IAC purpose?
Former ******
Joined: Nov 2004
Posts: 4,901
Likes: 2
From: Salt Lake City, Utah
Actually, not not wrap the sensor in teflon tape. The sensor uses engine ground for an accurate reading. Teflon interfers with the electrical ground. The threads on the sensor are tapered, so they get tighter the farther they thread in. They will seal themselves. Or use copper based gasket maker on the threads.
Lead Driver
Joined: Sep 2003
Posts: 7,016
Likes: 208
From: SoCal
Tapered pipe threads will not always seal themselves. In fact, you will find that almost none of them will, which is why you need thread sealants on all tapered thread fittings. Thread sealants in general are for filling the gaps between the engaging threads through which fluid will leak. That also means that there will always be parts of the threads of the two parts touching, as long as you torque it sufficiently. I've used Teflon tape on plenty of sensors with no problems. If you have doubts, check the continuity between the base of the sensor that threads into the engine and the engine.
Post Fiend
Joined: Apr 2005
Posts: 5,720
Likes: 5
From: Washington state
tape and seal away
the ECT and other sensors do NOT use the engine block/chassis as signal return /gnd to the PCM
the ECT has 2 leads, PCM input and SIG RTN which is the PCM ground reference.
if the PCM system tried to use the block/chassis, there would be interfering ground loops and voltage differences along with RFI causing problems with correct PCM operation....
the SIG RTN is the PCM's separate ground reference system
internal sensor leads do sometimes short out to the chassis mounting device...can cause real troubleshooting headaches especially if SIG RTN shorts to block/chassis
the ECT and other sensors do NOT use the engine block/chassis as signal return /gnd to the PCM
the ECT has 2 leads, PCM input and SIG RTN which is the PCM ground reference.
if the PCM system tried to use the block/chassis, there would be interfering ground loops and voltage differences along with RFI causing problems with correct PCM operation....
the SIG RTN is the PCM's separate ground reference system
internal sensor leads do sometimes short out to the chassis mounting device...can cause real troubleshooting headaches especially if SIG RTN shorts to block/chassis
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Mountain Pass
Joined: Jun 2003
Posts: 208
Likes: 3
From: Norfolk VA
She now idles perfectly!!! I replaced the ECT and it didn't make any change. The connections were really dirty on the old one and once I cleaned them off it read 29K Ohms at 72 degrees. The new one read 30K ohms. So....I ended up replacing the IAC and the PCV valve at the same time. The only bad thing is the old IAC had the connector coming off at an angle and the new one came out the back. The wires are just barely long enough to reach.
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m000996
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Mar 23, 2007 07:37 PM
