will a bad MAF cause high idle?
#1
Instructor
Thread Starter
Join Date: Nov 2009
Location: South Jersey
Posts: 134
Likes: 0
Received 0 Likes
on
0 Posts
will a bad MAF cause high idle?
All of a sudden I am idling at 1300 rpm.
Checked all over for vacuum leaks and found none. I took the maf off and cleaned it lightly with either and it seemed to idle for about 10 seconds then back up?
What else can cause it?
86.5
Checked all over for vacuum leaks and found none. I took the maf off and cleaned it lightly with either and it seemed to idle for about 10 seconds then back up?
What else can cause it?
86.5
#4
Addict
Rennlist Member
Rennlist Member
Join Date: Oct 2003
Location: Gone. On the Open Road
Posts: 16,574
Received 1,691 Likes
on
1,099 Posts
Yes. It is the valve that's buried. You can unplug it and test it directly with 12v without needing to remove the intake.
Also, bad ground path to the TEMP-II sensor can cause a high idle. Stuck throttle cable. Bad Idle/WOT switch.
Last, how did you test for intake leaks? Smoke machine? I ask, because it is really hard to figure out if the breather hoses under the intake are leaky without a smoke machine.
Also, bad ground path to the TEMP-II sensor can cause a high idle. Stuck throttle cable. Bad Idle/WOT switch.
Last, how did you test for intake leaks? Smoke machine? I ask, because it is really hard to figure out if the breather hoses under the intake are leaky without a smoke machine.
#5
Addict
Rennlist Member
Rennlist Member
Join Date: Oct 2003
Location: Gone. On the Open Road
Posts: 16,574
Received 1,691 Likes
on
1,099 Posts
EDIT: On your 86.5 it is way easier to check the ISV than on an S4. Middle pin on the valve is 12v. Apply ground to each outer pin - one at a time - and you should hear the ISV move.
Last, on the S3 motors there is a shorty harness from the idle/wot switch to the main engine harness. It can also be a problem. Most original-equipment shorties are dead by now. The harness is NLA. You have to make a new one from new connectors. Or I think 928sRUs sells a pre-made replacement.
Last, on the S3 motors there is a shorty harness from the idle/wot switch to the main engine harness. It can also be a problem. Most original-equipment shorties are dead by now. The harness is NLA. You have to make a new one from new connectors. Or I think 928sRUs sells a pre-made replacement.
#6
Rennlist Member
Agree with Dave C., probably the harness for the idle/WOT switch. Mine disintegrated as most do. 928sRUs does sell a replacement since it is NLA from Porsche.
#7
Instructor
Thread Starter
Join Date: Nov 2009
Location: South Jersey
Posts: 134
Likes: 0
Received 0 Likes
on
0 Posts
Yes. It is the valve that's buried. You can unplug it and test it directly with 12v without needing to remove the intake.
Also, bad ground path to the TEMP-II sensor can cause a high idle. Stuck throttle cable. Bad Idle/WOT switch.
Last, how did you test for intake leaks? Smoke machine? I ask, because it is really hard to figure out if the breather hoses under the intake are leaky without a smoke machine.
Also, bad ground path to the TEMP-II sensor can cause a high idle. Stuck throttle cable. Bad Idle/WOT switch.
Last, how did you test for intake leaks? Smoke machine? I ask, because it is really hard to figure out if the breather hoses under the intake are leaky without a smoke machine.