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Disconnecting electric motor mounts can resolve shake similar to CV axle?
So in my prepping the '00 for its new life as the commute car, I bypassed the IACV and disconnected the motor mounts at 168k today.
For the last 12-18 months, I've had a front-end shake that was like the all-too-familiar unbalanced CV axle or just an unbalanced tire. Rotating or balancing the tires didn't resolve it. It's always between 20 and 30. Clears up quickly after 30. More prominent when engine is under lugging-type load. (automatic trans) Nothing violent or rough, just a mild tremor in the car.
So disconnecting the motor mounts (in firm position) this evening seems to have resolved it. I had to make a quick 10-mile round trip to the store. First acceleration I immediately noticed it didn't shake. Several more stop-n-gos on my short trip and it definitely seems much smoother like our '02 with 100k less miles.
Am I crazy? Has anyone heard of this being a cause of shake under mild acceleration?
Also, is it worth it to replace the IACV or is just bypassing, drying, and plugging the ports good enough?
I'll start with the easy one - the IACV. I am assuming that you do not have a check engine light with code P0505, so that means the IACV is working. If you bypass the coolant, the chances of it shorting out are pretty small so I wouldn't bother replacing it. As for plugging the openings, there is no reason to, nothing will get into the motor section of the IACV.
The motor mount situation you describe doesn't make any sense. The ECU is supposed to put the motor mounts in firm mode when the engine rpm reaches 1,000. You disconnecting the motor mounts while in firm mode or letting the ECU control it should be the same thing when you are driving. What I think you might have is a failing ignition coil or fuel injector.
Thanks for the input. It's definitely a shake, though. I've had plenty of coils fail on me and I'd like to think I know what that feels like. I think at least 5 or 6. It's way too consistent and only in that range. I can take it right up to 6k when the engine really comes alive and it's smooth as butter. No throttle "stages" as I call them when a MAF is dying, either. Experienced one total failure and one partial/intermittent failure regarding MAFs.
But as I just posted in the "what'd you do to your max" thread, I have coils inbound tomorrow.
Will check back throughout the day but I'll post results of my 55+ mile commute in the evening after replacing the plugs and drain/fill ATF.
While the engine is most likely shaking as you say, it is not the motor mount causing it. Since you have some parts coming and you will be installing them, hopefully that will solve your problem.
Well, just shy of 60 miles on it today, and it really does seem like 80% of it is gone.
I think in the next month or so, I'm going to pull the Cattman Y and put the stock back in if it's not too difficult. I guess the engine sounds uneven. Maybe with the Y deleting one cat and not the front one, the stock catback makes it so quiet the engine sounds weird to me.
So what's the possibility of something like piston slap? Its VERY subtle. Maybe feels like a 10-15% loss in power. No noticeable difference in MPG.
Here's what's weird... I've never lost oil in this motor except when I had the leaking valve covers.
Well, I lost over 1/2qt in 2,000 miles since the scenario described below. I fixed the valve covers just before that, so maybe there's a leak I don't see/smell. I do have a worsening leak by the timing chain CPS. But it's nothing more than a light seepage.
So what kind of damage could putting the wrong spark plugs in do? I accidentally grabbed the spares for our 3.5 and put them in the 3.0. It crushed the electrodes down but not far enough to crush the insulators. I tested it with an extra plug and it probably took a pretty solid 20-30 pounds of force to smash them like so. Here's a pic of one of the plugs that came out.
I sent a scope down the cylinder and checked the pistons. Just a little nick of carbon off the top. comparison of 3.0 and 3.5 plugs
electrode smashed by piston
Stupid mistake on my part. Was rushing to get it done before work and screwed it up. I'll jump on the laptop and upload pics of the pistons if I still have them on there.
EDIT: Negative on the pics of pistons. Only saved pics of the 3.5
Last edited by mydecember1985; 03-27-2017 at 09:28 PM.
If it didn't break or crack the piston, then there wouldn't be a problem. Because of the oil usage, I would suggest you do a compression check and see what that shows.
03-21-2017, 08:57 PM
