Throttle body... what else?

[Calan]

I've got my TB off and replacing the shaft seals. I'm trying to clean it up some also, but have heard that I shouldn't get carb cleaner down into the lower part where the ISC sits. Should I remove the lower section (like 5 screws I think), and clean everything out?

Is there any other maintenance I should do while it's on the bench?

I've already replaced the BISS o-ring and cleaned the passages out there as best I can.

Thanks

 

[Auto RS T]

You can remove the ISC, clean it, and clean out the passage it sits in. There is an o-ring that seals it to the TB. Whether you do or don't replace the o-ring use a thin coat of silicone on it before you re-install.

Where you don't want to get the carb cleaner is in the FIAV part of the lower half. There is a wax plenum in there that could be damaged by the carb cleaner.

You can remove the lower half and clean it, there is a shaped o-ring that seals the halves together, I personally replace this with a very light coat of rtv as to not plug up the passages. If you do reuse it, use a thin coat of silicone to lube the ring and help give it a better seal.

When removing the 5 screws it is important to put a lot of downward force into the screw while trying to break it loose, they strip very easily. My trick is to get a bit that fits perfectly into the screw head and use a drill, that way I can put as much force down as I want and let the drill do the turning. When I put the screws back in I put a thin coat of neverseize on them, for easy future removal.

 

[kenamond]

I've got my TB off and replacing the shaft seals. I'm trying to clean it up some also, but have heard that I shouldn't get carb cleaner down into the lower part where the ISC sits. Should I remove the lower section (like 5 screws I think), and clean everything out?

Is there any other maintenance I should do while it's on the bench?

I've already replaced the BISS o-ring and cleaned the passages out there as best I can.

Thanks

Do you have new TB gaskets? I RTV the gaskets to insure a good seal against boost leaks.

 

[Calan]

Got it all back together and seems to be working fine ... for now The only boost leak seems to be coming from my air compressor connection

As for the gaskets, they are only a month or so old, so I made sure they were still in good shape and used a very thin layer of Copper RTV on both sides.

I checked the resistance of the ISC coils and they are fine, but not sure if the motor movement (just a tick in either direction) is normal or not. Just cleaned it up and mounted her (insert joke here).... and it seems to be ok. Car idles MUCH better... for now.

As I was removing the UICP, I found both wires (green and black) broken off of the top temp sensor of the thermostat housing, right at the connector. Since there was no way to fix the connector, I soldered two wires into the sensor itself, and then connected them to the broken wires. What a PITA... now I'm wondering how many more wires are gonna break that I can't see, since another temp sensor wire broke last week. I'm guessing this sensor is used by the ECU in various ways, including idle control.

I followed the shaft replacement vfaq to the letter, including having to drill out a screw and cutting my thumb on the throttle spring during reassembly... I'm nothing if not precise.

But everything seems ok and it idles/runs much better. Now I'm just waiting on my wideband and a FMIC next week probably. Hopefully I can eliminate this DAMN KNOCK and get a decent tune.

It's getting there slowly but surely!

 

[kenamond]

As I was removing the UICP, I found both wires (green and black) broken off of the top temp sensor of the thermostat housing, right at the connector. Since there was no way to fix the connector, I soldered two wires into the sensor itself, and then connected them to the broken wires. What a PITA... now I'm wondering how many more wires are gonna break that I can't see, since another temp sensor wire broke last week. I'm guessing this sensor is used by the ECU in various ways, including idle control.

I'm not sure what kind of temperature sensor is used in the thermostat, but thermocouples cannot be soldered and still function properly. They rely on the fact that the resistance in the thermocouple is sensitive to temperature, but if you solder, the resistance is changed significantly (relative to the changes the sensor is relying on from temperature change). Maybe the sensor is a different kind, but you might wan to verify that the coolant temps make sense on a logger (check them on a fully cold motor and see if they look like ambient temperature). On a 2g, the radiator fan is turned on by the ECU (which would rely on the coolant temp sensor) while the thermostat is a mechanical device (opens at 180*F on a 2g independent of the sensor). If the 1g is the same, the thermostat will open/close at the right temps, but the fan may not kick on/off at the correct temps. This could lead to overheating if you're not moving or in slow traffic.

 

[Calan]

I should probably clarify... I didn't weld to the sensor itself; I used a low wattage iron and welded a wire onto each of the terminals in the white plastic housing that was attached to the sensor. I then connected these wire "tails" to the two wires that had broken off of the other housing.

The sensor resistance was around 1 ohm, and dropped as I applied some heat to it (before soldering). This seemed low, but I figured soldering the wires couldn't make it any worse than not connected at all

I'll probably pick up a new one as soon as a can find out exactly which one it is and get it's part number.... and if I can find the mating end somewhere to splice into my existing wires.

FWIW, the two wires enter the harness right below (or behind) the o2 sensor plug.

My blue wire ties to the original green one, and black goes to black. (you can also see the other wire that broke last week in the background).

Think I should fill that white connector with epoxy?

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