Rough idle in drive but only when sitting at a stoplight

[Marlin]

If it is pronounced through the brakes, I too would tend to lean toward ABS, but then the light would be on. The fuse is under the hood, clearly labeled on the fuse diagram. That will have no effect on your vehicle other than no ABS and light on in the dash display. I pulled my fuse long ago...

[vt_maverick]

Which fuse is it? Looks like there are 2, one a 20A and the other a 40A:

[tom4bren]

If it is pronounced through the brakes, I too would tend to lean toward ABS, but then the light would be on. The fuse is under the hood, clearly labeled on the fuse diagram. That will have no effect on your vehicle other than no ABS and light on in the dash display. I pulled my fuse long ago...

I was just thinking that if the ABS is 'confused' it may try pulsing the system whilst at a full stop, causing the vibration. It's a long shot but easy to check out by just pulling the fuse.

[RickOKC]

Hmmm, I wonder if this was my mystery sound. Soon after I got my VX, I noticed a very low frequency sound/vibration when I was in gear with the brakes on. In fact, it reminded me of the sound brakes can make sometimes when you creep forward. Maybe it was the last dying gasp of the ABS. It took a few days but the mystery sound eventually disappeared.

[vt_maverick]

It's a long shot but easy to check out by just pulling the fuse.

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

[circmand]

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

pull them both or pull one then the other either way it tests the proposed problem. Have you given considerationof stopping by a brake place and letting someone wo can see and hear the problem make a suggestion? After all diagnosis by description is quite difficult . BTW dont rely on not seeing the light it may be burnt out.

[etlsport]

You can also try pulling the e brake while topped and releasing the regular brakes to see if that makes a difference. mine was plenty strong to hold me in place. Alas didn't do a thing for my rough idle though

[vt_maverick]

Just trying to do a little pre-diagnosis so I can determine if I need to start working on finding parts. I'm really not a big fan of being out of a car for a day only to hear that they couldn't get the part they need so I've got to go back, order it through Isuzu, then repeat the process again next week. The research paid off with the neutral safety switch issue, so I was just thinking the same way here.

We're going to be out of town for the holiday but I believe my garage is open Friday. I might drop off the VX Wednesday afternoon and let them keep it through Saturday since it doesn't impact my commute or anything.

[vt_maverick]

also turn off your climate control.. mine behaves exactly like this any time the AC is switched on (heating or cooling), whether the compressor is on or not.

i was actually just starting to wonder about the brake booster after reading your post the first time (couldnt respond from work) so thats my next step to curing the problem.

You know I tried turning off climate control on the way home, and it did seem to help. I'm going to test that theory more tomorrow morning before I pull the fuses. Figure I can get a baseline for climate control off but ABS (fuse anyway) on, then test climate on/off with the fuse pulled.

If it is HVAC related, anybody got a suggestion? It's a vacuum issue then I guess?

[vt_maverick]

what does it matter... pull them both or pull one then the other either way it tests the proposed problem.

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.

[Marlin]

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.

ABS is a stand alone system and not part of the brakes in the manner your thinking. Feel free to pull the ABS fuses, no worries, your brakes will still work just fine. Smiley and I have have been that way for a long time, and I am sure that there are others. If you don't like it, or it doesn't help, just put em back in.

[Ldub]

Happens from the moment I start her up until I get wherever I'm going. Seems to be something driven by the "tug of war" between the drivetrain and brake system.

Same symptom here...been that way since I bought her off the used car lot...

Thought I had a handle on it once when I diddled with the trans mount, but no bueno'.

Finally resigned myself to the fact that it's just a "normal" VX noise...if it's anything that's gonna break, that's when I'll fix it...

[VX KAT]

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.

[deermagnet]

I just Googled 'rough idle in drive when stopped'. There's a ton of stuff for this problem. It's mostly just shots in the dark, but motor and tranny mounts are frequently mentioned. Give Google a try and see if some of the possible causes might be applicable to your VX.

Mark

[vt_maverick]

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.

Could very well be. Maybe I'll crawl under the VX and take a picture of the top (inward facing) side of the plates to see if there's any shavings or scratch marks. That's a pretty scary thought. Maybe if I drop it off at the mechanic tomorrow afternoon I'll get an answer for you guys.

And thanks for the reassurances Marlin and Dub, I'll pull those fuses tomorrow and see what happens.