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Idle Vibration


Guest hkgnyc911

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Guest hkgnyc911

Hi, I have a '98 TT Auto (Stock) and currently experiencing some vibration problems when the car idles. This started happening after the battery after not using the car enough. There is no vibration during normal driving or when it is shifted on neutral, but only occurs when the car is on 'drive' and not moving, or when I apply the brakes and approaching idle (i.e. at a stop light). It doesn't seem to make it difference whether the A/C is on or not.

 

I brought it to a Toyota service center and after testing they say it is due to the battery dying and the idle needs to re-adjust itself. They say that it will be adjusted properly and the vibration will be gone after driving it more particularly under highway conditions when higher shifts happen. The vibration seems to get better after immediately after I drive it at high speeds, but is very noticeable and annoying (constant vibration at a very low hum) especially during in-city driving. I've had this car since it was new so I knew the vibration doesn't feel right.

 

What could the problem possibly be? The battery has died several times before but this never occurred. I thought it might be an engine mount problem, but the technician says it isn't. Thanks for your help and insights in advance.

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An inline six engine is perfectly balanced so any vibration you feel is going to be down to idle stability. Running lightened flywheels / changing TV dampers or a fooked IACV could all be possible causes.

 

Redex? It's not a Maestro, you know ;)

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Redex? It's not a Maestro, you know ;)

 

So that wasn't the best idea then?! What about a tune up, is that likely to help?

 

Digsy, dunno what the acronyms mean, I'm a newbie as you can see (to the forum, not to MKIV's since I've had 5). Whats the best course of action?

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i have this exact same problem & have so far done the following to find out the cause, with no joy as yet:

 

- fitted an improved earthing kit, to ensure that the earth connection is not to blame

-removed my amp/sub to ensure that this isn't draining the power

- had my engine/gearbox mounts inspected by Toyota

- swapped my front bumper & removed the front reinforcement bar to find out whether this was what was vibrating

 

my next plans are to try these:

 

- clean the IACV, as i have also noticed recently that it will ever so slightly drops the revs a little lower when coming to a standstill and then they pop back up again to where they should be & every now and then the car will have a lower idle from cold & once warm

- get a new set of plugs (they're coming up to being due anyway)

 

I have also noticed that mine only seems to do this around the 700 RPM mark. if it's slightly higher or lower, there isn't the same obvious vibration

 

i've taken to popping it into Neutral by habit now whenever i'm at a junction!

 

interested in anyone else's investigations & results

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i've taken to popping it into Neutral by habit now whenever i'm at a junction!

 

Me too!

 

Theres more to this than meets the eye. I've just moved onto high octane (for the first time ever, despite being on Supra no. 5!!!) and the vibrations have significanty reduced and seem a bit itermittant! I'm starting to think it might be something to put up with although the IACV cleanup sounds like a good idea.

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There is a procedure you can go through to make your ECU relearn its maps after you change fuel type. I don't know it by haert but a search should turn it up.

 

In case you hadn't already sussed it, IACV stands for Idle Air Control Valve so that is the thing above all that will control your idle stability on a stock car - although I think there is a manual idle adjust screw as well. What does your car actually idle at? Does it seem to be "hunting" for an idle point (AC off)?

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There is a procedure you can go through to make your ECU relearn its maps after you change fuel type. I don't know it by haert but a search should turn it up.

 

In case you hadn't already sussed it, IACV stands for Idle Air Control Valve so that is the thing above all that will control your idle stability on a stock car - although I think there is a manual idle adjust screw as well. What does your car actually idle at? Does it seem to be "hunting" for an idle point (AC off)?

 

if you disconnect the negative terminal on the battery i believe this will reset the ECU so that your fuel maps will start again, but someone may correct me on this

 

my car warm idles at approx 700 RPM, no hunting

 

on rare occasions when it does this thing where it idles lower when cold & warm it idles more like 500 RPM and there is no vibration at this RPM

 

it's almost like there's a slight miss, which is why i'm keen to change the plugs soon, in case it's the gap that's wrong or something which it doesn't like at that particular point on the rev range

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No, its bang on 650 in drive with footbreak on, and about 700 in neutral. No hunting. Cant really see much difference on rev counter between when it is and isnt vibrating. Maybe I'm worrying over nothing.

 

Deffo better since the high octane. Dunno if I'm kidding myself but it does seem nippier too! Its well tighter than the 93 NA I was running up until 2 Sundays back! :cool:

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Today I noticed the vibration is worse with the front lamps on. So it must be connected to the electrics. Move over IACV!!!!!

 

Gonna get a tune up next week cant hurt.

 

ok, so have you done any modifications that intervene with electrics at all? i thought this originally & took the sub/amp out the other week to see if it made any difference, which it didn't.

 

i replaced the battery with the recommended Halfords one as soon as i got the car as the one it came with was dead

 

i've also fitted a Blitz turbo timer & a couple of mechanical gauges (wired up so they light up with the headlights etc)

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Drive belt tensioner?....if you have an auto.

 

what different effects would this have if you were in Park or Neutral?

 

and mine only seems to be at around 700 RPM, any lower it's fine - anyone else have this same pattern?

 

i'm still thinking plugs at the moment :rolleyes:

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what different effects would this have if you were in Park or Neutral?

 

and mine only seems to be at around 700 RPM, any lower it's fine - anyone else have this same pattern?

 

i'm still thinking plugs at the moment :rolleyes:

 

Not sure, but I had a very similar thing which drove me up the wall. Whilst running at totbiv Mark from pheonix diagnosed the problem within 5 minutes.

 

I changed the part a few days later everything was sweet again :)

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Not sure, but I had a very similar thing which drove me up the wall. Whilst running at totbiv Mark from pheonix diagnosed the problem within 5 minutes.

 

I changed the part a few days later everything was sweet again :)

 

the drive belt tensioner?

 

cheers mate

 

i'll mention it to my mechanic man when i see him next :)

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