Vibration concern
12-03-2007, 02:28 PM
#1
Le Mans Master
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Vibration concern
I posted this on the ZR1registry....but not too many results, so why not try here too.
I have a vibration that occurs only at about 900-950 rpm. This can be with the clutch in or out, moving down the road or idle. If I hold the accelerator at that rpm, its really rough. It seems to lessen in severity when the engine is fully warm.
The car starts very well, runs smooth, accelerates smooth & really seems to work great. Other than this vibration, which is pretty noticable, the car & engine are awesome.
Its been suggested that this may be injectors......I'm not sure. It runs so good otherwise. I thought it was a transmission problem....not sure there either.
Has anyone had this similar problem or think it may be actually an injector problem? How can I test that theory? Man all I have left to do is deal with this & maybe a clutch r&r (noisy throw out & pilot bushing)....then the Z has no problems !!
I have a vibration that occurs only at about 900-950 rpm. This can be with the clutch in or out, moving down the road or idle. If I hold the accelerator at that rpm, its really rough. It seems to lessen in severity when the engine is fully warm.
The car starts very well, runs smooth, accelerates smooth & really seems to work great. Other than this vibration, which is pretty noticable, the car & engine are awesome.
Its been suggested that this may be injectors......I'm not sure. It runs so good otherwise. I thought it was a transmission problem....not sure there either.
Has anyone had this similar problem or think it may be actually an injector problem? How can I test that theory? Man all I have left to do is deal with this & maybe a clutch r&r (noisy throw out & pilot bushing)....then the Z has no problems !!
There must be someone with something to add.....
12-03-2007, 11:57 PM
#4
Melting Slicks
Back when Girlfriend was only firing on about 5 cylinders, the car vibrated badly at idle.
A lot would depend on how much a person know about cars.
For example, the other day my wife told me that her car vibrated a lot when she used the brakes in traffic on the freeway.
I took it out for a test drive, thinking to myself, hmmm...
I did the brakes and rotors earlier this year, they couldn't possibly be warped this soon...
Well, you guessed it, no vibrations.
So I asked her to show me what she meant.
Out we go on the back road and she slams the brakes to a very quick stop.
She says, THAT VIBRATION!!!
I told her that the ABS was a good thing, but maybe it wasn't such a good thing to be using it all the time...
12-04-2007, 08:48 AM
#5
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Actually a minor miss at idle could cause a vibration of sorts.
Back when Girlfriend was only firing on about 5 cylinders, the car vibrated badly at idle.
A lot would depend on how much a person know about cars.
For example, the other day my wife told me that her car vibrated a lot when she used the brakes in traffic on the freeway.
I took it out for a test drive, thinking to myself, hmmm...
I did the brakes and rotors earlier this year, they couldn't possibly be warped this soon...
Well, you guessed it, no vibrations.
So I asked her to show me what she meant.
Out we go on the back road and she slams the brakes to a very quick stop.
She says, THAT VIBRATION!!!
I told her that the ABS was a good thing, but maybe it wasn't such a good thing to be using it all the time...
Back when Girlfriend was only firing on about 5 cylinders, the car vibrated badly at idle.
A lot would depend on how much a person know about cars.
For example, the other day my wife told me that her car vibrated a lot when she used the brakes in traffic on the freeway.
I took it out for a test drive, thinking to myself, hmmm...
I did the brakes and rotors earlier this year, they couldn't possibly be warped this soon...
Well, you guessed it, no vibrations.
So I asked her to show me what she meant.
Out we go on the back road and she slams the brakes to a very quick stop.
She says, THAT VIBRATION!!!
I told her that the ABS was a good thing, but maybe it wasn't such a good thing to be using it all the time...
This car has 45k on it. Its the red 92 I bought from Perry through Ebay.
My idle is around 750 (ish)....so the miss is just off idle. Its only felt when taking off from a stand still because while driving & changing gears, rpm never really gets down below 1000-1100. I'm starting to think the injectors or just one may be bad.
How would I determine weather or not its fuel or primary ignition related?
..............so how hard is it to remove the plenum & do some injectors? It looks pretty straight forward. I know the coils are under there too.....should I just replace everything while the plenum is off? (coils, injectors,vac lines)
12-04-2007, 09:51 AM
#6
Melting Slicks
The idle you describe sounds like your ECM has it's original prom. Between shifts the idle should drop to ~850 rpms and when you come to a complete stop it should drop to 650rpms. The original version of the prom calibration didn't have such good idle control.
As far as injectors, this is what you need to know in order to test the primary injectors without removing the plenum:
http://zr1specialist.com/HAT%20Web/a...Resistance.htm
Typical injector failure is shorting of the internal coils. This is caused because the internal seals of the injector are degraded by the ethanol in today's gasoline. Back in 1987 when these cars were being designed they had no idea that anybody would ever put ethanol in gasoline.
Removing the plenum is not a huge deal if you're mechanically inclined and have a few tools. There is an awesome write up on JeffVette's site:
http://www.pnwzr1.net/PNWZR1.htm
It's under the tech section, called LT5 Tear Down.
It's even got pictures.
Checking the coils is fairly easy, use your ohm meter and measure each coil to ground. The should be 10k-20k ohms. A little variance is expected due the added resistance of the spark plug wires.
It's a great idea to check all the secondary vacuum stuff while the plenum is off. I don't know if I'd go as far as replace it all, but heck, it's your money, spend it as you wish. Familiarize yourself with the secondary operation and be sure to leak check the heck out of it. Also check the PCV valves and the hosing for it, it's a common vacuum leak area.
Clean the entire under plenum area and retorque the oil box bolts, they work themselves loose, it's a common thing.
Good luck!
As far as injectors, this is what you need to know in order to test the primary injectors without removing the plenum:
http://zr1specialist.com/HAT%20Web/a...Resistance.htm
Typical injector failure is shorting of the internal coils. This is caused because the internal seals of the injector are degraded by the ethanol in today's gasoline. Back in 1987 when these cars were being designed they had no idea that anybody would ever put ethanol in gasoline.
Removing the plenum is not a huge deal if you're mechanically inclined and have a few tools. There is an awesome write up on JeffVette's site:
http://www.pnwzr1.net/PNWZR1.htm
It's under the tech section, called LT5 Tear Down.
It's even got pictures.
Checking the coils is fairly easy, use your ohm meter and measure each coil to ground. The should be 10k-20k ohms. A little variance is expected due the added resistance of the spark plug wires.
It's a great idea to check all the secondary vacuum stuff while the plenum is off. I don't know if I'd go as far as replace it all, but heck, it's your money, spend it as you wish. Familiarize yourself with the secondary operation and be sure to leak check the heck out of it. Also check the PCV valves and the hosing for it, it's a common vacuum leak area.
Clean the entire under plenum area and retorque the oil box bolts, they work themselves loose, it's a common thing.
Good luck!
12-04-2007, 05:31 PM
#7
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The idle you describe sounds like your ECM has it's original prom. Between shifts the idle should drop to ~850 rpms and when you come to a complete stop it should drop to 650rpms. The original version of the prom calibration didn't have such good idle control.
As far as injectors, this is what you need to know in order to test the primary injectors without removing the plenum:
http://zr1specialist.com/HAT%20Web/a...Resistance.htm
Typical injector failure is shorting of the internal coils. This is caused because the internal seals of the injector are degraded by the ethanol in today's gasoline. Back in 1987 when these cars were being designed they had no idea that anybody would ever put ethanol in gasoline.
Removing the plenum is not a huge deal if you're mechanically inclined and have a few tools. There is an awesome write up on JeffVette's site:
http://www.pnwzr1.net/PNWZR1.htm
It's under the tech section, called LT5 Tear Down.
It's even got pictures.
Checking the coils is fairly easy, use your ohm meter and measure each coil to ground. The should be 10k-20k ohms. A little variance is expected due the added resistance of the spark plug wires.
It's a great idea to check all the secondary vacuum stuff while the plenum is off. I don't know if I'd go as far as replace it all, but heck, it's your money, spend it as you wish. Familiarize yourself with the secondary operation and be sure to leak check the heck out of it. Also check the PCV valves and the hosing for it, it's a common vacuum leak area.
Clean the entire under plenum area and retorque the oil box bolts, they work themselves loose, it's a common thing.
Good luck!
As far as injectors, this is what you need to know in order to test the primary injectors without removing the plenum:
http://zr1specialist.com/HAT%20Web/a...Resistance.htm
Typical injector failure is shorting of the internal coils. This is caused because the internal seals of the injector are degraded by the ethanol in today's gasoline. Back in 1987 when these cars were being designed they had no idea that anybody would ever put ethanol in gasoline.
Removing the plenum is not a huge deal if you're mechanically inclined and have a few tools. There is an awesome write up on JeffVette's site:
http://www.pnwzr1.net/PNWZR1.htm
It's under the tech section, called LT5 Tear Down.
It's even got pictures.
Checking the coils is fairly easy, use your ohm meter and measure each coil to ground. The should be 10k-20k ohms. A little variance is expected due the added resistance of the spark plug wires.
It's a great idea to check all the secondary vacuum stuff while the plenum is off. I don't know if I'd go as far as replace it all, but heck, it's your money, spend it as you wish. Familiarize yourself with the secondary operation and be sure to leak check the heck out of it. Also check the PCV valves and the hosing for it, it's a common vacuum leak area.
Clean the entire under plenum area and retorque the oil box bolts, they work themselves loose, it's a common thing.
Good luck!
12-04-2007, 08:59 PM
#8
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Update:
Ok, the test results for the injectors are in.
All the primaries are 13.7-13.9
All the secondaries are 26.4-26.7
The primary values are good according to the Marc Haibeck instructions given. There was no value given as to what the secondary values should be, but they were consistent between all 8
I drove the car a little more than I have been able to & have some new observations to report.
1. it seems the problem occurs farther throughout the rpm range than I first thought. Its worse at 900-950, but its there till around 2500rpm, at least thets where I cant feel it anymore.
2. Crabs....the idle is consistent with what you say...about 650 ata dead standstill FULLY warmed.
3. ECM was changed out this year at Gordon Kilibrews school along with the prom when Perry brought it there.
4.Perry just put in plugs & what looks like new wires...they dont have the LT5 logo on them.
It seems to me that its more of a mechanical problem as opposed to an electrical or fuel related one.
Questions:
1. Is it possible the flywheel has a lost or missing weight? & as far as that goes, does any of the clutch assy have weights or counter balance material that could be missing?
2.can there be internal problems, broken piston skirt, or something like that?
All the primaries are 13.7-13.9
All the secondaries are 26.4-26.7
The primary values are good according to the Marc Haibeck instructions given. There was no value given as to what the secondary values should be, but they were consistent between all 8
I drove the car a little more than I have been able to & have some new observations to report.
1. it seems the problem occurs farther throughout the rpm range than I first thought. Its worse at 900-950, but its there till around 2500rpm, at least thets where I cant feel it anymore.
2. Crabs....the idle is consistent with what you say...about 650 ata dead standstill FULLY warmed.
3. ECM was changed out this year at Gordon Kilibrews school along with the prom when Perry brought it there.
4.Perry just put in plugs & what looks like new wires...they dont have the LT5 logo on them.
It seems to me that its more of a mechanical problem as opposed to an electrical or fuel related one.
Questions:
1. Is it possible the flywheel has a lost or missing weight? & as far as that goes, does any of the clutch assy have weights or counter balance material that could be missing?
2.can there be internal problems, broken piston skirt, or something like that?
12-04-2007, 09:31 PM
#9
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Ok, the test results for the injectors are in.
All the primaries are 13.7-13.9
All the secondaries are 26.4-26.7
The primary values are good according to the Marc Haibeck instructions given. There was no value given as to what the secondary values should be, but they were consistent between all 8
I drove the car a little more than I have been able to & have some new observations to report.
1. it seems the problem occurs farther throughout the rpm range than I first thought. Its worse at 900-950, but its there till around 2500rpm, at least thets where I cant feel it anymore.
2. Crabs....the idle is consistent with what you say...about 650 ata dead standstill FULLY warmed.
3. ECM was changed out this year at Gordon Kilibrews school along with the prom when Perry brought it there.
4.Perry just put in plugs & what looks like new wires...they dont have the LT5 logo on them.
It seems to me that its more of a mechanical problem as opposed to an electrical or fuel related one.
All the primaries are 13.7-13.9
All the secondaries are 26.4-26.7
The primary values are good according to the Marc Haibeck instructions given. There was no value given as to what the secondary values should be, but they were consistent between all 8
I drove the car a little more than I have been able to & have some new observations to report.
1. it seems the problem occurs farther throughout the rpm range than I first thought. Its worse at 900-950, but its there till around 2500rpm, at least thets where I cant feel it anymore.
2. Crabs....the idle is consistent with what you say...about 650 ata dead standstill FULLY warmed.
3. ECM was changed out this year at Gordon Kilibrews school along with the prom when Perry brought it there.
4.Perry just put in plugs & what looks like new wires...they dont have the LT5 logo on them.
It seems to me that its more of a mechanical problem as opposed to an electrical or fuel related one.
How strong is the spark?
Does this occur in normal as well as full power mode. What is the amount of throttle position the issue come up at. If given more throttle does the issue go away?
Questions:
1. Is it possible the flywheel has a lost or missing weight? & as far as that goes, does any of the clutch assy have weights or counter balance material that could be missing?
2.can there be internal problems, broken piston skirt, or something like that?
1. Is it possible the flywheel has a lost or missing weight? & as far as that goes, does any of the clutch assy have weights or counter balance material that could be missing?
2.can there be internal problems, broken piston skirt, or something like that?
12-04-2007, 09:53 PM
#10
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Maybe I did the test wrong on the secondaries........I used the same method, but the engine was cooling off pretty well.
I havent tested the spark, I dont really know how. I know the old screwdriver grounding method, but not a true test on this engine. I can tell you that the engine fires almost immediately when hot or cold & seems strong at any rpm. Its not a "dog" ever. I can tell when the secondaries open up without a doubt. Its smooth throughout the rpm range.
Its very, very hard to tell if there is even a problem at all while driving down the road. When stopped I can give it just enough throttle off idle to feel it. At the 875-950 rpm range I can really feel it. As I increase the rpm or throttle position it gets smoother until I cant notice it at around 2300-2500 & on up. Wheather or not its in full power or not doesnt make a difference.....BUT remember, its not noticeable while driving just when sitting still.....or coasting & revving to the 900-1000rpm area.....clutch in or out.
I find it weird that it runs so damn good otherwise.
EDIT***I re-checked the secondaries----I get the same values as the first try***
I havent tested the spark, I dont really know how. I know the old screwdriver grounding method, but not a true test on this engine. I can tell you that the engine fires almost immediately when hot or cold & seems strong at any rpm. Its not a "dog" ever. I can tell when the secondaries open up without a doubt. Its smooth throughout the rpm range.
Its very, very hard to tell if there is even a problem at all while driving down the road. When stopped I can give it just enough throttle off idle to feel it. At the 875-950 rpm range I can really feel it. As I increase the rpm or throttle position it gets smoother until I cant notice it at around 2300-2500 & on up. Wheather or not its in full power or not doesnt make a difference.....BUT remember, its not noticeable while driving just when sitting still.....or coasting & revving to the 900-1000rpm area.....clutch in or out.
I find it weird that it runs so damn good otherwise.
EDIT***I re-checked the secondaries----I get the same values as the first try***
Last edited by 81c3; 12-04-2007 at 10:43 PM. Reason: added info
12-04-2007, 11:20 PM
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For the secondaries are you getting your power source from the quad driver?
I havent tested the spark, I dont really know how. I know the old screwdriver grounding method, but not a true test on this engine. I can tell you that the engine fires almost immediately when hot or cold & seems strong at any rpm. Its not a "dog" ever. I can tell when the secondaries open up without a doubt. Its smooth throughout the rpm range.
Its very, very hard to tell if there is even a problem at all while driving down the road. When stopped I can give it just enough throttle off idle to feel it. At the 875-950 rpm range I can really feel it. As I increase the rpm or throttle position it gets smoother until I cant notice it at around 2300-2500 & on up. Wheather or not its in full power or not doesnt make a difference.....BUT remember, its not noticeable while driving just when sitting still.....or coasting & revving to the 900-1000rpm area.....clutch in or out.
I find it weird that it runs so damn good otherwise.
I find it weird that it runs so damn good otherwise.
Last edited by Jeffvette; 12-04-2007 at 11:25 PM.
12-04-2007, 11:34 PM
#12
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For the secondaries are you getting your power source from the quad driver?
got me here what is a quad driver??? I have my meter hooked up between the INJ 1 fuse & the #1 secondary relay & the #2 secondary relay as per the directions in the link that Crabs gave me.
You can pull the plug wire boot off while the motor is running. You should hear a loud snapping sound as the spark arcs to get to the plug. Ok, so some "old school" methods will work.
LT5 is pretty efficient and will mask some problems. You throw an ordinary driver in the car, they probably would not notice it.
got me here what is a quad driver??? I have my meter hooked up between the INJ 1 fuse & the #1 secondary relay & the #2 secondary relay as per the directions in the link that Crabs gave me.
You can pull the plug wire boot off while the motor is running. You should hear a loud snapping sound as the spark arcs to get to the plug. Ok, so some "old school" methods will work.
LT5 is pretty efficient and will mask some problems. You throw an ordinary driver in the car, they probably would not notice it.
12-04-2007, 11:45 PM
#13
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I'm no professional driver by any means, but I am in tune with my cars. I have owned over 50 different vehicles, mostly good old fashioned V-8's....I must admit though, this LT5 has me a little spooked.
12-05-2007, 12:24 AM
#15
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Yes, thats exactly where I'm testing from. I have the power to the ECM disconnected via the orange wire with the plug in & tested the Yellow, white, black & Lt. green for the #2 relay & the white/blk, Lt. blue, red & pink for the #1 relay.
12-05-2007, 12:27 AM
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So here is how to do it on the secondary.
A - WHT/BLK to A1 on ECM harness
B - LT BLU to A12 on ECM harness
C - TAN
D - PNK/BLK
E - DK GRN
F - RED to A13 on ECM harness
G - PNK to A18 on ECM harness
A - YEL to A8 on ECM harness
B - WHT to A3 on ECM harness
C - BRN
D - PNK/BLK
E - GRY
F - BLK to A2 on ECM harness
G - LT GRN to A7 on ECM harness
A - WHT/BLK to A1 on ECM harness
B - LT BLU to A12 on ECM harness
C - TAN
D - PNK/BLK
E - DK GRN
F - RED to A13 on ECM harness
G - PNK to A18 on ECM harness
A - YEL to A8 on ECM harness
B - WHT to A3 on ECM harness
C - BRN
D - PNK/BLK
E - GRY
F - BLK to A2 on ECM harness
G - LT GRN to A7 on ECM harness
12-05-2007, 12:41 AM
#18
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I see where I'm going wrong...I was going from the FUSE panel to the secondary plug- ins. Thats how I did the primary injectors. I misunderstood & did the secondaries the same way. I didnt realize I needed to go from the secondary plug-in to the ECM harness.
The primary injectors I went from the ECM to the fuse panel......is that right? Thats what the link says I believe.
The primary injectors I went from the ECM to the fuse panel......is that right? Thats what the link says I believe.
12-05-2007, 12:43 AM
#19
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I see where I'm going wrong...I was going from the FUSE panel to the secondary plug- ins. Thats how I did the primary injectors. I misunderstood & did the secondaries the same way. I didnt realize I needed to go from the plug-in to the ECM harness.
The primary injectors I went from the ECM to the fuse panel......is that right? Thats what the link says I believe.
The primary injectors I went from the ECM to the fuse panel......is that right? Thats what the link says I believe.
Fuse panel inj1 slot to ecm pinouts
Secondary:
Quad driver to ecm pinouts
I don't think you will find anything wrong with the injectors though.
12-05-2007, 12:48 AM
#20
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Somehow, I dont think the injectors are the problem either. Its a good learning experience though & at least I'll know the procedure and can possibly help some bozo like me
in the future.The best way to describe the problem is like a tire out of balance. Tomorrow I will check the strength of the spark & get back to you.
Thanks again for your help.
