1999 Mercury Marquis Acceleration problem

JAY_M84

MEMBER
1999 MERCURY MARQUIS
V8
2WD
AUTOMATIC
120,000 MILES

Hello, I have a 1999 Mercury Grand Marquis and I have a problem. When started the vehicle runs fine at idle but when it is put into drive or reverse and you go to accelerate the vehicle barely moves and bogs down. As soon as you let off the gas peddle it smoothes out again and then try to hit the gas again it does the same thing again. I have replaced all the catalytic converters, 4 new 02 sensors, fuel filter, air filter, mass air flow sensor, spark plugs, ignition coils, cleaned the fuel injectors checked all fueses and relays, and the fuel presure is good and throttle position switch voltage is good as well and it still does the same thing. It is frustrating. Could it be the traction control acting up? If so where is the traction control modual in the this vehicle vehicle?

5 Replies

RACEFAN966

MECHANIC
5,029 POSTS

So tell me how did you test the TPS? Do you have a digital multi meter? Get back to me and we will go from there.

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Monday, June 1st, 2009 AT 10:29 AM

JAY_M84

MEMBER
3 POSTS

Yes I used a snap on solus pro that we have at work and with the car off I slowly pressed the gas peddle and watched the voltage to make sure that it went up smooth with no glitches.

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Monday, June 1st, 2009 AT 11:42 PM

RACEFAN966

MECHANIC
5,029 POSTS

Ok good just wanted to check and make sure the test was done right and it was. Now if you would I would like you to do an ohms test on the coolant temp sensor and the air charge temp sensor. Just simply unplug them and check the resitance of the sensors (not the wire harness) and if you do this when it is cold then you can get back to me with the resistance and the outside air temp at the time of test. Let me know what you find ok.

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Tuesday, June 2nd, 2009 AT 10:19 AM

JAY_M84

MEMBER
3 POSTS

I checked the resistance of both sensors at 60 deg. F. Coolant temp. Sensor 4.909 ohms air temp sensor 44.40 ohms. Thank you and let me know if that sounds about right.

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Wednesday, June 3rd, 2009 AT 6:32 PM

RACEFAN966

MECHANIC
5,029 POSTS

Ok after looking at the chart the coolant temp sensor seems to be ok. But the air temp sensor isn't. They ohm reading should be the same. This may not totally fix you problem but it is out of range. Just to be sure you did check the new tps to see if it was in range did you not? Let me know how it goes and we will go from there.