Engine mis and bucking

QuestionEdit

Last fall I had my EGR valve replaced and ever since then my engine is missing and bucking at 34 to38 MPH. It does it before and after those speeds but mostly between those speeds. And when it misses and bucks the RPM indicator rises. I have replaces the coil, plugs and wires and it still does it. Any suggestions?

AnswerEdit

Hi Dick, I am wondering whether, because you say the rpm RISES, whether the issue might not be related to the transmission shifting gears from 2nd to 3rd or 3rd to torque converter lock-up at that 34-38 mph speed range? It may be that the shift is not 'clean' and there is slippage in that action. You didn't tell me the year/make/model/engine/transmission of the vehicle so I can't be more specific. You might want to go to a nationwide autoparts store, such as Autozone, and ask for a fault code readout which they will often do for free. If you can't find a free readout then an independent garage will usually do it for $40 or less. Be sure that the readout covers both the engine controller and the transmission controller, and that they tell you the 4-digit fault code numbers that come out of the readout process. Let me know those numbers and we'll go from there to figure this out. If the mis/buck happened immediately after the egr was replaced then it may not be installed properly or a defective part. But that would possibly be revealed by the code readout process. If you would be so kind as the 'rate' this answer (see below) and notice that you are offered the choice to nominate me to be 'volunteer of the month' here at Allexperts. I am in a virtual tie to win that recognition at the end of this afternoon, so please consider responding "yes" to that question. Thank you, Roland