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Unread 09-17-2013, 10:20 PM   #1
BRKirkpatrick
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1998 ZJ 
 
Join Date: Mar 2013
Location: Irvine, CA
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Niner Shudder/Vibration After Seafoam

All,

I recently had unsteady idle issues, pulled and cleaned the IAC (with Seafoam), and Seafoamed through the TB.

Now, the idle is rock solid. However, I have developed an intense shudder/shaking/vibration. It is noticeable throughout the RPM range, with a significant increase ~1k-2krpm. It is present (but light) at idle as well. Today I replaced the spark plugs with Champion Copper, with no change in symptoms.

1. Could the Seafoam treatment have caused the shudder?
2. Plenum fix is on my to-do list (next week or so) - could a failing/failed plenum cause it?
3. Could it coincidentally be the harmonic balancer that happened to fail right after the Seafoam/IAC?
4. Anything else?

Thanks in advance for the help!

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Unread 09-17-2013, 10:26 PM   #2
94zjWAwheeler
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Seafoam is terrible for the engine my brother used it on his 90's 300zx a month later it had a loud rod knock
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Unread 09-17-2013, 10:30 PM   #3
BRKirkpatrick
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Well, read about it here, seemed well-enough regarded. Either way, that part is done, more concerned about how to fix the new problem .
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Unread 09-18-2013, 12:10 AM   #4
Oldfrog
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Quote:
Originally Posted by 94zjWAwheeler View Post
Seafoam is terrible for the engine my brother used it on his 90's 300zx a month later it had a loud rod knock
It's not terrible for an engine. That's a myth. It's a great fuel system/carbon cleaner.

Of course, it isnt a substitution for oil.....and if you use it in the crankcase, you are supposed to drain it out after driving it a little and refill with oil only.

Outboard engine users have been using it in their fuel for years now. I know, because I'm one of them. I recently pulled one of the heads on my Evinrude to replace a worn out head gasket. ( it was only 30+ years old) and the combustion chambers and piston tops were clean and free from carbon build up. I havent had to rebuild my carbs in over 10 years, either.
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Unread 09-18-2013, 12:17 AM   #5
Oldfrog
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Quote:
Originally Posted by BRKirkpatrick View Post
All,

I recently had unsteady idle issues, pulled and cleaned the IAC (with Seafoam), and Seafoamed through the TB.

Now, the idle is rock solid. However, I have developed an intense shudder/shaking/vibration. It is noticeable throughout the RPM range, with a significant increase ~1k-2krpm. It is present (but light) at idle as well. Today I replaced the spark plugs with Champion Copper, with no change in symptoms.

1. Could the Seafoam treatment have caused the shudder?
2. Plenum fix is on my to-do list (next week or so) - could a failing/failed plenum cause it?
3. Could it coincidentally be the harmonic balancer that happened to fail right after the Seafoam/IAC?
4. Anything else?

Thanks in advance for the help!
1. Not directly, but maybe a chunk of carbon it had loosened helped to stick a valve? ( I'm grasping here..)
2. Have no idea.
3. Very possible. Mine just went out at 241K with no warning.
4. Does it sound/feel like a dead miss of one cylinder? If so, pull the plug wires, one by one, to isolate the cylinder and work from there. ( injectors, etc).
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Stalling? Work through Zeejay's list
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Unread 09-18-2013, 12:25 AM   #6
jm8881
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I would bet it has something to do with messing with the iac more than anything else. They don't like to have the plunger pushed in or pulled out manually.
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Unread 09-18-2013, 04:48 AM   #7
newfieZJ
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Although not a fan of Seafoam , I don't think In have heard of it causing any engine issues on here . I prefer the controllable spray from Mopar CCC .

1) Possible but it can only clog up a few things . You already changed your spark plugs . Maybe it clogged the cat a little . Not too likely .

2)Plenum can cause it , but , it would be one bad plenum gasket . It would have to leak so bad it would saturate the combustion chamber and stop the spark . Not likely .

3)Balancer ? Had them bad before , no shudders . You could feel a sligt vibration but not too noticable . Make sure you look at it from the side carefully . It can be deceiving .

4)Could be and IMO most likely bad wires and/or needs a new cap and rotor . Was this done ?
Did you check the OBD for stored codes ? You need it scanned in the 98
Did you disconnect the battery after cleaning the IAC ? take 1/2 hour
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Unread 09-18-2013, 05:16 AM   #8
Technohead
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Seafoam?
snake-oil.jpg

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Unread 09-18-2013, 07:50 AM   #9
PolkaPower
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It could very well be the balancer. Mine went bad suddenly after I gave it full throttle after the plenum fix. The rubber ring failed and the inside ring was spinning/slipping faster than the outside ring. It was a terrible vibration throughout the whole truck especially at lower RPM's in all gears. Took me a week to realize that it was the balancer. It did not look bad but when I put a pry bar on it, it became obvious. I replaced a bunch of parts like motor mounts, injectors, ohmed out the plug wires, replaced the coil(which was bad but functioning anyway),ect.

Here is my thread on it http://www.jeepforum.com/forum/f13/s...ation-1415059/
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Unread 09-18-2013, 08:11 AM   #10
V65Ozzie
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Seafoam. It's a great product, if it's used for what it's intended. Around here they put that sheet in everything. Seriously, they truly believe it will turn a check engine light off for anything.
Add "Guaranteed to Pass" to that list.....People buy it because their check engine light is on and they can't pass the emmisions test. They put it in, get tested, fail, and then come back and complain and want a refund.....
READ THE FINE PRINT!!! That stuff will clean up the tailpipe emmisions, but we don't do tailpipe tests here!!
Sorry, ranting...rough day.....
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Unread 09-18-2013, 01:47 PM   #11
BRKirkpatrick
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@newfie - I have not done the cap and wires, just the plugs so far. I will check those out.

@Polka - I read your thread start to finish, that's what gave me the balancer idea . Just wondered if perhaps there was something else I was missing.

Coworkers suggested a vacuum leak somewhere. I wasn't aware they could cause such a violent shake, but I guess it would be easy enough to check for a leak there too. Lots of old hoses anyway.

All of this stuff has to get done eventually, I was just trying to defer some of it til later. Looks like more is getting done sooner after all .
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