LBZ: Vibrations At Idle

[c20elephant]

My truck is driving me batshit crazy at the start of this summer.

The Merchant Engine Mounts bring to life vibrations/rattles you never knew your truck had. Soooo short of changing my tune 40 times and driving for a day or two summer will be over, or, tearing into the dash and stuffing foam in there to maybe fix it does anyone have a suggested idle speed (or any other suggestions) that have/has been used with some success between the stock LBZ 680RPM and the stock LMM 720 RPM that might help or any other options in the tune that can be changed to help me keep what little sanity I have left in my life..???

Turning up the radio volume is not option neither is removing the resonator or muffler...

:feedback:

 

[WVRigrat05]

I had my truck set to idle at 680, and it drove me nuts, went to 720 same shit.
Set it to 710 and perfect.

If you build your motor for a mild build it will idle smooth as silk with MA mounts,
Lol.

 

[c20elephant]

Stock engine with 60,000 miles, I'll try 710 RPM to start...:thumb:

 

[Harbin_22]

Use the DVT tool in the scan tool and adjust the idle around to see if it helps instead of flashing it a bunch of times

 

[DAVe3283]

Use the DVT tool in the scan tool and adjust the idle around to see if it helps instead of flashing it a bunch of times

This. And don't be afraid to go a hair below 680 as well.

Though I did find a weird condition where setting the idle RPM to 600 caused it to not complete one of the emissions readiness tests due to stupid hard-coded values in the ECU. This was on a LB7 though.

 

[c20elephant]

Use the DVT tool in the scan tool and adjust the idle around to see if it helps instead of flashing it a bunch of times

I don't use the laptop/V2 combination very often and have never used the DVT tool, could you give me a quick rundown how to.? I have a stand built for it just never use it. I have an old laptop and I installed Windows 7 on it and keep it for truck use only.
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[Harbin_22]

Open the scan tool, connect to your vehicle with the little green button icon on the left. Once connected, there are tabs along the top of the screen. Look for the one that says DVT. Click that tab and it will open the DVT tool options. Look for the button towards the upper right of that screen that says activate. Click it. There is another tab on the left side of the screen that says "control". Click it. One option will be idle speed. Check the box next to it and slide the bar back and forth to turn it up or down.

 

[WVRigrat05]

Can you do this with a locked autocal efi download?

 

[TheBac]

Switch to bolted stock mounts if you really need to have the extra holding power in them. Yeah, Im being Capt Obvious.

IMO, 600rpm idle is not a good idea, either.
Boy, did that low an idle rattle the absolute living crap out of my truck when I tried Dave's tune. Went back to my old tuning and no issue.

 

[Harbin_22]

Can you do this with a locked autocal efi download?

Don't have a clue how autocal and logging works. It's in the Scan tool software

 

[c20elephant]

Switch to bolted stock mounts if you really need to have the extra holding power in them. Yeah, Im being Capt Obvious.

IMO, 600rpm idle is not a good idea, either.
Boy, did that low an idle rattle the absolute living crap out of my truck when I tried Dave's tune. Went back to my old tuning and no issue.

I installed the Merchant Engine Mounts awhile back to stiffen the front frame section, truck handles much better and the front end donkey dance is much less, Viking shocks maybe someday.....

I will check my problem exhaust system, the front pipe where I have my resonator connection might be hitting the torsion bar cross member, again.... The vibration/noise sounded a lot different this time and changes drastically from summer to winter temperatures (only 2 seasons here, summer/winter) that's why I was considering changing the idle, might be time to break out the rosebud torchhead for the exhaust and change the idle...

Harbin_22, thanks for the simple explanation for the DVT controls...:thumb:

 

[hondarider552]

Lol engine mounts don't do squat. Pick up the lower crossmember that Mike L has from me that is a direct replacement therapy and you will see what really makes the bottom end of the frame stronger.

I ran my race truck down to like 550rpm idle. As long as it didn't drop below 15psi hot idle I don't care what rpm it idles at. Quieted the truck down.

 

[c20elephant]

Drives and rides much different, so what you're saying Brian is the polyurethane bushings in the Merchant mounts do not tie the frame sections together via the engine and makes no difference compared to the stock rubber bouncing blocks in the OEM mounts.? We used to run solid mounts back when BeeLine Dragway was operational and it made a lot of difference.

Never seen a lower crossmember, have a picture of it.?

 

[hondarider552]

Mike L has them. Forget who made them. Been dang near 10 years.

I bet if someone swapped the mounts overnight when you were eeping you wouldn't have had the same views lol. More like the "ah crap, I busted my as for what gain"
US if your trying to make the frame stronger via trying go reinforce the block, your doing it wrong. That crossmember replaces the one under the oil pan. Believe Tony Burkhart has them too can't be sure.

 

[DAVe3283]

Switch to bolted stock mounts if you really need to have the extra holding power in them. Yeah, Im being Capt Obvious.

IMO, 600rpm idle is not a good idea, either.
Boy, did that low an idle rattle the absolute living crap out of my truck when I tried Dave's tune. Went back to my old tuning and no issue.

Funny, that idled smooth and quiet for me, but that was on the stock motor mounts in the original application. Different chassis must have different resonance.

Drives and rides much different, so what you're saying Brian is the polyurethane bushings in the Merchant mounts do not tie the frame sections together via the engine and makes no difference compared to the stock rubber bouncing blocks in the OEM mounts.? Never seen a lower crossmember, have a picture of it.?

It might help tie things together, but ask yourself, do you really want your engine to become a stressed member of the frame? What would it do to the block putting stress through it that was never intended to go into the motor? Luckily, I don't think the MA mounts transmit that much force into the motor if/when the frame flexes.

 

[c20elephant]

Mike L has them. Forget who made them. Been dang near 10 years.

I bet if someone swapped the mounts overnight when you were eeping you wouldn't have had the same views lol. More like the "ah crap, I busted my as for what gain"
US if your trying to make the frame stronger via trying go reinforce the block, your doing it wrong. That crossmember replaces the one under the oil pan. Believe Tony Burkhart has them too can't be sure.

If you have that much energy go for it, the mounts did what I wanted, no regrets. Aren't the 4x4's IFS substantially different than the 2x4's with just the strap connection/crossmember at the LCA.?

Funny, that idled smooth and quiet for me, but that was on the stock motor mounts in the original application. Different chassis must have different resonance.

It might help tie things together, but ask yourself, do you really want your engine to become a stressed member of the frame? What would it do to the block putting stress through it that was never intended to go into the motor? Luckily, I don't think the MA mounts transmit that much force into the motor if/when the frame flexes.

I don't beat on the truck, it'll never see offroad being a 2x4 and will never go down the 1/4 mile...

 

[hondarider552]

If you have that much energy go for it, the mounts did what I wanted, no regrets. Aren't the 4x4's IFS substantially different than the 2x4's with just the strap connection/crossmember at the LCA.?



I don't beat on the truck, it'll never see offroad being a 2x4 and will never go down the 1/4 mile...

Front end is identical.

 

[c20elephant]

Front end is identical.

I'm referring to how the IFS is mounted to the frame, IRRC the 4x4's have one or two additional holes in the frame for support of the IFS. Yes, the spindles, LCA's, UCA's are the same.

Mike L has them. Forget who made them. Been dang near 10 years.

I bet if someone swapped the mounts overnight when you were eeping you wouldn't have had the same views lol. More like the "ah crap, I busted my as for what gain"
US if your trying to make the frame stronger via trying go reinforce the block, your doing it wrong. That crossmember replaces the one under the oil pan. Believe Tony Burkhart has them too can't be sure.

Is this the part you're referring to, it will not fit the 2x4
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[hondarider552]

Don't see how it won't fit. You don't have a differential to get in the way of things.

 

[THEFERMANATOR]

Switch to bolted stock mounts if you really need to have the extra holding power in them. Yeah, Im being Capt Obvious.

IMO, 600rpm idle is not a good idea, either.
Boy, did that low an idle rattle the absolute living crap out of my truck when I tried Dave's tune. Went back to my old tuning and no issue.

600 is the stock idle speed for 01, so why is it bad? GM changed it because of the nasty harmonics you encounter in the 640-650 range. Mine is still at 600, and is fine, but you do notice the harmonics just off idle. As to polymounts, they're going to give you more vibrations at idle, just thenature of the beast. And the ladt thing in the world one would want to do is use the engine block to stiffen the frame. The engine is already under extreme forces justfrom running, let alone if you add more to it. Poly mounts stiffen things up, yes, but it comes at a cost. I'll never run them again.