MAF slowly going bad?
07-15-2014, 07:50 PM
#1
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MAF slowly going bad? Nope. Bad O2 sensor.
Hi guys,
As the title says, I'm wondering if the MAF in my car is slowly going bad.
It has never been redone. Only cleaned it with MAF Cleaner. Car has about 66k miles.
Two things:
1) The idle is a bit rough when warm. Nothing major but just enough to make the car shake a bit in park (or neutral).
At least more this year than before. You can feel it from the inside. In park, it idles at about 650 rpm.
Motor mounts are about seven years old. Not Porsche mounts. Engine still rocks when throttle applied. So the mounts are maybe not perfect but still good (I think).
2) When I drive the car and come to a complete stop, brake applied, in "Drive", the idle get down to less than 600 rpm for less than a second and get back to about 625 rpm.
This does not always happen but it did many times in the last week. The car doesn't stall but feels not far from doing so.
When I start the car when cold (about 18C), like in the morning, everything's perfect. It started at about 1100 and goes down to about 900 rpm in a few seconds. 10 maybe.
Car pulls very well. No performance problems.
Here's what have been done to the car this Spring:
- Intake removal (to fix an oil filler neck leak).
* Intake as been put back with all the same rubber gaskets. All were only about five years old and looks perfect.
* Cleaned the ISV and checked it putting 12v to it. Everything was perfect.
* Checked the idle switch. I can hear it click well and the fuel consumption rate goes to "0 L/100km" when I lift the throttle pedal while cruising. So I think everything's good there too.
- Injectors cleaned (Crusin Performance).
- Air pump removal. Vacuum line plugged at the throttle body and metal line to the cat (stock) plugged too.
- New temp II sensor.
- New timing belt. Same water pump (Ed's pump).
- Recoated cam gears. Timed when reinstalled with Ken's kit.
It looks like the idle is just a bit low when warm. If it would be just a little higher, everything would be perfect - I think.
If only the idle would be adjustable!
Now, my question is:
Can a failing MAF would cause this?
Or maybe an air leak, bad ISV, bad idle switch, bad timing, etc...
The car is still drivable of course but it bugs me that it is not as smooth as it should.
I know it's a long shot but what do you guys think?
What I should look at first?
Thank you in advance.
As the title says, I'm wondering if the MAF in my car is slowly going bad.
It has never been redone. Only cleaned it with MAF Cleaner. Car has about 66k miles.
Two things:
1) The idle is a bit rough when warm. Nothing major but just enough to make the car shake a bit in park (or neutral).
At least more this year than before. You can feel it from the inside. In park, it idles at about 650 rpm.
Motor mounts are about seven years old. Not Porsche mounts. Engine still rocks when throttle applied. So the mounts are maybe not perfect but still good (I think).
2) When I drive the car and come to a complete stop, brake applied, in "Drive", the idle get down to less than 600 rpm for less than a second and get back to about 625 rpm.
This does not always happen but it did many times in the last week. The car doesn't stall but feels not far from doing so.
When I start the car when cold (about 18C), like in the morning, everything's perfect. It started at about 1100 and goes down to about 900 rpm in a few seconds. 10 maybe.
Car pulls very well. No performance problems.
Here's what have been done to the car this Spring:
- Intake removal (to fix an oil filler neck leak).
* Intake as been put back with all the same rubber gaskets. All were only about five years old and looks perfect.
* Cleaned the ISV and checked it putting 12v to it. Everything was perfect.
* Checked the idle switch. I can hear it click well and the fuel consumption rate goes to "0 L/100km" when I lift the throttle pedal while cruising. So I think everything's good there too.
- Injectors cleaned (Crusin Performance).
- Air pump removal. Vacuum line plugged at the throttle body and metal line to the cat (stock) plugged too.
- New temp II sensor.
- New timing belt. Same water pump (Ed's pump).
- Recoated cam gears. Timed when reinstalled with Ken's kit.
It looks like the idle is just a bit low when warm. If it would be just a little higher, everything would be perfect - I think.
If only the idle would be adjustable!
Now, my question is:
Can a failing MAF would cause this?
Or maybe an air leak, bad ISV, bad idle switch, bad timing, etc...
The car is still drivable of course but it bugs me that it is not as smooth as it should.
I know it's a long shot but what do you guys think?
What I should look at first?
Thank you in advance.
Last edited by Bertrand Daoust; 03-20-2015 at 06:19 PM. Reason: Problem fixed
07-15-2014, 08:04 PM
#2
Nordschleife Master
Hey there Bertrand,
Seems like you've done a lot this Spring. An easy thing to start with with is to get some Deoxit on the MAF connectors. They are small and thin and you can't see much of them. I put 100% Deoxit via needle applicator to them - made quite the difference for me. I had symptoms similar to yours - tested Temp II and all was good - put in a new ISV - cleaned injectors/new O-rings, and others - still had a jittery idle - cleaning the connectors did it for me.
As to the car shake, 7 years is a long time for the mounts - the engine should move through the mount's absorption of vibration.
Best Wishes.
Craig
Seems like you've done a lot this Spring. An easy thing to start with with is to get some Deoxit on the MAF connectors. They are small and thin and you can't see much of them. I put 100% Deoxit via needle applicator to them - made quite the difference for me. I had symptoms similar to yours - tested Temp II and all was good - put in a new ISV - cleaned injectors/new O-rings, and others - still had a jittery idle - cleaning the connectors did it for me.
As to the car shake, 7 years is a long time for the mounts - the engine should move through the mount's absorption of vibration.
Best Wishes.
Craig
07-15-2014, 08:06 PM
#3
Rennlist Member
hi Bertrand........given the MAF is perhaps original it is highly possible its going out.
If it were my car I'd wait until the dredded snow arrives and send it to JDS for evaluation although by the time and expense you do this its easier to order a refurbed unit from Jim C.
When you had the intake off did you check/clean the throttle body etc? the bearings for the throttle body plate have Orings and are a serviceable item.............see Dwaynes write up for upfrade to double Oring parts.
Perhaps do a intake leak test..........again reference Dwaynes write up.
bon chance mon ami
If it were my car I'd wait until the dredded snow arrives and send it to JDS for evaluation although by the time and expense you do this its easier to order a refurbed unit from Jim C.
When you had the intake off did you check/clean the throttle body etc? the bearings for the throttle body plate have Orings and are a serviceable item.............see Dwaynes write up for upfrade to double Oring parts.
Perhaps do a intake leak test..........again reference Dwaynes write up.
bon chance mon ami
Last edited by the flyin' scotsman; 07-15-2014 at 08:24 PM.
07-15-2014, 08:15 PM
#4
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Hey there Bertrand,
Seems like you've done a lot this Spring. An easy thing to start with with is to get some Deoxit on the MAF connectors. They are small and thin and you can't see much of them. I put 100% Deoxit via needle applicator to them - made quite the difference for me. I had symptoms similar to yours - tested Temp II and all was good - put in a new ISV - cleaned injectors/new O-rings, and others - still had a jittery idle - cleaning the connectors did it for me.
As to the car shake, 7 years is a long time for the mounts - the engine should move through the mount's absorption of vibration.
Best Wishes.
Craig
Seems like you've done a lot this Spring. An easy thing to start with with is to get some Deoxit on the MAF connectors. They are small and thin and you can't see much of them. I put 100% Deoxit via needle applicator to them - made quite the difference for me. I had symptoms similar to yours - tested Temp II and all was good - put in a new ISV - cleaned injectors/new O-rings, and others - still had a jittery idle - cleaning the connectors did it for me.
As to the car shake, 7 years is a long time for the mounts - the engine should move through the mount's absorption of vibration.
Best Wishes.
Craig
I remember well reading that you used Deoxit with very good result on your MAF.
So I tried some there but it did not cure the problem.
I use Deoxit now on every connector I touch!
Great stuff.
07-15-2014, 08:19 PM
#5
Rennlist Member
Yes.
It could also be an air leak but with 66K miles the MAF would be showing its age depending on how the car is driven. The LH incorporates a burn-off cycle which heats the hot-wire for a moment each time the engine is shut off. This keeps the wire clean (burning off any deposits) but also erodes it a small amount for each cycle. This is the primary aging mechanism.
So if the car is driven mostly for long trips then miles accumulate with fewer burn-off cycles and the MAF will last a long time. But if most trips are shorter then it will age faster.
If you will be at OCIC in Kananaskis then I am sure that there will be a freshly-rebuilt MAF to borrow for a test. We can also connect a Shakrtuner and have a peek at what is happening in the LH.
Cheers, Jim
It could also be an air leak but with 66K miles the MAF would be showing its age depending on how the car is driven. The LH incorporates a burn-off cycle which heats the hot-wire for a moment each time the engine is shut off. This keeps the wire clean (burning off any deposits) but also erodes it a small amount for each cycle. This is the primary aging mechanism.
So if the car is driven mostly for long trips then miles accumulate with fewer burn-off cycles and the MAF will last a long time. But if most trips are shorter then it will age faster.
If you will be at OCIC in Kananaskis then I am sure that there will be a freshly-rebuilt MAF to borrow for a test. We can also connect a Shakrtuner and have a peek at what is happening in the LH.
Cheers, Jim
07-15-2014, 08:21 PM
#6
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hi Bertrand........given the MAF is perhaps original it is highly possible its going out.
If it were my car I'd wait until the dredded snow arrives and send it to JDS for evaluation although by the time and expense you do this its easier to order a refurbed unit from Jim C.
When you had the intake off did you check/clean the throttle body etc? the bearings for the throttle body plate have Orings and are a serviceable item.............see Dwaynes write up for upfrade to double Oring parts.
Perhaps do a intake leak test..........again reference Dwaynes write up.
good luck mon ami
If it were my car I'd wait until the dredded snow arrives and send it to JDS for evaluation although by the time and expense you do this its easier to order a refurbed unit from Jim C.
When you had the intake off did you check/clean the throttle body etc? the bearings for the throttle body plate have Orings and are a serviceable item.............see Dwaynes write up for upfrade to double Oring parts.
Perhaps do a intake leak test..........again reference Dwaynes write up.
good luck mon ami
Also I did not do any leaking test this year. Not yet!
By the way, do you know how much is a refurbed from Jim?
Merci mon ami.
07-15-2014, 08:34 PM
#7
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Yes.
It could also be an air leak but with 66K miles the MAF would be showing its age depending on how the car is driven. The LH incorporates a burn-off cycle which heats the hot-wire for a moment each time the engine is shut off. This keeps the wire clean (burning off any deposits) but also erodes it a small amount for each cycle. This is the primary aging mechanism.
So if the car is driven mostly for long trips then miles accumulate with fewer burn-off cycles and the MAF will last a long time. But if most trips are shorter then it will age faster.
If you will be at OCIC in Kananaskis then I am sure that there will be a freshly-rebuilt MAF to borrow for a test. We can also connect a Shakrtuner and have a peek at what is happening in the LH.
Cheers, Jim
It could also be an air leak but with 66K miles the MAF would be showing its age depending on how the car is driven. The LH incorporates a burn-off cycle which heats the hot-wire for a moment each time the engine is shut off. This keeps the wire clean (burning off any deposits) but also erodes it a small amount for each cycle. This is the primary aging mechanism.
So if the car is driven mostly for long trips then miles accumulate with fewer burn-off cycles and the MAF will last a long time. But if most trips are shorter then it will age faster.
If you will be at OCIC in Kananaskis then I am sure that there will be a freshly-rebuilt MAF to borrow for a test. We can also connect a Shakrtuner and have a peek at what is happening in the LH.
Cheers, Jim
Would love too but unfortunately, I won't be in Kananaskis.
I'm not use to travel that long yet - with the 928 that is!
I will try to find another one around here to see.
Then I would know for sure.
How much is a refurbed one please?
Thanks again.
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07-15-2014, 08:47 PM
#8
Nordschleife Master
With all you've done, the process of elimination leads to your original MAF. Hope it is bearable till winter, then have one of the pros tend to it then.
Bonne chance.
Craig
07-15-2014, 08:53 PM
#9
Rennlist Member
Bertrand,
Louie Ott handles MAF and LH rebuilds for John Speake, I do Sharktuners.
Louie's product page with pricing is here: http://performance928.com/cgi-bin/pa...&pass_parent=0
And his contact page is here: http://performance928.com/cgi-bin/fo...cgi?form_id=27
Cheers, Jim
Louie Ott handles MAF and LH rebuilds for John Speake, I do Sharktuners.
Louie's product page with pricing is here: http://performance928.com/cgi-bin/pa...&pass_parent=0
And his contact page is here: http://performance928.com/cgi-bin/fo...cgi?form_id=27
Cheers, Jim
07-15-2014, 11:24 PM
#12
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We sell rebuild MAF's for $295 plus a core charge so let me know if I can help you.
Best,
Roger
Best,
Roger
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
07-16-2014, 07:54 AM
#13
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Thank you very much Roger.
I'll try to swap mine first with a known good one and then make a move if necessary.
Thanks again guys for your help.
I'll try to swap mine first with a known good one and then make a move if necessary.
Thanks again guys for your help.
