Rough idle in drive but only when sitting at a stoplight

[Ldub]

Hmmmm, vibration/growling sound.....could it be what I'm having??...where something along the exhaust system is touching the Kilby skid plates? Mine rattles and growls when in Drive, and brakes applied at a stop.

It developed during my road trip. Jack and Dub both pushed/pulled on the muffler and some other exhaust pipes and it stopped. *Of course it's hot so be careful when you grab around there.*

I haven't had it evaluated yet.

Been under there with my own eyeballs, your problem is that the pas side (IIRC) exhaust makes contact with the kirbys...maybe a few washers between the frame & the skid plates would work?

[Marlin]

You said it was a grinding rubbing sound you could feel through the brakes. That is not the same as a rattle/vibration. There are so many heat shields on our exhaust, I have methodically removed them as they start to rattle. I have one left, and I had to remove the one above the transfer case as well. No more rattles
Mine only rattle when the brakes are on and I am sitting. That is your problem...a fast tink tink tink sound. Very annoying, but doesn't hurt anything, put it in neutral or start moving and it goes away.

[vt_maverick]

Update... I shut off the A/C on the way to work this morning and had no problems. Flipped it on at the stoplight just before our parking lot and the sound came right back. So does that change the diagnosis? I haven't pulled the ABS fuse yet, probably do that on the way home.

[tom4bren]

That's great, but which of the two fuses is it (see question above)?

"Quit changin the subject and answer the fookin question"

My favorite quote from Braveheart - ya gotta say it with a heavy Scottish accent.

[Bob Barker]

Update... I shut off the A/C on the way to work this morning and had no problems. Flipped it on at the stoplight just before our parking lot and the sound came right back. So does that change the diagnosis? I haven't pulled the ABS fuse yet, probably do that on the way home.

That makes me think it's a vibration somewhere. If the load on the engine changes and makes the noise come and go then I immediately think vibration. It's still a free check to pull the ABS fuses and then test for vibrations with/without a/c.

[circmand]

It matters (to me at least) because I don't understand what the ramifications of pulling them independently or together would be under normal circumstances, let alone when something is wrong. Disabling parts of your brake system just to see what happens without understanding what you're doing sounds like a recipe for disaster to me.

while the systems are seperate I did not mean to suggest pull them and go out on the road drive just pull then a brief driveway idle test to see if the problems still exists.

by the way have you greased your drive train lately. Not sure if it would cause this but it might.

[vt_maverick]

UPDATE: While the shop was trying to find the electrical gremlins in my fog lamp, I asked them to also track down the source of the vibration. Apparently it's being caused by the exhaust pipe rattling against the Kilby skid plate, so they checked all the hangers and found that everything was tucked up tight like it should be. They told me that there's like a 1mm clearance between the pipe and the plate at off/idle/park, but that the slight vibration associated with being in drive is causing it to contact. It's probably happening at speed too, but it's more noticeable when you're sitting still. They suggested cutting a hole in the plate to eliminate the rub, which I thought was a good idea given this problem and the concerns that Sue, I, and others have had with the potential for significant heat build-up with the Kilby plates. I'll take a pic when I get it back so you guys can see what was done.

Can't wait to pick it up to see how much better it drives/stops!

[Marlin]

Didn't need a mechanic to figure that out, see post #32...You gotta get down on the ground and get dirty, get to know your VX, be at one with her. Stop paying a stranger to feel her up on simple things

[VX KAT]

UPDATE: Apparently it's being caused by the exhaust pipe rattling against the Kilby skid plate, so they checked all the hangers and found that everything was tucked up tight like it should be. They told me that there's like a 1mm clearance between the pipe and the plate at off/idle/park, but that the slight vibration associated with being in drive is causing it to contact. It's probably happening at speed too, but it's more noticeable when you're sitting still. They suggested cutting a hole in the plate to eliminate the rub, which I thought was a good idea given this problem and the concerns that Sue, I, and others have had with the potential for significant heat build-up with the Kilby plates. I'll take a pic when I get it back so you guys can see what was done.

Can't wait to pick it up to see how much better it drives/stops!

I just had mine finally addressed last week....exhaust touching the Kilby's...so he tightened up the hanger some how a small amount. Said it will eventually return as the hanger loosens, but you don't want to put the exhaust up any higher, closer to undercarriage. I'm fine with that. Will address any cutting/venting issues later. Jack, Dub and RallyDude all suggested a backward facing cupped shape chunk of metal be welded over any hole we cut.

[vt_maverick]

Didn't need a mechanic to figure that out, see post #32...You gotta get down on the ground and get dirty, get to know your VX, be at one with her. Stop paying a stranger to feel her up on simple things

Actually I'm paying them to fix the problem since I don't have the tools to make the cuts myself. It's also not exactly easy to reinstall the Kilby plates by yourself and without it up on a lift - when Tom and I installed them we had to take turns holding the plates while the other bolted them down because they were so heavy.

Oil changes, bulbs, general troubleshooting, no problem.

[Marlin]

Actually I'm paying them to fix the problem since I don't have the tools to make the cuts myself. It's also not exactly easy to reinstall the Kilby plates by yourself and without it up on a lift - when Tom and I installed them we had to take turns holding the plates while the other bolted them down because they were so heavy.

Oil changes, bulbs, general troubleshooting, no problem.

I can imagine they are fairly bulky, its a PITA to get the front diff in as well. But a floor jack and 2x4 would make the plates no problem. As for cutting the steel. That is easy, 10 bucks at Harbor Freight gets you an angle grinder, then you can cut whatever you want Bwa ha ha ha ha ha ha ha ha ha!!!!! After that, there is no going back....come to the dark side.

[vt_maverick]

Well got her back a few hours ago and the problem is definitely fixed. Long term I'll need to figure out the patch solution mentioned above, but for now I'm very happy to have the smooth ride back.