Have a 93, 3.1, auto trans. Purchased this car in poor running condition. Car has a stumble off of idle, and when warm, it will lose power (felt like ignition)
So, I chased after an ignition module. I discovered upon removing the module, that someone had already changed it. Tested it anyways, and it was good. Researched a bit, and checked the crank sensor. Found crank sensor to be bad. Replaced crank sensor, and the loss of power went away.
Well, now with the loss of power issue gone, I had hoped that the stumble off idle would dissappear....but it hasn't.
Here's the dillema. Start car cold. Starts fine. Idles fine. Put in gear - still runs fine. Press accelerator - stumbles for a moment - if you are not aggressive with the throttle, it will die. Once past the hesitation (can last for a half a second, to about 2 seconds) car runs flawlessly. Runs great at ported throttle, great at WOT, pulls hard and long. But even when moving at hiway speeds, if you let the trottle come to idle position, an then bring the throttle back up off of idle, there is astill a hesitation. Does the same if the car is warm.
Now, if you start the car, put it in drive, and keep one foot opn the brake, and one on the throttle, holding the throttle just above idle (above the hesitation spot) it won't hesitate or stall....but if you keep your foot on the throttle at a steady spot, and place the trans in nuetral, the engine revs to about 1500-2000RPMs....
(NOTE: When starting cold, the accelorator is VERY hard to push....JUST off idle. It feels like the throttle plate is frozen to the throttle body....once the throttle opens, then its fine and operates normal. ALSO: after the initial hard opening, the throttle works great....doesn't get hard until car is allowed to get cold) Now, I know this isn't a freezing throttle plate, as it will do it if allowed toi sit in the heated shop overnight.
FIRST thing I thought was TPS has a bad spot. Checked it. Proper voltage throughout the range of travel. STILL, I replaced it, and the problem persists. Replaced the IAC. Still persists.
What am I missing here??? Car runs flawlessly other than the hesitation just off idle.
Help?
02 sensor How about the rubber vaccum hose going the Map Sensor. Hows the fuel filter & air filter, Has the car had a full tune up recently.
