2000 Mitsubishi Lancer 1.3 auto intermitant lack of power?

Question

Have a 2000 mit lancer 1.3 auto, most days she runs fine, then some mornings when you start and try to drive her she has a lack of power, when you try to accelerate nothing happen and then she takes off and then the engine slows down. Only bought the car 5 months ago (less than a 1000miles gone on since then), power seems to go up and down. I then turn her off and go back to her in the afternoon and she runs perfectly. Any help would be greatly appreciated. (just to note when it happens no warning lights come up on the dash, so the garage say there is no point on putting it on a diagnostic machine as no fault will have been recorded. As it only happens about once a week I don't want to leave it into a garage as it probably won't happen when they have it and tehy will probably charge me a fortune for nothing.

It happened again this morning, started the car, would'nt run properly, opened the bennet and you could hear a tapping noise coming from the rocker cover. Turned the engine off, pulled the cap off the spark plugs and replaced them, started engine back up and car runs fine, this is the second time this has happened where I take off and put back on the leads to the spark plugs and she runs fine ?

Answer 1

It could be a throttle position sensor. It tells the computer how far the throttle is pushed in. If it works erratic or is "not broken" the computer will not register the fault. The garage is right by telling you that. It could be a loose connection or even a dirty connector. Open the hood and try to look for the obvious 1st.

I friend of mine had a similar problem with his car. The only way to find out was using a Dyno and run a test with a laptop connected and monitoring the engine to see what was going on. That is how he tracked the bum sensor. No easy find neither, no error codes or nothing at all. The sensor was sending wrong signals but was not mess up enough to be register as with a fault code.

Answer 2

It sounds like the engine is bogging down, possibly the automatic transmission slipping. Check your spark plugs/wires/etc. Is it getting enough gas? Dirty air filter?