Northstar...could it be my headgasket?

[CarlaValentine]

I keep getting code P032: Open MAP sensor signal.

I have tried and tried to find a loose / unhooked vacuum line, to no avail.

I even tried taking my new MAP sensor off and putting the old one back on to see if that would help. But no.

Tonight when I went out to investigate a minor coolant leak (different topic) I noticed when I started the car, that I could HEAR the vacuum leak, but I still couldn't find it. I looked for about 15 minutes. It was somewhere in this area.

It was rhythmic...it followed the RPM's of the car. There was also steam from that area when I first started the car, but it's been raining all day so that's not a surprise. I have checked the brake booster, the map sensor, the PCV lines, the 2 lines on the throttle cable diaphragm thing (no idea what it's called, something with the cruise control I think) and the 2 lines that run above the throttle body. Those are the only ones I can see. Is there something else in there I'm not seeing that would have a rhythmic/pulsing vacuum?

[BodybyFisher]

Did you install the new plugs without gapping them?

[jackc]

Is there something else in there I'm not seeing that would have a rhythmic/pulsing vacuum?

On my 93 there was a plastic vacuum harness that I had to replace. I forget exactly what it is called, but am recalling that the evap purge system was involved. It was in the area between the throttle body and the firewall. It consisted of several thin plastic tubes that had become brittle and cracked. Seems like there was one long tube that went along the rear valve cover too.

[CarlaValentine]

Did you install the new plugs without gapping them?

Yes. They are AC Delco 41-950, and (according to the computer at the parts store) are pre-gapped to .050, which is what my car calls for. I didn't dare touch them with a gap gauge...didn't want to ruin the platinum pads. I also used a socket with the rubber inside it to grip the plugs, so they didn't drop into the holes when installing them and get damaged.

[BodybyFisher]

Did you install the new plugs without gapping them?

Yes. They are AC Delco 41-950, and (according to the computer at the parts store) are pre-gapped to .050, which is what my car calls for. I didn't dare touch them with a gap gauge...didn't want to ruin the platinum pads. I also used a socket with the rubber inside it to grip the plugs, so they didn't drop into the holes when installing them and get damaged.

For future reference, ALWAYS check the gap, they can change in shipping and handling.

[CarlaValentine]

Is there something else in there I'm not seeing that would have a rhythmic/pulsing vacuum?

On my 93 there was a plastic vacuum harness that I had to replace. I forget exactly what it is called, but am recalling that the evap purge system was involved. It was in the area between the throttle body and the firewall. It consisted of several thin plastic tubes that had become brittle and cracked. Seems like there was one long tube that went along the rear valve cover too.

The only tube I saw on the rear valve cover was for the PCV valve, but I will look to see if goes anywhere else that I may have missed. Guess I will just have to move some things and do some digging. lol.

[Cadillac Jim]

The intake manifold and EGR changed between the 1993-1994 and 1995-1999 Northstars, but I can speak for my 1997. The MAP sensor should be the same.

The MAP sensor doesn't have any vacuum lines running to it. It is a monolithic black box plugged into a grommet in the intake manifold near the throttle body, and it has a wiring harness cable plugged into it. The OBD I DTC P032 (Open MAP Sensor Signal) is most likely the same as OBD II DTC P0108 (Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage) but I'll also go through what the FSM says about P0107 (Manifold Absolute Pressure (MAP) Sensor Circuit Low Voltage). I'm using the 1997 model year FSM, pages 6-6-312 trhogh 6-316, the troubleshooting instructions for P0107 and P0108.

This DTC won't set unless your throttle position sensor (TPS) is working. If it is current, the multifunction indicator lamp (MIL), which is the Check Engine light if the code is CURRENT, i.e. if the test has failed the last three times you drove the car. The code will persist as a HISTORY code with no MIL light for forty conservative warm-up cycles with *no* failed emissions-related tests.

Interestingly, it says on page 6-315 that DTC P0108 can be set if the engine backfires, as in kicks back while you are trying to start it. This can happen to a normal engine in really cold weather when you start a partially warmed-up engine. You might try clearing the code and seeing if it doesn't come back. Or, you might see if a backfire popped the MAP sensor out of it's grommet in the intake manifold and, voila, your stealth vacuum leak *and* your P032.

The rest of the checklist is all about checking the electrical values of the MAP and TPS sensors. I suggest that you pop the beauty cover (be careful, those same 4 bolts hold on the intake manifold on the 1993-1994), locate the MAP sensor, and make sure that it connector and contacts are clean and tight and that it is properly seated. If that doesn't fix the MAP sensor problem, come back and someone with a 1993-1994 FSM can give you the voltages and resistances (or, failing a quick response, I can give you what my 1997 FSM says).

[Ranger]

Jim, she has a '94. No beauty cover. Her cover is a functional part of the manifold. I am not positive, but I think her MAP sensor might even be inside the manifold as well.

[Cadillac Jim]

Ranger: I accounted for the "four bolts that also hold on the intake manifold" in getting the cover off. I suspect that the MAP sensor is still in a grommet because it needs access to outside air on one side because it measures the difference in air pressure inside and outside the intake manifold plenum, and also it has a wiring harness connector. Between those two requirements for a MAP sensor, it would be a bit of a stretch to put it inside the manifold.

But, hey, I once heard that the first hard disk prototypes were made with a stationary disk with heads that rotated, and electrical contacts through slip rings like an alternator. And, this was in California, not Poland. Actually, it made some sense because the parts came from drum storage hardware, which has movable heads. But not much sense, no matter how you think about it.

Anyone checked or changed the MAP sensor in a 1993-1994, or have a FSM for those years handy?

Carla -- I think you would profit from having a factory shop manual (FSM) for your car handy. They are pricey when bought new from the GM printer, Helm, Inc., but a lot of people get them cheap on eBay. I did a search on "1994 Seville manual" and found these:

First one for $19

Second one for $30

Third one for $17

I stopped there; there are many more. There are lots of owner's mauals but I found that adding "shop" or "service" to the search terms didn't work well for this item on eBay.

[CarlaValentine]

I circled my MAP sensor in red in this picture(under the strut cross-brace). There IS a vacuum line on it. You can see it on the bottom left. It attaches to the brake booster.

I plan on getting a manual for my car. I'll have to have my brother order one for me and pay him for it, as I don't have a paypal account, or a credit card or anything like that. Hopefully I can do that this week. Also, mine is not a Seville, it's an Eldorado. I'll go on EBay and see what I can find.

[MAC]

Here is GM Service Manual that discusses P032.

This is a PDF file of 265 pages. If you search for P032 you will also find information. On p. 112 is the MAP Sensor Circuit diagram and on p. 113 is the Trouble Shooting diagram. I have the '94 factory Service Manual, so let me know if you need assistance locating where ground points are so you can check them.

Probably a dumb question, but did you remove the MAP Sensor connection to check for corrosion? If not, should you want to check it, be careful because the clip can snap off/break.

[Cadillac Jim]

... mine is not a Seville, it's an Eldorado. I'll go on EBay and see what I can find.

The difference between the Seville and the Eldorado from 1992-1997 is the wheelbase. They have the same shop manual. In some years, including 1997, the Deville is also covered in the same shop manual. The Eldorado sales were small compared to the Seville sales figures and it is often a "forgotten" model, so I searched on Seville. You can search on Eldorado, or send a message to the eBay guy or look at the pictures to see if the Eldorado is mentioned on the covers, or perhaps someone here will chime in.

Regarding tht MAP being external on teh 1993-1994 Northstar, that kind of thing is what I was taking a chance on when I used my 1997 model year experience and FSM as a basis. I do believe that the DTC might have been set on a backfire on starting or some such.

I would take off the vacuum line to the MAP sensor completely and examine it. If in any doubt whatsoever match the tubing at an auto parts store and replace it. Then check the connector and terminals, like MAC says. Reset the code and see if it stays reset. If so, your driveabilty (smoothness and power) should improve, and your gas mileage will go up.

[CarlaValentine]

... mine is not a Seville, it's an Eldorado. I'll go on EBay and see what I can find.

The difference between the Seville and the Eldorado from 1992-1997 is the wheelbase. They have the same shop manual. In some years, including 1997, the Deville is also covered in the same shop manual. The Eldorado sales were small compared to the Seville sales figures and it is often a "forgotten" model, so I searched on Seville. You can search on Eldorado, or send a message to the eBay guy or look at the pictures to see if the Eldorado is mentioned on the covers, or perhaps someone here will chime in.

Regarding tht MAP being external on teh 1993-1994 Northstar, that kind of thing is what I was taking a chance on when I used my 1997 model year experience and FSM as a basis. I do believe that the DTC might have been set on a backfire on starting or some such.

I would take off the vacuum line to the MAP sensor completely and examine it. If in any doubt whatsoever match the tubing at an auto parts store and replace it. Then check the connector and terminals, like MAC says. Reset the code and see if it stays reset. If so, your driveabilty (smoothness and power) should improve, and your gas mileage will go up.

The manual is listed as being for Deville/Seville/Eldorado/Concours so it's all the same in that respect.

I've checked the MAP connections over and over again, and they are fine, both the wiring connector and the vacuum connector. The hissing sound I am hearing is coming from somewhere to the left of where the MAP is. The only thing I can compare the sound to is the pulsating / ticking sound of a fuel injector, but it's hissing. Maybe I'm going crazy...I don't know. SES light comes on and stays on every time I start the car, and every time I check it, it's the same thing.

P032 CURRENT: Open MAP sensor signal

I clear it, and it just keeps coming back. This is frustrating to me. I need to get a service manual. I'm watching one on EBay now. Bidding closes in 4 days. Hopefully I get it.

I would like to take it for a test drive (I have yet to) but I want to get a new water pump belt and pulley on there first, and figure out what keeps throwing this code...

[Ranger]

I suspect that the MAP sensor is still in a grommet because it needs access to outside air on one side because it measures the difference in air pressure inside and outside the intake manifold plenum, and also it has a wiring harness connector. Between those two requirements for a MAP sensor, it would be a bit of a stretch to put it inside the manifold.

Good point.

[MAC]

The hissing sound I am hearing is coming from somewhere to the left of where the MAP is. The only thing I can compare the sound to is the pulsating / ticking sound of a fuel injector, but it's hissing. Maybe I'm going crazy...I don't know. SES light comes on and stays on every time I start the car, and every time I check it, it's the same thing.

P032 CURRENT: Open MAP sensor signal

I clear it, and it just keeps coming back. This is frustrating to me. I need to get a service manual. I'm watching one on EBay now. Bidding closes in 4 days. Hopefully I get it.

I would like to take it for a test drive (I have yet to) but I want to get a new water pump belt and pulley on there first, and figure out what keeps throwing this code...

Did you check to see if there is any fuel line leak under the cover and whether any of the fuel injectors are leaking. I suggest that you take the cover off and turn the ignition key to the "ON" position (do not start) and enter Diagnostics and check to see if there is any injector problem. Obviously, there should be no leaks nor should there be any spraying fuel.

The On-Board Computer can be used to diagnose possible fuel injector problems. For example, while the car is running (remember to never start the car with the cover off) enter Diagnostics and after it has cycled you will be asked if you want to enter into certain modes, including "PCM INPUTS". So press the fan 'LO' button as necessary to cycle to the PCM INPUT. I think you press it down two or three times and when you see PCM INPUTS, then press the fan 'HI' button to confirm that you want to enter PCM INPUTS. The first code should be PS01. You can cycle through the codes by pressing the 'WARMER' (red) and 'COOLER' (blue) buttons. You will see PS01, PS02, PS03, etc. Cycle to PS04, which is the Fuel Injector Disable function. Then you can toggle the fan 'WARMER' button to choose which injector you want to test. You will see a "--" for one second and then you will see '01', signifying that injector one has been selected. Just push the WARMER button to select injector 2, etc.

Look at the box where the outside temp is displayed which is where you will see the "--" and which injector you have selected. Once you select which injector you want to test then push the 'COOLER' button, which will disable the injector. Based on engine performance you should be able to determine if by disabling the injector the engine stumbles indicating the injector was working. If the engine does not stumble then obviously it indicates the injector may not be working. This must be done with the car in Park or Neutral. The car cannot be moving. This is just one of many tests you can perform using PCM System Diagnostics.

Here is a list of some of the codes and what they refer to:

PS01 = TCC Solenoid

PS02 = EGR Solenoid

PS03 = Idle Speed Control (ISC) Motor

PS04 = Fuel Injector Disable

PS05 = Fuel Pump Relay

PS06 = Not Used

PS07 = C/C Servo Position (Cruise Control)

PS08 = Cooling Fan Relays

PS09 = Temporary Spark Advance

PS10 = Injector Flow

PS11 = Transaxle Shift

PS12 = Long Term Fuel Trim Reset

PS13 = Learn and Adapt Reset (You don't have to disconnect the battery for 20 minutes, just reset it manually)

PS14 = Transaxle Adapt Reset

PS15 = Transaxle Oil Life

PS16 through 19 = Not Used

PS20 = Transaxle Pressure Control

PS21 = Knock Sensor Test

PS22 = Permanent Spark Retard

PS23 = Generator Enable/Disable

PS24 = Traction Control Disable (This is temporary to toggle between on and off)

I hope I've given you the right procedure to enter PCM INPUTS--I believe I have. I don't have my '94 Eldorado anymore.

[CarlaValentine]

The hissing sound I am hearing is coming from somewhere to the left of where the MAP is. The only thing I can compare the sound to is the pulsating / ticking sound of a fuel injector, but it's hissing. Maybe I'm going crazy...I don't know. SES light comes on and stays on every time I start the car, and every time I check it, it's the same thing.

P032 CURRENT: Open MAP sensor signal

I clear it, and it just keeps coming back. This is frustrating to me. I need to get a service manual. I'm watching one on EBay now. Bidding closes in 4 days. Hopefully I get it.

I would like to take it for a test drive (I have yet to) but I want to get a new water pump belt and pulley on there first, and figure out what keeps throwing this code...

Did you check to see if there is any fuel line leak under the cover and whether any of the fuel injectors are leaking. I suggest that you take the cover off and turn the ignition key to the "ON" position (do not start) and enter Diagnostics and check to see if there is any injector problem.

The On-Board Computer can be used to diagnose possible fuel injector problems. For example, while the car is running (remember to never start the car with the cover off) enter Diagnostics and after it has cycled you will be asked if you want to enter into certain modes, including "PCM INPUTS". So press the fan 'LO' button as necessary to cycle to the PCM INPUT. I think you press it down two or three times and when you see PCM INPUTS, then press the fan 'HI' button to confirm that you want to enter PCM INPUTS. The first code should be PS01. You can cycle through the codes by pressing the 'WARMER' (red) and 'COOLER' (blue) buttons. You will see PS01, PS02, PS03, etc. Cycle to PS04, which is the Fuel Injector Disable function. Once you see PS04, then press the and press the fan's 'HI' button to confirm you want PS04. Then you can toggle the he fan increase 'WARMER' button to choose which injector you want to test. You will see a "--" for one second and then you will see '01', signifying that injector one has been selected. Just push the WARMER button to select injector 2, etc. Look at the box where the outside temp is displayed which is where you will see the "--" and which injector you have selected. Once you select which injector you want to test then push the 'COOLER' button, which will disable the injector. Based on engine performance you should be able to determine if by disabling the injector the engine stumbles indicating the injector was working. If the engine does not stumble then obviously it indicates the injector may not be working. This must be done with the car in Park or Neutral. The car cannot be moving. This is just one of many tests you can perform using PCM System Diagnostics.

Here is a list of some of the codes and what they refer to:

PS01 = TCC Solenoid

PS02 = EGR Solenoid

PS03 = Idle Speed Control (ISC) Motor

PS04 = Fuel Injector Disable

PS05 = Fuel Pump Relay

PS06 = Not Used

PS07 = C/C Servo Position (Cruise Control)

PS08 = Cooling Fan Relays

PS09 = Temporary Spark Advance

PS10 = Injector Flow

PS11 = Transaxle Shift

PS12 = Long Term Fuel Trim Reset

PS13 = Learn and Adapt Reset (You don't have to disconnect the battery for 20 minutes, just reset it manually)

PS14 = Transaxle Adapt Reset

PS15 = Transaxle Oil Life

PS16 through 19 = Not Used

PS20 = Transaxle Pressure Control

PS21 = Knock Sensor Test

PS22 = Permanent Spark Retard

PS23 = Generator Enable/Disable

PS24 = Traction Control Disable (This is temporary to toggle between on and off)

I hope I've given you the right procedure to enter PCM INPUTS--I believe I have. I don't have my '94 Eldorado anymore.

This is actually the exact thing I did to figure out that I had 3 dead cylinders in the first place (before I changed the plugs and wires). I haven't done it again since changing them, but it may be a good idea. When I did it the first time it showed that cylinders 5, 7 and 8 were dead. It was also idling poorly, misfiring, and stalling then, and it doesn't do that now, but I will run this test again anyway. I hadn't thought about it until you mentioned it.

I still have yet to check my fuel pressure. I have the gauge next to me in my toolbox. I should probably do that tomorrow. Wayne probably wants his gauge back....

And for future reference, it's PCM OVERRIDE that you have to enter, at least on my car. Everything else is the same as you listed though. I printed out the instructions from another site I found a while back.

[MAC]

The hissing sound I am hearing is coming from somewhere to the left of where the MAP is. The only thing I can compare the sound to is the pulsating / ticking sound of a fuel injector, but it's hissing. Maybe I'm going crazy...I don't know. SES light comes on and stays on every time I start the car, and every time I check it, it's the same thing.

P032 CURRENT: Open MAP sensor signal

I clear it, and it just keeps coming back. This is frustrating to me. I need to get a service manual. I'm watching one on EBay now. Bidding closes in 4 days. Hopefully I get it.

I would like to take it for a test drive (I have yet to) but I want to get a new water pump belt and pulley on there first, and figure out what keeps throwing this code...

Did you check to see if there is any fuel line leak under the cover and whether any of the fuel injectors are leaking. I suggest that you take the cover off and turn the ignition key to the "ON" position (do not start) and enter Diagnostics and check to see if there is any injector problem.

The On-Board Computer can be used to diagnose possible fuel injector problems. For example, while the car is running (remember to never start the car with the cover off) enter Diagnostics and after it has cycled you will be asked if you want to enter into certain modes, including "PCM INPUTS". So press the fan 'LO' button as necessary to cycle to the PCM INPUT. I think you press it down two or three times and when you see PCM INPUTS, then press the fan 'HI' button to confirm that you want to enter PCM INPUTS. The first code should be PS01. You can cycle through the codes by pressing the 'WARMER' (red) and 'COOLER' (blue) buttons. You will see PS01, PS02, PS03, etc. Cycle to PS04, which is the Fuel Injector Disable function. Once you see PS04, then press the and press the fan's 'HI' button to confirm you want PS04. Then you can toggle the he fan increase 'WARMER' button to choose which injector you want to test. You will see a "--" for one second and then you will see '01', signifying that injector one has been selected. Just push the WARMER button to select injector 2, etc. Look at the box where the outside temp is displayed which is where you will see the "--" and which injector you have selected. Once you select which injector you want to test then push the 'COOLER' button, which will disable the injector. Based on engine performance you should be able to determine if by disabling the injector the engine stumbles indicating the injector was working. If the engine does not stumble then obviously it indicates the injector may not be working. This must be done with the car in Park or Neutral. The car cannot be moving. This is just one of many tests you can perform using PCM System Diagnostics.

Here is a list of some of the codes and what they refer to:

PS01 = TCC Solenoid

PS02 = EGR Solenoid

PS03 = Idle Speed Control (ISC) Motor

PS04 = Fuel Injector Disable

PS05 = Fuel Pump Relay

PS06 = Not Used

PS07 = C/C Servo Position (Cruise Control)

PS08 = Cooling Fan Relays

PS09 = Temporary Spark Advance

PS10 = Injector Flow

PS11 = Transaxle Shift

PS12 = Long Term Fuel Trim Reset

PS13 = Learn and Adapt Reset (You don't have to disconnect the battery for 20 minutes, just reset it manually)

PS14 = Transaxle Adapt Reset

PS15 = Transaxle Oil Life

PS16 through 19 = Not Used

PS20 = Transaxle Pressure Control

PS21 = Knock Sensor Test

PS22 = Permanent Spark Retard

PS23 = Generator Enable/Disable

PS24 = Traction Control Disable (This is temporary to toggle between on and off)

I hope I've given you the right procedure to enter PCM INPUTS--I believe I have. I don't have my '94 Eldorado anymore.

This is actually the exact thing I did to figure out that I had 3 dead cylinders in the first place (before I changed the plugs and wires). I haven't done it again since changing them, but it may be a good idea. When I did it the first time it showed that cylinders 5, 7 and 8 were dead. It was also idling poorly, misfiring, and stalling then, and it doesn't do that now, but I will run this test again anyway. I hadn't thought about it until you mentioned it.

I still have yet to check my fuel pressure. I have the gauge next to me in my toolbox. I should probably do that tomorrow. Wayne probably wants his gauge back....

And for future reference, it's PCM OVERRIDE that you have to enter, at least on my car. Everything else is the same as you listed though. I printed out the instructions from another site I found a while back.

Thanks for clearing up that it's PCM OVERRIDE. I glossed right by it in my Service Manual and my memory isn't too good. It's impressive that you know how to use PCM Diagnostics since not a lot of people venture into that part. It's a very helpful tool.

[CarlaValentine]

Well when my SES light first came on a while back, i wanted to check the codes. I figured it used the same method a lot of OBD1 GM's used (jumper wire under the dashboard, count the SES light cycles), but I saw there WAS no jumper on this car, so I ventured to the internet for help. When I saw how much more there was to this car's on board diagnostic system, I wanted to learn more about it, so I delved into it as much as I could. Then I started learning about the PCM Data monitors. Then someone on here mentioned the PCM OVERRIDE for the test you mentioned above, and when looking for that, I found a lot of other things as well. I know the in's and out's of this car's diagnostic system pretty well now.

If I ever do get into the auto industry, I think I would try to get into diagnostics. I prefer the challenge of figuring out what is causing a problem over that of actually fixing it. But that's not to say I don't enjoy both.

[adallak]

If I ever do get into the auto industry, I think I would try to get into diagnostics. I prefer the challenge of figuring out what is causing a problem over that of actually fixing it. But that's not to say I don't enjoy both.

Correct diagnosis is the half of successful treatment.

[MAC]

I circled my MAP sensor in red in this picture(under the strut cross-brace). There IS a vacuum line on it. You can see it on the bottom left. It attaches to the brake booster.

I plan on getting a manual for my car. I'll have to have my brother order one for me and pay him for it, as I don't have a paypal account, or a credit card or anything like that. Hopefully I can do that this week. Also, mine is not a Seville, it's an Eldorado. I'll go on EBay and see what I can find.

According to the '94 factory Service Manual (pgs. 6C-14 & 6C-17), the MAP Sensor is located inside the intake manifold, not outside. It's near the Fuel Pressure Regulator at the left rear corner.

Here is a quote:

The MAP sensor is mounted inside of the intake manifold and measures the changes in intake manifold pressure which results from engine speed and load changes...

I think what you circled in red is the Brake Booster Sensor judging by your statement that it's attached to the brake booster.

[CarlaValentine]

If I ever do get into the auto industry, I think I would try to get into diagnostics. I prefer the challenge of figuring out what is causing a problem over that of actually fixing it. But that's not to say I don't enjoy both.

Correct diagnosis is the half of successful treatment.

Trial and error works too. It's just a lot more time consuming, expensive, and frustrating. lol.

[CarlaValentine]

I circled my MAP sensor in red in this picture(under the strut cross-brace). There IS a vacuum line on it. You can see it on the bottom left. It attaches to the brake booster.

I plan on getting a manual for my car. I'll have to have my brother order one for me and pay him for it, as I don't have a paypal account, or a credit card or anything like that. Hopefully I can do that this week. Also, mine is not a Seville, it's an Eldorado. I'll go on EBay and see what I can find.

According to the '94 factory Service Manual (pgs. 6C-14 & 6C-17), the MAP Sensor is located inside the intake manifold, not outside. It's near the Fuel Pressure Regulator at the left rear corner.

Here is a quote:

The MAP sensor is mounted inside of the intake manifold and measures the changes in intake manifold pressure which results from engine speed and load changes...

I think what you circled in red is the Park/Neutral Safety Switch or Brake Booster Sensor.

hmmm....

that could be a problem.

I bought a new MAP sensor. I put it there. The thing I removed looked IDENTICAL to the thing I replaced it with.

In an attempt to clear the code, I even took off the new one, and put the old one back on, which is the one in the pic.

If that isn't the MAP sensor, then why would the connections look the same and why would it fit? Unless I screwed up, AND the parts store screwed up....

I better check that out tomorrow. Whoops.

In the meantime, I am going to look up both parts on rockauto and see which it is. I'll let you know.

if it's wrong, back to the parts store I go.

[MAC]

hmmm....

that could be a problem.

I bought a new MAP sensor. I put it there. The thing I removed looked IDENTICAL to the thing I replaced it with.

In an attempt to clear the code, I even took off the new one, and put the old one back on, which is the one in the pic.

If that isn't the MAP sensor, then why would the connections look the same and why would it fit? Unless I screwed up, AND the parts store screwed up....

I better check that out tomorrow. Whoops.

In the meantime, I am going to look up both parts on rockauto and see which it is. I'll let you know.

if it's wrong, back to the parts store I go.

I edited my above post to say that it's likely the Brake Booster Sensor. For the '94 Northstar, both the FPR and MAP gets or senses vacuum via under the engine cover. There are no vacuum lines. In 1995, the design changed to where the FPR was mounted outside of the intake manifold and thus a vacuum line was needed. I'm not sure if the MAP was also mounted outside. There are others here who can verify that.

[CarlaValentine]

Ok. Now I'm annoyed.

That is indeed the brake booster sensor.

Which means I changed the wrong thing. They both cost the same price, so I wouldn't have known the difference by that.

In a way I should be relieved though because this means maybe my MAP sensor really IS having problems, since I have been looking in the wrong place all this time.

I don't know who should feel more like an idiot...the person who gave me the wrong part, or me for not knowing the difference.

I'm not gonna beat myself up about it though. Now I know where to look for my problem.

grrrr. Oh well. I had to pull that cover off to check the fuel pressure one of these days anyhow.

I shoulda known....I was wondering why the MAP sensor would hook to the friggin brake booster? Duh.

Thank you MAC for pointing out that mistake to me, or I would have been searching endlessly for this mystery vacuum leak. Hopefully this puts an end to the searching.

[MAC]

Ok. Now I'm annoyed.

That is indeed the brake booster sensor.

Which means I changed the wrong thing. They both cost the same price, so I wouldn't have known the difference by that.

In a way I should be relieved though because this means maybe my MAP sensor really IS having problems, since I have been looking in the wrong place all this time.

I don't know who should feel more like an idiot...the person who gave me the wrong part, or me for not knowing the difference.

I'm not gonna beat myself up about it though. Now I know where to look for my problem.

grrrr. Oh well. I had to pull that cover off to check the fuel pressure one of these days anyhow.

I shoulda known....I was wondering why the MAP sensor would hook to the friggin brake booster? Duh.

Thank you MAC for pointing out that mistake to me, or I would have been searching endlessly for this mystery vacuum leak. Hopefully this puts an end to the searching.

You're Welcome!

The important thing is that when all is said and done that you've pinned it all down between wires, plugs, and a new MAP sensor. Except that you did mention something about a possible vacuum leak. If you can locate a leak, it's probably best to fix it first and see what happens. I suspect that any effect on engine vacuum may very well throw off an otherwise healthy MAP. If I remember, you did mention that idle is still a bit high, which indicates a potential vacuum leak. Just a suggestion. However, if the MAP is inexpensive then maybe it would be simple enough to take a chance and replace it and see what happens.