3.7 engine slight shake

[tommudd]

Find a nice stretch of road slam that right pedal on the floor run her out until nothing left, do that 3 or 4 more times and smile all the way, always makes mine run better. Did that twice today as a matter of fact:ROFLJest:
or keep worrying that something may be wrong when it more than likely isn't :shrug::icon_lol:

 

[twowings]

The MMO didn't help?

 

[JeepJeepster]

Tom, youve almost passed up my 1994 ZJ that I drive daily! 218,000 on her. All original, bought it new!

If you want a rough idle, you should try a I6 4.0 from 93-95. Idk what they did, but its like having a massaging seat at redlights. Rough cam I suppose.

 

[tommudd]

Tom, youve almost passed up my 1994 ZJ that I drive daily! 218,000 on her. All original, bought it new!

If you want a rough idle, you should try a I6 4.0 from 93-95. Idk what they did, but its like having a massaging seat at redlights. Rough cam I suppose.

Getting closer to yours ! :icon_lol:
Yes I had a 93 and a 95 both, constant vibes after driving to Florida one year my butt vibrated for two days after we got there:happy175:

 

[LibertyTC]

The MMO didn't help?

The MMO & Wynn's Engine Tune Up can was in the oil for 300 miles only.
In that time it was to the floor quite a few times up the mountain highways, and it seemed to help blow the dust out.
At the same time Chevron 94 octane fuel was in as well as 2 bottles on Chevron Techron Concentrate cleaner.
Unfortunately the shake is still present hot or cold at idle and slightly above.
I changed the oil to Penzoil Platinum Full synthetic and added a half a quart of
Risoline for good measure.

I do not know how accurate this is for checking stem seals, but a Hg vacuum gauge test may be a clue...
Link: https://www.youtube.com/watch?v=MZTa-hXn7Qs

 

[uss2defiant]

give that $6 mopar combustion chamber cleaner a shot

 

[profdlp]

I just ordered a couple cans of that myself. My idle is okay but my mpg has not been up to ***** lately.

Good luck, TC! :favorites13:

 

[uss2defiant]

I just ordered a couple cans of that myself. My idle is okay but my mpg has not been up to ***** lately.

Good luck, TC! :favorites13:

so far I've seen a slight improvement. Not significant.
I'll have to try another can down the road.

 

[dude1116]

Just never been a fan of additives. Just run em and change the oil!

 

[LibertyTC]

Lets see how the Jeep fares tomorrow on the vacuum test...
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Now I don't have to run to the shop to borrow one! arty52:

 

[profdlp]

Good luck, TC. :favorites13:

 

[LibertyTC]

Thanks Prof, stay "tuned" ..ok lets just hope the jeep is actually in tune...ha ha..
Will post back after 3 hours of afternoon dental drilling & the crowning excitement $$

 

[uss2defiant]

Lets see how the Jeep fares tomorrow on the vacuum test...
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Now I don't have to run to the shop to borrow one! arty52:

I don't know much about vacuum testing but I've seen vids of leak down testing with pressure. How does this other method work?
I assume you're trying to do a leak down test? but with vacuum?

 

[LibertyTC]

Here is a good read about vacuum testing!
Testing Engine Vacuum | Hemmings Motor News
Hope this helps..
Also see the video I posted back in post #25 this thread (one page back)

 

[uss2defiant]

i see.
where are you planning to hook it up to?

I'm not a mechanic but correct me if I'm wrong, this gives you a general probable idea of what is wrong and would not help you pinpoint where the problem is especially to those specific cylinders you've been having issues with, compared to a leak down test.

 

[LibertyTC]

The misfire count was not specific to one particular cylinder.
If the needle hold steady between 15-21 in the good range, without many vibrations, or variations at idle or slightly above, I will be very pleased.
Yes, the vacuum test will give me a general idea where to go with this next if it fails.
Leak down & compression testing as well as fuel related observations will be followed if it fails the vacuum test.
The vacuum gauge gets hooked up the the PCV line.

 

[LibertyTC]

The intake hose elbow is removed and connected up to supplied connector.
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On the 04 at rear of intake is the PCV Line/elbow now ready for testing.
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Jeep is started in Park and reads just below 19hg.
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The needle does not waiver at all throughout the testing. Everything seems to be within a normal range and gauge responds normally from opening throttle back to 5hg and then easily at idle again to 19hg.
I think I can sleep at night now, knowing it is probably not heads or stem seals/valves or intake etc.
Back to fuel injector or coils or?
This is really a different experience for me. Normally I can diagnose so much easier.
With the Jeep so computerized, and no check engine lights, might as well just forget it, until I do get an engine light!

 

[twowings]

I'm going to go out on a limb here and suggest that one of your coil pak connectors or the wiring to it is poorly conductive or grounding intermittently...

 

[LibertyTC]

I would agree with that except with the Snap On Scan tool/misfire count, it was across a broad range of cylinders, (a low- 1 or two count) not one specific cylinder.
Sometimes 2 or 3 cylinders report a misfire count only when slightly above idle.
Could it be a Crank or camshaft position sensor even the PCM or wires?

 

[twowings]

Well, you may have something there...that would indicate it's upstream of the individual wiring to the coil paks...your grounding straps to engine look good? touching bare metal at attachment points? Battery and alternator outputs nice and hot?