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Old 10-07-2021, 06:23 PM   #1
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P1128/1130 - my turn

2001 986 S - 85k miles

I have been getting these codes for the past month. Car runs and idles fine.

I followed the 101 things book to clean the MAF but the codes came back.

I read on another forum to disconnect the MAF and drive the car in order to rule out the MAF. If the codes come back itís something else. If not than itís probably the MAF.

Is that the correct next step?

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Old 10-08-2021, 08:55 AM   #2
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2001 986 S - 85k miles

I have been getting these codes for the past month. Car runs and idles fine.

I followed the 101 things book to clean the MAF but the codes came back.

I read on another forum to disconnect the MAF and drive the car in order to rule out the MAF. If the codes come back it’s something else. If not than it’s probably the MAF.

Is that the correct next step?
Those codes are most often caused by:
Vacuum leak of some type.
MAF sensor issue.
Fuel delivery issue.

The correct next step is a proper diagnosis of the issue.
So to try to help you I need to know what types of diagnostic tools you have available.

Best diagnostic tools are your senses.
Remove your engine cover and have a very good long look at the visual condition of your engine bay. Is it clean or dirty????
If it is dirty is it a dry dusty dirt???? or is it an oily residue type dirt.??????
If you have any oily residue type dirt on your hoses or any place in your engine bay then you have vacuum leaks.

Do you have a OBDII scanner???
Do you have a vacuum gauge???

If you have a OBDII scanner that reads MAF delivery in g/s and also MAF voltage.
Then you can look at the MAF signal in relation to RPM to see if it is near spec.

If you have vacuum gauge....... HOOKED UP CORRECTLY AND THE TEST RUN UNDER CORRECT CONDITIONS..... it will tell you if you have a vacuum leak.

Last edited by blue62; 10-08-2021 at 10:37 AM.
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Old 10-08-2021, 01:00 PM   #3
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Thanks for the great info.

I am not home this weekend so cannot give the complete visual inspection. I was in there on Wednesday to clean the MAF. The engine bay is very clean. I do not remember any oily residue. The car was serviced in March.

I have a Durametric but nothing else to diagnose.
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Old 10-08-2021, 02:00 PM   #4
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Thanks for the great info.

I am not home this weekend so cannot give the complete visual inspection. I was in there on Wednesday to clean the MAF. The engine bay is very clean. I do not remember any oily residue. The car was serviced in March.

I have a Durametric but nothing else to diagnose.
So with the Durametric you can check the MAF voltage and g/s.
Go into the engine module then click on actual values.
that will bring up a list of things.
Find MAF voltage.
with ....Key on but engine off..... MAF voltage should read 0.9 - 1.1 volts.
With .....engine running at idle...... MAF voltage should be 1.2 - 1.5 volts.
Let me know when your back at your car.
I will hook up my Durametric to my car and give you some running g/s figures to look at.

You can also buy a vacuum gauge for around $25.00 and I can tell you how to connect it and do a proper vacuum test with it.
If you decide to purchase one let me know I will point out the correct type.

Tell me how the car runs... do you notice anything different since the codes came up????? Does it idle correctly and at the proper RPM????
Are you using a stock air filter or is it after market????
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Old 10-11-2021, 12:55 PM   #5
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So with the Durametric you can check the MAF voltage and g/s.
Go into the engine module then click on actual values.
that will bring up a list of things.
Find MAF voltage.
with ....Key on but engine off..... MAF voltage should read 0.9 - 1.1 volts.
With .....engine running at idle...... MAF voltage should be 1.2 - 1.5 volts.
Let me know when your back at your car.
I will hook up my Durametric to my car and give you some running g/s figures to look at.

You can also buy a vacuum gauge for around $25.00 and I can tell you how to connect it and do a proper vacuum test with it.
If you decide to purchase one let me know I will point out the correct type.

Tell me how the car runs... do you notice anything different since the codes came up????? Does it idle correctly and at the proper RPM????
Are you using a stock air filter or is it after market????
I am back home and just checked MAF Voltage

Engine Off - 1.01 v
Engine Idle - 1.31 v

I saw other MAF values in the list.

I have no problem buying a vacuum gauge. If you can point me to a good one I can get one and then follow the instructions to test it out.

The car runs great AND there does not appear to be any difference since the codes started appearing. Upon startup it can idle rough ~600 - 1000 then settles in at around 800 RPM (based on the notches on the gauge being 200 intervals).

I am using a MAHLE Air Filter - It was changed probably 2 years ago.

Thank you so much for your help!
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Old 10-11-2021, 05:10 PM   #6
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I am back home and just checked MAF Voltage

Engine Off - 1.01 v
Engine Idle - 1.31 v

I saw other MAF values in the list.

I have no problem buying a vacuum gauge. If you can point me to a good one I can get one and then follow the instructions to test it out.

The car runs great AND there does not appear to be any difference since the codes started appearing. Upon startup it can idle rough ~600 - 1000 then settles in at around 800 RPM (based on the notches on the gauge being 200 intervals).

I am using a MAHLE Air Filter - It was changed probably 2 years ago.

Thank you so much for your help!
Looks like your MAF specs. (for those two tests) are within correct voltage range.
I will get you some running MAF specs. tomorrow or the next day.

You can buy a vacuum gauge at places like Orielly's auto parts.
Your looking for one that has around a 2 inch gauge face or bigger.
It should come with a section of hose and a fitting or two.
The most important fitting you will need is a "TEE" fitting.

Good that your using a stock air filter and not an after market like an oiled K&N they are hard on MAF sensors.

Interesting that the car runs "great" usually the car idles kinda rough when these two codes appear.
We will look at the MAF a little closer and see what a vacuum tests has to say.
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Old 10-11-2021, 05:56 PM   #7
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Looks like your MAF specs. (for those two tests) are within correct voltage range.
I will get you some running MAF specs. tomorrow or the next day.

You can buy a vacuum gauge at places like Orielly's auto parts.
Your looking for one that has around a 2 inch gauge face or bigger.
It should come with a section of hose and a fitting or two.
The most important fitting you will need is a "TEE" fitting.

Good that your using a stock air filter and not an after market like an oiled K&N they are hard on MAF sensors.

Interesting that the car runs "great" usually the car idles kinda rough when these two codes appear.
We will look at the MAF a little closer and see what a vacuum tests has to say.

As I said, it starts up a little rough but settles in.

Is this what I need?

HFS (R) Carburetor Carb Valve Fuel Pump Pressure & Vacuum Tester Gauge Test Kit https://www.amazon.com/dp/B00KRJFSFQ/ref=cm_sw_r_cp_api_glt_fabc_B51EGBDZ2G3WPSEA6KRE
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Old 10-11-2021, 06:48 PM   #8
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As I said, it starts up a little rough but settles in.

Is this what I need?

HFS (R) Carburetor Carb Valve Fuel Pump Pressure & Vacuum Tester Gauge Test Kit https://www.amazon.com/dp/B00KRJFSFQ/ref=cm_sw_r_cp_api_glt_fabc_B51EGBDZ2G3WPSEA6KRE
Yes that is perfect....

So a rough or lumpy or hunting idle that smooths out at higher RPM is an indication of a vacuum leak.
But once you have the vacuum gauge I will tell you how to connect it and do the test correctly and we should know if you have a vacuum leak.
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Old 10-14-2021, 03:07 PM   #9
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Yes that is perfect....

So a rough or lumpy or hunting idle that smooths out at higher RPM is an indication of a vacuum leak.
But once you have the vacuum gauge I will tell you how to connect it and do the test correctly and we should know if you have a vacuum leak.

The vacuum gauge has arrived. Let me know what I need to test.

Thanks John
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Old 10-14-2021, 04:38 PM   #10
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The vacuum gauge has arrived. Let me know what I need to test.

Thanks John
Take the car for a good 20-30 minute drive.

Remove the engine cover.
On the drivers side of the intake manifold you will see a rubber sleeve connecting the crossover tubes to the intake runners.
on that rubber sleeve is a nipple where a small plastic hose is connected. That plastic hose goes down to your fuel pressure regulator. Pull it out of the nipple on the rubber sleeve.

Now connect you vacuum gauge to your "Tee" fitting with a length of hose.
Connect the plastic hose you pulled out of the rubber sleeve to the "Tee" fitting.
Insert the remaining leg of the "Tee" fitting into the nipple on the rubber sleeve.

Start the car... just let the car idle and watch the gauge for a few minutes.
Note the readings on the gauge and also the needle action if any.
Your looking for a reading of 18 -22 Hg with a steady needle.

Let me know how it goes and the readings you get... also the needle action if any.
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Old 10-15-2021, 11:47 AM   #11
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Take the car for a good 20-30 minute drive.

Remove the engine cover.
On the drivers side of the intake manifold you will see a rubber sleeve connecting the crossover tubes to the intake runners.
on that rubber sleeve is a nipple where a small plastic hose is connected. That plastic hose goes down to your fuel pressure regulator. Pull it out of the nipple on the rubber sleeve.

Now connect you vacuum gauge to your "Tee" fitting with a length of hose.
Connect the plastic hose you pulled out of the rubber sleeve to the "Tee" fitting.
Insert the remaining leg of the "Tee" fitting into the nipple on the rubber sleeve.

Start the car... just let the car idle and watch the gauge for a few minutes.
Note the readings on the gauge and also the needle action if any.
Your looking for a reading of 18 -22 Hg with a steady needle.

Let me know how it goes and the readings you get... also the needle action if any.



This picture is standing on the drivers side. I’m not quite sure where the rubber sleeve with the nipple is. Can you point it out in this picture? Is it on the side above the "P" in PORSCHE or the "E"?

Thanks for your help!
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Old 10-15-2021, 01:51 PM   #12
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the nipple where you plug the T is right next to the power steering cap
.
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Old 10-15-2021, 06:13 PM   #13
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the nipple where you plug the T is right next to the power steering cap
.
Correct thanks Gilles. I was Salmon fishing all day just saw the post.
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Old 10-16-2021, 06:04 AM   #14
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Correct thanks Gilles. I was Salmon fishing all day just saw the post.

Thanks! Just to be sure, I circled where I will put the T.



John
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Old 10-16-2021, 11:12 AM   #15
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Correct thanks Gilles. I was Salmon fishing all day just saw the post.
Blue, I can imagine the awesome BBQ's meals at your place!
If I happen to be in your neck of the woods I would bring the tequila and beers :-)
.
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Old 10-16-2021, 05:47 PM   #16
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Thanks! Just to be sure, I circled where I will put the T.



John
That is correct
Sorry I am taking all day to reply but the hot part of the Salmon run is rather short.
Gotta fish when the bite is on.

Last edited by blue62; 10-16-2021 at 05:59 PM.
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Old 10-16-2021, 05:55 PM   #17
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Blue, I can imagine the awesome BBQ's meals at your place!
If I happen to be in your neck of the woods I would bring the tequila and beers :-)
.
I fillet most all fish I catch then cut the fillet into pieces and smoke them.
I am now looking into using the carcass and head.
Many different ways to make fish soup or fish stew.
Each country or region has their own spin on the dish.
Fun to experiment.
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Old 10-24-2021, 12:48 PM   #18
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Now connect you vacuum gauge to your "Tee" fitting with a length of hose.
Connect the plastic hose you pulled out of the rubber sleeve to the "Tee" fitting.
Insert the remaining leg of the "Tee" fitting into the nipple on the rubber.

I am getting back to this. I have bees sick all week.

I took the car for a drive and followed the process. I am getting ready to hook up the Tee fitting and there is no way it fits.



There are other parts in the gauge kit.



Any suggestions?

John
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Old 10-24-2021, 02:28 PM   #19
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any auto parts store will have smaller fittings. They are usually in the Help section. Just need a smaller T. Any of the vacuum ones are what you are looking for.
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Old 10-24-2021, 05:25 PM   #20
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I am getting back to this. I have bees sick all week.

I took the car for a drive and followed the process. I am getting ready to hook up the Tee fitting and there is no way it fits.



There are other parts in the gauge kit.



Any suggestions?

John
Find a TEE and hose that works.
Auto parts store
Hardware store
what ever will work

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