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Posted by: ThinAir Sep 27 2016, 10:00 PM

1973 2.0 liter with stock FI

It's been running and idling fine, but I've had a few hesitation issues so I decided that I would check the calibration of the TPS. First, I cleaned the TB, including making sure that the air passages were clear. Although I accidentally moved the idle screw a bit, it wasn't enough to worry about and I just expected my idle to need a little tweaking if it wasn't right.

I checked the TPS position with my ohm meter and also using a continuity tester (a trick I picked up from https://www.youtube.com/watch?v=UfmWGEFyDEU). I've done this procedure before as well as changed the circuit board and I didn't experience anything out of the ordinary.

After reconnecting all the vacuum lines and the throttle cable, the engine started right up, but idled very high. I tried closing the idle air screw, but the best I've been able to do is to get it down to 2000 rpm. The engine is warmed up enough that the oil temp needle is up from the bottom so I don't think it's a situation of a cold engine condition.

Any ideas what could be causing this? The TPS did end up in a different position by about 1 mark, but I've checked it several times and it appears to be properly adjusted.

When I had the TB off the engine, I looked through the various passages. I noticed that I could see a ball at the end of the idle air adjuster screw and it looked like there was space for it to move. Should I be able to completely close off that passage by turning in this screw or does it have a "stop"?

Posted by: pbanders Sep 27 2016, 10:14 PM

Most likely in doing the work, somehow, you caused a leak around the throttle plate. Could be any number of places. Just work methodically and check each hose into the plenum and see which one it is. Check the PCV, too, and the operation of the AAR to make sure it's closing after warm-up.

Posted by: krazykonrad Sep 28 2016, 09:16 AM

You've got a vacuum leak somewhere.

Konrad

Posted by: Dave_Darling Sep 28 2016, 01:33 PM

It is either an air leak, or the timing has advanced. Those are pretty much the only ways that the idle gets higher.

--DD

Posted by: McMark Sep 28 2016, 01:39 PM

2000+rpm? Sounds like you bumped the air line that connects to the oil filler neck (or the AAR). Look for 12mm ID hose (1/2") that's unplugged.

Posted by: Toast Sep 28 2016, 04:23 PM

A trick that someone taught me is while the car is running spray some carb cleaner on your lines to search for a fluctuation in your idel. If you get that on a line that was sprayed then that is where your leak is. Also check your gas cap gasket. Also if you move your idle screw even the tiniest it can affect the idle performance.

Posted by: Amphicar770 Sep 29 2016, 05:38 AM

I had same issue. Discovered I made same mistake as another member in that I placed one of the washers between the throttle body and the plenum box. You can use an unlit propane torch. When you hit the area with air leak you will see a slight but definite drop in idle. Make sure TB gasket is good

Posted by: ThinAir Sep 30 2016, 12:07 AM

Ding! Ding! Ding! We have a winner, folks! Ampicar770 gets the grand prize.

One of my attempts to remedy this was to use some form-a-gasket. When I removed the TB tonight I could see that it had not been dried when I started the car again and some of it had been sucked into the TB. I figured that meant that I should have not attempted to replace the TB without a new gasket.

I just went out and checked the engine, and sure enough - there's the washer at the base of the bolt. I had loosened one bolt, but left it place so that I could simply slide the TB into position. It's pretty obvious that I forgot about the washer and ended up with the TB on top of it.

I won't know for certain until I reassemble on Saturday, but I'm sure this is the problem.

Posted by: BeatNavy Sep 30 2016, 04:36 AM

When I did the same thing (left the washer under the TB) it screamed like a banshee from all the air it was sucking directly into the plenum through that narrow opening. I think when Amphicar770 had that issue he was hearing a god-awful noise as well.

Oh well, glad it's fixed.