1993 Camry 4 cyl. The engine jerks/hesitates at one second intervals while idling, driving, accelerating. It is as if the ignition is turning on and off. The local experts (including Toyota) are quick to say that it is: fuel pump, fuel filter, spark plug wires, plugs, distributor, dirt in fuel, fuse, etc. The odd factor that does not compute is that if I touch and hold the brake pedal just enough to activate the brake light switch, the problem goes away until I get off the brake! When I tell the experts about this, I get the "deer in the headlights" look and they scramble to cya to avoid saying "I don't know". I can't see that the brake pedal is physically touching anything that might be shorting out, so there might be some computer interaction with the brake signal? Can you think of any other malfunction that I can check before I take it to the dealer? I try to avoid this solution since I am on a survival budget. (The most dependable car that I have is a 1990 Corolla that will keep on going until it collapses from rust!.)

 

Today I got a new lead on why touching the brake causes the hesitation to go away. The vacuum is changing (reducing), and this may affect something. I was advised to look for a leak in one of the vac hoses. So far I haven't found a leak, but I could use some ideas on where to look for other components that a vac leak would affect. I am going to check the brake booster just in case there is a leak internally. Using the brake may be closing the internal leak?!

 

No luck with the leak check--the booster holds a vac when I suck out the hose. There is no change in idle speed when I pass propane over the visible hoses and connections. When I increase the throttle a little. it begins to surge. For no good reason I will next "Sea Foam" the throttle body.