I have a 1990 chevy corsica lt 6cyl 3.1 multi port fi dis ignition. the problem is it starts and idles fine, but when i push the gas it dies. before i changed some parts it wouldnt even start. ive changed the crankshft sensor,coolant temp. sensor,fuel filter,o2 sensor,pcv valve,map sensor,throttle position sensor,idle air control valve, i cleaned out the egr valve with throttle body cleaner, been told maybe a bad egr valve ,but thats expensive to replace ,if not problem.also maybe a bad speed sensor, also kind of expensive, anyone, can u help, thank you.

Jta91

• 99 Answers
• Posted on Jan 28, 2010

SOURCE: saturn starts but will not keep an idle and dies

Sounds like you are pretty knowledgeable with the maintenance. With that said do you know if the Engine Coolant Temperature Sensor (ECTS) has been replaced? I'd put that at the TOP of the list of parts to replace next. If it hasn't been replaced it is the cause of a lot of problems.

The factory one is plastic and cracks. When it cracks it sends the PCM a signal that the engine is -40F below zero. The PCM will compensate by dumping A LOT of fuel into the engine to try and warm it up. It will cause all kinds of starting and idling problems.

Autozone or the dealer sells the better brass tipped one. The ECTS is located just under and behind the upper radiator hose. You'll need to remove the air intake tubing to see it or get to it. It has two wires going to it and goes into a connector. Squeeze the connector at the "ears" and it will come off. A 10MM DEEP well socket will take it out. Swap it quickly because some coolant will come out (a couple of ounces). Hand tighten it and snug it with the socket (not too much because it will strip out). Connector back on (either direction it's non polar). Put the intake back on and enjoy better starting and idling.

Testimonial: "thank you very much. youve been most helpful and i will let you know how it works out for me as soon as i replace the ects"

SOURCE: I have changed everything: Spark

There are three components that will enrich the fuel mix: 1)engine coolant temperature sensor. If this is not working or the signal is interrupted by a wire breakage then the engine will run rich. The coolant sensor informs the ECU (high resistance) that the engine is cold at start up and so the ECU responds by increasing the fuel injection cycle to enrich the fuel air mix. Later on as the engine warms the resistance of the coolant sensor drops and the injection cycle is reduced by the ECU. If the sensor is faulty or has become disconnected (wire break or corrosion of the socket pins) the ECU assumes that the engine remains 'cold' and the engine runs permanently rich. 2) O2 sensor, operates completely independently of the EGR, if it is faulty and signals 'too much oxygen' then the ECU will significantly enrich the fuel mix to try and balance what it thinks is an excess of air. 3) Fuel pressure regulator. If the diaphragm has broken or there is a leak in the vacuum line this will result in higher than needed fuel pressure in the fuel rail at idle. The vacuum line acts against the spring pressure holding the valve closed. At idle, the inlet vacuum pulls back on the diaphragm reducing the fuel pressure required to open the valve. Low fuel pressure coupled with short duration injection times will mean a lean mix at idle. If the vacuum is compromised or the diaphragm damaged then the increase in rail pressure will make the fuel mix very rich to point of flooding the engine

SOURCE: 1994 chevy with 5.7 L

Sounds like you have a vacuum leak. When the engine is cold the leak is there but as the engine warms up the parts start to expand thus closing the gaps and sealing the leak. I had this problem on my personal vehicle and it turned out to be lower intake gaskets.