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1993 Mercury Topaz Runs bad

Tiny
FOX
  • MEMBER
  • 1993 MERCURY TOPAZ
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 170,000 MILES
The car starts fine runs good up to around 10 minutes then starts going crazy like its not getting gas or spark or air.

I have replaced the coil, distributor complete, mass air flow sensor, spark plugs, fuel filter. All from junk yards except plugs and fuel filter.

When it starts acting up I have to stomp on the gas to get it going then it will clear up and run fine for a bit then goes all to crap again some times when I stomp on the gas it bogs down then it all of a sudden picks up. I am continuously doing this while driving to get to where I am going also I smell a gas smell sometimes and it is getting really bad gas mileage. One other thing I did was beat all the stuff out of the catalytic converter.

Also took aprt EGR and cleaned it it was caked full of black hard stuff in the port going into the EGR cleaned all that.

I am at wits end not being able to figure this out.

I took it to O reillys and used their tester OBGII and it came up and gave these codes.

158 - mass air flow sensor - replaced junk yard
157 - mass air flow sensor
172 and 173 - lack of heated oxygen sensor bank one
186 - injector higher than expected
113 - intake air temperature sensor above average
332 - EGR valve flow insufiecieant

I was told that one of those things are bad and it has a trickle down affect on the other sensors and computer it just freaks out.
I just can't pin point the exact problem

all I can think is that maybe the air flow sensor I got from the salvage yard is bad also.

This is a good little car when running good excellent gas mileage. I use to get around 300 mile per tank fill up. Now I get under 200 miles a tank.
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Monday, August 10th, 2009 AT 1:25 PM

15 Replies

Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
OK do you have a digital multi meter? Did you have the coded cleared? What I need you to do is when it starts to run bad don't do this will going somewhere do this at home in the driveway, turn it off and unplug the mass air flow unit and then restart it and see how it idles. It will not have much if any throttle response so don't worry about that just see if it idles as it should with the mass air flow unit unpluged. Get back to me and we will take it from there.
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Tuesday, August 11th, 2009 AT 11:34 AM
Tiny
FOX
  • MEMBER
  • 10 POSTS
I have a multimeter.

I unplugged the mass air sensor it ran the same just idled.

I actually unscrewed the other sensor and took it completely off the filter cover and drove the car it did the same thing. Then I went to the salvage yard and got another one.

I have driven the car with the mass air sensor off the car and with the one I got from the salvage yard. The car does the same thing.

When I am driving it just all of sudden loses power and bogs down I push the gas pedal to the floor and it start bucking and then all of a sudden it clears up I go a ways further it comes back again It usually does it after driving it around 10 minutes my wife drives it mostly and she says it does it at startup sometimes and when stopping at redlights its just varies. I also was thinking that maybe there is trash in the gal tank getting stuck in fuel pump some way.
I am lost on this one just not sure what else to do.

Thanks for your help I will try what ever you suggest.
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Wednesday, August 12th, 2009 AT 8:18 AM
Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
Ok so what I need you to do is unplug the coolant temp sensor (it will be a two wire sensor near the thermostat) and ohm it and then ohm the air charge temp sensor (it is also two wire and in the intake tube or on the air box) do this test when the car is cold and get back to me with the readings and the air temp at the time of the test.
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Wednesday, August 12th, 2009 AT 10:36 AM
Tiny
FOX
  • MEMBER
  • 10 POSTS
I have not used the meter yet I will do that tomorrow.

Today I went out and started the car and let it idle.
It would idle fine for around 2 minutes then it would fall apart I would punch the excelerator it would clear up I also held the pedal down rpm was 3000 then it would fall apart like no gas or air.
So then I started turning it off after it started acting up and restarting it would run fine for a few minutes then fall apart I did that for about 20 or more times it did the same every time. Would turn it off restart it runs fine then falls apart.
It did the same thing every time.

Any help would be greatly appreciated.
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Monday, August 17th, 2009 AT 7:14 PM
Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
Ok you need to test the idle control motor. Are you able to use the multi meter to do a couple of test on it? Get back to me and I will get you the test procedure.
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Wednesday, August 19th, 2009 AT 10:25 AM
Tiny
FOX
  • MEMBER
  • 10 POSTS
Would this idle control motor cause the erratic behavior while driving. I have a meter I am not sure what to test or how or what to set the meter on.

I know open closed continuity
DC/AC
I know how to measure resistors

but what to set meter at and check these sensors is beyond me unless they work open or closed or variable resistance.

I guess a little pointer would help me test these things.

Thankyou
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Wednesday, August 19th, 2009 AT 2:08 PM
Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
Ok lets test the TPS (throttle possition sensor). I need you to set you meter on 12volt or 20 volt if you don't have 12 DC setting. You will hook up the meter with the + from you meter on the gray wire with the white stripe and the black or - from your meter to a good ground. Now turn key on engine off you should have.8 to 1 volt now slowly lift the throttle the voltage should steadly and gradually increase with no drops or glitches. At wide open throtlle you should get 4.5 to 5 volts. You can use a paper clip to back probe the wire at the connector. Let me know what you find. And then we will check the Idle control motor.
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Thursday, August 20th, 2009 AT 10:38 AM
Tiny
FOX
  • MEMBER
  • 10 POSTS
I checked it.
It was 1.0 then pushed pedal to floor it was 4.6
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Saturday, August 22nd, 2009 AT 11:04 AM
Tiny
RACEFAN966
  • MECHANIC
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Ok how did do in between? I also would like you to clean the throtte plate. You will need some throttle plate cleaner and a rag or two. You will need to disconnect the air intake hose going to the throttle body and the put a rag under neath the throttle body and spray it out real good. Then open the throttle and spray a little bit inside around the throttle plate and let it soak for a couple minute. Now get another rag and spray a little an wipe it out really good. Then when you are done put the air intake hose back on and start it and then see how it runs. Get back to me and we will check the Idle control actuator next.
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Tuesday, August 25th, 2009 AT 12:15 PM
Tiny
FOX
  • MEMBER
  • 10 POSTS
I already cleaned all of that and I also checked the Idle control motor took it off and had someone turn ignition to see if it moved and it did I cleaned it also put it back on. Also started engine and ran it and it moved also as I was revving engine up and down.

I am leaning more toward maybe a fuel pump or fuel pressure regulator now the car will start run fine then I can hold the xcelerator down to 3k rpm then it will act up like no fuel or air or something. Then I can drive the vehicle and it runs fine then goes all to crap I have to push the pedal to the floor kick it in then it clears up then comes back.
If I start it and run it not driving it runs fine then goes all to crap holding engine at 3k rpm I can turn it off when it runs fine and so on as long as I turn it off and restart it after it starts acting up. It runs fine then acts up.

I have looked for the fuel pressure regulator and I think it is on the passenger side right at the fuel rail has 3 hex screws holdin it on. I am thinking about replaceing this fuel pressure regulator and the fuel pump assembly from pull a part salvage yard.
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Tuesday, August 25th, 2009 AT 4:14 PM
Tiny
FOX
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Could it be the cam positioning sensor also.
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Tuesday, August 25th, 2009 AT 4:24 PM
Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
Ok first what is the fuel pressure? Have checked it? As for using a fuel pressure regulator from a wrecking yard I wouldn't. As fuel sits it slugges and then you will end up with that slug. As for the camshaft sensor it could be and we can test that. The idle air control valve may move but that don't mean it is good. Now if you would unplug it and ohm across the two terminals on the valve itself let me know what the ohms on the 200ohm scale.
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Wednesday, August 26th, 2009 AT 10:00 AM
Tiny
FOX
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  • 10 POSTS
What if I replace the fuel pump from salvage yard and fuel pressure regulator knew.
I have no way of checking these. How do I check the cam sensor.
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Wednesday, August 26th, 2009 AT 8:35 PM
Tiny
RACEFAN966
  • MECHANIC
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The only thing with fuel pumps and related items from a wrecking yard you don't know how long it has been sitting more then 6 months and it will start to gum up and then you will have no better if not worse then now. As for the cam sensor unplug it and ohm it and let me know what the ohm reading is.
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Thursday, August 27th, 2009 AT 10:11 AM
Tiny
FOX
  • MEMBER
  • 10 POSTS
Where is the cam sensor?
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Saturday, August 29th, 2009 AT 8:34 PM

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