Thread: Sensors

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Have a 1999 Pontiac Sunfire. 2,2 4ci. Evey so offten the car will want to bod down on take off. will not stall, but will act like it,s runining out of gas. You can stop. Cut engine off. Let it rest a few minints. And it will run alright again. It could go another 1000 miles or so and do it again. The engine light does not come on. Have had it in the shop a couple of times. They can't find anything wrong. Have supected the tranmission may not downshift some times. My question is this. Can a sensor stop working some times and then work again? Have ofcourse changed the gas filter, air filter. Put new plugs in. Kind of runing out of ideas, What would be some good advice? Thanks, John.

Update. Had a shop clean the throttle body and injectors. Drove again for aboyt 40 miles. And it did it again. Only this time it stalled. Never did that before. So far I,ve had the car in 4 shops, Have spent about 400 dollars. And still the proplem remians. I guess I,ll have to figure it out myseft. Need to learn about sensors and fuel injectors and the like. I,m an old chevy short block man. Can work on them okay. But anything after 1990 I,m lost. I guess I,ll go ahead and replace the catalytic converter and oxygen sensor. And then every week replace the other sensors. If that don,t work, I.ll replace the injectors. Rebuild the throttle body. I would have thought a dealer and some of these shops could have at least told me what the issue could be. With all the money I,ve paid to other people. I,ve could have done all these things already. I,ll never take a car to a shop again. If I can,t fix it myseft. I,ll junk it.

Does the motor have a crank sensor. The can sometimes cause an intermittent issue like that. I had a similar issue with a 97 Explorer. It did the same thing a couple of times and then quit altogether. Replaced the crank sensor and she fired right up. And has ran great since.

Just a thought for you to consider.

C

Update: Went ahead and took the 99 Sunfire to another shop. As before, they could not find anything wrong with it. Kept the the car for 3 days. He did not charge me any fee. But he did have an idea. My gas hand in the car does not work. Has'nt worked for a long time. He said that perhaps at times the car was low on gas. And that the pump may have issue with a low gas level. And or this may also be allowing some dirt in settell in in the tank. And this dirt may find it's way to the fuel injectors. He recomended to keep the tank almost full at all times and also to put some fuel injection cleaner in the tank when I got gas. So I,ve been making sure the tank level is high. And also I've been useing the high test gas, 93, instead of the 87. And I put some STP fuel injection cleaner in. I've run it about a 150 miles so far. And it has run fine. So maybe that's it. We'll see. Buy the way. On top of my engine it saids SFI. Does this mean Single Fuel Injection? My repair book saids all these cars come with MFI. So I was just wondering about that.

SFI=sequential fuel injection, the injectors fire in order, not all at the same time.

Ther is a sensor. Not sure at the moment what it,s call. It tells the fuel injectors when and much gas to put in the intake according to how far open the flap in the thotle body is. Could this sensor malfunton at times giving a fause reading. But not puting the engine light on. Maybe not telling the fuel injectors the right thing? Thanks, John