Hi, I'm new on the forum and I hope to get some help here.
Here is my problem:
(I apologize if it is a little bit long, but I want to give all the details so that I can have the right kind of advice)
My 94 1.6 liter sentra has 240 000 km (150 000 miles) and about a month ago my fuel economy dropped from 7-8 liters/100 kilometers to 12 liters/100km (sorry I don't know what it is in mpg). And the check engine light came on not so long after that. I checked the trouble code and it was the EGR valve malfunction. So I got myself a new EGR valve (a nice 140$ out of my pocket) and the problem seemed to be solved for about a week and the frist gas tank after that. I did the normal 8L/100km. One week later the check engine light came on again and I started noticing that the economy dropped again. I checked the trouble code and was the EGR valve again, but then, the same night, the light went off and didn't come back. And now the ECU shows normal functioning. But since then, my fuel economy is around 10L/100kms which would be fine for 2.4 liter engine or something like that but not for my tiny 1.6, which I rimind did always under 8L/100km. Also, I am absolutely sure that I don't have any gas leak and all my fuel and air filters are fine (which doesnt change much by the way). Besides that, other sensors such as O2 sensor and the ECT give the correct readings. Today I did a compression test and it turned out to be 180 psi for all 4 cylinders which is great for the age and mileage of the car. One detail though, when the compression test is performed, you are supposed to keep the throttle fully open so that the air can get in the cylinder. I forgot about this detail, but still got a good reading. But I heard that if you don't open the throttle the reading would be way lower. Is it true? And doest it mean that my throttle body is leaking air (sucking more even when closed) or it's something totally stupid and not to worry about? So what could be the problem that changed so suddenly and so radically my car's fuel economy? Can it be the new EGR valve that doesn't work as it is supposed to but doesn't set off a check engine code? I could go try to exchange it, but I want to be sure before I do that.
If someone can give me a precious advice, I would greatly appreciate. Thank you for your attention.
Saturday, February 10th, 2007 AT 7:17 PM