2 issues I need a bit of help with

[mowpow]

First issue is an idle issue. I've been crawling through threads but can't seem to get this one nailed down. Basically my car starts cold just fine and sits around 750-800 which is perfect. Once it's warmed up, it goes up to 1400 and stays there. No hunting, surging, etc, just 1400 constant. Today I checked everything I could with the vacuum hoses, idle screws, springs in the throttle body, all look fine. When it's at 1400, I pressed the idle microswitch and it does not change anything. The 1400 is also there if I shut the car off and turn it back on without pressing the gas. One thing about my car that's a bit unique is that I cut the O2 sensor off because my headers don't have provisions for one. Based on reading I think my vacuum stuff is OK because it's not surging or hunting. I am still a bit new to how these cars work but I was reading there is an open and closed loop of sorts. If so, the car seems to be doing the 1400 when it should be in closed loop. If this is correct, how I do I force open loop all the time because that's when it seems it runs the best?

Second issue is that my AC compressor is cycling weird. When I put it on Max, I hear the fans kick on and the compressor clicks. But then the compressor click off about 2 seconds later and so do the fans. This repeats over and over. I read cycling happens more often when Max is set and when the engine speed is higher so I figure I need to get the high idle settled down before tackling this. Definitely would like some input if there is something I can check now. Summer approaches here in TX so it would suck big time to not have the AC :).

Thanks for your help in advance, this board helped me through a coolant, brake, and fuel system swaps which I could never get done with out you guys.

Jake #3154

[NightFlyer]

First issue is an idle issue. I've been crawling through threads but can't seem to get this one nailed down. Basically my car starts cold just fine and sits around 750-800 which is perfect. Once it's warmed up, it goes up to 1400 and stays there. No hunting, surging, etc, just 1400 constant. Today I checked everything I could with the vacuum hoses, idle screws, springs in the throttle body, all look fine. When it's at 1400, I pressed the idle microswitch and it does not change anything. The 1400 is also there if I shut the car off and turn it back on without pressing the gas. One thing about my car that's a bit unique is that I cut the O2 sensor off because my headers don't have provisions for one. Based on reading I think my vacuum stuff is OK because it's not surging or hunting. I am still a bit new to how these cars work but I was reading there is an open and closed loop of sorts. If so, the car seems to be doing the 1400 when it should be in closed loop. If this is correct, how I do I force open loop all the time because that's when it seems it runs the best?

Second issue is that my AC compressor is cycling weird. When I put it on Max, I hear the fans kick on and the compressor clicks. But then the compressor click off about 2 seconds later and so do the fans. This repeats over and over. I read cycling happens more often when Max is set and when the engine speed is higher so I figure I need to get the high idle settled down before tackling this. Definitely would like some input if there is something I can check now. Summer approaches here in TX so it would suck big time to not have the AC :).

Thanks for your help in advance, this board helped me through a coolant, brake, and fuel system swaps which I could never get done with out you guys.

Jake #3154

Idle speed is controlled by the idle ecu manipulating the idle air motor (CIS). First, check for vacuum leaks - I like spraying around the running engine with directed bursts of carb cleaner and watching for any changes in the running of the engine (corresponding increases of rpm would suggest that you have a vacuum leak somewhere). Next, check the electrical connection on the idle air motor for any corrosion/bent/loose pins/etc, and make sure that the connector has a good seat. Next, check the grounds located at the back of the intake runners - make sure that they're clean, that the wire is actually attach to the ring loops, and that the connection is tight. Next, check to make sure that the full throttle micro switch isn't stuck closed (engaged). If everything checks out and the problem still persists, then I'd then pull the idle air motor and clean it out with carb cleaner:


The idle air motor can be cleaned out by removing it from the car completely and spraying it out with carb cleaner. Wear gloves and goggles! This stuff can burn the bejeezus out of your skin and eyes! Spray a bunch of carb cleaner in it and plug both of the ends. Now, shake it up as much as you can – up and down and roll it between your hands like you were trying to make a long snake out of Play-doh like in kindergarten. When you roll it, you should be able to hear it clicking back and forth. If you can’t hear anything moving in there, keep cleaning it or get a new motor. Make sure to shake out all of the excess carb cleaner and let the thing dry for a bit before you re-install it.

If the problem persists, then you need to electrically test the idle air ecu - the procedure is in the workshop manual.

Best of luck!

[David T]

First issue is an idle issue. I've been crawling through threads but can't seem to get this one nailed down. Basically my car starts cold just fine and sits around 750-800 which is perfect. Once it's warmed up, it goes up to 1400 and stays there. No hunting, surging, etc, just 1400 constant. Today I checked everything I could with the vacuum hoses, idle screws, springs in the throttle body, all look fine. When it's at 1400, I pressed the idle microswitch and it does not change anything. The 1400 is also there if I shut the car off and turn it back on without pressing the gas. One thing about my car that's a bit unique is that I cut the O2 sensor off because my headers don't have provisions for one. Based on reading I think my vacuum stuff is OK because it's not surging or hunting. I am still a bit new to how these cars work but I was reading there is an open and closed loop of sorts. If so, the car seems to be doing the 1400 when it should be in closed loop. If this is correct, how I do I force open loop all the time because that's when it seems it runs the best?

Second issue is that my AC compressor is cycling weird. When I put it on Max, I hear the fans kick on and the compressor clicks. But then the compressor click off about 2 seconds later and so do the fans. This repeats over and over. I read cycling happens more often when Max is set and when the engine speed is higher so I figure I need to get the high idle settled down before tackling this. Definitely would like some input if there is something I can check now. Summer approaches here in TX so it would suck big time to not have the AC :).

Thanks for your help in advance, this board helped me through a coolant, brake, and fuel system swaps which I could never get done with out you guys.

Jake #3154

Without an O2 sensor the motor can only run in "Open Loop". That is assuming the Lambda system is even functioning. Check for play in the quadrant link and make sure the throttle plates are fully closed at idle. Make sure the throttle cable is moving freely and allowing the springs to get the throttle plates closed. I would suggest you have a bung welded into your exhaust so you can get the O2 sensor going and have the Lambda operate in closed loop.
The cycling rate is very dependent on ambient temperature, amount of refrigerant, and the adjustment of the low pressure switch. 2 seconds on and off at idle is too much. I suspect you are a little low on refrigerant.

[mowpow]

Thanks for the tips, going to check these things. I read over the idle control and it sounds like it is independent of the lands system since it gets its rpm data from the distributor.

Going to take your advice David T and have a bung welded in. Otherwise I would have to constantly adjust the mixture screw to achieve stoich which I would have to use a wideband to read anyway thus requiring an O2 bung. Does that sound right?

[Jonathan]

Could your problem with the A/C cycling on and off be related to the 40 Amp cooling fan circuit breaker? If it was old and on it's way out, it might be cutting out intermittently.

Dave's mention of the Freon being low sounds more likely though and relatively easy to correct.

[djdogbone]

Here's a question; once you change over from R-13 to 134, what are the low side and high side numbers supposed to be?

[Bitsyncmaster]

Here's a question; once you change over from R-13 to 134, what are the low side and high side numbers supposed to be?

Low side is the same. Your low pressure switch sets that pressure. The high side is a little higher but is so dependent on the airflow through the condenser and the air temp. At idle speeds expect 200 to 300 PSI on the high side.