pinpointing engine vibration

Good evening


The vibration is still there and troubleshooting has eliminated the following failures:

- Harmonic balancer.

- Accessories (water/ power steering pumps, A/C compressor, alternator, supercharger, pulleys/tensioners)

- Transmission/drive train.

- Engine/transmission mounts.


I would now troubleshoot the ignition system as suggested by KMT in post #2. Coil pack, plugs, and wires for a miss fire.

If you have not already, check (if equipped) the EGR for carbon blockage and engine connections for vacuum leaks.

Check the canister purge valve solenoid vacuum line and rubber hose connector for damage.



Good Luck.
 
I checked all the plug wires, plugs, and coil pack. The plug wires were all between 5-10k ohms. The coil pack was 11.4k ohms for all three cylinder pairs. All the spark plugs looked good as well.


I do not have an EGR anymore.

What is a good way to check for vacuum leaks?

Also, where is the canister purge valve solenoid located?
 
Gap(s)?


What is a good way to check for vacuum leaks?

Smoke test

Also, where is the canister purge valve solenoid located?

Inside the pass. side fender, wedged between the cold air snorkel and the tub/body. Not fun to try to get to/work on.
 
I checked all the plug wires, plugs, and coil pack. The plug wires were all between 5-10k ohms. The coil pack was 11.4k ohms for all three cylinder pairs. All the spark plugs looked good as well.


I do not have an EGR anymore.

What is a good way to check for vacuum leaks?

Also, where is the canister purge valve solenoid located?



Good evening


Could have a problem with a coolant leak based on the last 2 set of spark plugs to the right of the picture. Maybe due to the picture angle/light but the spark plugs white insulator firing tip is very clean. Poor engine cooling system efficiency (leaking head gasket) and or intake manifold leak. Fuel injector o - rings could also be damaged causing an air leak.



As far as vacuum leak test as KMT suggest smoke test is the best method. Another means you can use the soap/water bottle squirt application. Listen for a change in rpm and or a "hissing" sound with bubbles. There are many other ways (like propane) which you can find searching the forum or You Tube videos.
 
Gap(s)?




Smoke test



Inside the pass. side fender, wedged between the cold air snorkel and the tub/body. Not fun to try to get to/work on.

Gaps are as follows (left side going up, then right side going up referencing picture above):
.047 .051 .054
.047 .049 .048

I'm guessing they should all be around .047 to .048 gap?

Good evening


Could have a problem with a coolant leak based on the last 2 set of spark plugs to the right of the picture. Maybe due to the picture angle/light but the spark plugs white insulator firing tip is very clean. Poor engine cooling system efficiency (leaking head gasket) and or intake manifold leak. Fuel injector o - rings could also be damaged causing an air leak.



As far as vacuum leak test as KMT suggest smoke test is the best method. Another means you can use the soap/water bottle squirt application. Listen for a change in rpm and or a "hissing" sound with bubbles. There are many other ways (like propane) which you can find searching the forum or You Tube videos.

The insulator tips in the picture look misleading. All of them are darkened, but most are only darkened on one half and still fairly white on the other half.
 
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I'm guessing they should all be around .047 to .048 gap?


Factory specs should be on a sticker on the header panel, under the hood. .052 ~ .056, as I recall, so, say .054" - Sorry if I missed it...how many miles on them? Did you look close at the ceramic around the tips for cracks?

If you haven't put them back in yet, I'd replace w/new, stock spec.

But if you've upped the boost, then we're told to reduce the gap a bit, depending on. Whatever gap, I'd set them all the same.

This is more about housekeeping at this point, tho... Assuming the firing order is valid, I don't see anything obvious from the plugs that would suddenly generate a new vibration.
 
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Normally those would be gapped .045"

Since you have plugs out, do a compression test. Be sure to block the bypass and TB open and disable the fuel injectors while doing it.
 
Normally those would be gapped .045"

Since you have plugs out, do a compression test. Be sure to block the bypass and TB open and disable the fuel injectors while doing it.

I did the computer cylinder balance test back when this first started and it reported back a 90 meaning I passed. Will a manual compression test be that much better?
 
After letting the car sit for a few months, I'm taking the easy way out and will just drive it as is.
 
Today I decided to check the coil pack again, and this time I pulled plug wires one at a time while it was running. All of them had spark, but when I pulled #3 it didn't seem to change how it was running.

This leads me to believe that it could either be the spark plug (the wire has already been tested and is good) or the injector. I do not believe it is the spark plug because I visually checked them all when I pulled them a while ago, and they all looked similar (as you can see in the picture above) and they were all re-gapped.

I'm leaning towards the injector going bad. The car has plenty of power when in the throttle, but the vibration is most apparent when idling or light throttle cruising. Maybe the injector isn't spraying under light load, but sprays when under heavy load? I haven't noticed any drastic change in fuel mileage...if anything it might have gone up slightly.

I plan to pull all the spark plugs (again :() and verify they all spark.

Is there a good way to test the injectors without pulling them? I have extras that I can swap in, but I'd like to avoid that unless necessary.
 
Good evening


You could ohms test the injectors without removing them to see if they are in limits. See attachment.


https://www.google.com/url?sa=t&rct...jector&usg=AFQjCNFtj6yaFpP2OSv4ZLZnThX1VK56RA



Have you ohms checked and or swap plugs wires to eliminate that issue? See attachment.


https://www.google.com/url?sa=t&rct...tegies&usg=AFQjCNHoLz_nCMBqEj9vTlqvP_HbBibuFw

I did the screwdriver trick to listen to the injectors and they all sounded fine. I went ahead and replaced the spark plugs, plug wires, and coil pack. I ran the computer cylinder balance test and it came back good. The damn thing still vibrates and doesn't have any codes...I'm at a loss
 
vibration

I did the screwdriver trick to listen to the injectors and they all sounded fine. I went ahead and replaced the spark plugs, plug wires, and coil pack. I ran the computer cylinder balance test and it came back good. The damn thing still vibrates and doesn't have any codes...I'm at a loss

Just gonna throw my 2 cents in. I had a 95 sc auto that had bad vibration issues when sitting at a light. I checked everything like you did. unfortunately my balancer broke off while driving. the balancer bolt had broken off the engine. have you removed the center balancer bolt?it threw off my timing. with it running at idle in my driveway nothing vibrated or moved only when in gear.
if its not the balancer or bolt have you checked the driveshaft and all connections?
gotta say visually my balancer did not seem to move or vibrate at all when seeing the engine running. but that bolt sheared right off. just hope if that is the problem you catch it in time.
 
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Good morning

It appears that overall health of the engine and transmission is good. I would take a look at the crank shaft pulley and bolts. Every DAYCO harmonic balancer installation I've done required a slight enlargement of one of the 4 crankshaft pulley mounting holes. But too much will cause the pulley to shift in rotation and a vibrating engine.

See attachments.

http://www.sccoa.com/forums/showthread.php?118747-BHJ-Broken-crank-pulley-bolts/page2

http://www.sccoa.com/forums/showthread.php?133244-balancer

http://www.sccoa.com/forums/showthread.php?132979-bad-harmonic-balancer-or-bad-rod-bearing

http://www.sccoa.com/forums/showthread.php?135586-Dorman-Harmonic-balancer-Not-sure-what-to-do/page2

You might find the bolts have "necked down" and or slightly bent.
 
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