QuestionQUESTION: Hi,I'm actually asking about my moms car. It will not start. It has sufficient spark, good compression, and fuel. we drove to the city yesterday without a hitch. Went out this morning and it would start. just cranks over.
I checked codes and nothing shows up.
btw the car has 249,900 miles on it
Thanks in advance and appreciate the help
everything is that that a normal engine would need to run.
ANSWER: Hi Joshua,
My favorite culprit for no start with no codes is the exhaust gas recirculation valve being stuck slightly ajar which leans out the mixture so the engine won't 'catch' and idle. Take a look at the egr valve to see if it might be stuck slightly ajar. It is located in a small pipe that branches off the right side exhaust manifold and routes back to the intake manifold at the rear of the engine. It is bolted directly into that small pipe, horizontally. The valve has a round top with a vacuum line, and flange area between it and the valve body mounted in the pipe. Inside the flange look to see the valve stem which has a circumferential slot. Use the tip of screwdriver in the slot to move the stem back and forth against spring-action in one direction that attempts to close the valve. Make sure that it closes to a dead stop by means of the spring. If it doesn't or appears to move with a lot of friction, then spray some WD-40 on the stem where it enters the valve body, work it some more back and forth, then see if it will start well. Such a partially ajar valve will prevent starting due to the leaning out of the mixture that is causes.
And there is no fault code that detects that problem. I assume that you do get a code 55 when you try for fault codes, otherwise, you haven't done the key switching correctly.
Roland
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---------- FOLLOW-UP ----------
QUESTION: Well, Roland. I managed to get to the EGR and did exactly what you stated with no luck. The egr that is on the care appears to be almost new. we have only had the car a couple of months and the lady who owned it before took really good car of it.
I even tried a shot of eather in each Throttle body with no luck.
Any other thoughts of what could be causing this. It ran great yesterday.
ANSWER: Hi Joshua,
If you have strong spark from all three coils, good spark plug wires, good plugs, and you do hear the fuel pump run for about a second when you turn the ignition key to run, then perhaps the mixture is not in the correct range, either due to an inaccurate MAP sensor but which is not so bad as to set a code, or similarly with the coolant temp sensor. The MAP signal (read between dark green/red and black/light blue wires) should read about 4.6v as it sits and drop when you are cranking it over. The coolant temp sensor near the thermostat housing on the top front of the engine should read about 4,000 ohms when cold. Other than watching for a code to show up I can't suggest any other cause for a no start,
Roland
PS Are there two throttle bodies (you used the term 'either')?
---------- FOLLOW-UP ----------
QUESTION: Hello. Yes, I hear the fuel pump. It has fuel pressure. I managed to pull the egr off the car and inspect and clean the unit. (very clean looks almost new) I reinstalled it with no luck. still no fire. if you stay on the starter long enough it will try and catch some. Sounds like it hits on one Cylinder.
where is the map sensor on these cars?
As to yesterday. I stated i tried a shot of ether in both of the
throttle bodies, Yes two TB's
IF the crank sensor failed again it would have thrown a code?
AnswerHi Joshua,
The MAP sensor is on the left side of the intake manifold, right next to the oil dipstick.
You could check the crand sensor function by measureing the voltage pulses: measure between the light blue/dark blue and black/light blue wires while you turn the crank by hand with a socket on the crank pulley bolt and the ignition 'on'. The voltage should oscillate between 5 and 0.3V several times per revolution if the sensor is producing pulses properly. Same with the cam sensor wires (tan/yellow and black/light blue). It may be that the sensor is just a bit too far from the surface it senses, if you didn't holt it with the paper spacer on the tip pressed against it while you tightened the retaining screw. I can imagine it might not set a code but I can't guarantee that possibility.
I see the two throttle bodies which I hadn't noticed before. Thanks. Did you try cleaning out the throats and buterfly plates, both sided thereof, on the throttle bodies? Excessive crud on those parts, and in the side air passageway, can cause starting/running problems too.
Roland
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