this. Thanks for all your help.
sounds like the fuel pressure check valve may be defective. do u have any system trouble codes?sounds like the fuel pressure check valve may be defective. do u have any system trouble codes?
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run fault codes to get some idea of which sensor is faulty . You have replaced the MAF sensor but what about the MAP sensor as well as it may have been that unit
May have a faulty air/fuel ratio sensor or o2 sensor, throttle body may need adjusting or have a stretched spring or there may be grime restricting air flow so it's flooding it.
no its not the crank sensor if it were your car would not even start. your problem most likely is the idle air control valve, try removing it and and cleaning it if it does not help it will have to be replaced.
The fact that the engine dies without warning and that the effect is intermittent indicates that the problem is electrical and that it is most likely a break of some kind. Start from the top and look at the main fuse and the main relay and then the fuel pump relay (sometimes the two are on the same board in the same relay unit). Really inspect these thoroughly and check the solder joints, sometimes you can get an annular crack running around a pin and it will not break the circuit until vibration or high temperature causes the crack to open briefly. When you switch the car on these relays should give a healthy click. Most electrical problems can be found with a wiggle or a tap; wiggle the wires, that is, and tap the device they connect to.
A short in the MAF (air density unit) should not necessarily cause the engine to die but maybe to change its idling characteristics. Unplug it whilst the engine is running to see its effect, in fact most devices may be unplugged to check their effect without doing any long term harm. Remove any foam that could interfere with its operation. Spray clean it with electrical spray cleaner (zero residue spray) but do not touch! Do not use carb. cleaner spray as it is too aggressive.
1) Check all the electrical things the ECU takes signals from in order to run the engine: throttle position sensor, idle speed control, Intake air temperature, manifold absolute pressure, engine temperature sensor. crank position sensor, cam position sensor
2) Check electrics, coil (bad to diagnose if intermittent) low tension, high tension distribution, plug leads and plugs, hall effect sensor.
3) Check air: check that all vacuum pipes making any kind of connection with the inlet manifold are air tight with no cracks or loose joints. If you have evaporation emission control make sure that the purge and vent valves close and open when they should. If you have Exhaust gas recirculation check that the valve opens and closes and that all feed ports to it are free and clear of carbon build up.
4) Now check fuel system: pre-pump, main pump, fuel filter, fuel pressure regulator, injectors
take off pipe going to the intercooler from the turbo see if oil is found and clean then other pipe from incooler check it .if oil is found .drain oil in intercooler .you have an oil leak from the turbo this is why you will have light on far left of dash
1995 940 has a crank position sensor mounted at the top rear of the engine which reads cranks position off the flywheel. Though not adjustable, it is a part which fails often causing weird and intermittent no start/hard start problems as well as other faults. While the part is not too expensive, you do have to crawl on top of the engine to see it, and its a pain to replace. Guess you could remove the hood, but I have changed mine without doing so. Get light on the area,and you can do it. If you are having timing too far advanced issues (running on when killing engine or "pinging" on acceleration several other parts may be suspect. Knock sensor, spark plug issues, carbon buildup, O2 sensor, lean condition and more. Good luck.
Probably IS the crank position sensor-classic symptoms. It is hard to reach (of course)-behind head at top of transmission bellhousing.Not a very expensive part-try it.Will the car fire at all? If so,then it may be the IAC-try holding down the gas pedal slightly if it runs,replace this.
So sorry I had not deleted this post. Problem is fixed. Turned out the spark plugs were getting soaked with lots of xtra fuel under hot start conditions due to a faulty coolant temp sensor. Replacing faulty part and new plugs has fixed this. Thanks for all your help.
sounds like the fuel pressure check valve may be defective. do u have any system trouble codes?
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