taking off intake / vacuum leak?
Thread Starter
Intermediate
Joined: Dec 2007
Posts: 36
Likes: 0
From: Shelby Twp. Michigan
taking off intake / vacuum leak?
I have been having some problems with my 1998. Car idles high, wants to die taking off, and sometimes cuts out at speed. I could not find what it was, but I did find that it maybe a vacuum leak? Is this likely? I am going to pull the intake tommorow and replace the oil pressure sensor and the vacuum hoses. Any tips or tricks? Do I need a new gasket? Is it likely that thats even the problem?
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Jake
If you spray carb cleaner over the intake and intake attachemts, you may be able to tell if you have a leak and where. The carb cleaner will cause the idle quality of the engine to change if you spray the carb cleaner over a leak area. Give that a try first.
BC
If you spray carb cleaner over the intake and intake attachemts, you may be able to tell if you have a leak and where. The carb cleaner will cause the idle quality of the engine to change if you spray the carb cleaner over a leak area. Give that a try first.
BC
Thread Starter
Intermediate
Joined: Dec 2007
Posts: 36
Likes: 0
From: Shelby Twp. Michigan
I tried that, basically sprayed every where I could see, or get to. No increase in idle. It seems if I give it a little bit of gas it won't stumble, but if I give it a little more gas it will. Any other ideas? Spark plugs? I really don't know
Drifting
Joined: May 2005
Posts: 1,590
Likes: 1
From: Littleton Colorado
Most likey not a vacum leak then. The gaskets on the manifold are realy hard to screw up, not that it can't be done.
In no particular order I would:
- clean the MAF (don't touch it, use a MAF and/or electrical contact cleaner).
- check the IAT wiring (known to have broken wires and yours is in the middle of the air bridge)
- and make sure the air bridge does not have any leaks.
- maybe even check the wires to the throttle.
After that check the codes, if you have some check look them up on the web, you would be surprised how much info you can get by searching on the code number
A good wire will look smooth, one with an internal break will have a rough spot at the break were the wire strands are bunching up inside.
Good luck with it.
In no particular order I would:
- clean the MAF (don't touch it, use a MAF and/or electrical contact cleaner).
- check the IAT wiring (known to have broken wires and yours is in the middle of the air bridge)
- and make sure the air bridge does not have any leaks.
- maybe even check the wires to the throttle.
After that check the codes, if you have some check look them up on the web, you would be surprised how much info you can get by searching on the code number
A good wire will look smooth, one with an internal break will have a rough spot at the break were the wire strands are bunching up inside.
Good luck with it.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Most likely not a vacuum leak then. The gaskets on the manifold are realy hard to screw up, not that it can't be done.
In no particular order I would:
- clean the MAF (don't touch it, use a MAF and/or electrical contact cleaner).
- check the IAT wiring (known to have broken wires and yours is in the middle of the air bridge)
- and make sure the air bridge does not have any leaks.
- maybe even check the wires to the throttle.
After that check the codes, if you have some check look them up on the web, you would be surprised how much info you can get by searching on the code number
A good wire will look smooth, one with an internal break will have a rough spot at the break were the wire strands are bunching up inside.
Good luck with it.
In no particular order I would:
- clean the MAF (don't touch it, use a MAF and/or electrical contact cleaner).
- check the IAT wiring (known to have broken wires and yours is in the middle of the air bridge)
- and make sure the air bridge does not have any leaks.
- maybe even check the wires to the throttle.
After that check the codes, if you have some check look them up on the web, you would be surprised how much info you can get by searching on the code number
A good wire will look smooth, one with an internal break will have a rough spot at the break were the wire strands are bunching up inside.
Good luck with it.
Good recommendations. 
There are a number of things that change when you rev up your engine that can cause a stumble:
1. Throttle angle measured by the throttle position sensor
2. Air Flow through the engine (measured by the Mass Air Flow Sensor)
3. Manifold Absolute Pressure "VACUUM" (measured by the MAP Sensor)
If the engine doesn't stumble when it cold but does when its warm, the engine is in closed loop when its warm and the Oxygen Sensors could be at fault.
When the engine stumbles do you ever see the check engine light or does it ever flash??
Have you ever tried to read the codes during the event? Give that a try and see if there are any codes at that moment.
Most things that don't work properly will set a DTC. See if you have any and post them.
BC
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Also take a look at the PCV valve connection to the intake. That rubber tube can develop holes in it on the bottom where its out of sight. It happened to mine.
