AAN: transmission vibration, or misfire?

Started by zeitgeist, July 23, 2012, 09:49:04 PM

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zeitgeist

Edit: Mystery solved, hanger bearing at fault apparently

UrS6 6 speed

slowburn

I'm no genius,but hitting anything in your car with enough force to buckle a wheel on the open road cannot be a good thing, and is probably a good place to start finding the root of the problem.I would lean towards the impact having bent something in the tranny.....
99 B5 S4 Avant
85 coupe quattro
72 fiat 124 coupe
97 corolla wagon

zeitgeist

Giltrap's transmission specialists took it for a drive and said 100% not transmission (which I found hard to swallow, but there you go).

So I guess I'm looking engine mounts, spark plugs, coils.
UrS6 6 speed

zeitgeist

Misfire ish- symptoms, after running for about 30 mins the idle gets more lumpy. Yet still removing seperate injector plugs makes it run worse. No codes thrown from the engine or transmission. Engine and trans test as running at acceptable temperatures.

'Uses a bit of fuel, but they use heaps anyway so...

Shudders most in first gear, barely at all in other gears, vibration in 3rd and 4th 'usually' not always. Foot down in 2nd 3rd 4th does not achieve same shudder as in first gear. As always, gears change perfectly fast and smoothly.

Tomorrow I will test coolant temp sensor G62. Then shoot myself.

Stab in the dark would say inspect driveshaft, which may still be shot as well; but nothing to do with the lumpy idle when hot?

C'mon guys, no one wants a challenge? ideas?
UrS6 6 speed

00quattro00

Where abouts are you? You can try some bits from my aan
Land Rover Discovery 300tdi
Land Rover 110 4bd1t

zeitgeist

I'm in Takapuna, are you Auckland too?

That would be off the hook handy... I would need to make a plan of what to try

Edit: Damn, i see you are Hastings
UrS6 6 speed

Lomax

Im not sure if I can be much help, but Im in Auckland (quit far tho - Manurewa) so we could meet up or smtin
1994 Audi UrS6 6-speed manual
2002 Audi Allroad 2.7T
1990 Mk2 Golf, 1994 UrS4, 1990 Audi 80 2.0E Manual, 1990 Audi 80 2.0E donor, 1991 Audi 90 2.3E, 1985 Toyota Corona

zeitgeist

Hey that's great thanks, I'll be in touch once I make a clear plan with desired outcomes etc :)
UrS6 6 speed

zeitgeist

high gear vibration eliminated (fingers crossed) on removing, cleaning and tightly refitting bypass valve.

Issue with takeoff  in-gear shudder remains, surely related to 0.6/7 bar gauge pressure reading at idle, I remember my old white sedan being 0.4. Intake manifold gasket? There isnt anything else I can think of apart from  BPV vacuum line which appears fine. Can't hear any hissing at any speeds and idle is stable. When I first got the car there was a squeal or hiss once or twice on boost, but I am now putting that down to BPV (710A) being old dirty and misaligned
UrS6 6 speed

BB

The best place to get your Audi fixed is at Euroline.
Rob has a very very good mechanic who solved a whole heap of issues that were too hard for me on a S6 for a good price.
They have all the parts they need either new or second hand on site and they have the experience and tools that not many have.
They replaced the fuel pump and found hidden broken wires and all sorts of stuff.
I was well impressed at the price as well as he ended up spending many many hours.
The end is nigh, but the end of what is the question?

zeitgeist

Hey cheers for that, good to know, so far it's been near impossible to get expertise on these cars
UrS6 6 speed

volcanoblack

I agree with the trans shop that hitting a bump is not likely to cause internal trans damage. More likely suspension damage or driveline (CV joint) - which you have checked. (?)

Also agree Audi Gods are not happy. Hard bump could = loose wire somewhere?

Why not replace the BPV with a 710N? The 710A diaphragm is much flimsier. Since cleaning this solved some of your problem.

Injector #1 fault code - maybe this injector is not working properly even though it seems to be clicking away. (easy to check with parts swap as volunteered from other members here).

I know this will sound off the wall - but you did change the trans fluid before this all started happening right? I don't know about the DEX3 fluid you put in but I know we had a discussion about how much fluid to use.

Checking the fluid level is near impossible with your situation (no dipstick and no check level plug hole).

So my suggestion - unless you find another reason for the vibration - is to drain the fluid out of the trans and have the shop measure it. Check this against the recommended starting point for filling the trans after service, "add approx. 2.7 liters of ATF".

If the amount of fluid that comes out is vastly different, refill the trans making any adjustment you want to get closer to the 2.7 litres.

volcanoblack

Here's a post over on QuattroWorld with what can go wrong in suspension if hitting something hard enough.

http://forums.quattroworld.com/s4s6/msgs/198829.phtml

cheers.


zeitgeist

Interesting points, now that I've had the trans shop assess it as 100% not the tranny, I have been able to accept that it is OK. It after all changes smoothly and quickly.

My next port of call is misfire due to vacuum leak between the throttle body and intake ports. Being as it seems to be more rough when hot after driving a while, I'm leaning towards thermal expansion increasing the size of a vacuum leak. It's idle manifold pressure is .6-.7 bar which is so different to the .4 that the white sedan used to read.
UrS6 6 speed

Lomax

my idle manifold pressure is also around 0.7 bar, but then I think i might have a leak somewhere too...

with the thermal expansion, shouldnt that decrease the leak? since the material is expanding?
1994 Audi UrS6 6-speed manual
2002 Audi Allroad 2.7T
1990 Mk2 Golf, 1994 UrS4, 1990 Audi 80 2.0E Manual, 1990 Audi 80 2.0E donor, 1991 Audi 90 2.3E, 1985 Toyota Corona

zeitgeist

Good call, depends where it is I guess. I was sorta basing that statement on the fact that the misfire is larger when hot. Mind you, this could be fuelling-related.
UrS6 6 speed

user2154

#16
tbh, a misfire is pretty obvious when it happens. If you can't diagnose it (misfire vs "vibration"), then you should take it to a mechanic, they will be able to tell you pretty quickly if it is a misfire or not.

I had a misfire (while driving) after fooling around with some stuff under the hood, can't remember what it was exactly but it may have been maf cleaning...

to cut a long story short.. After a lot of trouble-shooting, I started the car, unplugged the idle control valve while the car was running, and plugged it back in.

The misfire disappeared. I suspect a loose connection to the idle control valve was my problem..

zeitgeist

Mmm yeah not too keen to take it to mechanics really as it so far does what I bout it for, gets me from a to b until I get a decent car, and the bill would likely eat well into the actual value of the car.

You are right re: misfire, it did get a misfire the other day on one cylinder and it was very very obvious. So no misfire.

Im leaning towards driveshaft centre support bearing and univeersal and or the driveshaft CV's. s**t. If I had a hoist I'd get the exhaust off and have a look myself, just no time to f**k around under a car on axle stands these days. I may when I have time book it into a local mechanic to remove the exhaust etc for inspection.

Does anyone have driveshaft advice if it is this? I am aware that it is well documented online, but all refer to dead links of rebuild kits, etc etc. anything NZ appropriate?

Cheers
UrS6 6 speed

00quattro00

Land Rover Discovery 300tdi
Land Rover 110 4bd1t

zeitgeist

#19
edit: Just saw the post above get posted as I was typing. this is not a reply, although it does contain the answer to above question.

Booked in for driveshaft bearing/joint inspection this wednesday when it gets a new warrant.

FYI (as I may be selling this soon to aid purchase of a smaller car)

-There is no misfire, I traced the marginal lumpyness to moisture at the connection where the coil to spark plug connector meets the coil.
-there is no transmission problem, as checked by specialist.
-2004 model alloys fitted as replacement to those stated earlier as buckled

On the plus side, I've done a bunch of Ruapehu trips recently and she does 30- 31 MPG every time!! Very impressed.

Buy it with a new warrant if anyone likes, $3000ish. It is a 1994 S4 Avant in very dark purply blue.
UrS6 6 speed