Questions and Answers

Toyota Corolla Missing When Coasting Q. Dear Mr Ciulla, I have recently subscribed to auto repair.about and its extremely interesting and immensely helpful. I have a problem or that's what I think, with my Toyota Corolla and would like your advice. Details as follows: 1994 Toyota Corolla Sedan 1.6 liter Manual transmission 135,000 kilometers Fuel Injection ABS brakes P/S, A/C, Cruise control

At times when I am in either fourth or fifth gear and I tend to slow down, the car begins to jerk or hesitates, as if it is missing. If I change to a lower gear or press on the gas pedal the jerk stops. It does not happen always only at times, specially when driving at speeds of 60 to 80 kph and in top gear.

I would assume that if the speed is reduced when continuing to drive in high gear, the car would normally start to "drag" thus calling for a shift to a lower gear!! Could the problem be due to an erratic EGR valve?

The vehicle was serviced at 130,000 kilometers and throttle body was cleaned while in situ, including addition of solvents, poured one in the gas tank, one with the engine oil and one poured in slowly while the engine was idling through the camshaft cover. This did improve the hesitation and missing phenomenon though. Your assistance will be highly appreciated.

Thanks,
Asgar

A. Normally when you are driving in fifth gear, and you let off the gas, the car will just coast. If not shifted it will coast down smoothly until the rpm gets too low to keep the car moving. Then to accelerate, you will need to shift down. I hope I'm explaining this clearly.

In other words you are cruising on the interstate at 115 kph. You take your foot off the gas and the vehicle slows down to 95 kph. At this point you do not need to down shift to speed up or slow down. Now you slow down to 65 kph. You can still slow down without down shifting, but you would need to down shift to accelerate.

The reason you feel drag will in gear and slowing down is because the engine is slowing you down. The engine is now just a drag. The effects of this drag becomes more apparent the slower you go.

It is very possible there is a problem with the EGR control system. What you can do to test this theory is to unplug the vacuum line to the EGR valve and plug it off. If the symptoms disappear, you have found the problem.