Expert: Roland Finston - 12/22/2011

Question
QUESTION: daughter has a 2000 neon with the 2.0L sohc. car suddenly stopped running, i am able to crank the engine and actually had it fire and run extremely rough and I had to have the gas pedal all the way to the floor.  if i let up on the gas, it will stall.  I have spark, fuel and air.  could the timing belt have jumped teeth, or should i be looking at cam or crank sensors?
thank you,
steve

ANSWER: Hi Steve,
If you have spark, fuel, and air (what do you mean by that?, perhaps compression?) it is possible that the timing belt jumped or it could be any other of a large number of possiblities. The best way to get a hint is to get the diagnostic trouble codes stored in the engine controller memory. To get them you turn the ignition key:"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then EITHER watch the odometer window to see the mileage reading disappear and be replaced by 4-digit number(s) preceded by P OR if that doesn't happen then watch the check engine light, which remains 'on', to see it start to flash, pause, flash, etc. Count the number of flashes before each pause, then repeat the process to be sure of an accurate flash count. Let me know what you find. I can't be certain which will appear. In the '01 model (I don't have the '00 manual) it is the odometer readout, in the '97 it is the light readout.
I doubt it is a sensor, so don't throw money at the problem. It might be that the egr valve is stuck ajar if you have the egr (none on the '01, was one on the '97). So check for that or not and if you have it then put the tip of a screwdriver in the slot of the valve stem and move it back and forth noticing spring-action in one direction that tries to close. If it seems gummy then spray some WD-40 on the stem where it enters the valve body and work it some more. That valve when ajar will do exactly what has happened.
Roland
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---------- FOLLOW-UP ----------

QUESTION: thats great information to get me started. i have a code reader and will try to pull any code present.  where is the egr valve located on this engine? i am assuming on the back of the engine near the exhaust?  would the computer store a code without the check engine light being on?  she bought the car from someone who replaced the engine and I am pretty sure it is an 00.  i have verified spark and have pressure on the fuel rail, so i guess i should take a look at the egr valve.

ANSWER: The egr is attached to the rear of the cylinder head and it has vacuum hoses from an actuator mounted above it on the air inlet. A small pipe from the exhaust manifold comes around to it.
Some codes don't turn on the check engine light. And the egr when stuck ajar also doesn't turn it on.

---------- FOLLOW-UP ----------

QUESTION: went to the car, pulled the following codes- P1684, P0171, P0132, P0133 and P0134.  the engines does not have an egr valve.  if you feel its not a sensor, should i start with timing? are there any relays that i should be looking at?

Answer
Hi Steve,
The 130 series codes are telling you that the upstream oxygen sensor on the exhaust system is bad or its wiring is shorted, and the 171 is pointing to the fuel/air ratio which is probably too lean because of the the oxygen sensor not working correctly. So start with a new sensor.
Then see how it runs. Disconnect the battery for a minute after you change out the sensor and check the fragile wires, which will erase the old codes except for the 1684 which says the battery must have been disconnected recently.
Roland