Idle problems
Senior Member
Joined: May 2007
Posts: 1,567
From: eastern NC
RE: Idle problems
ORIGINAL: lbelew
Hello, wires are good. Installed new burnoff relay with no luck. No vacuum leaks. Idle is still erratic until I pull off the connector to the ESC. Plan on installing a newa new knock sensor tomorrow since it failed the ping test, I think I'll have a spare ESC standing by as a trouble shooting aid. What else do you guys thinkI should check.Thanks.
Hello, wires are good. Installed new burnoff relay with no luck. No vacuum leaks. Idle is still erratic until I pull off the connector to the ESC. Plan on installing a newa new knock sensor tomorrow since it failed the ping test, I think I'll have a spare ESC standing by as a trouble shooting aid. What else do you guys thinkI should check.Thanks.
If your induction ain't suckin' air somewhere, THEN the spark timing control has a loose wire - NOT a short!
Check to see what the voltage should be from the computer, to the actual device that changes the spark time. Say for instance, at idle, it's 5 volts when warmed up. Get your multi-meter on that circuit and verify that you got a constant5V signal. Cross yer fingers (and yer little piggies), that you don't have steady signal.
Since you have surging, at idle, AND at speed, you might indeed not be leakin' intake, but the spark time is gettin' fluctuated erroneously. THAT would manifest at speed, but suckin' air would NOT manifest at speed.
I'm guessin that now the signal to the timing controller is shorting out 1) either between the computer and the timer controller, or 2) between one or more sensors that the computer gets it's information from, when it makes the timing decision to send to the timer controller.
Say for instance the coolant temperature, exhaust temp, and maybe some other 'reads' influence the computer's timing decision. If one of 'em has loose wire (NOT A TOTAL SHORT-OUT), and your computer is getting a yo-yo reading from one of 'em, you got your surge, due to timing variation.
Check the pc-to-timer voltage, then check by the wiring diagram for the voltageFROM the sensors,TO the pc,for timing control.[sm=smiley29.gif][sm=sigh.gif][sm=smiley5.gif][sm=headbang.gif][sm=outcold.gif][sm=sick.gif][sm=smiley11.gif]
Senior Member
Joined: Aug 2007
Posts: 383
RE: Idle problems
I take it he'stalking about the Electronic Spark Control Module, if so, it's located under the hood on the passengers side, mounted on the left hand side of the AC blower housing. Also,there's a Distributor Ignition Module located inside of the distributor, but I doubt thats the one in question.
Senior Member
Joined: May 2007
Posts: 1,567
From: eastern NC
RE: Idle problems
ORIGINAL: lbelew
Hello, maybe a dumb question but what is and where is the timing controller. Thanks.
Hello, maybe a dumb question but what is and where is the timing controller. Thanks.
There has to be some device that the computer controls, which in turn fires the plugs. I think rshive named it there - the ESC module, or the other module that he referred to, the Distributor Ignition module. ONE of those two, which is controlled by the computer,has got to be the issue here...
How 'bout it there, rshive - which one actually varies the spark time??? That has to be the problem...
Senior Member
Joined: Aug 2007
Posts: 383
RE: Idle problems
From what I understand, they both play an important roll in the spark timing.
Did a little searching and found this info on the subject...
Electronic Spark Control (ESC) senses knocking and adjusts timing to fit fuel octane.
Solid valvetrain components, open exhaust systems and many other high-performance engine components inherently create noise that a knock sensor can perceive to be spark knock, even if the engine is running properly. The end result is that power output can be unnecessarily reduced.
To control spark knock, and to use maximum spark advance to improve driveability, an Electronic Spark Control (ESC) system is used. This system consists of a knock sensor, Electronic Spark Control module,and the ECM. The ECM monitors the ESC signal to determine when engine knock occurs. The (ECM) Electronic Control Module receives the signal from (ESC) Electronic Spark Control module (mounted beside the AC blower housing), and retards the (EST) Electronic Spark Timing to reduce detonation.
HEI Ignition Control
(Module inside the distributor)
The ECM uses the (EST) Electronic Spark Timing circuit to control spark advance and ignition dwell, when the ignition system is operating in the EST mode.
There are 2 modes of ignition system operation. These modes are as follows:
Module mode - the ignition system operates independently of the ECM/PCM, with module mode spark advance is always at 10 degrees BTDC. The ECM has no control of the ignition system when in this mode. I take it, that is open loop mode, correct me if I'm wrong
EST mode - the ignition spark timing and ignition dwell time ( the length of time the ignition coil is saturated)is fully controlled by the ECM. EST spark advance and ignition dwell is calculated by the ECM. Closed loop mode?
Did a little searching and found this info on the subject...
Electronic Spark Control (ESC) senses knocking and adjusts timing to fit fuel octane.
Solid valvetrain components, open exhaust systems and many other high-performance engine components inherently create noise that a knock sensor can perceive to be spark knock, even if the engine is running properly. The end result is that power output can be unnecessarily reduced.
To control spark knock, and to use maximum spark advance to improve driveability, an Electronic Spark Control (ESC) system is used. This system consists of a knock sensor, Electronic Spark Control module,and the ECM. The ECM monitors the ESC signal to determine when engine knock occurs. The (ECM) Electronic Control Module receives the signal from (ESC) Electronic Spark Control module (mounted beside the AC blower housing), and retards the (EST) Electronic Spark Timing to reduce detonation.
HEI Ignition Control
(Module inside the distributor)
The ECM uses the (EST) Electronic Spark Timing circuit to control spark advance and ignition dwell, when the ignition system is operating in the EST mode.
There are 2 modes of ignition system operation. These modes are as follows:
Module mode - the ignition system operates independently of the ECM/PCM, with module mode spark advance is always at 10 degrees BTDC. The ECM has no control of the ignition system when in this mode. I take it, that is open loop mode, correct me if I'm wrong
EST mode - the ignition spark timing and ignition dwell time ( the length of time the ignition coil is saturated)is fully controlled by the ECM. EST spark advance and ignition dwell is calculated by the ECM. Closed loop mode?
Senior Member
Joined: May 2007
Posts: 1,567
From: eastern NC
RE: Idle problems
ORIGINAL: rshiver
From what I understand, they both play an important roll in the spark timing.
Did a little searching and found this info on the subject...
Electronic Spark Control (ESC) senses knocking and adjusts timing to fit fuel octane.
Solid valvetrain components, open exhaust systems and many other high-performance engine components inherently create noise that a knock sensor can perceive to be spark knock, even if the engine is running properly. The end result is that power output can be unnecessarily reduced.
To control spark knock, and to use maximum spark advance to improve driveability, an Electronic Spark Control (ESC) system is used. This system consists of a knock sensor, Electronic Spark Control module,and the ECM. The ECM monitors the ESC signal to determine when engine knock occurs. The (ECM) Electronic Control Module receives the signal from (ESC) Electronic Spark Control module (mounted beside the AC blower housing), and retards the (EST) Electronic Spark Timing to reduce detonation.
HEI Ignition Control
(Module inside the distributor)
The ECM uses the (EST) Electronic Spark Timing circuit to control spark advance and ignition dwell, when the ignition system is operating in the EST mode.
There are 2 modes of ignition system operation. These modes are as follows:
Module mode - the ignition system operates independently of the ECM/PCM, with module mode spark advance is always at 10 degrees BTDC. The ECM has no control of the ignition system when in this mode. I take it, that is open loop mode, correct me if I'm wrong
EST mode - the ignition spark timing and ignition dwell time ( the length of time the ignition coil is saturated)is fully controlled by the ECM. EST spark advance and ignition dwell is calculated by the ECM. Closed loop mode?
From what I understand, they both play an important roll in the spark timing.
Did a little searching and found this info on the subject...
Electronic Spark Control (ESC) senses knocking and adjusts timing to fit fuel octane.
Solid valvetrain components, open exhaust systems and many other high-performance engine components inherently create noise that a knock sensor can perceive to be spark knock, even if the engine is running properly. The end result is that power output can be unnecessarily reduced.
To control spark knock, and to use maximum spark advance to improve driveability, an Electronic Spark Control (ESC) system is used. This system consists of a knock sensor, Electronic Spark Control module,and the ECM. The ECM monitors the ESC signal to determine when engine knock occurs. The (ECM) Electronic Control Module receives the signal from (ESC) Electronic Spark Control module (mounted beside the AC blower housing), and retards the (EST) Electronic Spark Timing to reduce detonation.
HEI Ignition Control
(Module inside the distributor)
The ECM uses the (EST) Electronic Spark Timing circuit to control spark advance and ignition dwell, when the ignition system is operating in the EST mode.
There are 2 modes of ignition system operation. These modes are as follows:
Module mode - the ignition system operates independently of the ECM/PCM, with module mode spark advance is always at 10 degrees BTDC. The ECM has no control of the ignition system when in this mode. I take it, that is open loop mode, correct me if I'm wrong
EST mode - the ignition spark timing and ignition dwell time ( the length of time the ignition coil is saturated)is fully controlled by the ECM. EST spark advance and ignition dwell is calculated by the ECM. Closed loop mode?
So now where do we go with his 43 code, I think it was... IF, that code is still logged??? I think it was "Timing was being retarded for too long,OR, signal to retard timing was being sent for too long"...
I doubt that it is being retarded too long for an actual knock problem. I'm inclined to think there's a weak (not missing) electrical connection either from the computer to the timing controller (whichever device that is), OR, the computer is gettin' a just-as-bad signal FROM one of the sensors that the computer uses to 'decide' advance/retard.
Attached - a not totally technical schematic. I'm guessin' he's got an erratic signal in one of the variable-to-pc leads, or in the ECM-to-timer lead.
[IMG]local://upfiles/5243/FB7B5D78773A44E8952297F90F96CB55.jpg[/IMG]
Senior Member
Joined: Aug 2007
Posts: 383
RE: Idle problems
OK, I went back and looked, he had code 43 & 44
43 - Electronic spark control unit
The ESC retard signal has been on for too long or the system has failed a functional check
44 - Lean exhaust
Check the ECM wiring connections, particularly terminals 15 and B. Check for vacuum leakage at the TBI base gasket, vacuum hoses or the intake manifold gasket. Replace the oxygen sensor
The timing may be retarding to the point that the engine runs poorly. Like cwb said, you could have a bad connection causing an erratic signal to the ECM.
An EGR malfunction can also cause the timing to retard also. I'll explain it the way it was told to me. The EGR helps keep the cylinders cool by recirculating exhaust gas back onto the cylinders, exhaust gasses won't burn, in effect, cooling the cylinders. If the EGR valve isn't working, the cylinders heat up to the point of detonation (engine ping or knock), the knock sensor detects the knock and retards the timing. So the EGR also plays an important roll in maintaining the proper timing.
Also, fault codes can be misleading sometimes. I worked on a GM pickup once where the guy rinsed the engine off with water and the engine wouldn't start, no fuel from the throttle body injectors, the code that we were getting was a faulty HEI spark module, we replaced it and still had the same no start problem. It ended up that the throttle position sensor (TPS)had a small crack and water made it's way inside causing the ECM to think the engine was flooded, thus no fuel from the injectors. We replaced it and it ran like a top. Thing is, we never got a code about the TPS. Fault codes are more or less a reference point, somewhere to start.
43 - Electronic spark control unit
The ESC retard signal has been on for too long or the system has failed a functional check
44 - Lean exhaust
Check the ECM wiring connections, particularly terminals 15 and B. Check for vacuum leakage at the TBI base gasket, vacuum hoses or the intake manifold gasket. Replace the oxygen sensor
The timing may be retarding to the point that the engine runs poorly. Like cwb said, you could have a bad connection causing an erratic signal to the ECM.
An EGR malfunction can also cause the timing to retard also. I'll explain it the way it was told to me. The EGR helps keep the cylinders cool by recirculating exhaust gas back onto the cylinders, exhaust gasses won't burn, in effect, cooling the cylinders. If the EGR valve isn't working, the cylinders heat up to the point of detonation (engine ping or knock), the knock sensor detects the knock and retards the timing. So the EGR also plays an important roll in maintaining the proper timing.
Also, fault codes can be misleading sometimes. I worked on a GM pickup once where the guy rinsed the engine off with water and the engine wouldn't start, no fuel from the throttle body injectors, the code that we were getting was a faulty HEI spark module, we replaced it and still had the same no start problem. It ended up that the throttle position sensor (TPS)had a small crack and water made it's way inside causing the ECM to think the engine was flooded, thus no fuel from the injectors. We replaced it and it ran like a top. Thing is, we never got a code about the TPS. Fault codes are more or less a reference point, somewhere to start.
Senior Member
Joined: May 2007
Posts: 1,567
From: eastern NC
RE: Idle problems
ORIGINAL: rshiver
43 -
The ESC retard signal has been on for too long or the system has failed a functional check
43 -
The ESC retard signal has been on for too long or the system has failed a functional check
Now... where's Rip Van ibeleWinkle here? Hey! Wake up 'ere.
Thread Starter
Joined: Jul 2007
Posts: 54
RE: Idle problems
Thanks again guys. Wondering if a slight rattle in my catalytic converter can cause my idle problem. Also hooked up a pressure gauge to my schraeder valve and am reading 28psi, a little low. When I plug the return line I get 70psi. If I run the car with the return line returning the fuel to a gas can I get 28psi. What do you think. No codes present but still erratic idle a low power off the line and crappy cruise performance. No surges at power but not alot of power.