QuestionHi Roland,
First - thank you for all your prompt answers on questions for my 1999 Sebring 2.5 V6 Coupe, they were all helpful and right on. Second - my same car started to turn off inermitently (every few days) when i am about to stop and while releasing the accelerator pedal or i am stoped and about to accelarate before i touch the pedal. Also intermitently while on a freeway driving at high speeds again when i start releasing accelerator pedal i would see my RPM falls to 0, car stumps a little bit and then RPM comes back to 2700 RPM again. Can you help me isolate the problem once more and perhaps even tell me how hard would it be to replace whatever needs to be replaced? I appreciate you help on this and hope to hear from you soon.
Thanks, Boban.
PS: check engine light is not coming on :)
AnswerHi Boban,
I don't recall the earlier problems but I am going to suggest that the egr valve is sticky and so it is diluting the mixture by remianing open whereas it should be closing tightly at the times you are experiencing these failures.
The first thing I would do is check the mechanical function of the egr valve which is located along a pipe that runs from the left exhaust manifold (on the side of the engine facing the front of the car) to the intake manifold area (where the incoming air in the large rubber tube enters the throttle). That valve is metal and has a round fitting with a vacuum hose attached, mounted on the top of the valve, and the round part is attached to the main body of the valve by a sort of saddle. Inside the open saddle you will see a metal rod (with a slot) that connects the round top fitting to to the valve body. That rod is a stem on the valve and it is supposed to go in and out in response to the engine vacuum which varies with RPM and throttle opening (gas pedal position). Take a spray can of WD-40 or other penetrating lubricant and spray the stem where it enters the valve body and then use a regular screwdriver blade tip inserted in the slot to lever the valve in and out to try and free up its motion. Also check all the rubber vacuum hoses associated with the valve and a nearby vacuum solenoid valve. If the valve seems to open (against the action of a spring) and close firmly by the spring action when using the screwdriver blade to facilitate the motion, then you should be able to now have a smooth running engine. You can, once it is idling, check that the valve stem moves when you rev the engine from idle to 2500 rpm and back to idle. If it still won't smooth out, then removing and cleaning the interior of the valve, or buying a new one if it seems too crudy and corroded inside.
So those are a couple of actions to take now. And of course, keep checking for codes.
Roland
hi Roland once again :) I did examine the EGR Valve and it appeared that solenoid located beside it would start producing the hissing noise after a while of idling and engine would start shaking a little bit so i ended up replacing that part together with EGR Valve (could not find someone who sells solenoid only). Now the hissing and shaking is gone but car still acts the same. Dies on a freeway or at low RPMs before stop. After it dies 2 scenarios happen: starts right away or it doesnt start but after leaving an engine to coll for 5 minutes i start it back no problems. Also when leaving car to idle for 10minutes it turns of as well. Can you please give me another advice? i will be taking the car to dealer most likely even though there are no engine codes and will hope they can find something but in the meantime your advice on the above is greatly appreciated.. i was also wondering if you knew how to check fuel pump pressure in case it is fuel pump causing problems, but then again, the car starts usually with no problems after it turns of. Answers are appreciated. Have a nice day, Boban PS -
Hi Boban,
The trouble with going to the dealer with this history is that it may not act up for them, which then opens the door to a "fishing trip" of throwing parts at the problem until it is solved or you give up. Unless they can get the car to malfunction in the shop and if without any fault codes/check engine light the possibilities are pretty numerous. I don't know what to make of the heat/cool issue but you might want to check the coolant temperature sensor, specifically the resistance of that sensor as the engines goes from cold to hot. It should measure 7,000-13,000 ohms when cold and change downward smothly to 700 to 1000 ohms at operating temperature (200F). You will find it located adjacent to the coolant filler neck on the engine proper. Lift the tab to remove the electrical connector and measure across its terminals.
Because the gas pedal seems to be involved in the unexpected dieing, I would also check the throttle position sensor for possible discontinuity when it gets hot. That sensor is on the side of the throttle body and it is attached to the butterfly valve shaft of the throttle body. It has three wires and again if you lift the tab and remove the 3-wire plug you will have access to the sensor. I would place one lead of the ohmmeter on the center pin of the sensor and the other on either of the side pins. Then notice that as you move the throttle lever the resistance reading will change smoothly from closed to full open. Get the feel of that, and then take your meter with you when you believe you will be able to get the engine to act up and when it does I would immediately stop (safely of course) and do a remeasurement of the sensor under the failure conditions to see if there is a discontinuity in the resistance as you move the throttle from closed to open. The fuel mixture is controlled partially by that sensor so if it had a temperature dependent discontinuity that would cause the problem.
On the fuel pump, that is probably not the issue but in any case you have to have a fuel pressure gauge and fitting to tap into the port on the fuel rail to measure it. But you don't believe that is the issue.
So checking the sensors seems to me to be a good idea. The other thing you might want to check at the time of failure is whether you are getting spark, but you will need to have a helper on board to crank the engine while you observe under the hood. Just bring along a spare sparkplug, when the failure occurs pull off a spark plug wire cap from a plug on the engine, plug in your spare plug, hold the wire cap/spare plug combo by the rubber and press the threads of the club against the cylinder head so as to "ground" the plug just like it would be if screwed into the engine. Then have the helper crank over the engine while you watch for a spark to jump the gap. If it doesn't then the spark coil or the rotor (both located inside the distributor) are suspect of breaking down when hot. A spare rotor might be worth having to test that theory. The coil itself is part of the distributor and that is a much more expensive part so I would npt buy one of those without more proof that is the cause of the failure (e.g. the rotor doesn't solve the problem).
So those are my suggestions.
Please let me know if they are of any help to you.
Roland
P.S. Thanks for the kind and generous rating of my efforts.
