My eclipse has recently been having a lot of problems with fuel delivery. This started when I couldn't get the engine to fire. It would crank, but no fire. Eventually it would start, but it took 10-15 minutes to do so. It got worse after that, I would be driving and the engine would just. Die. The fuel just cut, and I couldn't get it started again for 10 or more minutes. So I checked the spark, it was good. After, I went on to check all parts of the fuel delivery; fuel pump, pressure in rails, fuel pump relay. All were fine, and I finally narrowed it down to either the ASD relay, or the PCM. So I replaced the relay, and it fired great every time. However, when I let the car idle for a few minutes, the engine started cutting, but it would catch itself suddenly. As if the fuel pump was being turned on and off every 10 seconds, but the car didn't die. Then it started throwing codes, but I haven't checked them yet. I'm thinking that I should disconnect the battery to reset the pcm, maybe the relay will work then? If not, what could be the problem?
NO! Don't disconnect the battery. That will erase the codes and you'll lose that valuable information. "Resetting the PCM" was a common GM solution. They had a ton of computer problems and everyone thought disconnecting the battery was the magic fix for everything.
If you have spark, the ASD relay and circuitry is working. Look for a fuel problem in that case. The most common failures are the crankshaft position sensor and camshaft position sensor, depending on which engine you have. When they fail, often by becoming heat-sensitive, and working again once they cool down, the Engine Computer won't turn on the ASD relay and you won't have spark or fuel pump power.
The place to start is by having the codes read. That will indicate the circuit or system that needs further diagnosis.
October, 10, 2012 AT 7:49 PM
The idling coould be too low causing the problem. Try cleaning the throttle body abd IAC.
Retrieve the trouble codes and see what they say.
October, 10, 2012 AT 8:28 PM
But it didn't start malfunctioning like that until I replaced the relay. I've already cleaned the throttle body, recently replaced the TPS so the idle is great. Thanks for saving me from absolute doom with the battery though, that could have been a disaster. I did think about checking the cam and crankshaft position sensors, however, if the car fired up perfectly after replacing the relay, but then developed a different problem after the the replacement, would it still be the position sensors?
October, 10, 2012 AT 8:33 PM
The most common way those sensors fail is by becoming heat-sensitive. They especially like to fail after a "hot soak". That's when they stay cool from normal air flow, but when you stop for gas, the heat from the engine migrates up into them and they cause a no-start condition. They will work again after cooling down for an hour or two.
Gotta head out of town for a few hours. Will check back on your progress tonight.
October, 10, 2012 AT 8:37 PM
October, 10, 2012 AT 8:38 PM
You mentioned throwing codes so retrieving the trouble codes shold be the first thing to do. Guess work is a waste of time and energy and can be costly as well.
October, 10, 2012 AT 8:47 PM
I'll check the codes tonight and update on what they are once I finish!
October, 11, 2012 AT 12:57 AM
Okay, did the "key dance" But I'm having trouble deciphering the codes. A little help would be greatly appreciated. Codes: 32, 42, 42, 10 then 55 as the end sequence. I'm having some trouble figuring out which code is which. Except for 10, which is the ASD. Here's a link, maybe you can help? http://www.2gnt.com/index.php?d=PCM%20Error%20Codes
October, 11, 2012 AT 1:10 AM
Also, now the engine isn't dying; however, when I lightly tap the throttle, the rpms shoot up and the throttle plate seems to stay open too long. Could it be something with the EGR? I have no idea of what I'm looking for at this point, my mechanic skills only go so far.
October, 11, 2012 AT 2:25 AM
Tapping the throttle causing the rpm to go up indicates the IAC valve is not stable.
Code 10 - MFI Relay Control circuit.
Code 32 - Upstream HO2S stays at center.
Code 42 - Ignition Coil # 2 Primary Circuit
Code 55 - AV valve position sensor.