Stalls when EST bypass unplugged...
Thread Starter
Melting Slicks
Joined: May 2001
Posts: 3,270
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From: Winchester VA
Cruise-In V Veteran
Stalls when EST bypass unplugged...
I installed a MSD 6AL today along with a new distributor gear. When I unplug the EST bypass to set base timing it stalls.
I obviously had the dist out and reinstalled as close to removal postion as possible. I marked rotor position on the firewall, sort of==> This was difficult, the old gear's teeth (bronze gear, long story...) were almost worn off and there was a ton of play.
As it is, the car has some serious hesitation on acceleration.
What do you guys think, am I really off on the distributor install?
Is there somrthing about the MSD that I can't disconnect the EST? If so, how do I set base timing?
I obviously had the dist out and reinstalled as close to removal postion as possible. I marked rotor position on the firewall, sort of==> This was difficult, the old gear's teeth (bronze gear, long story...) were almost worn off and there was a ton of play.
As it is, the car has some serious hesitation on acceleration.
What do you guys think, am I really off on the distributor install?
Is there somrthing about the MSD that I can't disconnect the EST? If so, how do I set base timing?
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Originally Posted by RainDelay
I installed a MSD 6AL today along with a new distributor gear. When I unplug the EST bypass to set base timing it stalls.
I obviously had the dist out and reinstalled as close to removal postion as possible. I marked rotor position on the firewall, sort of==> This was difficult, the old gear's teeth (bronze gear, long story...) were almost worn off and there was a ton of play.
As it is, the car has some serious hesitation on acceleration.
What do you guys think, am I really off on the distributor install?
Is there somrthing about the MSD that I can't disconnect the EST? If so, how do I set base timing?
I obviously had the dist out and reinstalled as close to removal postion as possible. I marked rotor position on the firewall, sort of==> This was difficult, the old gear's teeth (bronze gear, long story...) were almost worn off and there was a ton of play.
As it is, the car has some serious hesitation on acceleration.
What do you guys think, am I really off on the distributor install?
Is there somrthing about the MSD that I can't disconnect the EST? If so, how do I set base timing?
Difficulty in getting the engine to continue to run is normal though. You will have to play with the throttle manually until it will idle on its own.
One of the ways I do it is to first start the engine with the EST CONNECTED. Let it run until it's fully warmed up and in closed loop. Then shut the engine down and disconnect the EST.
This seems to allow the engine to continue to run on its own easier and quicker than if the engine was cold and the EST disconnected.
If that fails, another little trick I use is to open the minimum air flow setting using the torx head screw on the throttle body. I open it until the engine idles at 1000 to 1200 rpms of so.
Then after letting it run at that engine speed for a minute to two, I begin to gradually reduce the minimum air flow setting by using the same screw.
When I get the RPM to where I want it, the engine then idles on it's own, allowing me to set the base timing.
I shoot for a minimum airflow RPM of 700, which is higher than a stock engine calls for because of the cam, etc., I'm running. My PROM is burned for 850, so 700 is just below the threshold of the Desired Idle RPM burned in the PROM.
Hope this helps.
Jake
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From: The Top of Utah
I, also, have no clue as to how the MSD affects things, but I would guess that the timing is retarded, excessively. It seems that when I set my timing, properly, the timing runs at about 22* BTDC with the EST connected. If I were working on your car, the first thing I would do is check the timing with the EST connected. If it isn't in the 20* to 24* BTDC range I would adjust the timing and see if that allows it to run with the EST disconnected so you can time it properly.
RACE ON!!!
RACE ON!!!
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Originally Posted by CFI-EFI
I, also, have no clue as to how the MSD affects things, but I would guess that the timing is retarded, excessively. It seems that when I set my timing, properly, the timing runs at about 22* BTDC with the EST connected. If I were working on your car, the first thing I would do is check the timing with the EST connected. If it isn't in the 20* to 24* BTDC range I would adjust the timing and see if that allows it to run with the EST disconnected so you can time it properly.RACE ON!!!
Jake
Thread Starter
Melting Slicks
Joined: May 2001
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From: Winchester VA
Cruise-In V Veteran
Originally Posted by CFI-EFI
I, also, have no clue as to how the MSD affects things, but I would guess that the timing is retarded, excessively. It seems that when I set my timing, properly, the timing runs at about 22* BTDC with the EST connected. If I were working on your car, the first thing I would do is check the timing with the EST connected. If it isn't in the 20* to 24* BTDC range I would adjust the timing and see if that allows it to run with the EST disconnected so you can time it properly.
RACE ON!!!
RACE ON!!!
In fact, I went up to 30+ and it still stalled when I disconnected the EST. This, combined with just knowing how the dist has been positioned previously lets me know my timing is in the ballpark. I double checked the install and it's right on, rotor to #1 post at TDC.
I will call MSD tomorrow for more info on the interaction between the box and the dist/timing control.
I also guess I should give it a few revs with the timing light on it to make sure I'm getting advance.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Originally Posted by RainDelay
Good, that's what I needed. That is the range it's in.
In fact, I went up to 30+ and it still stalled when I disconnected the EST. This, combined with just knowing how the dist has been positioned previously lets me know my timing is in the ballpark. I double checked the install and it's right on, rotor to #1 post at TDC.
I will call MSD tomorrow for more info on the interaction between the box and the dist/timing control.
I also guess I should give it a few revs with the timing light on it to make sure I'm getting advance.
In fact, I went up to 30+ and it still stalled when I disconnected the EST. This, combined with just knowing how the dist has been positioned previously lets me know my timing is in the ballpark. I double checked the install and it's right on, rotor to #1 post at TDC.
I will call MSD tomorrow for more info on the interaction between the box and the dist/timing control.
I also guess I should give it a few revs with the timing light on it to make sure I'm getting advance.
So you're saying that the timing is in the range that CFI-EFI posted about at idle, right? 20-22 degrees BTDC.
You're also saying that you can rev the engine and the timing advances and falls depending on the RPMs of the engine, right?
You need to use the timing light or a data logger to see that this is occuring.
If that's the case, then I'd go back to square one.
Anytime a problem occurs, I first go back and look at the LAST change I made; that's usually the cause of the problem. Same thing with the home computer (PC). I'd disconnect the MSD, set everything back to the way it was before.
If the engine THEN idles correctly with the EST connected and still idles with it disconnected, you'll know that it's the MSD or MSD installation that's causing the problem.
Keep us posted.
Jake
Thread Starter
Melting Slicks
Joined: May 2001
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From: Winchester VA
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Originally Posted by JAKE
So you're saying that the timing is in the range that CFI-EFI posted about at idle, right? 20-22 degrees BTDC.
You're also saying that you can rev the engine and the timing advances and falls depending on the RPMs of the engine, right?
You need to use the timing light or a data logger to see that this is occuring.
If that's the case, then I'd go back to square one.
Anytime a problem occurs, I first go back and look at the LAST change I made; that's usually the cause of the problem. Same thing with the home computer (PC). I'd disconnect the MSD, set everything back to the way it was before.
If the engine THEN idles correctly with the EST connected and still idles with it disconnected, you'll know that it's the MSD or MSD installation that's causing the problem.
Keep us posted.
Jake
You're also saying that you can rev the engine and the timing advances and falls depending on the RPMs of the engine, right?
You need to use the timing light or a data logger to see that this is occuring.
If that's the case, then I'd go back to square one.
Anytime a problem occurs, I first go back and look at the LAST change I made; that's usually the cause of the problem. Same thing with the home computer (PC). I'd disconnect the MSD, set everything back to the way it was before.
If the engine THEN idles correctly with the EST connected and still idles with it disconnected, you'll know that it's the MSD or MSD installation that's causing the problem.
Keep us posted.
Jake
I called MSD, there is no interface between timing control and it's operation. I knew it didn't control timing but....
So like you said Jake, I need to disconnect the box and see what happens. I'm glad I took the time to build the harness, a couple of plugs and it's out of the loop
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Let us know what, if any, difference it makes.
Other than the possiblility (probability) of a vacuum leak, there are a few sensors that may cause what you're experiencing:
MAF
IAC
TPS
02
ECM
Coolant Temp
Are you able to check the timing with the EST disconnected, even at higher than idle RPMs?
I just went back and checked one of my saved Diacom traces and it shows that at 750 RPMS, in closed loop and engine idling, my timing is 28/29 degrees in reference to TDC. At 60 MPH, closed loop, timing is over 40 degrees.
Jake
Other than the possiblility (probability) of a vacuum leak, there are a few sensors that may cause what you're experiencing:
MAF
IAC
TPS
02
ECM
Coolant Temp
Are you able to check the timing with the EST disconnected, even at higher than idle RPMs?
I just went back and checked one of my saved Diacom traces and it shows that at 750 RPMS, in closed loop and engine idling, my timing is 28/29 degrees in reference to TDC. At 60 MPH, closed loop, timing is over 40 degrees.
Jake
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Brett Foote
Safety Car
Joined: Feb 1999
Posts: 3,504
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From: Mexico Beach FL
Like the others, I've no idea what the MSD is.
But, most GM ignition systems with a "bypass" have some other means to trigger the coil, or coils, when the EST is disconnected.
As an example, the Northstar DIS module has two crankshaft reference pulses. These reference pulses are used to determine which coil is to be fired by the EST signal when not in bypass mode. However, when the system is bypassed (like, limp-home mode), the two crankshaft reference pulses can also be used for a fixed 10 degrees advance -- no EST needed.
My point is, without EST, something else has to determine the ignition trigger. What does MSD have to do this?
Tom Piper
But, most GM ignition systems with a "bypass" have some other means to trigger the coil, or coils, when the EST is disconnected.
As an example, the Northstar DIS module has two crankshaft reference pulses. These reference pulses are used to determine which coil is to be fired by the EST signal when not in bypass mode. However, when the system is bypassed (like, limp-home mode), the two crankshaft reference pulses can also be used for a fixed 10 degrees advance -- no EST needed.
My point is, without EST, something else has to determine the ignition trigger. What does MSD have to do this?
Tom Piper
Thread Starter
Melting Slicks
Joined: May 2001
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From: Winchester VA
Cruise-In V Veteran
Originally Posted by Tom Piper
My point is, without EST, something else has to determine the ignition trigger. What does MSD have to do this?
Tom Piper
The MSD only controls the coil when its told to. It is tied in after the pickup coil, the HEI module, ESC module and ECM. When the EST is disconnected, it still gets the signal exactly as the coil would see it.
I hope that makes sense.
I will take the MSD out of the circuit tomorrow morning and see what happens...
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Originally Posted by RainDelay
I will take the MSD out of the circuit tomorrow morning and see what happens...
Keep us posted.
Jake
Thread Starter
Melting Slicks
Joined: May 2001
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From: Winchester VA
Cruise-In V Veteran
Originally Posted by JAKE
GOOD MOVE! If the engine was running fine BEFORE the MSD installation, but now doesn't, guess where I'd look.
Keep us posted.
Jake
Keep us posted.
Jake
Engine warm, at idle, w/MSD, Timing at 25* with EST connected......stalls when EST disconnected, sputters a few times then dies.
At 1500 RPM w/MSD..... rpm drop but does not stall.
w/o MSD....normal function.
w/MSD connected, engine at 2000RPM timing shows ~32*....this tells me that I am getting advance.
My conclusion to this point is that the MSD is not defective but what it does to the spark (multi spark discharge) is just enough to exaggerate the effect of the EST bypass. My next test will find the threshold RPM at which disconnecting the EST w/ MSD installed does not cause stalling.
I also have a thread going on their tech support forum.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
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From: Kempner Texas
First, never connect or disconnect the EST with the engine running. A voltage spike can kill the EST circuit in the ECM.
Second, if you cannot get the engine to idle at 550rpms or lower with MSD connected but the EST disconnected you won't be able to set the initial timing with the timing light.
So even though you may see over 20 degrees with the engine running with the EST connected, you won't know what the initial timing setting is.
If you insist on keeping the MSD, all I can suggest is to disconnect or by-pass it, disconnect the EST wire, start the engine and set the initial/base timing.
Then shut down the engine, disconnect the battery for 30 seconds or so to clear the error code, then reconnect the battery, MSD and EST and you're done.
There's obvioulsy something wrong here, but the above's the only work-around I can think of.
Jake
Second, if you cannot get the engine to idle at 550rpms or lower with MSD connected but the EST disconnected you won't be able to set the initial timing with the timing light.
So even though you may see over 20 degrees with the engine running with the EST connected, you won't know what the initial timing setting is.
If you insist on keeping the MSD, all I can suggest is to disconnect or by-pass it, disconnect the EST wire, start the engine and set the initial/base timing.
Then shut down the engine, disconnect the battery for 30 seconds or so to clear the error code, then reconnect the battery, MSD and EST and you're done.
There's obvioulsy something wrong here, but the above's the only work-around I can think of.
Jake
Instructor
Joined: Aug 2004
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Originally Posted by RainDelay
So here are the results...
Engine warm, at idle, w/MSD, Timing at 25* with EST connected......stalls when EST disconnected, sputters a few times then dies.
Engine warm, at idle, w/MSD, Timing at 25* with EST connected......stalls when EST disconnected, sputters a few times then dies.
Did you look at the right wiring diagram for your ignition system? Perhaps your new harness has a poor connection or is made for the wrong application?
Anyway, good luck!
Race Director
Joined: Feb 1999
Posts: 12,772
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From: Indianapolis IN
Steve, you probaby have this right but,,,,
do you have the power feed for the 6AL going straight to the battery? You have to have a good size wire go from the battery to the 6AL or you will have issues, ask me how I know
do you have the power feed for the 6AL going straight to the battery? You have to have a good size wire go from the battery to the 6AL or you will have issues, ask me how I know
Thread Starter
Melting Slicks
Joined: May 2001
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From: Winchester VA
Cruise-In V Veteran
Originally Posted by Blower91
Did you look at the right wiring diagram for your ignition system? Perhaps your new harness has a poor connection or is made for the wrong application?
Anyway, good luck!
Anyway, good luck!
The MSD set on your car uses the 7 pin or the 5 pin conector .
If you wired it to the 5 pin the EST will kill the engine if it is the 7 pin hook up.
If you wired it to the 5 pin the EST will kill the engine if it is the 7 pin hook up.
do you have the power feed for the 6AL going straight to the battery? You have to have a good size wire go from the battery to the 6AL or you will have issues, ask me how I know
Between this and my other thread about the signal intermittently dropping out at mid rpms, my ignition system is driving me crazy.
Instructor
Joined: Aug 2004
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Originally Posted by RainDelay
Between this and my other thread about the signal intermittently dropping out at mid rpms, my ignition system is driving me crazy.
Thread Starter
Melting Slicks
Joined: May 2001
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From: Winchester VA
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Originally Posted by Blower91
You don't happen to have a nearby friend with a spare MSD box? Just to rule out the possibility that your unit is faulty. Perhaps unlikely, but it does happen brand new electronics you buy are broken before you even bought them.
The reason I have two seperate threads is that the miss is there w/out the MSD box, in fact it was there before I even bought the box. The MSD was as much about getting a rev limiter as it was any possible performance.
I appreciate everyone's input, the ideas keep me on my toes and make sure I'm not missing something. New ways to look at it...
