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Discussion Starter · #1 · (Edited)
This is a complicated problem, but i'll try to explain as best as possible.

Their are two problems:

1) I got a 91' Ford Probe from a family member, they told me it has problems. They already replaced the engine (with a rebuilt one), and the car runs but with problems.

The car starts up with a little hesitation, but after about 10 seconds it will die. A mechanic took a look at it and has a guess that the Air Mass Meter is bad in it. When we unplug it, the car runs fine at idle. I let it run for about 15 mins, and it had no problem with it unplugged (it stayed at about 800RPMs).

When you punch the gas and then let off, it will die, but if you slowly go back down it'll stay running. Different if you do it slowly because around 2,300-2,500RPMs the needle starts to jump down to 2G RPM and back up to where it was, and seems to want to die. But anytime the Air Mass Meter is plugged back in, it automatically dies, no matter what the RPMs are at. (also at high RPMs white smoke comes out the tail pipe)

The engine also has a slight knock to it, but I checked the spark plugs and they all are working.

A friend told me that it could be the MAP senor, that could be the problem.

What could be wrong besides the Air Mass Meter, and whats an estimate to have it fixed?


2) When put into any gear, it seems like it's still in park. If we try to rev it up a bit past idle, the car dies.

I noticed a button on the gearshift that reads, "Manual Shift" and a light on the dash that says, "Manual Shift". The light keeps blinking, and when the button is pressed it doesn't seem to do anything (the light keeps blinking).

I read up on the Manual Shift on the car, and it's to allow the driver to manually shift the first three gears of the car (for better performace).


A thanks to anyone who replys to this, because this has me stumped. :4-dontkno
 

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when my map sensor went it would not idle pulling up at the lights you had to put it in neuteral to keep the revs up,so your symptoms seem to point to something else
 

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Unplug a sensor and see what happens, does the engine run better?

Try only the MAP, MAF or 02 sensor seperately, one at a time. If the car runs better, this is because it has gone into "Limp" mode and may indicate a sensor is bad. If it does not run better, you may have a vacuum leak, ignition problem, or machanical engine problem (compression or valve train??)

From my expierence vacuum leaks, ignition problems and O2 sensors tend to be the biggest problem if other sensors are not bad. A bad sensor "should" give some code to the computer, however, this is not always the case.

JamesO
 

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Start with the Mass air flow sensor! I know for a fact that if you unplug it, and it runs without stalling, then it needs replaced! This sensor also sends alot of info to the PCM and when it is not working properly, then it will cause all sorts of other problems.
 
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