Idle problem cont. May have found solution...
Safety Car
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Well, I got it running perfect, except the est wire was still disconnected. 
I went and talked to the mechanic today. He suggested plugging the wire back in and unplugging the knock sensor. If it runs perfect like that, chances are the sensor is bad or it is picking up a false knock. Seems logical to me.
I guess what's going on here is that the timing is, maybe not perfect, but acceptable. When the wire is plugged in, the computer, for whatever reason, is advancing timing like crazy. I can't even get it to run with the wire plugged in and the engine cold. Wire off, perfect.
I'll let y'all know how it goes.
I went and talked to the mechanic today. He suggested plugging the wire back in and unplugging the knock sensor. If it runs perfect like that, chances are the sensor is bad or it is picking up a false knock. Seems logical to me.
I guess what's going on here is that the timing is, maybe not perfect, but acceptable. When the wire is plugged in, the computer, for whatever reason, is advancing timing like crazy. I can't even get it to run with the wire plugged in and the engine cold. Wire off, perfect.
I'll let y'all know how it goes.
If the knock sensor is pickin' up a knock, and the timing is gettin' backed up/retarded, the motor will actually increase revs a little, and probably SEEM smoother.
Reason is, advancing timing makes the 'explosion' earlier in the piston cycle, and harder for the piston to reach TDC, and then de-compress (power part of stroke). Retard timing - like the KS does - and the 'explosion' is later, and it's 'easier' for the piston to approach TDC (cause it's already there almost), and the motor increases revs slightly.
You can test the KS by tapping the block next to the KS, and observing for rpm change (IF it is already a steady RPM!!!). It is detecting a [false] knock, and backs up timing.................................. ...
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Melting Slicks
Joined: Jan 2008
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From: Jasper Texas
I've read about that test, but I can't actually perform it. I can't get the car to run with the est wire plugged in. Without it plugged in, the knock sensor's signal goes nowhere.
I'm going to let the car cool off a little more, then unplug the knock sensor and plug in the est wire. If the car fires up and runs good, I've found what is telling the computer to change timing, but I won't know why. It could be bad, or it could be good but actually picking something up.
I'm just lost here; the car runs perfect with the wire disconnected, but runs like crap when connected. That means the computer is adjusting timing for some reason. I've eliminated the esc module as the culprit. The timing could be not perfect, but it runs just fine with the wire off, so that can't be the problem. Only other thing I can think of is the knock sensor. Is there anything else in this circuit that could be telling the computer to change timing?
I'm going to let the car cool off a little more, then unplug the knock sensor and plug in the est wire. If the car fires up and runs good, I've found what is telling the computer to change timing, but I won't know why. It could be bad, or it could be good but actually picking something up.
I'm just lost here; the car runs perfect with the wire disconnected, but runs like crap when connected. That means the computer is adjusting timing for some reason. I've eliminated the esc module as the culprit. The timing could be not perfect, but it runs just fine with the wire off, so that can't be the problem. Only other thing I can think of is the knock sensor. Is there anything else in this circuit that could be telling the computer to change timing?
Safety Car
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From: :45 minutes from everywhere / E-I-E-I-O
Does it still trip up a 42 code? That problem needs to be diagnosed.
I think you should check your static timing. Turn the motor till the rotor is at #1 plug wire connector in the distributor cap, then pull the plug and see if the piston is at TDC. It couldn't be off 180, since it runs at all.
Have you had the distributor out at all? Did you miss by one gear tooth when you put it back in?
I think you should check your static timing. Turn the motor till the rotor is at #1 plug wire connector in the distributor cap, then pull the plug and see if the piston is at TDC. It couldn't be off 180, since it runs at all.
Have you had the distributor out at all? Did you miss by one gear tooth when you put it back in?
Thread Starter
Melting Slicks
Joined: Jan 2008
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From: Jasper Texas
I haven't had the distributor out. It'll start up and run for about a second or two with the wire connected, but it dies out pretty quickly. The car only sets a code 42 with the wire disconnected, which it should do.
The only codes I've had in 7 months are: code 34 (fixed with a base idle adjustment), code 42 (only because the est wire is disconnected), and a code 43 (its very rare that I've seen this code, but I have had it pop up about once a month).
If I plug the est wire back in, I won't get a code unless its a 43, which is very rare.
The only codes I've had in 7 months are: code 34 (fixed with a base idle adjustment), code 42 (only because the est wire is disconnected), and a code 43 (its very rare that I've seen this code, but I have had it pop up about once a month).
If I plug the est wire back in, I won't get a code unless its a 43, which is very rare.
Thread Starter
Melting Slicks
Joined: Jan 2008
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From: Jasper Texas
Results from unplugging knock sensor and plugging est back in:
Car fired right up, idled very smooth. CEL flashing repeditvly. Idle is high, idle was at 1500 rpms in park.
With all the bad, that was the first time the car ran good with the est wire connected, coincidence? I don't think so...
Maybe my knock sensor isn't bad, but somewhat "soft", picking up a knock that isn't a knock.
Car fired right up, idled very smooth. CEL flashing repeditvly. Idle is high, idle was at 1500 rpms in park.
With all the bad, that was the first time the car ran good with the est wire connected, coincidence? I don't think so...
Maybe my knock sensor isn't bad, but somewhat "soft", picking up a knock that isn't a knock.
Last edited by cwyates4; Jul 16, 2008 at 06:39 PM.
Thread Starter
Melting Slicks
Joined: Jan 2008
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From: Jasper Texas
Whoops, left the paper clip in the diagnostic port on that last test, so I did it again.
I don't think the problem is connected to the knock sensor now. It runs the same with the knock sensor connected as it does with it disconnected (with the est wire plugged in). With the est wire unplugged, all is well.
I don't think the problem is connected to the knock sensor now. It runs the same with the knock sensor connected as it does with it disconnected (with the est wire plugged in). With the est wire unplugged, all is well.
Melting Slicks
Joined: Jan 2001
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From: Chesapeake VA
With a 1500RPM idle, it should be difficult to tell if it is rough or not.
You mentioned that when you adjusted your distributor:
It did have better throttle response though, due to the advanced timing, but idle was pathetic.
I am assuming you adjusted your distributor by adding advance, yes? If so you should try retarding the advace and see what it does. Ideally this would be done in conjunction with a timing light. However, if the balancer has slipped, it will show correct ignition timing, when in fact you are too advanced, and when you plug the EST wire back in the computer adds even more advance and thus the idle quality degrades significantly.
If the timing light shows 6 degrees, but the idle still degrades when the EST wire is disconnected, try retarding the timing back to 2 degrees or even 0 degrees and see what that does.
You mentioned that when you adjusted your distributor:
It did have better throttle response though, due to the advanced timing, but idle was pathetic.
I am assuming you adjusted your distributor by adding advance, yes? If so you should try retarding the advace and see what it does. Ideally this would be done in conjunction with a timing light. However, if the balancer has slipped, it will show correct ignition timing, when in fact you are too advanced, and when you plug the EST wire back in the computer adds even more advance and thus the idle quality degrades significantly.
If the timing light shows 6 degrees, but the idle still degrades when the EST wire is disconnected, try retarding the timing back to 2 degrees or even 0 degrees and see what that does.
Thread Starter
Melting Slicks
Joined: Jan 2008
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From: Jasper Texas
It idled at 1500 rpms today, but I only because I forgot to take out the paper clip from the diagnostic port. 
After I took it out, it idled at 1100 in park, 800 in gear. Thats about where I like it, and the cam likes it there too.
This morning, I pulled some timing out, put it back to where it was originally (I'd guess 0 degrees without seeing it on a timing light).
I know the est wire is what allows the timing to be advanced, but I can't figure out what is making it advance. It doesn't seem to be the knock sensor, and it can't be the esc module. Something isn't adding up. Maybe I should plug the wire in and continue to retard the timing to see what happens?
If I make a vid clip to show the difference between wire unplugged and wire plugged in, would that help? Maybe a light bulb would appear over head after hearing/seeing what I'm dealing with.
After I took it out, it idled at 1100 in park, 800 in gear. Thats about where I like it, and the cam likes it there too.
This morning, I pulled some timing out, put it back to where it was originally (I'd guess 0 degrees without seeing it on a timing light).
I know the est wire is what allows the timing to be advanced, but I can't figure out what is making it advance. It doesn't seem to be the knock sensor, and it can't be the esc module. Something isn't adding up. Maybe I should plug the wire in and continue to retard the timing to see what happens?
If I make a vid clip to show the difference between wire unplugged and wire plugged in, would that help? Maybe a light bulb would appear over head after hearing/seeing what I'm dealing with.
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Safety Car
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From: :45 minutes from everywhere / E-I-E-I-O
It idled at 1500 rpms today, but I only because I forgot to take out the paper clip from the diagnostic port.
After I took it out, it idled at 1100 in park, 800 in gear. Thats about where I like it, and the cam likes it there too.
This morning, I pulled some timing out, put it back to where it was originally (I'd guess 0 degrees without seeing it on a timing light).
I know the est wire is what allows the timing to be advanced, but I can't figure out what is making it advance. It doesn't seem to be the knock sensor, and it can't be the esc module. Something isn't adding up. Maybe I should plug the wire in and continue to retard the timing to see what happens?
If I make a vid clip to show the difference between wire unplugged and wire plugged in, would that help? Maybe a light bulb would appear over head after hearing/seeing what I'm dealing with.
After I took it out, it idled at 1100 in park, 800 in gear. Thats about where I like it, and the cam likes it there too.
This morning, I pulled some timing out, put it back to where it was originally (I'd guess 0 degrees without seeing it on a timing light).
I know the est wire is what allows the timing to be advanced, but I can't figure out what is making it advance. It doesn't seem to be the knock sensor, and it can't be the esc module. Something isn't adding up. Maybe I should plug the wire in and continue to retard the timing to see what happens?
If I make a vid clip to show the difference between wire unplugged and wire plugged in, would that help? Maybe a light bulb would appear over head after hearing/seeing what I'm dealing with.
After you confirm #1 near TDC (DO NOT GO BY BALANCER DEGREES), and cap/rotor at #1 fire, THEN check the balancer marks...
Last edited by schrade; Jul 17, 2008 at 01:51 AM.
Thread Starter
Melting Slicks
Joined: Jan 2008
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From: Jasper Texas
Ok, I'm just tired of messing around with this thing.
Today was the first time in a very long time that I cranked the car completly cold, and it ran under its own power. This was with the est wire disconnected of course. It seemed to have a slightly rough idle at first, but leveled off quickly. I turned it off, plugged the timing wire back in, cranked and died twice, then finally started and ran, but really rough. Disconnected wire, started and ran perfect.
I've been driving it around town like this the past few days, and its a real pleasure to drive with the wire disconnected. Even though the computer can't advance timing, I can still get all the way to the redline pulling strong, no ill effects, don't know why though?
My mechanic is taking it in Monday, so I'll probably just leave it alone until then. He is going to set timing first, check all the ignition components, check the balancer, and check all the connections from the electronic spark control circuit to the computer. Hopefully he finds something!
On top of the running problem, my belt tensioner is in failing condition and getting worse. Its caused my steering wheel to get tighter, a/c to be useless, water temps raise from 180 to 200, and dropped my voltage while running from ~13.8 to ~13.3. Cars!
Today was the first time in a very long time that I cranked the car completly cold, and it ran under its own power. This was with the est wire disconnected of course. It seemed to have a slightly rough idle at first, but leveled off quickly. I turned it off, plugged the timing wire back in, cranked and died twice, then finally started and ran, but really rough. Disconnected wire, started and ran perfect.
I've been driving it around town like this the past few days, and its a real pleasure to drive with the wire disconnected. Even though the computer can't advance timing, I can still get all the way to the redline pulling strong, no ill effects, don't know why though?
My mechanic is taking it in Monday, so I'll probably just leave it alone until then. He is going to set timing first, check all the ignition components, check the balancer, and check all the connections from the electronic spark control circuit to the computer. Hopefully he finds something!
On top of the running problem, my belt tensioner is in failing condition and getting worse. Its caused my steering wheel to get tighter, a/c to be useless, water temps raise from 180 to 200, and dropped my voltage while running from ~13.8 to ~13.3. Cars!
Last edited by cwyates4; Jul 17, 2008 at 11:59 PM.
Thread Starter
Melting Slicks
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From: Jasper Texas
No, but I had a good thought last night. I think my connecter to the electronic spark control module may be missing a pin. There are 5 wires going to the connecter, and 5 prongs for the esc module, but it appears I may be missing a pin in the connecter itself. I'll have to get a pic and show y'all, or maybe someone could post the a wiring diagram for this circuit...
Found the wiring diagram for the circuit. It checks out normal, darn! Now I'm going to go through the code 43 troubleshooting process and see where that leads me, although I haven't thrown a 43 in some time.
http://members.shaw.ca/corvette86/Code%2043.pdf
Found the wiring diagram for the circuit. It checks out normal, darn! Now I'm going to go through the code 43 troubleshooting process and see where that leads me, although I haven't thrown a 43 in some time.
http://members.shaw.ca/corvette86/Code%2043.pdf
Last edited by cwyates4; Jul 18, 2008 at 10:19 AM.
Thread Starter
Melting Slicks
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From: Jasper Texas
Did some more testing today. I found there are only two ways to keep the car running right now.
A. disconnect timing wire
or
B. with timing wire connected, use right foot until car reaches closed loop, then it will run with the wire connected, but still rough.
Tried tapping on the block by the knock sensor with timing wire connected, idle seemed to smooth, but didn't rise any. I'm guessing the knock sensor is in working order and is sending correct info to the esc module. I know the esc module itself is working, now I wonder about the connections between it and the computer.
A. disconnect timing wire
or
B. with timing wire connected, use right foot until car reaches closed loop, then it will run with the wire connected, but still rough.
Tried tapping on the block by the knock sensor with timing wire connected, idle seemed to smooth, but didn't rise any. I'm guessing the knock sensor is in working order and is sending correct info to the esc module. I know the esc module itself is working, now I wonder about the connections between it and the computer.
Thread Starter
Melting Slicks
Joined: Jan 2008
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From: Jasper Texas
Did some more testing this afternoon. With the car warmed up, I plugged in the est wire, caused the car to idle at 1200 rpms in park, and fairly rough. I pulled one plug wire at a time, and noticed the idle smoothed out some, and dropped to 1100 rpms. It actually ran smoother with a plug wire (any of the 8) off. It wouldn't rev very well, obviously, but the idle was smoother. Go figure.
Now a question, with the timing wire plugged in, and all 8 plug wires on, I think I hear a knock, is this because the engine is advancing timing too much? With the est wire unplugged, the knock disappears.
My mechanic is getting it monday, but I'm still looking for ideas. I'd like to be able to point him in the right direction, not have him hunting all over the place like I have been.
Now a question, with the timing wire plugged in, and all 8 plug wires on, I think I hear a knock, is this because the engine is advancing timing too much? With the est wire unplugged, the knock disappears.
My mechanic is getting it monday, but I'm still looking for ideas. I'd like to be able to point him in the right direction, not have him hunting all over the place like I have been.
Le Mans Master
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From: Hellinois
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Have you tried taking the distributor cap off to see if the shaft of the dist. is sloppy? I realize a worn out distributor would affect the engine's behavior all the time whether the EST is plugged in or not but I would still take a look at it.
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Melting Slicks
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From: Jasper Texas
I had thought of doing that, but never did. Today with the est wire disconnected on a cold start, it cranked right up, was a hair rough and idle was low (500-600 rpms). After about 30 seconds, idle picked up to 700-800 rpms, and ran good. The car has yet to stall on me with the wire disconnected; connect the wire and it'll die whenever it wants.
Le Mans Master
Joined: Dec 2000
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From: San Diego, Ca
Good idea to check wiring - lose the reference and you lose the injectors. In fact, you might just see if they're firing when you plug the EST module back in. To do so, I'd leave an injector unplugged and then see if a test light continues to blink as you plug the module in. If not, that'll give you a clue as to where to look next. Also, if you've swapped out the pickup coil - or maybe someone did before you bought it - make sure it's the right one. If the ignition lead is yellow, you need a pickup coil with a yellow wire. If it's white, the coil wire can be any color except yellow.
Pro
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From: Rolling Meadows IL
Did you do this test? Did you check your timing with a timing light.
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Melting Slicks
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From: Jasper Texas
Didn't check static timing or set timing with a light, not going to do it myself, just let my mechanic take care of it. I tend to have bad luck with working on cars, such as breaking bolts (death of my l98 T/A), and other stupid stuff.
I'm taking it to him Monday afternoon. Getting the timing issue fixed and getting a new oil leak nailed down. I should have it back Monday evening, maybe tuesday. I'll let y'all know what he found, but with the suggestions here on the forum, I'm guessing the static timing is off; Hence the reason I can pull a plug wire and notice no ill effects.
I'm taking it to him Monday afternoon. Getting the timing issue fixed and getting a new oil leak nailed down. I should have it back Monday evening, maybe tuesday. I'll let y'all know what he found, but with the suggestions here on the forum, I'm guessing the static timing is off; Hence the reason I can pull a plug wire and notice no ill effects.
Le Mans Master
Joined: Dec 2000
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From: San Diego, Ca
You can pull plug wires and injector connectors all day long and it won't effect it - the IAC simply opens a little bit more to maintain targeted idle. So if you want a meaningful test, you'll need to disable the IAC first. That's the beauty of these systems or maybe what makes it a bit too frustrating. If you want to learn more, including a couple of shortcuts to figure out whether it's got a weak cylinder, pickup Ben Watson's Chevy Fuel Injection. It'll tell you a lot and since very little has really changed in the last 25 years, give you enough to keep you out of trouble with the Toyota that's in your future.