Questionwhen excellerating slowly between 40 pmh-60mph or when cruise control kicks in going up hills, car jerks, balks, etc. when gas applied heavily, smooths out. Starting to idle roughly also, Any suggestions? Thank you
AnswerHi Carol,
So there are no fault codes. That complicates things a bit. There are about 18 different reasons for poor running of the engine. My favorite and an easy one to check is the possibility that the exhaust gas recirculation valve is sticking ajar which results in an incorrect fuel/air mixture.
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 start the 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 doesn't run well then I would question the age/mileage on the spark plugs. Do you have any record of how far you have gone since the plugs were changed?
After that we are into some testing that requires tools that may be too costly/complicated to get into without having some experience. If you have that, let me know and I can run through some of the tests.
But let me know about the egr troubleshooting and if that doesn't solve it, tell me about the spark plugs.
Roland
Hi Carol,
The most direct way to check these problems out is to readout the engine controller memory for any faults that it may have recognized and stored as two digit code numbers.
Turn the key: "on-off-on-off-on and leave on" doing this in less then 5 seconds. Watch the check engine light which remains on to flash, pause, flash, pause, etc. Count the number of flashes before each pause, keep track of the numbers. Repeat to verify your count. Group the numbers in pairs in the order they came out. The last number will always be 55 (last sets of flashes are 5 flashes each) which is the code for end of readout. Then write back with the results and we'll go from there. You can also get a decoder at:
www.allpar.com/fix/codes.html
Tell me which engine you have so that I can give you specific advice on what to do in light of the codes.
Roland
