406oc.co.uk

Looking for ideas folks.

For some time now, I've noticed the engine shaking the car on tickover. Trouble is, it comes and goes. It's usually OK when starting from cold and only slightly noticeable when up to full temperature, but If I stop at a junction when it's only been running a few minutes it's really quite severe. If you take up the drive, without moving the car it smoothes out.

Now I've checked and double-checked the engine / gearbox mountings and can't find a problem. I can't rock the engine in any direction significantly by hand. No clonks or other noises, (except a front-suspension-sounding rattle over bumps, that I can't find either, come to think of it).

Was thinking DMF far a while, but it doesn't make any other noises and clucth operation is fine.

Could I have a faulty injector? (no EML or warning messages tho).

Might I have lost the drive to the balancer shafts?

This has been a gradually increasing problem - going from barely perceptable say 6 months ago, to bl00dy annoying now.

There was a guy on here ages and ages ago who had a failing DMF and reported this kinda wobble on idle as he concluded that in it's last knockings the assembly would rotate out-of-balance and eventually started hitting the bell housing

Not saying yours is the same though, are you really sure the engine mounts are fine?

Wouldn't you be able to 'see' a faulty injector vie the diag socket?

Welly wrote: are you really sure the engine mounts are fine?

Well, I can't think of any other way of checking them. (Plus I can't imagine an intermittently dodgy mounting).

Wouldn't you be able to 'see' a faulty injector vie the diag socket? [/quote]

TBH I haven't looked, but I'm guessing that if there's no EML and no Bong! / MFD message, the ecu's happy.

I have exactly this wobbling. As far as I know the 90s don't have a DMF. I mentioned the wobbling to my mechanic and suggested engine mounts, but he said the mounts were OK and "yeah, they do wobble quite a bit".

Mine wobbles a bit when it's cold. So does the car

am i missing somthing here ?

all those moving parts inside an engine ? its bound to "wobble" isnt it ?

Mine wobles abit Ahem imean the engine,
when its cold ipresume the fuel filter is long over due to be changed,
once it run for 2mins its smooth,

Appreciate those words of comfort guys, but mine never used to wobble at all.

Another crazy thought: the first, just detectable wobble started when I removed the FAP element. It seemed to get worse when the CAT got evicted too. For a while I had myself convinced the lack of back pressure in the exhaust removed a form of 'damping' which had previously evened things out. Always sounded a bit far-fetched and it doesn't explain the more recent deterioration, (13k since the CAT got re-homed).

I'm coming round to thinking it's a leaky injector, dribbling a bit of fuel in when it shouldn't.
I will try changing the fuel filter first and filling the bowl up with injector cleaner - I've never used any before, what would you use & how much should you pay?

Failing that, I guess it's like tracing a misfire on a petrol?
Can you safely run it at tickover with an injector disconnected, to work out which cylinder's playing up, or would this fry the ecu?

Pretty sure it can't be mechanical as it pulls perfectly & evenly at all but the tiniest throttle openings.

Didn't someone say the injectors run in a cascade off each other, so if you disconnect one the engine won't run?

Duly noted Steve, thanks - I'll do some more checking before I risk anything.

Got some Millers diesel treatment and a new fuel filter, then got absolutely drowned taking the dogs out, so sod it! It can wait for another day.

Theres a thread on the turbo deisel forum
dont know if anyone from here goes on there and as read it but theres mention of starting a deisel engine up on pure injector/fuel cleaner "by" by- passing the fuel pipes and letting the car run off the stuff out of a container,

iwas thinking of giving it a try but wouid this kill a hdi,

I'm sure jasper recommends at least dosing the filter bowl, (which was what I intended).

I imagine it'll get through 50 ml or so pretty quickly and be back to a regular diet of ULSD before the ecu etc can object in the customary Teutonic manner and the BSI can translate, 'Achtung! das dieselöl ist nicht gut!' into 'Antipollution Fault'

Fill the whole filter housing with the injection cleaner and put the rest in the tank.

I've done this a hundred times without any problem and had nice clean emissions afterwards.

Well, I finally tried the injector cleaner today - made no difference at all.

Did a bit more checking & noted the following:
1. Looking at the engine when idling, there is more movement at the gearbox end of the assembly.
2. Looking directly downwards on the gearbox mounting, the bracket moves about 5 mm either side of it's central position. (Is this excessive)?
3. There is a bit of a rattle, particularly from below, seems loudest near the bellhousing.
4. Wobble is at its worst a bit faster than idle, say about 1000 RPM, once it gets above say 1200 RPM, it smoothes out completely.
5. With the 136bhp/235lbft map loaded there is no driveline vibration under acceleration, (but lots with the 178bhp/295lbft map).
6. Mpg seems worse on the 'standard' map.

More confused than ever now.

Any ideas for eliminating something / narrowing it down?