Idle surge / O2 sensor.
10-27-2005, 11:27 AM
#16
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John Speake/all: On this topic, when cold I have to keep foot on pedal for 2-3 minutes or idle drifts down to die. When warm it holds at 800rpm. I've changed idle control valve, all vacuum hoses, wires, cleaned and balanced injectors. Maybe she is just showing her age. Did this before and after chips. Otherwise she runs like a banshee. It is an inconvenience I'd like to eliminate if I knew the answer.
10-27-2005, 11:51 AM
#17
"On this topic, when cold I have to keep foot on pedal for 2-3 minutes or idle drifts down to die."
You need to check the throttle switch & make sure it's closing. Use an ohmmeter.
Turn the A.C. on when warm, if the idle isn't constant, the idle circuit isn't working.
Check here ( www.systemsc.com/diagnostic.htm ) for troubleshooting info.
You need to check the throttle switch & make sure it's closing. Use an ohmmeter.
Turn the A.C. on when warm, if the idle isn't constant, the idle circuit isn't working.
Check here ( www.systemsc.com/diagnostic.htm ) for troubleshooting info.
10-27-2005, 12:44 PM
#18
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Loren: the '85 has a Throttle Valve Switch on the throttle body -- probably impossible to reach with intake in place. The link says: "0-5 volts" Is this the switch you refer to? So, cold, w/o A/c on, it would read near zero, ?
There is a "Termo Switch located in the pipe in front of the the intake "T" pipe. Please let it be this sensor as it is most accessible.
There is a "Termo Switch located in the pipe in front of the the intake "T" pipe. Please let it be this sensor as it is most accessible.
10-27-2005, 01:40 PM
#19
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NickT,
The idle control system is out of range when engine is cold. (what was your air temp this morning ?)
It would appear that the idle system is working. As Loren suggested to Steve, check that the engine will hold idfle speed when you switch the aircon on and off.
How old was the MAF you swapped out for ?
SteveG
Throttle closed switch can be checked with a simple resisance check from pin 3 of LH ECU to ground. Less than 5ohms when throttle closed, very high when throttle open. Check for the click from the switch as the throttle opens and closes.
Regards
The idle control system is out of range when engine is cold. (what was your air temp this morning ?)
It would appear that the idle system is working. As Loren suggested to Steve, check that the engine will hold idfle speed when you switch the aircon on and off.
How old was the MAF you swapped out for ?
SteveG
Throttle closed switch can be checked with a simple resisance check from pin 3 of LH ECU to ground. Less than 5ohms when throttle closed, very high when throttle open. Check for the click from the switch as the throttle opens and closes.
Regards
10-28-2005, 09:01 AM
#20
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Originally Posted by John Speake
NickT,
The idle control system is out of range when engine is cold. (what was your air temp this morning ?)
It would appear that the idle system is working. As Loren suggested to Steve, check that the engine will hold idfle speed when you switch the aircon on and off.
How old was the MAF you swapped out for ?
Regards
The idle control system is out of range when engine is cold. (what was your air temp this morning ?)
It would appear that the idle system is working. As Loren suggested to Steve, check that the engine will hold idfle speed when you switch the aircon on and off.
How old was the MAF you swapped out for ?
Regards
It was a very cool morning 50F. As I suspected when I left work it was back to normal, surge surge surge. Switching on the AC, lights and what ever else has little change. I mean that it appears the ISC is working fine and maintaining the surging
The MAF is third the age of mine, 50K on it I believe, it is no spring chicken either, but the engine acts the same way with either one in. Speaking of which, I must return it to Dave before he thinks I have run off with it.
10-28-2005, 10:49 AM
#22
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Originally Posted by John Speake
Did it hunt right from start up when you left work ?
If so, this tends to rule out the O2 sensor.
If so, this tends to rule out the O2 sensor.
10-28-2005, 11:36 AM
#24
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I drove a very interesting '86.5 this weekend, which wnet like a bat out of hell ....... when we dropped the cats, we found that the O2 sensor was completely disconnected. When we connected a new sensor the car felt less peppy.
10-28-2005, 12:25 PM
#25
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One thing I have not mention is that before this, during deacceleration, my ARM1 lights would all be out, now it continues to sweep. I also have more "burbbling" out of the exhaust during deacceleration. I thought the same thing Heinrich, was sure I would find an inlet leak..
10-28-2005, 01:08 PM
#26
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Originally Posted by NickT
One thing I have not mention is that before this, during deacceleration, my ARM1 lights would all be out, now it continues to sweep. I also have more "burbbling" out of the exhaust during deacceleration. I thought the same thing Heinrich, was sure I would find an inlet leak..
That's an indication that the TPS is not closing or that it is otherwise broken/disconnected or not being picked up by the LH. This can cause high and variable idle. I think the test at the LH plug has been provided already.
10-28-2005, 01:27 PM
#27
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Originally Posted by Bill Ball
That's an indication that the TPS is not closing or that it is otherwise broken/disconnected or not being picked up by the LH. This can cause high and variable idle. I think the test at the LH plug has been provided already.
I'll add that to my list for this weekend... thanks Bill!!
10-29-2005, 05:15 AM
#28
"That's an indication that the TPS is not closing" - Bill Ball -
It's not a TPS (throttle position sensor) but a TS (throttle switch) as they're functionally different.
Do as John & I suggest, measure the idle switch (TS) for about zero ohms at pins 2 to 5 @ the
LH ECM connector with the throttle at rest.
It's not a TPS (throttle position sensor) but a TS (throttle switch) as they're functionally different.
Do as John & I suggest, measure the idle switch (TS) for about zero ohms at pins 2 to 5 @ the
LH ECM connector with the throttle at rest.
10-29-2005, 06:10 AM
#29
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Originally Posted by Lorenfb
"That's an indication that the TPS is not closing" - Bill Ball -
It's not a TPS (throttle position sensor) but a TS (throttle switch) as they're functionally different.
Do as John & I suggest, measure the idle switch (TS) for about zero ohms at pins 2 to 5 @ the
LH ECM connector with the throttle at rest.
It's not a TPS (throttle position sensor) but a TS (throttle switch) as they're functionally different.
Do as John & I suggest, measure the idle switch (TS) for about zero ohms at pins 2 to 5 @ the
LH ECM connector with the throttle at rest.
